Sains Malaysiana 44(4)(2015): 571–579

Petroleum Source Rock Properties of the Neogene Bhuban Shales, Bengal Basin, Bangladesh

(Pencirian Punca Batuan Petroleum di Syal Neogene Bhuban, Lembangan Bengal, Bangladesh)

MD. FARHADUZZAMAN¹*, WAN HASIAH ABDULLAH¹ & MD. AMINUL ISLAM²

¹Department of Geology, Faculty of Science, University of Malaya, 50603 Kuala Lumpur

Malaysia

²Department of Petroleum Geoscience, Faculty of Science, Universiti Brunei Darussalam, Gadong BE1410, Brunei Darussalam

Received: 10 June 2013/Accepted: 18 November 2014

ABSTRACT

The present study evaluates the petroleum source rock generation potential of the Neogene Bhuban shales from Bangladesh. Organic geochemical and organic petrological methods were used for analyzing 11 drill core samples from 4 gas fields in the basin. Source rock potential, maceral composition, organic matter abundance, biomarker distribution, thermal maturity, hydrocarbon generation and depositional environment were evaluated. Kerogen in the studied shale samples is classified mainly as Type III with lesser amounts of Type II. Vitrinite is the dominant maceral group observed in the analyzed Bhuban samples followed by liptinite and inertinite. Vitrinite reflectance, Tmax and biomarker parameters indicate the thermal maturity ranges from just pre-oil window to mid-oil window. Based on its total organic carbon (TOC), extractable organic matter (EOM) and hydrogen index (HI), the analyzed Bhuban shales are ranked as mainly poor to fair source rocks but with good gas generation potential. The dominant terrestrial environment prevailed during the deposition of the studied Bhuban shales while the condition was sub-oxic as indicated by cross-plots of pristane versus phytane and sterane versus pristane/phytane ratios.

Keywords: Bengal Basin; Bhuban shale; hopane; hydrocarbon potential; sterane

ABSTRAK

Kajian ini membincangkan penilaian batuan punca bagi petroleum sampel syal Bhuban Neogene dari Bangladesh. Geokimia organik dan petrologi organik telah digunakan untuk menganalisis 11 sampel teras gerudi daripada 4 medan gas di kawasan tersebut. Potensi batuan punca, komposisi maseral, kedapatan bahan organik, taburan petanda biologi, kematangan terma penjanaan hidrokarbon dan persekitaran pengenapan dinilai. Kerogen dalam sampel syal yang dikaji kebanyakannya dikelaskan sebagai Jenis III dengan jumlah Jenis II yang lebih kecil. Vitrinit adalah kumpulan maseral yang dominan dalam sampel Bhuban yang dianalisis diikuti oleh liptinit dan inertinit. Pantulan vitrinit, Tmax dan parameter bio penanda menunjukkan kematangan terma daripada hanya pra-minyak ke tingkap-minyak pertengahan. Berdasarkan data TOC, EOM dan HI, syal Bhuban yang dianalisis kebanyakannya dinilai sebagai miskin ke sederhana sebagai batuan sumber dengan potensi penjanaan gas yang baik. Persekitaran daratan dominan semasa pengenapan syal Bhuban dikaji manakala keadaan pengenapan adalah sub-oksik sebagaimana yang dicadangkan berdasarkan plot pristana melawan fitana dan sterana melawan nisbah pristana/fitana.

Kata kunci: Hopana; lembangan Bengal; potensi hidrokarbon; sterana, syal Bhuban

REFERENCES

Alam, M., Alam, M.M., Curray, J.R., Chowdhury, M.L.R. & Gani, M.R. 2003. An overview of the sedimentary geology of the Bengal Basin in relation to the regional tectonic framework and basin-fill history. Sedimentary Geology 155(3-4): 179-208.

Farhaduzzaman, M., Wan Hasiah, A. & Islam, M.A. 2014. Hydrocarbon source potential and depositional environment of the Surma Group shales of Bengal Basin, Bangladesh. Journal of the Geological Society of India 83(4): 433-446.

Farhaduzzaman, M., Wan Hasiah, A. & Islam, M.A. 2013a. Petrographic characteristics and paleoenvironments of the Permian coal resources of the Barapukuria and Dighipara Basins, Bangladesh. Journal of Asian Earth Sciences 64: 272-287.

Farhaduzzaman, M., Wan Hasiah, A., Islam, M.A. & Pearson, M.J. 2013b. Organic facies variations and hydrocarbon generation potential of the Permian coals and related sediments, Barapukuria and Dighipara Basins, NW Bangladesh. Journal of Petroleum Geology 36(2): 117-138.

