Oil & Gas Geology ›› 2021, Vol. 42 ›› Issue (3): 661-672, 764.doi: 10.11743/ogg20210312

• Petroleum Geology • Previous Articles     Next Articles

Characteristics and distribution of platform-margin reef-shoal reservoirs in Changxing-Feixianguan Formations to the west of ocean trough, E'xi-Chengkou area

Guoqi Wei(), Wei Yang*(), Mancang Liu, Saijun Wu, Wuling Mo, Hui Jin, Juehong Shen, Cuiguo Hao   

  1. Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China
  • Received:2018-12-17 Online:2021-06-28 Published:2021-06-23
  • Contact: Wei Yang E-mail:weigq@petrochina.com.cn;yangw69@petrochina.com.cn

Abstract:

An integrated analysis of outcrop, drilling, log and seismic data of the Changxing-Feixianguan Formations in E'xi-Chengkou area has led to new understandings of the characteristics of the platform-margin reef-shoal reservoirs therein.(1) The Changxing-Feixianguan Formations are a rimmed carbonate platform, composed of basin, slope, platform-margin reef-shoal, open platform, restricted platform and evaporated platform facies from east to west.(2) A platform-margin belt was developed during the sedimentation of Changxing-Feixianguan Formations with the Changxing Formation dominated by platform-margin reef facies and Feixianguan Formation by platform-margin oolitic shoal facies.This massive reef-shoal complex expands broadly and continuously in the area.(3) The platform-margin reef-shoal in the Changxing Formation consists of reef base, reef core and reef cap.The reef core is mainly cemented reef and baffle-frame reef, and the reef base and cap are mainly the biodetritus shoal facies distributed in Fengtong Township in Wanyuan City, Panlongdong Village in Xuanhan County, Manyue Township in Kaixian, Well Fengtan 1 and Jiantianba Township with no obvious signs of migration.(4) The platform-margin reef-shoal facies in the Feixianguan Formation is dominated by widespread oolitic dolomite and oolitic limestone and gradually migrating basinward from the second member to the fourth member of Feixianguan Formation.The facies in the second member is mainly distributed in Batai Town in Wanyuan City, Manyue Township in Kaixian, Shuanghekou of Wanzhou District in Chongqing, Zhaigouwan and Shibaozhai areas.The facies in the third member migrated eastward to Ningchang area, and that in the fourth member to Kongjiagou area.The shoal facies of the second member of Feixianguan Formation is highly dolomitized and superimposed onto the reef-shoal facies of Changxing Formation.

Key words: west of the ocean trough, platform-margin zone, lithofacies paleogeography, reef-shoal facies, distribution, Changxing-Feixianguan Formations, E'xi-Chengkou area

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