yasin commented.pdf

MEKELLE UNIVERSITY
COLLEGE OF NATURAL AND COMPUTATIONAL SCIENCES
SCHOOL OF EARTH SCIENCES
DEPARTMENT OF GEOLOGY
HYDROGEOLOGY STREAM
ASSESSMENT OF WATER WELL DRILLING CHALLENGES IN NORTHERN AFAR, ETHIOPIA
A THESIS SUBMITTED TO MEKELLE UNIVERSITY, SCHOOL OF EARTH SCIENCES,
DEPARTMENT OF GEOLOGY IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR
DEGREE OF MASTER OF SCIENCE IN HYDROGEOLOGY
Student Name: Yasin Ali
Advisors Name: Fethangest W/mairem (PhD)
Co-Advisors Name: Abdlewasie (PhD)
June, 2022
Mekelle
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Declaration of Originality
I hereby declare that, the thesis work entitled “Assessment of Water Well Drilling
Challenges in Northern Afar, Ethiopia” is my original work prepared for the partial
fulfillment of the Degree of Master of Science in Hydrogeology, Department of Geology,
Addis Ababa Science and Technology University under supervision of the down listed
advisors during 2022?. I further declare that this work has not been presented or submitted
to any other university or institution for the award of any degree or diploma. All sources
and materials used for the thesis have been duly acknowledged.
Author Signature Date
Yasin Ali
_________________________________________________________________
Advisors Signature Date
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Approval Page
This is to certify that the thesis prepared by Mr. Yasin Ali entitled “Assessment of Water
Well Drilling Challenges in Northern Afar, Ethiopia” and submitted as partial
fulfillment for the award of the degree of master of science in Hydrogeology complies
with the regulation of the university and meets the accepted standards with respect to
originality, contents and quality.
Signed by the Examining Board
Advisor Signature Date
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________ External Examiner Signature
Date
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Internal Examiner Signature Date
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Chairperson Signature Date
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DGC Chairperson Signature Date
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College Dean / Associate Dean for GP Signature Date
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Abstract
The Afar Depression is one of the most impressive places in east Africa, which attracts
the attention of many scientists. The general tectonic structure and the geological history
of the area made it one of the most interesting places in the world for different approaches
of geosciences. On the contrary, the general weather condition (very hostile) creates
difficulties for many researchers to reach the area.
In addition to its unique geological character, the Afar depression becomes the a target
area for its potential of hosting different economically valuable minerals deposits.to make
this wonder full area comfortable for geoscientists, visitors, investors and the community
that vulnerable to water shortage and recurrent drought, climate-resilient potable water
source and supply is needed.
Drilling of wells which are one of the common practices to supplying the urban and rural
community with safe water. Problems occurring during drilling can be avoided sometimes
but, on other occasions, they are beyond the drilling crew’s control; the causes are
numerous and their effects are undesirable. This paper evaluates the drilling challenges
most frequently encountered with associated 95 wells drilled in the northern zone of afar,
as well as identifying their causes and effects, and finally suggests recommendations
aimed to increase drilling success and reducing its adverse impact of it. Data from 95
wells in the northern zone of Afar were used for comparison. The collected data were
filled in a format: the localities of the wells (woreda) where the drilling problem was
encountered, at what depth of the wells drilling problems were encountered, in which
geological formation the drilling problems were encountered, Drilling methodology that
were applied on the wells when drilled, Drilling institutions who were drilled the wells
and the assumed causes that were responsible for the encountered problems. The analyzed
data were obtained from supervision of actively drilling wells, well completion reports,
drilling logs, iInterviews and focal group discussion.
Because of the poor technical performances of drillers and the challenging geological
conditions, drilling wells in northern zone of Afar faced many drilling problems. Stacking
of tools was major drilling problem experienced, these problems occurred following other
drilling problems like collapsing, a dropdown of upper boulders and lost circulation

resulting in further problems of stuck pipe and drill string failure. Alluvial deposit was
the most difficult formation which most drilling problems were occurred. Drilling
problems due to the formation increased with depth, with major challenges experienced
at depths of about 30-90 m, the drilling institution which most wells that were drilling
problems was private drilling companies by DTH drilling mechanism. It was concluded
that to minimize the drilling problems in the northern zone of Afar ensuring competent
professionals are selected to carry out drilling works. It is not possible to totally eliminate
drilling problems, but minimizing it and increasing rate of drilling success in a shorter
project implementation time.

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Acknowledgment
First of all I would like to thank the merciful, power full ,and creator of everything
almighty ALLAH for giving me encouragement and health to do this research paper.
I also acknowledge Samara University for their full sponsorship to attend the master’s
program that which is the perquisite prerequisite for this paper. My special thank is
extended to my advisor DR.FETHANEGEST Fethangest and co–adviser
DR.ABDelUWASSIEDr. Abdelwassie Husseienefor Their unlimited support, guidance
and patience from the beginning to the end of my research work. They built me with the
basic knowledge of hydrogeology and gave me their professional advice. Not only giving
their invaluable advice and constructive comment during preparation of this paper but
also they treat me as little brother of them. My sincere gratitude goes to my lovely wife
Ww/ro Mayram Abdella for her appreciation and patience during my field work and her
encouragement during preparation of this paper Finally, I would like to acknowledge
institutions and personals that support me in different ways during my research works
like those who share important data for my job, those who facilitate field work by
covering transportation, accommodation, and meal during my stay on their actively
drilling sites, those who support me financially and morally.

CONTENTS
Declaration of Originality.................................................................................................. I
Approval Page ..................................................................................................................II
Abstract........................................................................................................................... III
CHAPTER ONE.......................................................................................................... XIX
1.0 INTRODUCTION................................................................................................. XIX
1.1Background and Justification ................................................................................. XIX
1.2 Location and Accessibility of the Study Area.....................................................XIIXI
1.3 Physiographic and Climate of the Study Area...................................................XIVXI
1.4 Literature Review .............................................................................................XIVXII
1.5 Statement of the Problem................................................................................ XVIXIII
1.6 Research Objectives......................................................................................XVIIIXIV
1.6.1 General Objective......................................................................................XVIIIXIV
1.6.2 Specific Objectives....................................................................................XVIIIXIV
1.7 Methodology, Tools, Data Description and Data Source............................... XIXXIV
1.7.1 Research Design ..............................................Error! Bookmark not defined.XIV
1.7.2 Source of Data .................................................Error! Bookmark not defined.XIV
1.7.3. Data Collection Methods.................................Error! Bookmark not defined.XV
Chapter Two ........................................................................................................XXIXVII
2.1. Regional Geologic Setting of Afar Depression ............................................XXIXVII
2.2. Local Geology of the Area ..........................................................................XXIIIXIX
Chapter three............................................................................................... XXXVIXXVII
3. Hydrogeology of Afar depression .......................................................... XXXVIXXVII
3.1. Local hydrogeological ..................................................................... XXXVIIIXXVIII
Chapter four.......................................................................................................XLXXXI
4. Drilling challenges .........................................................................................XLXXXI
4.1. Drilling challenges (problems) .................................................................. XLIXXXII
Chapter five .................................................................................................XLVIIXXXVI
Result and Discussion................................................................................ XLVIIIXXXVI
3.1. Drilling problem Analysis in the case of Northern Afar .................... XLVIIIXXXVI
3.1. Case Study .........................................................................................XLVIIIXXXVII

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3.2. Result of Analyses and Interpretation.........................................................LIXXLVII
3. 2.1.Konaba area .............................................................................................LIXXLVII
3.2.2. Dallol area...................................................................................................LXVLIII
3.2.3 Barahle area ..............................................................................................LXVIILIV
3.2.4 Abaala and Erebt area..............................................................................LXVIIILVI
3.2.4.1.Abala.....................................................................................................LXVIIILVI
3.2.4.2. Erebti area.............................................................................................. LXIXLVI
3.2.5 Afdera area................................................................................................. LXXLVII
3.2.6 Magale area................................................................................................ LXXILIX
3.2.7 Bidu area.................................................................................................... LXXIILX
3.3. Comparisons between Variables................................................................LXXIIILXI
Chapter –five ..............................................................................................LXXXIIILXXI
5 .0 Conclusion and Recommendation.......................................................LXXXIIILXXI
5.1. Conclusion...........................................................................................LXXXIIILXXI
4.2. Recommendations.............................................................................. LXXXIVLXXII
5. References............................................................................................LXXXVILXXIII
6. ANNEX ...............................................................................................LXXXIXLXXVI
List of Table
Table: 1Sample of Questioner’s format.........................................................................….XLIX47
Table 2: summaries of descriptive analysis of considered parameters (variables) during interviews
and supervision……..................................................................................................................L48
Table 3:-lithological description of belbel site...................................................................LXIII63
Table 4:-Casing arrangement the borehole of the belbel borehole.................................... LXIV63
Table 5:-Lithological logging of sodonta ............................................................................. CIX96
Table 6:-Lithological logging of dataleyta ........................................................................ CXIII99
Table 7:-Drilling information of well id ATW 1............................................................. CXIV101
Table 8:-Lithological logging of ATW 1...........................................................................CXV101
List of Figures
Figure 1:-location map of study area................................................................................... XIIIXI
Figure 2:- Stratigraphy of Afar Depression (adapted from Varet, 1978; Beyene &
Abdelsalam, 2005)......................................................................................................... XXIIIXXI
Figure: 3 Geological map of study area...............................................................................XXV
Figure 5: lithological logging of four wells which the drilling problems were encountered at
alluvial deposit at different depth............................................................................................ LVL