Farhaduzzaman, M., Wan Hasiah, A. & Islam, M.A. 2013c. Organic geochemical and petrological evaluation of the Early Pliocene Boka Bil shales of the Bengal Basin, Bangladesh. Malaysian Journal of Science (under review).

Farhaduzzaman, M., Wan Hasiah, A. & Islam, M.A. 2012a. Depositional environment and hydrocarbon source potential of the Permian Gondwana coals from the Barapukuria Basin, Northwest Bangladesh. International Journal of Coal Geology 90-91: 162-179.

Huang, W.Y. & Meinschein, W.G. 1979. Sterols as ecological indicators. Geochimica et Cosmochimica Acta 43(5): 739- 745.

Imam, B. 2013. Energy Resources of Bangladesh. 2nd ed. University Grants Commission, Dhaka.

Islam, M.A. 2009. Diagenesis and reservoir quality of Bhuban sandstones (Neogene), Titas Gas Field, Bengal Basin, Bangladesh. Journal of Asian Earth Sciences 35(1): 89-100.

Jamaluddin, M., Nasrin, N., Rahman, M., Anwara, H. & Bygdevold, J. 2001. Bangladesh petroleum potential and resource assessment 2001. HCU-NPD, Dhaka.

Koeverden, J.H., Karlsen, D.A. & Backer-Owe, K. 2011. Carboniferous non-marine source rocks from Spitsbergen and Bjørnøya: Comparison with the Western Arctic. Journal of Petroleum Geology 34(1): 53-66.

Mackenzie, A.S., Patience, R.L., Maxwell, J.R., Vandenbroucke, M. & Durand, B. 1980. Molecular parameters of maturation in the Toarcian shales, Paris Basin. Changes in the configurations of acyclic isoprenoid alkanes, steranes and triterpanes. Geochimica et Cosmochimica Acta 44(11): 1709-1721.

Murray, A.P., Sosrowidjojo, I.B., Alexander, R., Kagi, R.I., Norgate, C.M. & Summons, R.E. 1997. Oleananes in oils and sediments: Evidence of marine influence during early diagenesis? Geochimica et Cosmochimica Acta 61(6):1261- 1276.

Pearson, M.J. & Alam, M. 1993. Bicadinanes and other terrestrial terpenoids in immature Oligocene sedimentary rocks and a related oil from the Surma Basin, N.E. Bangladesh. Organic Geochemistry 20(5): 539-554.

Peters, K.E. & Cassa, M.R. 1994. Applied source rock geochemistry. In The Petroleum System-From Source to Trap, edited by Magoon, L.B. & Dow, W.G. The American Association of Petroleum Geologists Memoir 60: 93-120.

Peters, K.E. & Moldowan, J.M. 1993. The Biomarker Guide- Interpreting Molecular Fossils in Petroleum and Ancient Sediments. New Jersey, Englewood Cliffs: Prentice-Hall Inc.

Peters, K.E., Walters, C.C. & Moldowan, J.M. 2005. The Biomarker Guide- Biomarkers and Isotopes in the Environment and Human History. London: Cambridge University Press.

Philp, R.P. 1985. Fossil Fuel Biomarkers: Applications and Spectra. Amsterdam: Elsevier Science Publishers B.V.

Reimann, K.U. 1993. Geology of Bangladesh. Berlin-Stuttgart, Germany: Gebruder Borntraeger.

Seifert, W.K. & Moldowan, J.M. 1986. Use of biological markers in petroleum exploration. In Biological Markers in the Sedimentary Record, edited by Johns, R.B. Amsterdam: Elsevier Science Publishers B.V.

Shamsuddin, A.K.M., Huq, M.M., Faruque, M.A., Chudhury, Z., Akhteruzzaman, M., Rahman, M., Haque, A., Talukder, M.W., Bygdevoll, J. & Rafdal, J. 2004. Bangladesh gas reserve estimation 2003. HCU-NPD, Dhaka, Bangladesh.

Wan Hasiah, A. 1999. Organic facies variations in the Triassic shallow marine and deep marine shales of central Spitsbergen, Svalbard. Marine and Petroleum Geology 16(5): 467-481.

Waples, D.W. & Machihara, T. 1991. Biomarkers for Geologists: A practical guide to the application of Steranes and Triterpanes in petroleum geology. The AAPG Methods in Exploration Series 9, Tulsa.

Waseda, A. & Nishita, H. 1998. Geochemical characteristics of terrigenous- and marine-sourced oils in Hokkaido, Japan. Organic Geochemistry 28(1-2): 27-41.

*Corresponding author; email: farhad.geo@siswa.um.edu.my