This document provides an overview of well logging concepts and techniques. It discusses key well log formats and presentations, including standard tracks used for depth, resistivity, porosity, and other measurements. Common logs like SP, gamma ray, resistivity, neutron, and density are examined. Signatures indicating lithology, fluid content, and invasion are described. Proper interpretation requires understanding scales, crossovers caused by lithology changes, and matrix effects. An example of logs in a horizontal well is also provided.
WELL LOG : Types of Logs, The Bore Hole Image, Interpreting Geophysical Well Logs, applications, Production logs, Well Log Classification and Cataloging
Introduction
Petrophysic of the rocks
It is the study of the physical and chemical properties of the rocks related to the pores and fluid distribution
Porosity, is ratio between volume of void to the total voids of the rock.
Permeability, is ability of a porous material to allow fluids to pass through it.
Electric, most of the sedimentary rocks don’t have conductivity.
Radiation, clay rocks have 40K, radiate alpha ray.
Hardness, it depends on the cementing material and thickness of the sediments.
WELL LOGGING
The systematic recording of rock properties and it’s fluid contents in wells being drilled or produced to obtain various petrophysical parameters and characteristics of down hole sequences (G.E Archie 1950).
The measurement versus depth or time, or both, of one or more physical properties in a well.
These methods are particularly good when surface outcrops are not available, but a direct sample of the rock is needed to be sure of the lithology.
A wide range of physical parameters can be measured.
In some cases, the measurements are not direct, it require interpretation by analogy or by correlating values between two or more logs run in the same hole.
Provide information on lithology, boundaries of formations and stratigraphic correlation.
Determine Porosity, Permeability, water, oil and gas saturation.
Reservoir modeling and Structural studies… etc.
Types of Well Logging
Logs can be classified into several types under different category
Permeability and lithology Logs
Gamma Ray log
Self Potential [SP] log
Caliber log
Porosity Logs
Density log
Sonic log
Neutron log
Electrical Logs
Resistivity Log
For contact : omerupto3@gmail.com
well logging project report_ongc project studentknigh7
It briefs well logging basics for students of geophysics on well logging or partly on reservoir characterization. It can be good note book for summer ,winter training in well logging data analysis and open hole log interpretation
WELL LOG : Types of Logs, The Bore Hole Image, Interpreting Geophysical Well Logs, applications, Production logs, Well Log Classification and Cataloging
Introduction
Petrophysic of the rocks
It is the study of the physical and chemical properties of the rocks related to the pores and fluid distribution
Porosity, is ratio between volume of void to the total voids of the rock.
Permeability, is ability of a porous material to allow fluids to pass through it.
Electric, most of the sedimentary rocks don’t have conductivity.
Radiation, clay rocks have 40K, radiate alpha ray.
Hardness, it depends on the cementing material and thickness of the sediments.
WELL LOGGING
The systematic recording of rock properties and it’s fluid contents in wells being drilled or produced to obtain various petrophysical parameters and characteristics of down hole sequences (G.E Archie 1950).
The measurement versus depth or time, or both, of one or more physical properties in a well.
These methods are particularly good when surface outcrops are not available, but a direct sample of the rock is needed to be sure of the lithology.
A wide range of physical parameters can be measured.
In some cases, the measurements are not direct, it require interpretation by analogy or by correlating values between two or more logs run in the same hole.
Provide information on lithology, boundaries of formations and stratigraphic correlation.
Determine Porosity, Permeability, water, oil and gas saturation.
Reservoir modeling and Structural studies… etc.
Types of Well Logging
Logs can be classified into several types under different category
Permeability and lithology Logs
Gamma Ray log
Self Potential [SP] log
Caliber log
Porosity Logs
Density log
Sonic log
Neutron log
Electrical Logs
Resistivity Log
For contact : omerupto3@gmail.com
well logging project report_ongc project studentknigh7
It briefs well logging basics for students of geophysics on well logging or partly on reservoir characterization. It can be good note book for summer ,winter training in well logging data analysis and open hole log interpretation
EAGE Paper (2013) by Dr. Ron Masters, Geoscience Advisor, Headwave, Inc.