Figure 6: cross sectional view of the four wells which the drilling problems were encountered at
alluvial deposit at different depth........................................... Error! Bookmark not defined.LII
Figure 7: location maps of wells drilled with problems ....................................LXXXIILXXXVII
List of Graph
Graph: 1 showing applied methodology in graphic manner.................................................. XX33
Graph 2: percentage of localities of Drilled wells which at drilling problems Encountered during
drilling ....................................................................................................................................LII53
Graph 3: percentages of Encounter problems during drilling in the study area from collected
data........................................................................................................................................LIII54
Graph 4: Percent of Geological formations at which drilling problems are encountered .... LIV55
Graph 5: Percent of Depth of drilled wells at which Drilling problems are encountered .... LVI58
Graph 6: Drilling institution that were drilled the wells which the drilling problems
encountered during drilling................................................................................................. LVII59
Graph 7: Percent of type of Drilling method that were applied during drilling .................LVIII60
Graph 8:-Reasons (causes) that were responsible for the encountered drilling problems.... LIX61
Graph 9: cause of problem versus localities...........................................................................LX63
Graph 10: comparisons between the Encounter problems with the localities of the drilled well
.........................................................................................................................................LXXIV77
Graph 11: Correlations of the encounter drilling problems with depth of the wells........LXXV78
Graph 12: Encounter problems versus Geological formation .........................................LXXVI78
Graph 13: Encounter drilling problems comparing with Applied Drilling method ...... LXXVII79
Graph 14: Encounter problems versus drilling institution ............................................ LXXVII80
Graph 15: Encounter problems versus causes of the problems ....................................LXXVIII80
Graph 16: localities of wells versus drilling methodology..............................................LXXIX81
Graph 17: Localities of the wells versus Geological formation ......................................LXXIX82
Graph 18: Drilling institutions versus Drilling methodology...........................................LXXX82
Graph 19: Drilling institutions versus causes of problems...............................................LXXX83
Graph 20: localities wells versus cause’s problems ........................................................LXXXI83
List of picture
Picture: 1Representative outcrops of the basement complex of Dallol area: (a) Quartz swarms
enriched mafic metavolcanics; (b) Meta-agglomerates; (c) Metapyroclastics (ash-tuff); (d)
Slates/Phyllites; (e) Metacarbonatesinterbedded with thin layers of slate; (f) overturned and east-
verging fold in the slate-carbonate units; (g-i) Granitoids intruded by felsic and mafic dykes
........................................................................................................................................ XXVIII38
Picture2:-bird’s eyes view of konaba woreda.................................................................... XXV39
Picture: 3 fracture and weathered commonly granodiorite intrusive rock around alhena kebele
................................................................................................. Error! Bookmark not defined.39
Picture: 4alluvial deposit exists around belbel kebele of kunaba ......................................XXIX40
Picture: 5 Topographical views of barahle woreda................ Error! Bookmark not defined.40
Picture: 6Abaala series of elongated ridges and hills interrupted by flood plain .................Error!
Bookmark not defined.41
Picture: 7 contact between sandstone and limestone around erebti town (north of the town)
............................................................................................................................................ XXX42
Picture 8: Scoracious Basalt around Bahra Plain (Erebt) ...............................................XXXI43

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Picture: 9 alluvial deposit around Afdera woreda .......................................................... XXXIV44
Picture: 10Vesicular basalt and network of quartz vein around megale............................XXXI45
Picture: 11relatively younger aphanetic basalt dykes intruding older vesicular basalt..XXXII45
Picture 12:-belbel collapsed well with drill tools................................................................LXV68
Picture 13-coring sampling from Dallol(around muslayi)................................................ LXVII69
Picture 14: Drilling activity held on Scoracious basalt at kusrawad in Afdera ................. LXXI74
Picture 15:-Drilling activity held on Scoracious basalt at Aguma in Biduwareda ..........LXXIII76
List of Annex
Annex 2:-Questioner’s format LXXXIX90
Annex 3: Summary of case study XC90
Annex 4:-General description of wells that overviewed during study CVII97
Annex 5: Summary of descriptive analysis of considered parameters CXVIII107

