Hubungan antara diagenesis, reflektan vitrinit, dan kematangan batuan pembawa hidrokarbon batuan sedimen Miosen di Cekungan Bengkulu

Rachmat Heryanto

Abstract


http://dx.doi.org/10.17014/ijog.vol2no2.20074

The Early-Middle Miocene Seblat and Middle-Late Miocene Lemau Formations are two of sedimentary rock lithstratigrphic unit that occur in the Bengkulu Basin. Lithologically, the Seblat Formation consists of mudstone with some interbedded sandstones and conglomerate in the lower part and tuffaceous mudstone with some limestone lenses in the upper part. The Lemau Formation, however, comprises dominant sandstones with interbedded shales and sub-ordinate conglomerates and mudstone beds in the lower part, and mudstone with sandstone intercalations and coal seams in the upper part.

Hydrogen Index (HI) versus Temperature Maximum (T) diagram shows that the source rock maturation at most of the samples is late immature to early mature. The vitrinite reflectance the dispersed organic matter (DOM) ranges from 0.37 to 0.55%; whereas of the coal seam ranges from 0.76 up to 0.94%. This indicates that the source rock maturation is defined to be late immature to early mature. The data indicate a burial history for about 2,500 m in depth, where the paleotemperature reached 80o C.

Diagenetic processes observed from the Seblat and Lemau Sandstones are compaction, the forming of authigenic minerals and secondary porosities. The diagenetic stage includes the mesogenetic mature A, which equivalent to mudrock stage II, with the paleotemperature of 80o to 95o C, and the burial thickness of 2 to 3 km.

There is a relationship between diagenetic stage, vitrinite reflectance, and maturation of organic matter of hydrocarbon source rock, caused by the burial depth.

 


Keywords


Seblat; Lemau; diagenetic; thermal maturity; vitrinite reflectace; source rocks

References


Amin, T.C, Kusnama, Rustandi, E., dan Gafoer, S., 1994. Geologi Lembar Manna dan Enggano, Sumatera, Skala 1:250.000. Pusat Penelitian dan Pengembangan Geologi, Bandung.

Burley, S.D., Kantorowicz, J.D., dan Waugh, B., 1987. Clastic Diagenesis. Dalam: Edward, A.B., dan Foster, N.H.(Ed), Reservoir II Sandstone. American Association of Petroleum Geologists, Treatise of Petroleum Geology Reprint Series, p. 408-455.

Gafoer, S., Amin, T.C., dan Pardede, R., 1992. Geologi Lembar Bengkulu, Sumatera Skala 1:250.000. Pusat Penelitian dan Pengembangan Geologi, Bandung.

Guntoro, A., dan Djajadiharja, Y.S., 2005. Tectonic Scenario of the Sumatra Fore-Arc Basin in Relation To the Formation of Petroleum Systems. International Conference on Geology, Geotechnology and Mineral Recources of Indochina (GEOINDO 2005) 28-30 November 2005, Khon Kaen, Thailand.

Helmod, K.P. and van de Kamp, P.C., 1984. Diagenetic mineralogy and controls on albitization and laumontite formation in Paleogen Arkose, Santa Yenz Mountains, California. In: McDonald, D.A. and Surdam, R.C. (Eds), Clastic Diagenesis. American Association of Petroleum Geologist, Memoir, 37, p. 239-276.

Heryanto, R., 2005. Laporan Penelitian Sumber Daya Hidrokarbon di Cekungan Bengkulu, Bengkulu. Pusat Penelitian Pengembangan Geologi, Badan Geologi, Departemen Energi dan Sumber Daya Mineral (Laporan Internal).

Heryanto, R., 2006a. Karakteristik Formasi Seblat di Daerah Bengkulu Selatan. Jurnal Sumber Daya Geologi, 16, h. 179-195.

Heryanto, R., 2006b. Provenance batupasir Formasi Lemau di Cekungan Bengkulu. Seminar Nasional Geologi Indonesia: ”DINAMIKA DAN PRODUKNYA”. Pusat Survei Geologi, Bandung, 5-6 Desember 2006.

Heryanto, R., 2007. Diagenesis Batupasir Formasi Lemau di Cekungan Bengkulu dan Potensinya sebagai Batuan Reservoar Hidrokarbon. Mineral dan Energi, 5, h. 58- 70.

Heryanto, R. dan Panggabean, H., 2006. The Tertiery Source Rock Potential of the Bengkulu Basin. International Geosciences Conference and Exhibition, Jakarta, 14-16 Agustus 2006.

Kantsler, A.J., Cook, A.C., and Smith, G.C., 1978. Rank variation, calculated paleotemps in understanding oil, gas occurrence. Oil and Gas Journal, Nov. 20, 196-205.

Pettijohn, F.J., Potter, P.E., and Siever, R., 1987. Sand and Sandstone. 2nd ed. Springer-Verlag, New York, 553p.

Schmidt, V. and McDonald, D.A., 1979. The role of secondary porosity in the course of sandstone diagenesis. In: Schole, P.A. and Schluger, P.R. (Eds), Aspect of diagenesis. Society of Economic Paleontologist and Mineralogist, Special Publication, 26, p. 175-207.

Yulihanto,B., Situmorang, B., Nurdjajadi, A., dan Sain, B., 1995. Structural Analysis of the onshore Bengkulu Forearc Basin and Its Implication for Future Hydrocarbon Exploration activity. Proceedings, Indonesian Petroleum Association Twenty Fourth Annual Convention, October 1995.


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