In this paper, we present a method that can unequivocally identify AvO anomalies, even if they have not previously been recognized as prospects, even if they have not been mapped. It does not require any prior knowledge about local conditions in the subsurface, or about which AvO class is locally likely to indicate reservoirs and hydrocarbons. Of course, quantitative interpretation of vital reservoir characteristics like porosity and saturation remains essential and still requires deep expertise.
With the improvements in seismic processing over two decades, we can now consider polarity and phase as well as amplitude and spatial extent. Frequency, velocity, amplitude/offset and shear wave information can also help in the positive identification of hydrocarbon indicators
Advanced logging evaluation gas reservoir of Levantine basinFabio Brambilla
Experience gained in recent activity in the Levantine basin has allowed for the development of a formation evaluation strategy for accurate gas reservoirs description in this region. The proposed evaluation approach considers operational issues of deep water wells, challenging borehole conditions (high salinity mud, deep invasion) and other geological features of these clastic reservoirs and their fluids. Our case study highlights benefits of the integrated evaluation of new laterolog resistivity data together with 2D NMR inversion results optimized for a gas bearing reservoir. Furthermore borehole imaging logs are included in our evaluation approach. The recently developed multi laterolog tool has an advantage of four multiple depths of investigation. It provides a detailed high 1ft vertical resolution radial resistivity profile overcoming the deep invasion often present in these reservoirs. The NMR acquired in gas oriented acquisition mode exploits the multi-frequency capability of the logging device. Combined together multiple G•TE and multiple TW experiments contribute to robust determination of the T1 and T2 reservoir fluid properties. This acquisition sequence allows for continuous hydrocarbon typing applying the T1/T2 vs T2 2D maps method, which is practical for these reservoirs given the T1 contrast between gas and other fluids. Consequently we are able to perform accurate HI corrections and therefore improve the estimates of NMR permeability and saturations. Further in the workflow we compare NMR and Stoneley wave permeability’s and assess in details their differences. The geological study performed with the combination of simultaneously acquired ultrasonic and resistivity borehole images provides additional insight into the reservoir architectures, taking advantage during the analysis of the different logging responses of the petrophysical factors to acoustic and resistivity investigation for a detailed delineation of the productive beds. The advantages of this integrated approach are illustrated with field data examples.
Avo ppt (Amplitude Variation with Offset)Haseeb Ahmed
AVO/AVA can physically explain presence of hydrocarbon in the reservoirs and the thickness, porosity, density, velocity, lithology and fluid content of the reservoir of the rock can be estimated.
Well logs can be states as “a recording against depth of any of the characteristics of the rock formations traversed by a measuring apparatus in the well-bore.”
The spontaneous potential log, commonly called the self potential log or SP log, is a passive measurement taken by oil industry well loggers to characterise rock
Palestine last event orientationfvgnh .pptxRaedMohamed3
An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
This presentation provides a briefing on how to upload submissions and documents in Google Classroom. It was prepared as part of an orientation for new Sainik School in-service teacher trainees. As a training officer, my goal is to ensure that you are comfortable and proficient with this essential tool for managing assignments and fostering student engagement.
The Indian economy is classified into different sectors to simplify the analysis and understanding of economic activities. For Class 10, it's essential to grasp the sectors of the Indian economy, understand their characteristics, and recognize their importance. This guide will provide detailed notes on the Sectors of the Indian Economy Class 10, using specific long-tail keywords to enhance comprehension.
For more information, visit-www.vavaclasses.com
This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
2. 1. Rudimentary definitions
2. hydrocarbons presence determination
3. hydrocarbons quantity and recoverability
determination
4. The Borehole Environment
3. 1. Reading A Log
2. Examples of Curve Behavior And Log Display
3. Electrical Properties Of Rocks And Brines
4.