CHAPTER ONE
INTRODUCTION
1.1 Background and Justification
Afar is characterized by an arid and semi-arid climate with low and erratic rainfall.
Rainfall is bi-modal throughout the region with a mean annual rainfall below 500 mm in
the semi-arid western escarpments decreasing to 150 mm in the arid zones to the east.
Afar rregion is increasingly drought prone area.
Groundwater is the critical underlying resource for human survival and economic
development in extensive especially in drought -prone areas. The characteristics of
groundwater differ in a number of ways from surface water. Since groundwater responds
slowly to changes in rainfall, the impacts of droughts are often buffered (Calow et al.,
1997). In areas with a long dry season, groundwater is still available even when surface
sources such as rivers and streams have run dry. Groundwater is generally
microbiologically uncontaminated and to a certain extent naturally protected from
pollution.
The groundwater is accessed through a range of approaches largely dependent on the
depth of the groundwater, ranging from hand-dug wells, shallow drilling and deep drilling
down to range of several hundred meters depending on the depth of groundwater. Where
the deeper groundwater conditions require drilling, this results in higher unit costs per
beneficiary but the schemes tend to be more resilient to variable climatic conditions and
drought.
GenerallyGenerally, the cost of drilling in Ethiopia is ever increasing and specifically the
cost escalation is very high in Afar region reaching $250/m due to the site location far
from the drilling company location, the climatic condition of the region, lack of water for
drilling purposes at the vicinity of drilling sites and poor road infrastructure.
The Afar Regional Government and its allies are investing huge amount of budget to
increase the number of residents who have access to safe and clean water, and yet the
percentage of the population who has access to clean and safe water is very minimal.
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Moreover, as the groundwater development expanded, search for groundwater has
extended to hydrogeological less favorable area reducing further the drilling success rate.
(Summary report on improving drilling success rate in the Afar Region (UNESCO-Addis,
2015).
According to this report, the failure in pinpointing productive sites is primarily attributed
to lack of adequate scientific information as well as complexity of hydrogeology of the
region. Generally, the drilling success rate in Afar is far below the national average mainly
because of the complex geological condition and the arid climate. It is reported to be not
more than 50%.
The objective of those these works was to iImprove drilling success rate in selected
woredas of Afar region having critical water shortage. water short selected woredas in
Afar regions by deploying state- of -the science that help to improve existing groundwater
information: the assumption behind of these works was the existing condition of the
region which stated by these reports was “ Out of ten water wells drilled in Afar region,
7 or more wells could turn dry or saline”, just because wells are drilled without having
adequate groundwater information .Combination of appropriate methodologies including
conventional and satellite data will be used to improve existing groundwater information
thereby improving drilling success rates.
However, most of the test boreholes located by using the Combination of appropriate
methodologies suggested and applied by these report in the Afar region was face drilling
problems during drilling and some of them was were failed due to the drilling challenges
encountering during drilling and others was were abandoned due to the salinity.
For example ((Mmuslayi borehole in kori (dropped drilling string) and haiten of erebti
(collapse) and tio of bidu (salinity) ).
From the evidence on the ground, Locating favorable productive sites to be drilled could
not bring the desired outcomes due to the drilling challenges occurring during drilling
that can be caused by natural condition or /and manmade fault which can cause for
hindering the target of drilling in the Region (by Technical problems).
Groundwater investigation and identification of the resource is also a big task and needs
skilled man power and investment. For a successful completion of groundwater
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developments projects both feasibility study and water well construction management is
mandatory.
In the drilling world, the most apparent representative problem is the nature of the job
itself. It is a job that you cannot see with your naked eye what really is happening deep in
the subsurface. Thus, the major problem emanates from the nature of the job, dDue to
lack of skillful management less attention is paid to resource allocation, i.e., human,
financial and material resources. This situation can be considered as the second
representative problem. The problems enhanced by inexperienced technical performances
and those encountered due to the incompatibility of the drilling methods with the
formations to be drilled are also notable due to using weak, old and incompatible drilling
machine during drilling.
Efforts made on this paper is to reviewing of water well drillers note, well completion
reports and discussion with senior hydro-geologists, chief drillers and drilling super
intendants, data collection of drilling challenges, dDrilling history of boreholes in
different regions and geologic settings of the country. This paper evaluates the drilling
challenges most frequently encountered with associated 95 wells that were faced drilling
problems during drilling from 240 drilled wells in the northern afar, as well as identifying
their causes and effects, and finally suggests recommendations aimed to increase drilling
success and reducing adverse impact of it.
1.2 Location and Accessibility of the Study Area
The study area is known as kilbatti rasu Rasu (northern Northern zoneZone) of the
Afar Regional State of North Eastern Ethiopia. This zone encompasses eight woredas,
these are Dallol, Kunaba, Barahle, Abala, Erebti, Megala, Afdera and Bidu woredas
and in the global grid they lies approximately between longitudes of 39º0"0' to 42º0"0'
east and latitudes and from 12º0"0' to 15º0"0' north. Among the eight woredas five are
accessible through asphalt road they are Barahle, Abala, Erebti, Afdera and Bidu
whereas Megala is accessible through gravel road and the remaining two woredas are
accessible through dry weather road.
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Figure 1: Location map of the study area
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1.3 Physiographic and Climate of the Study Area
The physiography of the study areas is the product of Volcanism, sedimentation and
tectonism. The above listed processes are the controlling factors for the formation of the
high lands, low lands and stream channels. Generally, the elevation of the area varies
from -120m in dalol Dalol depression to 3000m around atsbiAtsbi. Due to the variety of
impact of the physiographic factor and different geology we have different features in
study area.
The climate of the area in general comes under the influence of the Inter Ttropical
Cconvergence Zone (ITCZ) which is a zone of low pressure that marks the convergence
of dry tropical easterlies Easterlies and moist equatorial Equatorial westerlyWesterly. The
seasonal rainfall distribution is highly controlled by the annual migration of inter tropical
convergence zone across the area. The climate of the area is influenced mainly by altitude
which is ranging from -120m in dalol depression to 3000m in around atsbi. The climate
of the study area in general falls under dega Dega in few areas, and sub-tropical to desert
in most parts of the study area according to Ethiopian Traditional way of agroAgro-
climatic zoning (Bayyisa, 2003).
1.4 Literature Review
Many groundwater exploration works have been done in the northern Afar for different
purposes by different bodies like academic societies which are giving more concentration
on structural analysis related evolution of rifting system. Governmental institution and
mining companies have visited the area starting from 1838 (Garland, 1980 cited in Fetha
et al, 2006). Even though various researches have been conducted in the area, from the
hydrogeological point of view, yet there are no detailed and well-organized
hydrogeological studies in the area generally and specifically there is almost nothing
regarding to the title of this research. However, only limited studies are available for the
areas under investigations which include Hydrogeology of the Mekele area by (Tesfaye
chernet Chernet and G.Tsadik Eshetu, 1982), Hydrogeology of Ethiopia and water
resource development (Tesfay eCchernet and G.Tsadik Eshetu, 1993) and other local
scale surveys by the Tigray Water Resources, Mines and Energy Bureau, Afar Water
Resources Bureau, Afar Design and Supervision Enterprise of Several local scale surveys
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have also been made which include reports, maps and raw data mainly focusing on
locating water supply wells for rural and sub-urban settlements.
There is no any work to be reviewed in the study area related to the current studies
specifically and rare in generally in Ethiopia, except only little effort, have been made to
identify the water well drilling challenges and the mitigation measures in Ethiopia. Abebe
G/.Hiwot in his case study submitted on 25th WEDC (Water, Engineering and
Development Center) conference for integrated development of water supply and
Sanitation showed major causes of borehole drilling challenges in Ethiopia. Msc Thesis
done by Tesfaye&Eleni also showed the challenges on drilling and pumping test in the
sector. Technological defects
Msc Thesis done by Tesfaye also showed the challenges on drilling and pumping test in
the sector.
Furthermore, Summary report on improving drilling success rate in the Afar Region
(Elidar, Erepti and Atsbi Woredas) (UNESCO-Addis, June 2015) trying to address the
low drilling success rate in the region due to failure in sitting potential area for
groundwater, the failure in pinpointing productive sites is primarily attributed to lack of
adequate scientific information as well as complexity of hydrogeology of the region.
These report states out of ten water wells drilled in Afar and Somali regions, 7 or more
wells could turn dry or saline, just because wells are drilled without having adequate
groundwater information. suggested a combination of appropriate methodologies
including conventional and satellite data will be used to improve existing groundwater
information thereby improving drilling success rates.
According to this report it is documented that in arid setting of Afar and Somali up to
50% of drilled wells return negative results, salinity is often in excess of WHO drinking
water quality standard and Modern integrated technologies such as combination of radar
and optical remote sensing, geological mapping, geophysical survey, water quality survey
could increase success rate to more than 70%.
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According to Carter et al, 2003, Wells should be designed so that they are fit for their
intended purpose. This means that the diameter, depth, casing type and backfill materials,
screen open area and other design features should be well‐matched to need specifically
water demand, longevity, hydraulic efficiency and cost of the project. Furthermore,
Danert et al. 2007, mentioned on the article paper, cost effectiveness of borehole in sub-
Saharan African countries unveiled that cost of drilling well in Africa is higher than India.
Seifu Kebede 2013, on his book ground water in Ethiopia mentioned the history,
occurrence, development and storage of ground water potential in regions and basins
including aquifer types and classifications. Furthermore, in Africa ground water Atlas,
Seifu Kebede et.al. 2018, mentioned briefly the hydrogeology of Ethiopia with aquifer
type classification and occurrence.
Wogayehu, 2017, in his Msc. Thesis showed the drilling challenges and possible geologic
and technical solution focusing on Tana basin and its surrounding area.
1.5 Statement of the Problem
Groundwater is one of the main sources of water supply for rural and urban areas of the
arid regions of Ethiopia. (UNESCO-Addis, June 2015) according to this report, in a recent
years, the number of water wells drilled has dramatically increased through the
intervention of various international and local initiatives. However, the success rate of
drilling productive wells in arid lowlands is still very low (30-50%), even by sub-Saharan
standard. means that the failure of drilling is very high. The failure in pinpointing
productive sites is primarily attributed to lack of adequate scientific information as well
as complexity of hydrogeology of the region (UNESCO-Addis, June, 2015).
Even if a favor productive sitesfavor productive sites are selected using adequate
scientific information by well skilled professionals very carefully, drilling success rate in
drilled wells are not satisfactory. This is indicates that drilling a small hole into
underground formation that may or may not be well consolidated introduces the
possibility of some type of hole problems. The potential for drilling problems may be
shown by the geology used in well planning or by past experiences. An essential first step
in the promotion of good drilling practices is the planning of the well, a systematic
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approach to outlining procedures and practices must be followed in every case. A
comprehensive well plane is the first line of defense in controlling costs. Leaving anything
to chance can result in needless additional expenditures. Data acquisition is the first step
in well planning. In which the key to achieving objectives successfully is to design drilling
programs on the basis of anticipation of potential drilling problems rather than on caution
and containment.
The well plan at initial planning meeting and data gathering stage should be designed to
attack?? potential drilling and well completion problems operation which may be occur
during practice (J.J.Azar,2006). It is almost certain that problems will occur while drilling
a well, even in very carefully planned wells. For example, in areas in which similar
drilling practices are used, drilling problems may have been reported where no such
problems existed previously because formations are nonhomogeneous and anisotropic,
therefore, two wells near each other may have totally different geological conditions. So
we can say different lithology has different operations problems. The most of this problem
that may be occure are predictable and geological information such as formation tops,
surface casing setting depth, objective depth, sampling and logging requirement are great
help in prediction.
Even though, the Regional Government and its allies are investing huge amountnumber
of resources to increase the number of people which have access to safe and clean water,
yet the percentage of the population who has access to clean and safe water is very
minimal. Moreover, the rural people particularly women and children are the victims of
the critical problem. Furthermore, much cannot be mention as a positive remark regarding
the water supply and sanitation aspects of the urban and semi-urban areas of the region
generally and specifically the northern parts of regional state of the Afar.
A thorough study of all hole problems encountered on offset wells is very important to
effectively plan any new well. This study should include a direct caparison of how these
problems were dealt with in different situation. In this way problems can be anticipated
and, if not entirely prevented, efficiently handled. This problem can results borehole loss,
thus with the proper management and enough knowledge about the problem can do a
successful operation. The most prevalent drilling and well completion problems in the
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study area include: pipe sticking, lost circulation, hole deviation, drill pipe failure (twist
off and wash out), bore hole instability (shale problems),abnormal pressure zone, kick
and blowout, mobile formation, mud contamination, producing formation damage,
problems in hole cleaning, bit ballingbailing, packer failure equipment and personnel
related problems.
There are very many a number of reasons that can be attributed as possible causes to this
these significant problems. Among the reasons, groundwater resource development
activities that have seen been facing numerous problems right away from the planning to
the implementation and management stages are worth mentioning. Drilling of wells
which is one of the common practices to supplying the urban and the rural community
with safe water has been observed to have repeated problems and thereby a number of
wells abandoned as the result of the problem and facilitating the overall potable water
shortage.
Therefore, Understanding and anticipating area specific common drilling problems,
understanding their causes, and planning solutions are necessary for an overall well cost
control which ensures successfully reaching the target depth anddepth and the overall
achievement of the objective. of the drilling approaches which are believed would help
in improving the prevailing conditions and assist in achieving future prospective i.e.,
lesser drilling and completion problems with decreasing abandoned wells and more safe
and sustainable water supply to the community.
1.6 Research Objectives
1.6.1 General Objective
The general objective of this study is to identify, classify and prioritize the well drilling
challenges in the study area and to come up with possible solutions.
1.6.2 Specific Objectives
➢ To identify common drilling problems in the area with respect to geology, technological
use and technical capability.
Commented [u35]: No need of this paragraph

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➢ To classify and prioritize the problems based on their frequency and cause.
➢ To describe causes and consequences of well drilling problems in the area.
➢ To make correlation among the encounter problems in the area
➢ To propose possible mitigation for the identified problems.
1.7 Methodology,
The research on drilling challenges basically giving attention on well drilling completion
reports, however many daily drilling notes, information gained from the main actors in
drilling activity from their experience in area generally and specifically the borehole
which drilling challenge faced and published and unpublished reports could not able to
reflect the actual drilling challenges, cause of the problems and the mitigation measured
on the. Hence the methodology focused on the following:
• Gathering the available well completion reports in the area and identifying the
encountered drilling challenges and location.
• Identifying technical personals who were involved in drilling activities in the
borehole which the drilling challenge encountered.
• Distributing Questionaries’ and conducting interview with technical staff’s
involving drilling activities on the identified drilling challenges encountered
boreholes which both questioners and interviews had similar purposes.
• Cascading focus group discussion with hydrogeologist from client ,consultant
and contractor and chief drillers was part of drilling program
• Conducting field visit for active drilling sites in the area during the research for
additional data collection
• Data processing and analyze using special geo-statistics software for proper data
manipulation and summarize to generate important information
• Identification and correlating field borehole data including location, depth and
lithology with possible drilling challenge using Arc GIS software and the
Statistical Package for Social Scientists (SPSS) Software updated version 20 for
windows
Commented [F36]: How many boreholes were used in this
study? And how many interviews were made?
Commented [D37R36]:
Commented [F38]: Incomplete paragraph and is not clear.
Commented [D39R38]:
Commented [F40]: For what reason do you use the geo-
statstics?
Commented [D41R40]:

.
Graph: 1 shows the applied methodology in a graphic manner

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CHAPTER TWO
GEOLOGICAL SETTING
2.1 Regional Geologic Setting of Afar Depression
The East African Rift System (EARS) is one of the largest sub-aerial tectonic wonders
of the globe, a place where the earth’s internal (active and passive) forces are currently
trying to create new plates (e.g., the Somalian and Danakil Microplates) by splitting apart
the old African plate (Hagos et.al., 2011 and references there in). The EARS, therefore,
provides opportunities to examine plume-driven continental flood volcanism (Furman et
al., 2004) and the birth and growth of the Afar triple junction as continental rifting
advances to incipient seafloor spreading (Hayward and Ebinger, 1996).
The Afar Depression is bordered on the west by the Ethiopian escarpment, on the east
and northeast by the Danakil Microplate, and on the south by the Somalian Plateau. The
elevation drops radically from the rift bounding Ethiopian plateau that stands well above
3500 meters above sea level to the lowest point in northern Afar Depression (Dallol
Depression) at ~120 meters below sea level (Tesfaye et al., 2003)
On the bases of geology and geography, the Afar Depression is divided into north, central,
and south sectors (Tesfaye et al., 2003). The central sector dominated by graben and horst
structures and bounded to the west and east by axial volcanic ranges, is occupied by
Pliocene flood basalts and Quaternary sedimentary rocks. The flood basalts, which are
inter-bedded with less common and more silicic layers and volcanic centers, are
collectively termed the ‘‘Afar stratoid series’’ (CNR-CNRS [Afar team], 1973; Varet and
Gasse, 1978; Barberi and Santacroce, 1980).
Available age data indicate that the stratoid series was emplaced between 4.0 and 1.0 Ma
(Barberi et al., 1975; Barberi and Santacroce, 1980). Parallel sets of grabens that strike
North West are typical of the region; the mean elevation of Central Afar is 450 m.
The Tendaho graben is one of the largest in the central sector of the Afar Depression.
Southern Afar like Central Afar is dominated by horst and graben structures. Unlike
Central Afar, however, the grabens in Southern Afar strike north-northeast, and the

topography has a mean elevation of ;700 m. The Tendaho-Goba’ad Discontinuity, a
narrow northwest- to west-northwest– trending fault zone, separates Central Afar from
Southern Afar (Harding et al., 1990; Ebinger and Hayward, 1996).
The northern part of the depression, with a mean elevation of; 70 m, is dominated
by axial volcanic ranges. The, 1-m.y.-old shield volcanoes of the axial range are typically
produced by basaltic fissure eruptions aligned in northwest southeast belts, parallel to the
regional tectonic trend of the Red Sea (Barberi and Varet, 1977; Varet and Gasse, 1978).
The northern Afar Depression also hosts Miocene to Holocene evaporites and fluvial
sedimentary rocks (CNR-CNRS (Afar team) 1973). The deepest parts of the depression
are commonly filled with recent lacustrine sediments, evaporite beds and floored by
fissure-fed basaltic lava flows. The earliest sedimentation started in the Oligocene–
Miocene along the newly developed marginal grabens with the clastic ‘Red Series’, and
continued in the Pliocene–Recent by Piedmont sediments and shallow water carbonates
(Barrat et al., 1998 and references there in).

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Figure 2:- Geological Stratigraphy of Afar Depression (adapted from Varet, 1978; Beyene &
Abdelsalam, 2005)
2.2. Local geology of the area
The geology of the area covered by Neoproterozoic Basement Complexes, Generally,
they are divided into metavolcanic Metavolcanic /meta volcano-i clastic rocks,
metasedimentary Metasedimentary successions and post-tectonic granitoidsGranitoids,
Mesozoic Sedimentary Successions, the Miocene-Pliocene Volcano-sedimentary
Sequences, Evaporates and Younger Sedimentary Deposits and Alluvial fans composed
of clay, silt, sand, gravel and boulders. Which the above listed geological formations are
Commented [F42]: Is this geological Map or stratigraphy??
Commented [D43R42]:
Commented [F44]: Geological map of your area that represents
you area and having representative geological section is required?
Commented [D45R44]:

uneven distributed on the study ar
ea. Here below the geological map of the study area.

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Figure: 3 Geological map of the study area
Commented [u46]: Concentrate on the major lithologic units
that are important for your work. Therefore, put Metavolcanics
together, metasediments together and so on. No need for detailed
lithological classification.
Commented [F47]: Is this your work? If not refer? The legend
should also be within the frame of the map
Commented [D48R47]:

S.N Map
Symbol
Lithological Description
1 Pc Phyllite Partly Intercalated With Limestone And
Dolomite
2 Pq Quartzitic Phyllite
3 Ps Conglomeratic Phyllite And Schist
4 PP Undifferentiated Phyllites
5 Pzf Quart Diorites
6 Gu Undifferentiated Granitic Intrusions
7 J1ss Alternating Layers Of Sandstone And Siltstone
8 J1 Ferugineous Silt And Clay
9 J2i Fossiliferous Limestone
10 J2 Limestone And Sand Stone Intercalation
11 Jtg Fine Crystalline Limestone Marl And Shale
12 E2as Alajae Formation And Aiba Basalt
14 B1 Olivine Basalt With Intercalation Of Intermediate Lavas
And Tuff
15 B2 Undifferentiated Lavas, Slags And Cinder-Cones
16 B3 Block Lava Fields And Strato Volcano
17 Rr Alkaline-Obsidian And Ignimbrites
18 Rh Acidic Flows Of High Viscosity, And Undifferintated
19 Rtt Trachyte-Rhyolite, Probably Partly Ignimbrite
20 R Undiferentiated Acidic Volcanic–Rhyolite And Trachyte
21 Qb Basaltic Flows And Alkaline And Per-Alkaline Silsic
Rocks
22 T’s Gypsiferous Conglomerates, Sandstone, And Siltstone
23 Tssv Light Red Partly Solidified Gravel And Sand
24 Tc Marly And Fossiliferous Limestone Intercalations
25 Tss Partly Solidified,Clavey,Gypsemferous Gravel,Sand And
Silt

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26 TS Undiferentiated Danakil Formation
27 Thy Halite, Beded With Rare Gypseferous And Calcareous
And Raddish Clavey Intercalation By Gypsemfreous
Rocks
28 Th Halite,Interbeded With Rare Gypsemferous ,Calcareous
And Anhydrite Beds
29 Q1Y Gypsum With Rare Calcareous Intercalations
30 Q1I Friableand Gypsemferous Limestone With Coral And
Oyster Beds
31 Q1t Sediments Of Zariga Formation Covered By Sheet-Flood
Terraces
32 Q2b Gypsum And Limestone Covering Basalt
33 Q2I Gypseferous And Fossiliferous Limestone
34 Q2 Undifferentiated Calcareous And Gypsiferous Sediments
35 Qt Extensive Alluvial Fan
36 Sa Wind Blow Sheet Sands
37 D Dunes
38 I Lacustrine Deposits
39 h Re- Precipitated Salty Crust
40 hs Salty Mud Around Lakes
41 fl Silt, Sand And Gravel

Basement rocks (slate and phyliite)
Highly weathered and fractured slatic and phyliitic rocks are observed around in the study
area. These rocks are exposed due to erosional; stream cut and road cut effects. These
rocks also contain quartz and basaltic dikes at different places with different orientation
and width.
Picture: 1 Representative outcrops of the basement complex of Dallol area: (a) Quartz swarms
enriched mafic metavolcanics; (b) Meta-agglomerates; (c) Meta pyroclastics (ash-tuff); (d)
Slates/Phyllites; (e) Metacarbonates interbedded with thin layers of slate; (f) overturned and
east-verging fold in the slate-carbonate units; (g-i) Granitoids intruded by felsic and mafic dykes

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Picture: 2 birds eye views of konnaba area from top to down
From the above pictures we can understand that the valley and grabens are filled by
sediment with various size and the high altitude area covered by tsaliet group meta
volcanic rocks which greenish, partly conglomeratic schist –phylites in the konnaba area.
Sandstone
This rock is exposed north of erebti Erebti and western part barahle Barahle area covering
high land area. At it’s out crop it has fine to coarse size, having different colors (gray to
reddish), is highly weathered and fractured.
valleys filled with sedements
tsaliet group meta volcanics
Commented [u49]: Adjust the photos to serve your objective.
For example, if you mention a dyke, you have correlate the
encountered drilling problems with the dyke

Picture: 3 contact between sandstone and limestone around erebti Erebti town (north of the
town)
Lime stone: Highly weathered and fractured limestone is observed to north and southwest
of Erebti town, North West of abala Abala and western part of barahle Barahle area.
Different sizes of basaltic dikes are also observed in this unit. It is also shows some
stratification with clear bedding plane at places. The rock has gray to darkish color
showing different colors at different places.
Basalt
Highly weathered and fractured Scoraceous Basaltic rocks are observed around the study
area at the low land area forming high landhills in the plain area, formed in the form of
cones. It is clearly observed on flat (Bahrin plain).More over basaltic dikes up to 50m
width is observed to north of erebti Erebti Town in Mesozoic rocks, limestone formation
and dikes observed in basement rock have very thin (up to 1m) width than in
limestone(see picture 3 ).

