2D Seismic Data Interpretation and Volumetric Analyis of Dhulain Area, Upper Indus Basin, Pakistan
1.
2. 2-D SEISMIC DATA INTERPRETATION AND
VOLUMETRIC ANALYSIS OF DHULIAN AREA
UPPER INDUS BASIN, PAKISTAN.
FASIH AKHTAR
WASEEM ABBAS
HASNAIN ZAHOOR AWAN
SUPERVISOR: M. FAHAD MAHMOOD
EXTERNAL SUPERVISOR: Mr. SARMAD HASSAN SHARIF
2010-2014
3. OUTLINE OF PRESENTATION
Introduction Of the Area
Objectives
Methodology Adopted
Overview of Potwar Sub Basin
Petroleum System
Seismic Interpretation
Petrophysical Analysis
Conclusions
4. OBJECTIVES
To carry out the seismic data interpretation and mapping of the area
in order to understand the subsurface structural geometry of
Dhulian anticline.
Preparation of Time and Depth Sections
Petrophysical Analysis of Dhulian-43 well to understand the
reservoir potential of the structure.
Volumetric Analysis of the area to calculate remaining potential of
the structure.
5. AREA OF INVESTIGATION
The Study area of Dhulian is located in the Eastern
Potwar basin.
The Dhulian Area is bounded by Latitude 33 12'41“N
and Longitude 72 12'00“E.
The Nearest city to the Dhulian study area is Pindi Gheb.
Oil was also discovered for the first time in Indo-
Pakistan from Paleocene reservoirs, during further
appraisal of Dhulian structure.
7. A total of 49 wells were drilled in Dhulian oil field
Three wells have been drilled by Attock Oil Company
(A.O.C.)
46 wells have been drilled by Pakistan Oilfields Limited
(P.O.L)
Seven wells did not reach objective reservoirs and three wells
could not be put on production due to various technical
reasons.
14. STRUCTURE
Dhulian fold is flanked by the Soan Syncline to the south and by the
tight Pindi Gheb syncline to the north
The Dhulian structure was originally thought to be a conventional
anticline with a fold axis trending northeast southwest.
Based on this new seismic evidence, Dhulian structure was proved to
be a thrust-bounded salt-cored anticline,
It is cut across by a major wrench fault that splits Dhulian into two
major fault blocks
As a result, the Dhulian structure may be compartmentalized.
17. Depth Contour Maps
Time to Depth Conversion
Velocity Analysis
Time Contour Maps
Time Picking
Marking of Faults
Marking of Prominent Reflectors
T-D Chart
METHODOLOGY
18. DATA USED
Line
Name
PDK-102 PDK-103 PDK-104 PDK-113
WELLDATA
Line Dip line Dip line Dip line Strike line
DHULIAN-43
(Gamma ray
log, Neutron
Log and
Resistivity logs)
Line
Direction
North-South North-South North-South East-West
SP Range 108-188 108-218 108-298 108-340
Date
Recorded
1981 1981 1981 1981
21. SEISMIC SEQUENCES & REFLECTION
FEATURES
In the study area four sets of seismic sequence are encountered on the basis of
seismic reflection features.
Sequence 1: Continuous and Dark reflectors at the bottom of Seismic Section
stands for the basement of Pre-Cambrian age.
Sequence 2: Strong to medium continuous reflections, great change in
thickness, it is Infra Cambrian aged Salt Ranges Formation composed of salt
and evaporates. A great decollement plane is development.
Sequence 3: Parallel and continuous reflections high amplitude and
frequency. It stands for Paleocene –Eocene ages formation. The traditional
reservoirs in Potwar were developed in this sequence.
Sequence 4: Parallel and weak to continuous reflections. It stands for
Miocene aged Mollasse architecture.
22. REFLECTORS MARKING
In total three horizons have been mapped throughout the study
1. Chorgali Formation (Eocene)
2. Lockhart Formation (Paleocene)
3. Wargal Formation (Permian)
These three horizons comprise the target horizons for
hydrocarbon exploration in the study area.
Chorgali Formation was picked as it is a very strong
reflector beneath the Kohat Formation i.e. Eocene
23. Lockhart Formation (Paleocene) was picked in the base of
decreasing acoustic impedance from Nammal Formation
to Patala Formation and then increasing peak of Lockhart
Formation.
Wargal Formation was picked below to Lockhart
Formation. The reflection continuity is fair to good.