5. Standard log presentation formats
Reading a log with ease
requires familiarity with
some of the standard log
formats.
The formats for
traditional logs and most
field logs are shown in
Figure.
It contains three tracks.
A narrow column
containing the depth is
found between track 1
and tracks 2 and 3.
The latter are contiguous
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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6. Different scale types
In the normal linear presentation,
the grid lines in all three tracks
having linear scales each with ten divisions
In the logarithmic scale
We have logarithmic presentation for tracks 2 and 3
Four decades are drawn to accommodate the electrical
measurements, which can have large dynamic ranges
scale begins and ends on a multiple of two rather than unity
In a hybrid scale
We have a logarithmic grid on track 2 and a linear in track 3
Electrical measurements that
may spill over from track 2 into track 3 will still be logarithmic
even though the indicated scale is linear
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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7. SP and GR log headings used for
clean formation determination
Figure shows the typical
log-heading presentation
for several of the basic logs.
The upper two
presentations show
two variations for SP,
which is always in track 1.
the SP decreases to the left
The bottom presentation
shows
the caliper,
a one-axis measurement of
the borehole diameter,
the gamma ray,
which are also generally
presented in track 1.
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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8. clean sections determination
The rule given for finding clean sections was that
the SP becomes less negative for increasing shale,
so that deflections of the SP trace to the right
will correspond to increasing shale content
The GR curve, as it is scaled
in increasing activity
(in American Petroleum Institute (API) units) to the right,
will also produce curve deflections to the right
for increasing shale content.
Thus the two shale indicators can be expected to
follow one another as the shale content varies.
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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9. The induction log heading and
schematic of the formation
Although modern tools
have a larger selection of
curves with different
depths of investigation,
the displays are similar
A traditional resistivity log
heading along with a
schematic indication of the
zones of investigation is
shown in the figure
three zones corresponding
approximately to the
simultaneous electrical
measurements of different
depths of investigation
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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10. dual induction-SFL
The particular tool associated with this format (previous slide)
is referred to as the dual induction-SFL and
will normally show three resistivity traces (units of ohm-m)
The trace coded ILD (induction log deep)
the deepest resistivity measurement and
correspond to Rt when invasion is not severe
The curve marked ILM (induction log medium)
is an auxiliary measurement of intermediate depth of penetration and
is highly influenced by the depth of invasion
The third curve, in this case marked SFLU (spherically focused log),
is a measurement of shallow depth of investigation and
reads closest to the resistivity of the invaded zone Rxo.
By combining the three resistivity measurements,
it is possible, in many cases,
to compensate for the effect of invasion on the ILD reading
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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11. Log headings
for three porosity devices
The top two correspond to
two possible formats
for simultaneous
density and neutron logs
The porosity is expressed as
a decimal (v/v) or in porosity
units (p.u.), each of which
corresponds to 1% porosity
The bottom
is the sonic log format
It is with the apparent transit
time Δt increasing to the
left.
In all three presentations,
the format is such that
increasing porosity produces
curve deflections to the left
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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12. matrix setting
in neutron and density logs
For the neutron and density logs,
another point to be aware of is the matrix setting
This setting corresponds to
a rock type assumed in a convenient pre-interpretation
that establishes the porosity
from the neutron and density device measurements
the matrix setting SS,
means that the rock type is taken to be sandstone
If the formations being logged are indeed sandstone,
• then the porosity values recorded on the logs
will correspond closely to the actual porosity of the formation
if the actual formation matrix is different, say limestone,
• then the porosity values will need to be shifted or corrected in
order to obtain the true porosity in this particular matrix
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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13.