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Picture 4: Scoracious Basalt around Bahri Plain (around Erebti)
The Ashenge Group is composed of mainly Alkali basalt. Towards Chercher Mountains
the basalt are more fractured and weathered. The dominant geological unit is weathered
vesicular basalt formations which intruded by concordant quartz veins with a thickness
varying from few centimeters to meters.
Picture: 5 Vesicular basalt and network of quartz vein around megale area
In some areas of the megale woreda there are relatively younger aphanetic basalt dykes
intruding older vesicular basalt have been observed.

Picture: 6 relatively younger aphanetic Aphanetic basalt Basalt dykes intruding older vesicular
basalt
Alluvial deposit
Alluvial deposits are located at relatively lower elevated area covering lower morphologic
places and along stream sides. These deposits are the result of weathering and erosion
effect of the rocks found in high land areas of the surrounding place. The outcrop of
alluvial deposit is greater than 10m, as shown from stream cut, containing clay, and sand
and gravel size.

Picture: 7 alluvial deposit in harsoma & kusrawad of afdera and belbel of kunoba area (a)
Profiles of alluvial sediments in the eastern part of belbel and (b) in the western part, at the foot
of the mountains.
Commented [u50]: Not clear

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The stratigraphic succession of the western margin of northern Afar Depression
Figure 4: existing simplified sketch for entire stratigraphic succession of western afar
depression(source: A preliminary Geological and Generalized stratigraphy of western margin of
Northern Afar Depression, Dallol Area, Northern Ethiopia, Hagos etal, 2016)

CHAPTER THREE
HYDROGEOLOGY OF AFAR DEPRESSION
3.1 Hydrogeology of Afar depression
Alluvial Deposits, in Afar has higher yield in floodplains, have moderate to high
permeability, with measured transmissivity from 1-500 m²/day and having a discharge up
to 20 lit/sec. These aquifers can be both confined and unconfined; the thickness ranges
from 0 - 400 meters; salinity is very variable. However, alluvial deposit in northern
Ethiopia has a relatively low yield. Overlying basement rocks can store a good amount of
water and have characteristics of high permeability and water infiltration capability.
Typically are shallow in depth and have laterally limited extent, and form perched
aquifers. Manual hand dug wells and flowing springs are common. (Seifu Kebede, 2018)
The general hydrogeological condition of the Afar region can be explained as follows :
Based on the observation from well drilling logs of different boreholes drilled in different
geological environments of the region the major water bearing geologic units in the area
can be categorized into two main groups as extensive and unconsolidated Alluvial
aquifers (including the Alluvial fans) of Sand and Gravel at shallow to deep level and the
deep fractured aquifers of Basalts , Scoracious basalts and sometimes with highly
fractured Ignimbrites and trachytes. The unconsolidated Alluvial aquifers in the region
occupy the wide Alluvial plains of the region like Teru, Awra, Gulina, Ewa, Chifra,
Worenso-Mille, Middle Awash, Tendaho, Alidege, Erebti and Bahri plains as well as
marginal structural Grabens like Sheket, Ayshet , Borkena and Robit Grabens. The
narrow structural Grabens in central Afar including the Dobi , Guma, Hanle, Manda-
Inakir grabens are filled by thin layers of these aquifers at shallow depth overlaying the
deep fractured aquifers below the Alluvials.The Alluvial fans in the Denakil depression
and marginal Grabens including the Musley, Saba and Erebti and other numerous smaller
Alluvial fans in the same area and at the foot of Denakil horest are also the major aquifers
of fresh water zone in these areas.
Significantly variable sediment thickness in Alluvial Alluvial fans and in fluvio-lacustrine
sedimentary basins is observed Water chemistry and (salinity level)of groundwater in
Commented [u51]: Zero aquifer thickness????????????
Commented [u52]: Whose work is this? Reference is necessary

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lacustrine and fluvio-lacustrine sediment is generally high due to the composition of the
dominant sediment mostly calcareous and gypsiferous or silt and clay with fine sand.)
Strongly fractured Afar stratoid basalts and Quaternary basalts are also the second group
high productive aquifers in the region below the Alluvial in most parts of the region.
Recharge source for the deep regional fractured aquifers is the groundwater flow from
marginal highlands precipitation in the western and eastern plateau areas of the rift.
However recharge source for shallow fractured stratoid basalt aquifers in many of narrow
structural grabens are limited to the nearby highlands and volcanic centers. Therefore
understanding the local meteorological condition is very important. In addition to the
hydraulic properties of the subsurface formations, the groundwater flow regime is also
controlled by the complex structural and tectonic features. The groundwater flow system
in the region can be grouped into two main groundwater basins depending on the flow
direction controlled and drained by two different surface water bodies (Lakes) in and
outside the region where the groundwater is discharging. Accordingly the deep
groundwater from north western and northern rift margins and areas including some parts
of Awra, Gloina, Teru Kori and Bidu groundwater is controlled by Lake Afdera and on
the other hand the groundwater regime in Central west, eastern, north eastern and southern
part of the Afar region (dominantly groundwater of the Awash basin) is controlled by the
Lake Asal which is the lowest lake surface (-156m below sea level) in Africa located at
Djibouti boarder. These also includes the groundwater in the north eastern part like the
Tenadaho graben (Aysaita, Dubti and Logiya areas) Gega, Seha and Serdo plain, Elidear
and Bure areas.
According to (UNICEF, 2016) report groundwater in the Afar region occurs either of this
forms:
➢ Shallow and deep cold groundwater in fractures, sediments and basaltic aquifer
➢ Deep geothermal waters with surface manifestation with the form of hot springs
➢ Riparian fresh groundwater along awash river and major tributaries
➢ Buried old river channels and wadis Fresh groundwater occurrences along rift margins

Figure 5: W a t e r Point Distribution Map of The Region
3.1. Local hydrogeology
Figure 6: W a t e r Point Distribution Map of The Region
Commented [u53]: Where is the source data for piezometric
lever contouring?
Commented [F54]: Is this Hydrogeological Map? This is
difficult to accept as hydrogeological map because it lacks aquifers,
flow direction, streams etc. In addition the wells are not coded
(named) to identify one from the other. The legend of the wells is
not clear. The color and representation of the rocks or aquifers
should follow standard.
Commented [F55]: Is this hydrogeological map? I suggest this
to be the geological map and convert this to hydrogeological map
using hydraulic property of the rocks?

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Unconsolidated
Named
Aquifers
Aquifer
Productivity
General Description
Water
quality
Alluvial
sediments
Afar Region
- High
Productivity.
Northern
Ethiopia -
Low
Productivity.
Afar Region: alluvial deposits
in floodplains have moderate
to high permeability, with
measured transmissivity from
1-500 m²/day and yields of up
to 20 l/s. These aquifers can
be unconfined and confined;
they vary in thickness from 0
- 400 metres; water table
depth is typically in the range
1 to 60 metres; typical
borehole depth is 100 m;
salinity is very variable.
In the Holocene alluvial
aquifer borehole yields of 0.1
to 1 l/s have been recorded.
Water levels are usually less
than 5 m below ground
surface.
Northern Ethiopia: alluvial
sediments overlying basement
rocks can store appreciable
volumes of water and are
characterisedcharacterized by
high permeability and high
water infiltration capacity.
They are typically shallow
and have limited lateral
extent, and form perched
aquifers. Springs and hand-
dug wells are common, with
recorded yields ranging
between 0.05 l/s and 0.17 l/s.
Variable
salinity
Alluvio-
lacustrine
sediments
Variable
productivity,
but can be
highly
productive in
places
These sediments have highly
variable permeability. Fine
sand deposits have the highest
permeability, with some
boreholes providing more
than 10 l/s with minimal
drawdown. Transmissivities
range up to 700 m²/day and
specific yields are of the order
of 3.2 l/s/m. In several places
Variable
salinity
Commented [F56]: This table must be used to map the
hydrogeology and classify the aquifers based on their hydraulic
property discussed in the table.

higher transmissivities have
been noted. For example, a
150 m deep borehole in
alluvio-lacustrine deposits at
the foot of the southern
plateau has a transmissivity of
3012 m²/day. These aquifers
can be both unconfined and
confined; they vary in
thickness from 0 to 400
metres; water table depth is
typically in the range 1 to 60
metres; and the typical
borehole depth is 100 m.
Fine-grained sands
interbedded with massive
volcanic tuffs and fine ash are
known to have low
productivity in many places
(e.g. in the central Ethiopian
Rift). In the eastern part of the
country the total thickness of
these sediments can reach
about 300 m. In most of the
outcrops, they consist of
conglomerates, sandstone and
mudstone, which are
gypsiferous and locally bear
saline groundwater.
CHAPTER FOUR
DRILLING CHALLENGES
Water well is an excavation or structure created in the ground by digging, driving, boring,
or drilling to access groundwater in underground aquifers. Drilling a small hole into
underground formation that may or may not be well consolidated introduces the
possibility of some type of hole problems. The potential for drilling problems may be
shown by the geology used in well planning or by past experiences. An essential first step
Commented [F57]: Not clear
Commented [D58R57]:

