An Integrated Approach to Assess and Map Organic Shale Reservoirs- A Case History from Central Part of Lower Indus Basin, Pakistan
Abstract
The present study is focused to evaluate and map the unconventional resources particularly, organic shale reservoirs in Lower Indus Basin Pakistan. As typical organic shale reservoirs are tight and very heterogeneous in nature. Advancement in technology has made it possible to exploit low permeability reservoirs worldwide. However, in Pakistan, cost effective price of commodity, optimized drilling and hydraulic fracturing are required to exploit the unconventional resources commercially. Prior to optimized drilling and hydraulic fracturing, delineation of sweet spots for organic shale resources is pre-requisite. Integration of geochemical and petrophysical data shows that shales of Middle and Lower Cretaceous horizons in the study area has retained enough hydrocarbon potential for exploration and are comparable to world known shale gas producing reservoirs. The estimated OHIP (gas equivalent) values shows that the Sembar Formation contains approximately 34 TSCF, Talhar Shale has 0.6 TSCF and 3.41 TSCF in shales of Massive Sand. Assessment shows that better OHIP values, reasonable resource density, fair to very good TOC values, moderate to good effective porosities, low water saturation, appropriate stress barriers, favorable fracking characteristics and high net pay of the Sembar Formation and lower shale of Massive Sand can be attributed for good and low risk targets for shale gas exploitation in the study area.
References
Ahmad, N., Fink, P., Sturrock, S., Mahmood, T., & Ibrahim, M., 2004. Sequence stratigraphy as predictive tool in Lower Goru fairway, Lower and Middle Indus Platform, Pakistan. PAPG, ATC, 85–105.
Ahmed, N., Mateen, J., Shehzad, K., Mahmood, N., and Arif, F., 2012. Shale gas potential of Lower Cretaceous Sembar Formation in Middle and Lower Indus Basin, Pakistan: Pakistan Journal of Hydrocarbon Research, 22, pp. 51–62.
Akar, C., Mastalerz, M., Schimmelman, A., and Drobniak, A., 2015. Comparison of hydrocarbon potentials of New Albany Shale and Maquoketa Group in Indiana, USA: Jacob Journal of Petroleum and Natural Gas, 1(1), pp. 1-3.
Archie, G. E., 1942. The electrical resistivity log as an aid in determining some reservoir characteristics: Transactions of the AIME, 146(1), pp. 54–62.
Baig, M. O., Harris, N. B., Ahmed, H. and Baig, M. O. A., 2016. Controls on reservoir diagenesis in the Lower Goru sandstone formation, Lower Indus Basin, Pakistan: Journal of Petroleum Geology, 39, pp. 29–47.
Bhuyan, K., & Passey, Q., 1994. Clay estimation from GR and neutron-density porosity logs. SPWLA, Tulsa, Oklahoma, USA. pp. 1–15.
Brohi, I. A., Solangi, S. H., Abbasi, S. A., Bablani, S. A., Khokhar, Q. D., Sahito, A. G., and Brohi, A. U., 2013. Joint system and economic significance of Lakhra Formation in the vicinity of Khanu Brohi, Jamshoro, Sindh: Sindh University Research Journal-SURJ (Science Series). 45(2), pp. 381–386.
Brooks, J., 1981. Organic Maturation of Sedimentary Organic Matter and Petroleum Exploration: A Review. In organic maturation studies and fossil fuel exploration, pp. 1–38. Academic Press, London.
Espitalie, J., Madec, M., and Tissot B., 1980. Role of mineral matrix in kerogen pyrolysis; Influence on petroleum generation and migration: American Association of Petroleum Geologists Bulletin, 64, pp. 59–66.
Harry Dembicki, Jr., 2017 Practical Petroleum Geochemistry for Exploration and Production, pp. 10–69.
Harilal, & Tandon, A. K., 2012. Unconventional shale gas plays their characterization through 3-D seismic attributes and logs. SPG, India, pp. 1–8.
