Oil & Gas Geology ›› 2020, Vol. 41 ›› Issue (4): 874-883.doi: 10.11743/ogg20200419

• Methods and Technologies • Previous Articles     Next Articles

Quantitative analysis on pore evolution in feldspar-rich coarse clastic sandstone: A case study of Es2 in the north part of Liaodong uplift

Longlong Guo1,2(), Hongde Cheng1, Xiaobo Huang2, Jun Wang1,*(), Chong Feng2   

  1. 1. Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu, Sichuan 610059, China
    2. CNOOC Tianjin Branch, Tianjin 300452, China
  • Received:2020-04-13 Online:2020-08-01 Published:2020-08-11
  • Contact: Jun Wang E-mail:guoll10@cnooc.com.cn;cdut_wangjun@foxmail.com

Abstract:

The coupling relationship between pore evolution and hydrocarbon charging plays an important role in hydro-carbon accumulation.However, an accurate quantitative analysis of the pore evolution is difficult.A porosity evolution model was therefore constructed with quantitative calculation parameters determined through analyses of microfabric, authigenic minerals, diagenetic sequences and thermal evolution of feldspar-rich coarse clastic sandstone reservoirs in the second member of the Shahejie Formation(Es2) in the north part of Liaodong uplift.The results show that the water-rock reaction of feldspar together with its products has a dominant effect on the reservoir porosity.While analyses of parameters including reservoir sorting coefficient, cement mass fraction, plane porosity of residual primary intergranular pores, total plane porosity, and plane porosity of dissolved pores, are important to the accuracy of quantitative calculation.The research indicates that compaction caused the strongest damage to the reservoirs from 38 to 23.3Ma, resulting in a porosity decrease of 15%.Cementation, which lasted almost the whole diagentic period, followed up to cut back the porosity by another 10.4% on average.However, erosion from 19 to 2 Ma served to increase the porosity by 9.8%.The physical properties of the reservoirs were gradually improving with hydrocarbon-charging and deteriorating as hydrocarbon charging ended.

Key words: low permeability, diagenesis, pore evolution, reservoir, Shahejie Formation, Bohai Bay Basin

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