Oil & Gas Geology ›› 2022, Vol. 43 ›› Issue (4): 877-888.doi: 10.11743/ogg20220411

• Petroleum Geology • Previous Articles     Next Articles

Genesis and development model of tight oil reservoir sand body in continental lacustrine basin: A case study on the Upper Triassic Chang 6 pay zone, Ordos Basin

Jingchun Tian1,2(), Qingshao Liang1,2(), Feng Wang1,2, Wei Yu1,2   

  1. 1.Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu,Sichuan 610059,China
    2.State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu,Sichuan 610059,China
  • Received:2022-01-14 Revised:2022-05-18 Online:2022-07-14 Published:2022-07-14
  • Contact: Qingshao Liang E-mail:tjc@cdut.edu.cn;liangqs@cdut.edu.cn

Abstract:

The pay zone in the 6th member of the Upper Triassic Yanchang Formation (Chang 6 pay zone) is one of the tight oil-rich intervals in the Ordos Basin. The study on the characteristics and genesis of tight oil reservoir sand bodies is of guiding significance to further exploration and development of tight oil in the basin. Apart from multiple previous research results, we make a thorough analysis of cores from the Chang 6 pay zone in Huachi-Qingyang area to clarify the types and characteristics of the tight oil reservoir sand bodies therein, and discuss in detail the superimposing reservoir sand bodies of diverse types in the pay zone. The results show that the tight oil reservoir sand bodies of the Chang 6 pay zone can be mainly grouped into four types: delta front, seismite, debris-flow, and turbidite types. Four kinds of superimposing relationship are formed vertically, including seismite type superimposing with delta front type, seismite type superimposing with debris-flow type, debris-flow type superimposing with turbidite type, and seismite/debris-flow types superimposing with turbidite type. From the delta front to the center of the lacustrine basin, we can find sand bodies of diverse genesis in vertical superimposition due to changes of palaeogeomorphic settings and environmental conditions, which serve for constructing a genetic model of the tight oil reservoir sand bodies in the Chang 6 pay zone based on the regional depositional pattern.

Key words: genetic model, reservoir sand body, tight oil, Chang 6 pay zone, Upper Triassic, Ordos Basin

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