32. TIME CONTOUR MAPS
Contouring the time structure maps and finding structural traps are
one of the basic goals of Seismic data interpretation.
In this respect three time contour maps have been prepared on three
different horizons in the whole area at the scale of 1:50, 000.
1. Time Contour Map of Chorgali Formation (Eocene)
2. Time Contour Map of Lockhart Formation (Paleocene)
3. Time Contour Map of Wargal Formation (Permian)
33. TWT Map on Top Chorgali of Dhulian D & P
Lease
TIME CONTOUR MAP OF CHORGALI
FORMATION
34. TWT Map on Top Lockhart of Dhulian D & P Lease
TIME CONTOUR MAP OF LOCKHART
FORMATION
35. TWT Map on Top Wargal of Dhulian D & P Lease
TIME CONTOUR MAP OF WARGAL
FORMATION
36. DEPTH CONTOUR MAPS
The following depth maps have been prepared at the scale of
1:50,000 with respect to mean sea level.
1. Depth Structure Map of Chorgali Formation
2. Depth Structure Map of Lockhart Formation
3. Depth Structure Map of Wargal Formation
These maps have been prepared mainly using the drilling well tops
available on different wells in Dhulian area.
40. PETROPHYSICAL ANALYSIS
Well Dhulian-43.
Located on:
Lattitude 33 12'41“N
Longitude 72 12'00“E.
Total Depth:
3788 meters
Interpretation is done on Chorgali and Lockhart Formation.
41. WORK FLOW
Marking of
Zone of
Interest
Lithology
Identification
Volume of
Shale
Effective
Porosity
Total
Porosity
Saturation of
Water
Saturation of
Hydrocarbon
Summation
42. MARKING ZONE OF INTEREST
Formation
Starting depth
(m)
Ending depth
(m)
Total thickness
(m)
Chorgali
Fm
2494m 2560m 66m
Lockhart
Fm
2783m 2839m 56m
63. N = 7758 * GRV * N/G * Φ * So * 1/Bo
Where
7785 = Conversion factor (acre-ft*7758 =barrels)
GRV = Gross Rock Volume (acre-ft)
N/G = Net to Gross Ratio (decimal)
Φ = Porosity of this net reservoir rock (decimal)
So = Oil Saturation (decimal)
Bo = Formation Volume factor.
VOLUMETRIC RESERVE ESTIMATION
64. RESULT OF VOLUMETRIC RESERVES
Reserve Calculation
(7758*Area(acre)*Net Pay(ft)*Avg. Porosity(phi)*Sw)/Bg
Formation Case Contour
Area
(Acre)
Net Pay
(ft)
Phi avg.
(fraction)
Sw avg.
(fraction)
Bo
OIIP
(MMBL)
Recovery
Factor
Recoverable
Reserves
(MMBL)
GOR
(scf/stb)
Gas
Recovery
(BCF)
Chorgali
P90 2470 3706 130 0.05 0.28 2.047 65 30 19.5 1975 38512.5
P50 2600 6177 130 0.05 0.28 2.047 109 30 32.7 1975 64582.5
P10 2700 9884 130 0.05 0.28 2.047 175 30 52.5 1975 103687.5
65. CONCLUSIONS
The multifold seismic acquired by OXY and POL demonstrated that Dhulian
subsurface structure is more complicated than what was originally thought.
The structure is a three way dip closure bounded by thrust fault.
Based on this new seismic evidence, Dhulian structure was proved to be a
thrust-bounded salt-cored anticline.
It is cut across by a major wrench fault that splits Dhulian into two major fault
blocks.
66. RECOMMENDATIONS
For more detailed study and to define potential sites in the area, more
seismic lines are required.
High resolution seismic data and wire line logs should be acquire in future
operations.
3D seismic survey should acquire in future to obtain the maximum
information of subsurface.
67. REFERENCES
Dolan P., (1990) Pakistan: a history of petroleum
exploration and future potential; in Classic
Petroleum province edited by Brooks J. Special
Publication of The Geological Society London
Iqbal B. Kadri, (1995), Petroleum Geology of
Pakistan
Khan M. A. Ahmed R., Raza H. A., and Kemal A.,
(1986), Geology of Petroleum in Kohat-Potwar
depression, Pakistan, AAPG Bulletin, Vol 70, No. 4
Iqbal, M.W.S, and Shah, S.M.I, 1980. A guide to the
Stratigraphy of Pakistan.V.53