14. An SP log over
a clean section bounded by shales
shale sections
The intervals of high SP
above 8,500 ft and
below 8,580 ft
The value of
the typical flat response
is called the shale base line
Sections of log
with greater SP deflection
(with a more negative value
than the shale base line)
are taken as clean, or
at least cleaner, zones
One clean section is
the zone between
8,510 and 8,550 ft
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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15. A GR and caliper log over the same
section as previous slide
Note the similarity between
the GR trace and the SP trace
GR (solid)
In the clean sections,
the gammy ray reading is
on the order of
15 to 30 API units,
while the shale sections
may read as high as
75 API units
the caliper (broken)
It follows much of the same
trend as GR because
the shale sections can
“wash out,”
• increasing the borehole size
compared to the cleaner
sand sections that retain
their structural integrity
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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16. An induction log over a water zone
with a HC zone above it
The shallow, deep, and
medium depth resistivity
curves are indicated.
The zone below 5,300 ft
is possibly water,
Assuming the resistivity of
the formation water
is much less
(i.e., the water is much
more saline) than the
resistivity of the mud
Mud resistivity effect:
the shallow resistivity
curve,
which for the most part
stays around 2 ohm-m
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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17. An induction log over a water zone
with a HC zone above it (Cont.)
At 5,275 ft,
a possible hydrocarbon zone
ILD is much greater
than in the supposed water zone
However, this increase in resistivity
may not be the result of hydrocarbon
presence.
A decrease in porosity
could produce the same effect for a
formation saturated only with water
The real clue here is that
even though the Rxo reading
has also increased
(means the porosity has decreased),
there is less of a separation
between the Rxo and Rt curves
than in the water zone.
This means that
the value of Rt is higher
than should be expected from the
porosity change alone.
By this plausible chain of reasoning,
we are led to expect that this zone
may contain hydrocarbons.
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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18. Sample neutron and density logs
the density-porosity estimate
(φd , or DPHI, on the log heading), in solid,
the dotted neutron porosity,
the compensation curve Δρ (or DRHO)
(The auxiliary curve Δρ)
indicates little borehole irregularity
is the correction which was applied to the
density measurement in order to correct
for mudcake and borehole irregularities
It can generally be ignored if it hovers about
zero, as is the case at certain depths.
Note, once again, the built-in assumption
that the matrix is sandstone.
Density and neutron derived
porosity equality:
the presence of liquid-filled sandstone is
confirmed.
(for the 20 ft section below 700 ft)
Density and neutron derived
porosity separation:
caused by an error in the assumed matrix or
by the presence of clay or gas
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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19. A neutron and density log
exhibiting gas in the formation
presence of gas from
a comparison of the neutron
and density logs.
With gas in the pores the
formation density is less than
with oil or water,
so that the apparent density
porosity is higher.
At the same time
the hydrogen content of gas is
less than oil or water
so the neutron porosity is
lower.
Thus, in the simplest of cases,
gas is indicated in any zone in
which
the neutron porosity
is less than
the density porosity.
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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20. The signature of shale on
a neutron and density combination log
Shale produces
the opposite effect
[rather than gas]
the neutron porosity
may far exceed
the density porosity
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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21. Neutron and density crossover
caused by changes in lithology
All of these generalities are
true only if the principal
matrix corresponds to the
matrix setting on the log.
The effect of having the wrong
matrix setting on the log
(or having the matrix change
as a function of depth)
is shown in Fig figure.
Several sections show
negative density porosity.
These are probably due to
anhydrite streaks,
• which, because of their
much higher density,
are misinterpreted
as a negative porosity.
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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22. An example of
an LWD log in a horizontal well
In track 1 is
the familiar GR along
with three curves indicating
the time delay between drilling
and the three types of
measurements made;
depth track
the tool rotation rate is there
Track 2 contains
two types of resistivity
measurements,
each with multiple
depths of investigation
that overlay in this example.
The third track contains
the LWD versions of
the neutron measurement (TNPH),
the density measurement (ROBB),
and the density correction (DRHB).
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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23. A basic set of logs for
performing a wellsite interpretation
clean and possibly
permeable zones
identification
an inspection of
the SP and GR
four clean, permeable
zones
labeled A through D
resistivity readings are
contained in the second
track.