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in the promotion of good drilling practices is the planning of the well, a systematic
approach to outlining procedures and practices must be followed in every case. A
comprehensive well plane is the first line of defense in controlling costs. Leaving anything
to chance can result in needless additional expenditures. Data acquisition is the first step
in well planning. In which the key to achieving objectives successfully is to design drilling
programs on the basis of anticipation of potential drilling problems rather than on caution
and containment. The well plan at initial planning meeting and data gathering stage should
be designed to attack potential drilling and well completion problems operation which
may be occur during practice (J.J.Azar,2006). It is almost certain that problems will occur
while drilling a well, even in very carefully planned wells. For example, in areas in which
similar drilling practices are used, drilling problems may have been reported where no
such problems existed previously because formations are nonhomogeneous and
anisotropic, therefore, two wells near each other may have totally different geological
conditions. So we can say different lithology has different operations problems. The most
of this problems that may be occure are predictable and geological information such as
formation tops, surface casing setting depth, objective zone and depth, sampling, coring
and logging requirement are great help in prediction. A thorough study of all hole
problems encountered on offset wells is very important to effectively plan any new well.
This study should include a direct caparison of how these problems were dealt with in
different situation. In this way problems can be anticipated and, if not entirely prevented,
efficiently handled. This problem can results borehole loss, thus with the proper
management and enough knowledge about the problem can do a successful operation.
The most prevalent drilling and well completion problems include: pipe sticking, lost
circulation, hole deviation, drill pipe failure (twist off and wash out), bore hole instability
(shale problems),abnormal pressure zone, kick and blowout, mobile formation, mud
contamination, producing formation damage, hole cleaning, bit balling, packer failure
equipment and personnel related problems.
4.1. Drilling challenges (problems)
It is not uncommon to have problem in any field of activity, the degree and the magnitude
of the problems, however, vary to the nature of the causes of the problems. In this where
Commented [D60R59]:

the causes and process of all problems that may be occur during drilling operation are
described, regardless the region which practice is done and must be consider them in well
planning program and designing process.
4.1.1 Loss of circulation
Loss of circulation is the most common drilling problem and defined as the partial or
complete uncontrolled flow of mud into a formation, sometimes referred to as thief zone
(Wikipedia.com)??. Total loss of circulation, however, occurs when all the mud flows
into a formation with no return to surface. If drilling continues during total loss of
circulation, it is referred to as blind drilling. This is not a common practice in the field
unless the formation above the thief zone is mechanically stable, there is no production,
and the fluid is clear water. Blind drilling also may continue if it is economically feasible
and safe.
4.1.2. Pipe sticking
An event which causes the drilling operation to stop is described as a Non-Productive
Time (NPT) event. Pipe sticking and lost circulation are the two main events which cause
NPT in the drilling industry. Pipe sticking take place when part of drill pipe or collars are
stuck in the hole and it cannot be freed and pulled out of the hole without damaging the
pipe and without exceeding the drilling rig’s maximum allowed hook load
(J.J.Azar,2006). There are basically two mechanisms for pipe sticking:
1) Differential sticking or Wall sticking.
2) Mechanical sticking.
1. Differentially Stuck Pipe (DSP)
DSP occurrence are common everywhere and account for a significant amount of NPT
and ends up as one of the major causes of increased well cost. In some areas, events
related to DSP can be responsible for as much as 40% of the total well cost. DSP can
Commented [F61]: Not complete citation. Would you please
use other known books?
Commented [F62]: Is it your finding? If not put the source.

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occur when a part of the drill string contacts the bore hole wall opposite the permeable
formation. The severity of sticking depends upon the magnitude of this pressure
differential, the area of contact between pipe and mud filter cake, and the friction which
must be overcome to move the pipe. During all drilling operation the drilling fluid
hydrostatic pressure is designed and maintained at a level which exceeds the formation
pore pressure by usually 200 psi. In a permeable formation, this pressure differential
(overbalance) results in the flow of drilling fluid filtrates from the well to the formation.
As the filtrate enters the formation the solids in the mud are screened out and a filter cake
is deposited on the walls of hole. The pressure differential across the filter cake will be
equal to the overbalance. When the drill string comes into contact with the filter cake, the
portion of the pipe which becomes embedded in the filter cake is subject to a lower
pressure than the part which remains in contact with the drilling fluid. As a result, further
embedding into the filter cake is induced. The drill string will become differentially stuck
if the overbalance and therefore the side loading on the pipe is high enough and act over
a large area of the drill string.
2. Mechanical Sticking
In mechanical sticking the pipe is usually completely stuck with little or no circulation.
In differential sticking, the pipe is completely stuck but there is full circulation.
Mechanical sticking can occur as result of the hole packing off (or bridging) or due to
formation and bottom hole assembly BHA (wellbore geometry).
4.1.3. Hole Deviation
Hole deviation is the unintentional departure of the drill bit from a preselected borehole
trajectory. Whether drilling a straight or curved-hole section, the tendency of the bit to
walk away from the desired path can lead to higher drilling costs and lease-boundary legal
problems (Adam T.etal, 1986). Deviation problems are much more severe and are often
related to geologic structure, hole size and bottom hole drilling assembly clearances
(J.J.Azar, 2006).

4.1.4. Formation Damage
Producing formation damage has been defined as the impairment of the unseen by the
inevitable, causing an unknown reduction in the unquantifiable. In a different context,
formation damage is defined as the impairment to reservoir (reduced production) caused
by wellbore fluids used during drilling/completion and work over operations. It is a zone
of reduced permeability within the vicinity of the wellbore (skin) as a result of foreign-
fluid invasion into the reservoir rock. Typically, any unintended impedance to the flow
of fluids into or out of a wellbore is referred to as formation damage (Thomas D.C, 1988).
4.1.5. Hole Cleaning Problems
Hole cleaning is the ability of a drilling fluid to transport and suspend drilled cuttings.
Good solids control begins with good hole cleaning. One of the primary functions of the
drilling fluid is to bring drilled cuttings to the surface in a state that enables the drilling-
fluid processing equipment to remove them with ease. To achieve this end, quick and
efficient removal of cuttings is essential. In aqueous-based fluids, when drilled solids
become too small to be removed by the solids-control equipment, they are recirculate
down hole and dispersed further by a combination of high-pressure shear from the mud
pumps, passing through the bit, and the additional exposure to the drilling fluid. The
particles become so small that they must be removed via the centrifuge overflow (which
discards mud, too) and/or a combination of dilution and chemical treatment. Thus, to
minimize mud losses, drilled solids must be removed as early cleaning problems (Jiao
etal, 1992).
4.1.5.1. Detection of hole cleaning problems
Historically, the combination of the necessity to pump or back ream out of the hole and a
notable absence of cuttings coming over the shale shaker prior to pulling out of the hole
has been a reliable indicator of poor hole cleaning. When some cuttings are observed,
however, the quantity of cuttings itself does not adequately reflect hole-cleaning
efficiency. The nature of those cuttings, on the other hand, provides good clues: Good
cuttings transport is indicated by sharp edges on the cuttings, whereas smooth and small
cuttings can indicate poor hole cleaning and/or poor inhibition. With the advent of

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pressure while drilling (PWD) tools and accurate flow modeling, a number of other
indicators have come to light that foreshadow poor hole cleaning and its attendant
consequences.
4.1.5.2. Drilling elements affecting hole cleaning
Critical elements that can affect hole cleaning include the following;
4.1.5.2.1. Annular fluid velocity
Flow rate is the dominant factor in cuttings removal while drilling directional wells. An
increase in flow rate will result in more efficient cuttings removal under all conditions.
4.1.5.2.2. Hole inclination angle
Laboratory work has demonstrated that, when hole angle increases from zero to
approximately 67 from vertical, hole cleaning becomes more difficult, and flow-rate
requirement increases. The flow-rate requirements reach a maximum at approximately 65
to 67º, and then slightly decrease toward the horizontal. Also, it has been shown that at
25 to approximately 45º, a sudden pump shutdown can cause cuttings sloughing to
bottom, and may result in a mechanical pipe-sticking problem. Although hole inclination
can lead to cleaning problems, it is mandated by the needs of drilling inaccessible
reservoir, offshore drilling, avoiding troublesome formations, and side tracking and to
drill horizontally into the reservoir. Objectives in total field development (primary and
secondary production), environmental concerns, and economics are some of the factors
that intervene in hole angle selection (Sanjit etal, 2003).
4.1.5.2.3. Hole eccentricity
In the inclined section of the hole, the pipe has the tendency to rest on the low side of the
borehole, because of gravity. This creates a very narrow gap in the annulus section below
the pipe, which causes fluid velocity to be extremely low and, therefore, the inability to
transport cuttings to surface. When eccentricity increases, particle/fluid velocities
decrease in the narrow gap, especially for high-viscosity fluid. However, because
eccentricity is governed by the selected well trajectory, its adverse impact on hole
cleaning may be unavoidable (Sanjit etal, 2003).

4.1.5.2.4. Mud properties
The functions of drilling fluids are many, and can have unique competing influences. The
two mud properties that have direct impact on hole cleaning are viscosity and density.
The main functions of density are mechanical borehole stabilization and the prevention
of formation-fluid intrusion into the annulus. Any unnecessary increase in mud density
beyond fulfilling these functions will have an adverse effect on the ROP and, under the
given in-situ stresses, may cause fracturing of the formation. Mud density should not be
used as a criterion to enhance hole cleaning. Viscosity, on the other hand, has the primary
function of the suspension of added desired weighting materials, such as barite. Only in
vertical-well drilling and high-viscosity pill sweep is viscosity used as a remedy in hole
cleaning (Sanjit etal, 2003).
Equipment and Personnel-Related Problems Equipment tThe integrity of drilling
equipment and its maintenance are major factors in minimizing drilling problems. Proper
rig hydraulics or pump power for efficient bottom and annular bore hole development,
and cleaning are essential. Furthermore, proper hoisting power, derrick design loads and
drilling line tension load allow safe over pull in case of a drill pipe and casing stacking
problems. Well-control systems such as ram, internal and annular preventers are all
necessary for reducing the risk of drilling challenges. Proper monitoring and recording
systems of the drilling rig also crucial to monitor trend changes in all drilling parameters
and can retrieve drilling data at a later date, proper tubular hardware specifically suited to
accommodate all anticipated drilling conditions. Effective drilling fluid and consumable
handling and maintenance equipment will also enhance the function of drilling rigs with
accessories and extend year of service and help to acquire quality and timely completion
of drilling projects.
Personnel iIn Ethiopia, most of the drillers found in the water well drilling industry and
currently operating in the field lack basic standard training on the drilling of water wells
with various methods of drilling, using appropriate drilling fluids and troubleshooting
when the major drilling challenges encountered on the field. The most important thing is
that in order to have effective and efficient performances one has to believe in the
Formatted: Indent: Left: 0"

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requirements of different types of training programs and attitudinal changes to the
workers and the management group and skill training’s which would help to minimize
the above noted technical problems. During drilling and completion operations, qualified
personnel are crucial and key to the success of those drilling operations. Drilling
technology training centers should continue training and education for drilling personnel
and supervisors both formally and informally to successful drilling and well completion
practices. In general, all the problems related to manpower are the results of poor
planning, lack of experience and skill deficiency can be improved through appropriate
training field exposure and awareness of drilling fluids and consumables.
Commented [u64]: This the appropriate literature review which
fits to your objective. So move it to the literature review part.