Hashmy, K. H., David, T., Abueita, S., & Jonkers, J., 2012. Shale reservoirs: Improved production from stimulation of sweet spots. SPE, Perth, Australia, doi:10.2118/158881-MS
Jarvie, D. M., 2012. Shale resource system for oil and gas: Part 1 - Shale gas resource systems. In Breyer J. A. (eds.). Shale reservoirs-Gaint resources for the 21st century. AAPG Memoir, 97, pp. 69-87.
Kadri, I. B., 1995. Petroleum Geology of Pakistan: Karachi, Pakistan Petroleum Ltd., pp. 15– 275.
Kim, T., Hwang, S., and Jang, S., 2016. Petrophysical approach for estimating porosity, clay volume and water saturation in gas bearing shale: A case study from the Horn River Basin, Canada: Austrian Journal of Earth Sciences, 109(2), pp. 289–298.
Mahmoud, S., 2015. Integrated sequence stratigraphy of the Cretaceous Lower Goru deposits, Lower Indus Basin, Pakistan. AAPG, Discovery Article No. 10815, pp 1. 39.
Makay, A. F., and Ramadam, M. A. M., 2008. Nature of organic matter, thermal maturation and hydrocarbon potentiality of Khatatba Formation at East Abu-Gharadig Basin, North Western Desert, Egypt: Australian Journal of Basic and Applied Sciences, 2(2), pp. 194– 209.
Malkani, M. S., 2012. Revised lithostratigraphy of Sulaiman and Kirthar basins, Pakistan. Abstract Volume, Earth Sciences Pakistan, pp. 23–24.
Nady, M. M. E., Ramadan, F. S., Hammad, M. M., and Lotfy, N. M., 2015. Evaluation of organic matters, hydrocarbon potential and thermal maturity of source rocks based on geochemical and statistical methods: Case study of source rocks in Rias Gharib oilfield, central Gulf of Suez, Egypt: Egyptian journal of petroleum, 24, pp. 203–211.
OGDCL, 1988. Pakistan Hydrocarbon Habitat: Exploration Promotion Package. Min. Petrol. and Nat. Res., OGDCL, Islamabad, Unpublished report, 14-20.
Peter, K. E., and Cassa., 1994. Applied source rock geochemistry. In Magoon, L. B., and Dow, W.G. (eds.): The petroleum system - from source to trap. AAPG Memoir, 60, pp. 93– 120.
Ramana M., and Chavali, M., 2020. A novel hydraulic fracturing gel realization for unconventional reservoirs: Beni-Suef University Journal of Basic and Applied Sciences, pp. 1–7.
Rickman, R., Mullen, M. J., Petre, J. E., Grieser, W. V., & Kundert, D., 2008. A practical use of shale petrophysics for stimulation design optimization: All shale plays are not clones of the Barnett Shale. SPE, pp. 5-11.
Sondergeld, C. H., Newsham, K. E., Comisky, J. T., Rice, M. C., and Rai, C. S., 2010. Petrophysical considerations in evaluating and producing shale gas. SPE, Richardson, Texas, pp. 60–120.
Tian, H., Pan, L., Xiao, X. M., Wilkins, R. W. T., Meng, Z. P., and Huang, B. J., 2013. A preliminary study on the pore characterization of Lower Silurian black shales in the Chuandong Thrust Fold Belt, southwestern China using low pressure N2 adsorption and FE-SEM methods: Marine and Petroleum Geology, 48, pp. 8–19.
Wandrey, C. J., Law, B. E., and Shah, H. A., 2004. Sembar Goru/Ghazij composite total petroleum system, Indus and Sulaiman-Kirthar geologic provinces, Pakistan and India: US Geological Survey Bulletin, pp. 14– 22.
Waxman, M. H., and Smits, L. J. M., 1968. Electrical conductivities in oil bearing shaly sand sands: Society of Petroleum Engineers Journal, 8(2), pp. 107–122.
Xiaodong, M., and Mark D. M., 2017. Lithologycontrolled stress variations: A case study of the woodford shale, Oklahoma. SPE/AAPG/SEG, pp. 1–9.
