Hydrocarbon Reservoir Evaluation and Fault Seal Analysis of Balkassar Area, Potwar Sub Basin, Pakistan
Abstract
Balkassar oilfield is one of the major hydrocarbon producing field in Potwar Plateau, Upper Indus
Basin, Pakistan. This field has been producing oil and gas from fractured carbonate deposits of Eocene
and Paleocene age. So, in order to delineate the hydrocarbon potential of the Balkassar area, 2D seismic
interpretation and petrophysical analysis has been carried out and is represented in the current study
using five seismic lines and one well. Balkassar field is geographically located in central part of Potwar
Sub-basin. Geologically it is located in Himalayan foreland fold and thrust belt, which is dominated by
thrusting and folding features. The salt tectonics is responsible for the formation of structural traps in
Balkassar area. The direction of deformation is in NW- SE direction. The main reservoir formations of
Balkassar area are Chorgali Formation and Sakesar Limestone which are charged by shales of Patala
Formation of Paleocene age. Formations were identified on the seismic section on the basis of timedepth
chart and well tops. Petroleum trap is a structural trap where major thrust and back thrust bound
the anticline, and sealing impact is provided by both clays of Murree Formation and faults which is
further confirmed through fault seal analysis (Allan diagram). One reservoir zone has been identified in
Chorgali Formation using petrophysical analysis, which indicates effective porosity of 3.08%, 40.5%
water saturation and 59.5% hydrocarbon saturation. Based on the statistical analysis performed, it is
concluded that the Chorgali Formation is more economically promising as compared to Sakesar
Limestone. Volumetric reserves calculation is done to estimate the volume of original oil in place (OOIP)
for the Chorgali Formation, which comes out to be 18.6 Million Barrels for P90 case.
References
[2] E.C. Rankey and J.C.Mitchell, “That's why it's called interpretation: impact of horizon uncertainty on seismic attribute analysisâ€, Lead. Edge, vol. 22, pp. 820-828, 2003.
[3] C.E. Bond, C.Philo and Z.K.Shipton, “When there isn't a right answer: interpretation and reasoning, key skills for Twenty-first century geoscienceâ€, Int. J. Sci. Educ., vol. 33, no. 5, pp.629-652, 2011.
[4] B.A. Shami and M.S. Baig, “Geomodeling for the enhancement of hydrocarbon potential of Joya Mair field, Potwar, Pakistanâ€, PAPG, SPE, ATC, Islamabad, pp. 124-145, 2002.
[5] I.A.K. Jadoon, W. Frisch, T.M. Jaswal and A. Kemal, “Triangle zone in the Himalayan foreland, north Pakistanâ€, Special Paper of the Geological Society of America, vol. 328 pp. 277–286, 1999.
[6] R.J. Lillie, G.D. Johnson, M. Yousaf, A.S.H. Zamin, and R.S. Yeats, “Structural development within the Himalayan foreland fold-and-thrust belt of Pakistan, In: Sedimentary Basins and Basin-forming Mechanismsâ€, Canadian Society of Petroleum Geologists, Memoir, no. 12, pp. 379-392, 1987.
[7] R.W. Butler, M.P. Coward, G.M. Harwood and R.J. Knipe, “Salt control on thrust geometry, structural style and gravitational collapse along the Himalayan mountain front in the Salt Range of northern Pakistanâ€, Dynamical Geology of Salt and Related Structures, pp.339-418, 1987. Academic Press.
[8] D.A. Pivnik and W.J. Sercombe, “Compression- and transgression-related deformation in the Kohat Plateau, NW Pakistanâ€, Geological Society Special Publication no. 74 (eds. Treloar,P.J. and Searle, M.P.), pp. 559-580, 1993.
[9] T.M. Jaswal, R.J. Lillie and R.D. Lawrence,“Structure and Evolution of the Northern Potwar Deformed Zone Pakistanâ€, AAPG Bulletin, no. 81, pp. 308-328,1997.
[10] M. Riaz, P. Nuno, T. Zafar and S. Ghazi, 2 D seismic interpretation of the meyal area, Northern Potwar deform zone, Potwar Basin, Pakistan, Open Geosci. vol. 11, no.1, pp. 1-16, 2019.
[11] E.R. Gee, “Further note on the age of the saline series of the Punjab and of Kohatâ€, Proc. of the Indian Academy of Sciences Section B, vol. 16, pp. 95-153, 1947.
[12] S. Ghazi, N. Mountney, A. Butt and S. Sharif, “Stratigraphic and Paleo environmental framework of the Early Permian sequence in the Salt Range, Pakistanâ€, J. Earth Syst. Sci., vol. 121, no. 5, pp. 1239–1255, 2012.
[13] S.I. Shah, “Stratigraphy of Pakistanâ€, Government of Pakistan Ministry of Petroleum & Natural Resources, Geological Survey of Pakistan, GSP, pp. 245-273, 2009.
[14] I.B. Kadri, “Petroleum geology of Pakistan, sedimentary basins and their evolutionâ€, Pakistan Petroleum Limited, 32pp, 1995.
[15] A.H. Kazmi and I.A. Abbasi, “Stratigraphy & historical geology of Pakistanâ€, Department & National Centre of Excellence in Geology, NCEG, pp. 524, 2008.
[16] M.A. Khan, R. Ahmed, H.A. Raza and A. Kemal, “Geology of petroleum in Kohat-Potwar Depression, Pakistanâ€, Am. Assoc. Pet. Geol. Bull., vol. no. 70, pp. 396–414, 1986.
[17] O.C. Mullins, M. Hashem, H. Elshahawi, G. Fujisaw, C. Dong, Betancourt and T. Terabayashi, “Hydrocarbon composition analysis in situ in open hole wireline loggingâ€, Society of Petrophysicists and Well-Log Analysts, SPWLA, June 6-9,2004.
[18] B.N. Taylor, "B.8 factors for units listed alphabetically - Section B", Guide for the use of SI Units, NIST, Academic Dictionaries and Encyclopedias, 2007.