CHAPTER FIVE
RESULT AND DISCUSSION
5.1. Drilling problem Analysis in the case of Northern Afar
In order to meet the proposed objectives of the research, supervising the actively drilling
sites in the study area and collecting data from the research perspective and distributing
the questionnaires which have the same objective with the supervision were the first steps
of this research. The collected data was analyzed using Statistical Package for Social
Sciences (SPSS Version 20.0). All the questionnaires collected were referenced and items
in the questionnaire were coded to facilitate data entry. The coding of the data was based
on degree of the frequency of the variables and then proceeds to descriptive analyses and
the result presented as table and graphical style.
The variable was coded before to Enter the Statistical package for social sciences (SPSS)
in the following manner based on the result of interviews and observation of the
investigator during supervision of actively drilling sites in the study area.
Geological formation: on the Questioners format geology was refers to the geological unit
which exists on the depth of drilling problems encounter exactly for example, at 40m
stacking drill pipe occurred what geological unit you noticed exactly at that depth?
Suppose the answer of the this question was boulder if so the format was filled in that
manner but for the analysis purpose the investigator take inclusive name like, alluvial
deposit and under alluvial deposit, boulders, gravels, gravel sand and sand with fine gravel
.for example in the case of encounter problems ;hammer cutting, damaging drill machine
and breakdown of top of drill machine were included under the category of equipment
damage and this logic was applied on other variables under investigation.
5.2. Case Study
In fields like drilling it would not be surprise if one gives more attention to the happening
data rather than the theoretical approaches (Abebe, 1999). Based on the broadly described
theoretical background information trying to understand down problem and then acting
accordingly is the only way out to tackle faced drilling and completion problems (Abebe,
Commented [u65]:

of 121
1999). To make practical such an approach, information on actual practical experiences
have to be collected, discussed, analyzed and the final findings be noted and compiled in
a manner that they can be useful for future reference and exchange of experience. About
ninety-five boreholes were collected from the study area (Northern zone of Afar).
The collected data were filled in a format that contains the following information.
➢ The localities of the wells (Wworeda) where the drilling problem encountered during
drilling
➢ At what depth of wells the drilling problems were encountered
➢ which geological formation the drilling problems were encountered
➢ Drilling methodology that were applied on the wells when drilled
➢ Drilling institutions who were drilled the wells
➢ The assumed causes that were responsible for the encountered problems
Table: 1 Sample of Questioner’s format
Site name
Location
(woreda) Depth (m)
Encounter drilling
problems
Geological
formation
(unit)
Drilling
method
Drilling
institution Causes
1.Ararahu Barahle 80 Pipe stacking
Alluvial
deposit DTH private technical
2.muluhtaf
bh#1 Dallol 75
Surface borehole
collapse, bit broken granite DTH
DTH private
Technical
and
technolog
ical
3.balbel
bh#1 Kunaba 114 Sever collapse
Alluvial
deposit DTH Private technical
4.nama
gubi#3
Afdera 32
The water became
highly saline Silty clay
Direct
mud
rotary Governmental
Geologica
l
5.Urkudi
Abaala 56
Cutting did not came
to surface
clay with
fine gravel
DTH Private
Technolo
gical
6.aytinaba Erebti
80,
100,
120 &
180 Sever circulation loss
Highly
fractured
limestone
Direct
mud
rotary governmental
Geologica
l
7.Dermena Magale 150
Damaging drill
machine
Ttrachyt direct
mud Private
Technolo
gical
Commented [u66]: No need
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Commented [F67]: Which one is the depth of the Borehole?
Formatted: Centered
Formatted: Centered
Formatted: Centered

There were seven variables in the Questioner sheet seven of them analyzed using
Statistical Package for Social Sciences (SPSS Version 20.0) and the descriptive result of
the variables are as follow.
Table 2: summaries of descriptive analysis of considered parameters (variables) during
interviews and supervision
In order to see the drilling problems in terms of locality I take locality as one the
parameters to be analyzed
Variable
Name
Sub
categories
of
variable
name
Frequency Percent
Localities
of wells
Dallol 23 24.2
Konaba 17 17.9
Afdera 13 13.7
Barahle 12 12.6
Abaala 11 11.6
Erebt 9 9.5
Magale 7 7.4
Bidu 3 3.2
Encounter
Problems
Stacking 29 30.5
Circulation
loss
11 11.6
Circulation
loss and
Stacking
13 13.7
Equipment
Damage
16 16.8
Collapse 16 16.8
Bad
Quality
10 10.5
Geological
formation
Alluvial
deposit
58 61.1
Limestone 10 10.5
Scoracious
Basalt
7 7.4
Commented [F68]: The number of wells mentioned in this table
is not compatible with the map that show the well distribution. Eg
the number of wells in Afdera is 13in the table but 4 in the map.

of 121
Others 20 21.1
At what
depth the
problems
encounter
<30 m 17 17.9
30-60 m 33 34.7
60-90 m 35 36.8
Above
90m
10 10.5
Table name??
Variable Name Sub categories of
variable name
Frequency Percent
Drilling
institution
Private 62 65.3
Governm
ental
33 34.7
Drilling
method
DTH 36 37.9
Direct
mud
54 56.8
Others 5 5.3
Cause of
problems
Technical 23 24.2
Geological 36 37.9
Technological 11 11.6
Technical and
Geological
21 22.1
Technical and
Technological
4 4.2
From this table one can understand the frequency of the variables and percentage.
The frequency and percent of the variables in this table originated from data collected
from the study area then coded and analyzed using Statistical Package for Social Sciences
(SPSS Version 20.0).
Formatted Table

Graph 2: percentage of localities of Drilled wells which at drilling problems Encountered during
drilling
This graph tells us ,at how many wells were problems encountered during drilling from
each administrative woredas in percentage the among the 95 wells .This mean not only in
this amount of wells were drilled with drilling problems in each woreda. But it means
that among the number of wells that were analyzed, which amount geographically belongs
to which woreda in percentage.
%Percent=number of wells included that were problems encountered during drilling
in the woreda divided by the total number of wells were included from each woreda
multiplies by hundred.
Commented [F69]: It is not labeled?
Commented [F70]: I am not clear with this comparison. I prefer
the spatial distribution of the boreholes to indicate where the
problem is/
Commented [F71]: Are this wells the total number of boreholes
drilled in the area or the number of boreholes encountered drilling
problem.
Commented [F72]: Is it from the total number of wells in each
locality taken or from the total number of wells encountered with
drilling problems? Are you comparing using the same number of
wells in each parameter or not

of 121
Graph 3: percentages of Encounter problems during drilling in the study area from collected
data.

Graph 4: Percent of Geological formations at which drilling problems are encountered
Under the category of “Others” in this graphs shale’s, Meta sediments and granite were
included.
Here “Geological formation “refers the geological unit at which the problems were face
during drilling.

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Figure 34: lithological logging of four wells which the drilling problems were encountered at
alluvial deposit at different depth
Commented [F73]: The log is not clear

Graph 5: Percent of Depth of drilled wells at which Drilling problems are encountered
Considerations taken during assignation of coded depth for the encountered problems,
similar problems encountered at different depth in the well, in this case the frist depth
which the problems were encountered taken and assign. for example Aytinaba site in
Erebt, at 80 meter, 100m, 120m and 180m sever circulation loss was occurred that were
resulted abandoned of the well .during the data assignation assignment on SPSS first
depth which is 80meter taken and this logic was applied in another cases for example, in
the case of wells that were different drilling problems encountered during drilling at
different depth taking the first depth which problem encountered logic was again applied.
As an example; MW#19 site in Dallol circulation loss encountered at 46m, stacking at
66m and hole deviation at 80m. In this case 46m was taken as the response for the question
at what depth the problem encountered. The reason behind this logic is the limitation of
Commented [F74]: What is your reason or base to decide the
depth you put here?
Commented [F75]: Avoid long statements and try to correct the
Grammer.

of 121
the software Statistical Package for Social Sciences cannot analyze multi cases for one
variable.
Graph 6: Drilling institution that were drilled the wells which the drilling problems encountered
during drilling
Since drilling institution is an organization that established from man powers to handle
drilling (drillers, drilling equipment mechanics, electricians and hydrogeologists) and
drilling equipment to drill. So the ability to hire well experienced manpower and
supplying drilling equipment that enables to complete the planned drilling activity can
varies from institution to institution. It should be noted that the integrity of drilling
equipment and its maintenance are major factors in minimizing drilling problems.
Generally drilling institutions are the key to the success or failure of drilling operation.
Commented [F76]: Does this have significant implication?

