Unconformity Played an Important Role in the Accumulation of the Tight Sandstone Reservoirs

Abstract:

There are low porosity and permeability in the Jurassic sandstone in the Yongjin Block, Junggar Basin. Reservoir is main controlled element of petroleum accumulation. It is adverse to hydrocarbon pool. However, unconformity effectively promotes the porosity and permeability of sandstone under it. An important unconformity between Jurassic and Cretaceous Periods developed in the central Junggar Basin. The chemical index of alteration (CIA) values indicate that it experienced physical weathering during development, transported the matrix off the semi-weathering rock, and consequently improved the reservoir quality of sandstone. Water with organic acids that are generated during organic matter maturation could dissolve the feldspar in semi-weathered zone, and would remove the dissolved products from the sandstone. All these would further improve reservoir quality. There are tight sandstone of the Jurassic which is adverse to hydrocarbon accumulation. However, because unconformtiy ocured and experienced the reservoir-improved geologic progresses. The semi-weathered zone of J/K unconformity became the preferred pathway for petroleum migration due to these two geological processes. The Paleo-soil layer on top of the J/K unconformity formed a good trap for the passing hydrocarbons, and accumulated it to become a commercial petroleum pool.

• Periodical: Advanced Materials Research (Volumes 524-527)
• Pages: 248-251
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.524-527.248
• Online since: May 2012
• Authors: Hai Yan Hu, Zhen Duo He
• Keywords: Petroleum Accumulation, Tight Sandstone Reservoir, Unconformity

References

[1] Catalan, L., Fu, X. W., Chatzis, F., et al. 1992. An experimental study of secondary oil migration: AAPG Bulletin 76: 638-650.

[2] Chen, Z. H., M. Zha, K. Y. Wu 2002. Relationship between hydrocarbon migration-accumulation and unconformity at Cretaceous bottom of Luliang uplift in Junggar Basin. Xinjiang Petroleum Geology 23: 283-285 (in Chinese).

[3] David U., Lenka S., Radomir G., 2009. Palaeodrainage systems at the basal unconformity of the Bohemian Cretaceous Basin: roles of inherited fault systems and basement lithology during the onset of basin filling: BULLETIN OF GEOSCIENCES, v. 84, 577-610.

DOI: 10.3140/bull.geosci.1128

[4] Emery, D., K. J. Myers, R. Young 1990. Ancient subaerial exposure and fresh water leaching in sandstones. Geology 18: 1178-1181.

DOI: 10.1130/0091-7613(1990)018<1178:aseafl>2.3.co;2

[5] Fu, G., Z. J. Xu, D. L. Han 2001. Role of surface of unconformity. Information of oil or gas reservoirs 25: 1-4 (in Chinese).

[6] Giles, M. R., R. B. de-Boer 1990. Origin and significance of redistributional secondary porosity . Marine and Petroleum Geology 7: 378-397.

DOI: 10.1016/0264-8172(90)90016-a

[7] Hao, F., H. Y. Zou, M. F. Wang 2002. Research advances and frontier areas of mechanisms of petroleum accumulation. Geological Science and Technology Information 21: 7-14 (in Chinese).

[8] Hindle, A. D. 1997. Petroleum migration pathways and charge concentration: a three-dimensional mode. AAPG Bulletin 81: 1451-1481.

DOI: 10.1306/3b05bb1e-172a-11d7-8645000102c1865d

[9] Hong, T.Y. 2006. The study on the features of the bottom cretaceous unconformity and its controlling affect on the hydrocarbon accumulation in the hinterland of Junggar Basin. A Dissertation Submitted to China University of Geosciences for Doctoral Degree: 1-90 (in Chinese).

[10] Mikko N. 2011. The Pyhantaka formation, southern Finland: a sequence of metasandstones and metavolcanic rocks upon an intra-orogenic unconformity: BULLETIN OF THE GEOLOGICAL SOCIETY OF FINLAND, v. 83: pp.5-23.

DOI: 10.17741/bgsf/83.1.001

[11] Nesbitt, H. W., G. Markovics 1997. Weathering of granodioritic crust, long-term storage of elements in weathering profiles, and petrogenesis of siliciclastic sediments. Geochimica et Cosmochimica Acta 61: 1653-1670.

DOI: 10.1016/s0016-7037(97)00031-8

[12] Singh, M., M. Sharma, H. J Tobschall 2005. Weathering of the Ganga alluvial plain, northern India: implications from fluvial geochemistry of the Gomati River. Applied Geochemistry 20: 1-23.

DOI: 10.1016/j.apgeochem.2004.07.005

[13] Surdam, R. C., L. J. Crossey, E. S. Hagen, and H. P. Heasler 1989. Organic-Inorganic interactions and sandstone diagenesis. AAPG Bulletin 73: 1-23.

DOI: 10.1306/703c9ad7-1707-11d7-8645000102c1865d

[14] Thomas, M., J. A. Clause 1995. Scaled physical model of secondary oil migration. AAPG Bulletin 79: 19~29.