Shale Gas Potential In Jambi Sub-Basin, Indonesia: Insights From Geochemical and Geomechanical Studies
DOI:
https://doi.org/10.25299/jgeet.2020.5.2.4191Keywords:
Gumai Formation, Talangakar Formation, source rock, Young's modulus, Poisson's ratio, brittleness indexAbstract
Jambi sub-basin, which is located in South Sumatra, Indonesia has enormous potential of shale gas play. Yet, detailed geological studies are rarely undertaken to understand this relatively new hydrocarbon play concept. This paper presents a combination of geochemical and geomechanical studies with the aim to better understand: (1) the maturity level of source rock; (2) the mechanical properties of shale; and (3) the quality of hydrocarbon source rock. This research began with determination of wells that penetrate the Talangakar and Gumai Formations that have shale in it. Source rock analysis was done by using TOC (total organic carbon), S1, S2, S3, Tmax, and Ro (vitrinite reflectance) data. Geomechanical evaluation was done by using XRD and well logs data. Brittleness index was obtained by using Jarvie et al. (2007) formula, based on the XRD data. S-wave and P-wave are used to calculate the rock strength, Young's modulus and Poisson's ratio with UCS-To methods.Source rock in the Geragai belongs to the of moderate-to-good category because it has more than 0.5% TOC and potentially forms gas because it has a type III kerogen. JTBS-2 well is the only well in the Geragai area which already mature and has been able to produce hydrocarbons, because it passed the oil and gas windows. Source rock in the Betara belongs to moderate-to-good category because it has more than 0.5% TOC potentially forms gas because it has a type III kerogen. Most formations in the Betara are not yet mature based on the value of Ro and Tmax. In wells that have not reached the oil window nor gas windows, the prediction line drawn on the Petroleum Source Rock Summary chart, estimated that they would pass the gas window at Lower Talangakar Formation or Lahat Formation at depth of more than 8000 feet. The results of XRD analysis showed that the Betara had a high brittleness index with an average of 0.809. Talangakar Formation has a higher rock strength values than Gumai Formation, both in Betara high and Geragai deep. The principle that say the rocks which have high TOC values will have a high value of BI can be proven in the study area, the rocks that have high Ro will have a high value of BI, cannot be identified in the study area. With sufficient high value of rock strength and low abundance of clay minerals, the rocks at Talangakar Formation is good for hydraulic stimulation.
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References
Boles, J.R. dan Franks, S.G. (1979): Clay diagenesis in Wilcox sandstones of southwest Texas: implications of smectite diagenesis on sandstone cementation, J. Sediment. Petrology 49
Clure, J. (2005): Fuel Resources: Oil and Gas, 139-140 dalam Barber, J., Crow, M.J., Milsom, J.S., Sumatra: Geology, Resources and Tectonic Evolution, 302 hal., The Geological Society, London-United Kingdom.
de Coster, G.L. (1974): The geology of the Central and South Sumatra Basins, Proceedings of the Third Annual Convention and Exhibition Indonesian Petroleum Association, Jakarta, Indonesia, June, 77 - 110.
Ginger, D. dan Fielding, K. (2005): The petroleum system and future potential of the South Sumatra Basin, Proceedings of the Thirtieth Annual Convention and Exhibition Indonesian Petroleum Association, Jakarta, Indonesia, August, 68 – 70.
Jackson, A. (1961): Oil exploration – a brief review with illustrations from South Sumatra, Contributions from The Departement of Geology, Institut Teknonolgi Bandung, 1-9.
Jarvie, D.M., Hill, R.J., Ruble, T.E., dan Pollastro, R.M. (2007): Unconventional shale-gas systems: The Mississippian Barnett Shale of North-Central Texas as one model for thermogenic shale-gas assessment, Bulletin of American Association of Petroleum Geologist V.91 No.4, Tulsa, Oklahoma, USA, 475 – 499.
Katahara, K. (2006): Overpressure and shale properties: stress unloading or smectite-illite transformation, 2006 Society of Exploration Geophysicists Annual Meeting, New Orleans, Louisiana, USA.
Kataren, L.R. (2014): Estimasi overpressure berdasarkan data log talikawat pada Sub-Cekungan Jambi, Cekungan Sumatra Selatan, Tesis Magister Istitut Teknologi Bandung, 93-99.
Nations, J.F. (1974): Lithology and porosity from accoustic shear and compressional wave transit time relationship, SPWLA Fifteenth Annual Logging Symposium, Article Q, 1 – 16.
Patra Nusa Data (2006): Indonesian Basin Summaries, Patra Nusa Data, Jakarta, 29 – 30.
Peters, K.E. dan Cassa, M.R. (1994): Applied source rock geochemistry, 93 – 100 dalam Dow, W.G., Magoon, L.B., The petroleum system – from source to trap, 639 hlm., The American Association of Petroleum Geologists, Tulsa, Oklahoma, U.S.
Salim, Y., Djumhana, N., Yustika, M.P., Isjmiradi, Sidjaja, M., dan Fauzi, M., (1995): Remaining potential of the South Sumatra Basin, Technical Study Report, South Sumatra AMI Study Group, Jakarta, Indonesia, 29 – 48.
Swabrick, R.E. dan Osborne, M.J. (1998): Mechanism that generate abnormal pressure, American Association of Petroleum Geologist Memoir 70, Tulsa, Oklahoma, USA.
Swabrick, R.E., Osborne, M.J., dan Yardley, G.S. (2002): The magnitude of overpressure from generating mechanism under realistic basin condition, American Association of Petroleum Geologist Memoir 76, Tulsa, Oklahoma, USA.
Waples, D.W. (1985): Geochemistry in Petroleum Exploration. International Human Resources Development Co., Boston, 33-94.2016. Stratigraphy Seismic and sedimentation Development of Middle Baong Sand , Aru Field , North Sumatera Basin. J. Geoscience, Engineering, Environment, and Technology 1, 51–58.
Putra, D.B.E., Choanji, T., 2016. Preliminary Analysis of Slope Stability in Kuok and Surrounding Areas. J. Geoscience, Engineering, Environment, and Technology 1, 41–44.
Selley, R., Robin, L., Cocks, M., Plimer, I., 2005. Encyclopedia of Geology. Geology 3345. doi:10.1016/B0-12-369396-9/00102-7
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