Graph 7: Percent of type of Drilling method that were applied during drilling
In this graph under the category of “Others” includes wells were drilled both DTH and
direct mud rotary method used together and coring

of 121
Graph 8:-Reasons (causes) that were responsible for the encountered drilling problems
5.3 Result of Analyses and Interpretation
5.3.1 Konaba area
Ffrom over all cases that was collected and analyzed for this research koresearch kounaba
holds 17.9% among this percent equipment damages, collapse and stacking accounts
7.37% ,6.32% and 4.21% respectively so we can say that the most frequent problems that
were encountered during drilling in cases of konaba were equipment damage, collapsing
of bore hole and stacking of drill tools. Among this problems 6.32% were occurred at the
depth interval of 30-60m, 5.26% were occurred at the depth interval of 60-90m ,4.21%
at depths less than 30m and only 2.11% (11.79%) were occurred depths greater than 90m.
Sso the depth interval 30-60m were the most challenging depths which was were
Commented [F77]: Why is repeated

35.3%(6.32%) of the encountered problems were occurred. The statistical analyses result
of geological formation at which the drilling problems were encountered indicates more
than 76% of the geological formation was alluvial deposit and 23.5% was granite, among
the seventeen (17) wells of kunaba that were included in the data analyses all wells were
drilled by private drilling institution and more than 88% of the wells were drilled by using
DTH drilling method. According to the statistics, the causes that were wasresponsible for
encountered drilling problems encountered in the case of konaba were poor technical
performance, technological defects, poor technical performance and unfavorable
geological conditions and poor technical performance and technological defects were the
responsible causes for the problems encountered during drilling in this locality.
Here below there is graph that show the contribution of each causes
Graph 9: cause of problem versus localities
From this graph one came up with the conclusion can understand that the most dominant
causes which were responsible to be occurred for drilling problems in the case of konaba
was poor technical performance. .Tthis factor was responsible for more than 35.3% of the
encountered drilling problems in the area and the second most frequent cause why the
drilling problems were encountered in the konaba was technological defects which holds
Commented [F78]: Konaba or Kunaba?
Commented [F79]: Why zero at the lower part of Technical,
geological. Technological, Technical and Technological? There is
also difference between the count in this diagram and table2.
Commented [F80]: Contribution Percentage of each problem in
each locality
Commented [F81]: We cannot read this figure from the diagram
above?

of 121
more than 23.5% of the cause of the problems encountered during in the area. Problems
that were encountered due to poor technical performance and unfavorable geologic
condition accounts more than 17.65% and problems encountered poor technical
performance and technological defects were also accounts more than 17.65%.
Selective cases among the wells that were analyzed from kunaba, the borehole in balbel
selected to discuss in detail.
In this site starting drilling was unthinkable by drilling machine because of the existence
of big boulders. So the remedies taken toTo mitigate the problem drilling was conducted
by removing the five meters boulder material by digging and refilling by clay material
and proceed again the drilling. be start the drilling was digging the bore hole by labor up
to 5m in depth really it was cobbles seen not boulders during the digging. To reach the
depth of 5meter was took five consecutive days and when they reach that depth, stopped
digging by hand and then starting backfilling of the excavated hole, to bring clays that
used for back fill of the excavated borehole the contractor was gone the distance around
27meter more than seven times because there was only a service vehicle’s on the site.
tThe clay that have been bring couldn.t succeeded the aim why they it bring, so in order
to narrow the large diameter excavated by hand and to continue further drilling using
another alternative became obligation for the contractor. Then the driller and the owner
of drill machine agreed to fill the boreholes with smooth flat big rocks one overlapping
the other both sides of the holes and filling the gap between the big rock by boulders then
on top of the smooth flat big rock sacks filled with sand overlaid and grouted by cement
after some hours later drilling began with the DTH drilling methodology. After the
drilling reached the depth of 10m due to drop down of boulder stacking of drill pipe
occurred this problem was tackle using foams, then temporary surface casing installed up
to 8m when drilled depth reach at 10m some sacks that were filled with sand lowered and
grouted cement was burst then compressor shut off by itself and hoes was bursting. The
compressor taken further maintenance to Mekele, after days the stacked tools removed
from the boreholes and the bore hole collapsed with temporary surface casing abandoned.
All this activities were conducted by the order of owner of drilling machine, there was no
any geologist that follows and guides the driller. Ggenerally private drilling institution
that were conduct drilling in kunaba had not site geologist.in the case of this site the
above?
above?
above?
Commented [F85]: In this area conducting drilling is very
difficult due to the existence of boulders on the top five meters
depth.
Commented [F86]: Use either konaba or kunaba?

newly graduated fresh geologist that was conduct Part-time milestone supervision was
allocated on side of client which have no any idea about drilling.
For this site the recommended drilling method was both DTH and direct mud rotary
during investigation and the contractual agreement to drill was taken by the regional
drilling enterprise and they gave it to subcontract for this private driller.
After the abandoned of this drilling site, mobilization of the machine to 10m air distance
from a site and starting drilling there and when the drilling started the supervisor after the
communicated with his senior geologist he gave order to shift their drilling methodology
from DTH to direct mud rotary but the driller and his chief driller was un not willing to
shift from the method they know which was DTH. The driller told us he have no any
experience in direct mud rotary drilling. The owner of drill machine and his driller
response for the supervisor we will make the well productive but any means the drilling
continues with facing drilling problems like stacking and with repeated failure of driller
machine like bursting of hoes ,stopping compressors it functions, breaking of shovels of
drill machine up to 114m,the target depth was 140m but due to the repeated failure of
machine and the repeated stacking due to the nature of geology they agreed to stop further
drilling and installs of casing. Before the installation of casing the supervisor ordered the
driller to the flushed and reamed up to the depth of the well which reached. For this
purposes installation of 19 drill pipes were conducted and starting flushing. During
flushing of the well ejection of water which incorporated with big boulders that were
move a long distance horizontally and vertically had been occurred and there were surface
collapse near the hole, after a few minutes the whole borehole collapsed that was resulted
loosing 19 drill pipe with hammer bit. The collapse was occurred due to poor
performance of the driller and the technological defects of the drilling machine, the
contractor immediately requested the supervisor to bring him other site within the area.
The supervisor response to him Ican.t select a drilling site what I can do only is
supervising selected sites for drilling so what you are asking me beyond of my capacity
and power. The contractor contacted with senior geologist that was conducted
investigation study for the site, and senior geologist contacted with a fresh supervisor and
told to him the suggested points by phones and then supervisor gave him a site and a drill
machine had mobilized from the collapsed site to newly shifted one due to the losing of

of 121
all drill tools with drill hammer was remained in the well which collapsed, in order to
start drilling the contactor move mekele to bring drill tools after two days drilling was
started with rock roller hammer by applying the DTH drilling methodology, when the
drilling reached 35m due to encountering big boulder that caused stacking of hammer bit
ended with breaking down and losing in it, when this happened there was no geologist at
the site then the contractor himself moved again and sited on the bottom of mountains
that is not preferable for groundwater occurrences to make a site suitable for himself,
after four days later the supervisor came and told to them he is responsible and will not
sign of takeoff sheet. Then contractor creates a propaganda that the supervisor is not
interested to drill safe water for local community and there were opposition from
community to the supervisor then he inform his chief and agreed to continue drilling if
the contractor agreed if there is no water ,not asking to any payment. Even the drilling
was conducted on the rock the breakdown of materials was continued because of the two
main reasons lack of experience of driller and the repeated breakdown of drilling machine.
With full of problems the drilling reached 90m up to encountering basement rock. To
complete the well was take more than a month’s.
The lithological description of this well as follow
Table 3:-lithological description of belbel Belbel site
DEPTH
RANGE
(m)
THICKN
ESS, (m)
FROM TO
0 10 10 Boulders & gravels
10 15 5 Fractured black limestone
15 20 5 Highly weathered marl
20 27.5 7.5 Highly weathered & moderately fractured marl
27.5 40 12.5 Highly weathered & moderately fractured
meta-limestone
40 52.5 12.5 Highly weathered & highly fracured black
limestone
52.5 70 17.5 Moderately fractured & weathered black
limestone
70 85 15 Moderately fractured & slightly weathered
black limestone
85 100 15 Fresh massive limestone
Commented [F87]: I feel this is too detail to discuss here.

Table 4:-Casing arrangement the borehole of the belbel borehole
DEPTH RANGE,
(m)
CASING TYPE DIAMETE
R
(inch)
LENGTH
, (m)
FROM TO
(+)0.75 10.00 Steel Surface
casing
14 10.75
(+)0.751
0
31.60 PVC blind 8 32.35
31.60 37.30 PVC Screen 8 5.70
37.30 43.00 PVC blind 8 5.70
43.00 54.40 PVC Screen 8 11.40
54.40 60.10 PVC blind 8 5.70
60.10 71.50 PVC Screen 8 11.40
71.50 100.0
0
PVC blind 8 28.50
The casing arrangement and lithological description was done by fresh geologist
During development he the well was compressor estimated yield was 3l/s and but after
pumping during pump test the discharge yield of the well was 1.5l/s. Bbased on this
report the client sent professional to the make civil work and for this purpose the client
arrange crane, pick up car and four professions moved a distance around 500km from the
samara to belbel site. The reported amount of water was not there and they couldn.t install
pump and because of that the civil work was not conducted.
We can summarized that the project already fail and the cause of failure was
➢ Inappropriate selection of drilling methodology
➢ Failures due to lack of expertise or inexperience and poor performance of the driller
➢ Failures caused by poor supervision
➢ Weak management follow up
➢ Technological defects
So generally these can categorize under the poor technical performance and technological
defects.
Formatted: Justified
Commented [F88]: I am nor clear with this statement?
Commented [F89]: Not clear! Better to remove.
Please focus on the drilling problems.

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