What is the fluid in each
zone?
the lowest resistivity
values =water
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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24.
25.
26. electrical property measurements
An important component of the well logging suite
is
the measurement of
electrical properties of the formation.
These measurements deal with
• the resistivity of the formation or
• the measurement of spontaneously generated voltages.
o These voltages are the result of
an interaction between
the borehole fluid and
the formation with its contained fluids.
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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27. spontaneous potential
Historically, the first logging measurements were
electrical in nature.
The first log was a recording of
the resistivity of formations as a function of depth and
was drawn painstakingly by hand.
Unexpectedly, in the course of attempting
to make other formation resistivity measurements,
“noise” was repeatedly noted and
was finally attributed to a spontaneous potential.
• It seemed most notable in front of permeable formations.
Both of these measurements
are still performed on a routine basis today.
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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28. Resistivity
Resistivity is
a general property of materials,
as opposed to resistance,
which is associated with
the geometric form of the material
the dimensions of resistivity are
ohms-m2/m, or ohm-m
The units of its reciprocal, conductivity,
are Siemens per meter.
In well-logging,
milli Siemens per meter (mS/m)
a material of resistivity 1 ohm-m
with dimensions of 1 m on each side
will have a total resistance, face-to-face,
of 1 ohm.
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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29. Resistivity measurement
Thus a system to measure resistivity
would consist of a sample of the material
to be measured contained in a simple fixed geometry.
If the resistance of the sample is measured, the
resistivity can be obtained from the relation:
which becomes, using Ohm’s law:
This constant k,
referred to as the system constant,
converts the measurement of a voltage drop V,
for a given current I , into the resistivity of the material.
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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30. A schematic diagram of a mud cup
for determination of its resistivity
A current, I ,
is passed through the sample of
drilling fluid and the corresponding
voltage, V, is measured.
the system constant can be
calculated to be 0.012 m.
The resistivity, ρ, in ohm-m, is then
obtained from the measured
resistance R by:
a sample of salt water with a
resistivity of 2 ohm-m in the
chamber would yield a total
resistance of 166 ohms
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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31.
32. Resistivity values
There are two general
types of conduction:
electrolytic and
the mechanism is
dependent upon the
presence of dissolved
salts in a liquid
• such as water
electronic
Examples of electronic
conduction are provided
by metals, which are not
covered here
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33. Resistivity in different materials
Notice the range of resistivity variation for salt water,
which depends on the concentration of NaCl.
Typical rock materials are in essence insulators.
The fact that reservoir rocks have any detectable
conductivity is usually the result of
the presence of electrolytic conductors in the pore space.
The conductivity of clay minerals is also
greatly increased by the presence of an electrolyte.
In some cases, the resistivity of a rock may result from
the presence of metal, graphite, or metal sulfides.
Fall 13 H. AlamiNia
Well Logging Course: Getting familiar with logs
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34. sedimentary rocks resistivity
the resistivity of formations of interest may range
from 0.5 to 103 ohm-m, nearly four orders of magnitude.
The conductivity of sedimentary rocks
is primarily of electrolytic origin.
It is the result of the presence of water or
a combination of water and hydrocarbons
in the pore space as a continuous phase
will depend on
the resistivity of the water in the pores and
the quantity of water present.
To a lesser extent, it will depend on
lithology of the rock matrix, its clay content, and its texture (grain
size and the distribution of pores, clay, and conductive minerals).
will depend strongly on temperature
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Well Logging Course: Getting familiar with logs
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35. Determination of the resistivity of an
NaCl solution f(NaCl concentration, T)
the resistivity
of saltwater
(NaCl)
solutions is a
function of
the
electrolyte
concentration
and
temperature
G/G
is grains per
gallon
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Well Logging Course: Getting familiar with logs
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36. 1. Ellis, Darwin V., and Julian M. Singer, eds. Well
logging for earth scientists. Springer, 2007.
Chapter 2 and 3