›› 2017, Vol. 38 ›› Issue (6): 1-1.doi: 10.7657/XJPG20170612

   

Origin, Migration and Distribution of Oil in Strike-Slip Fault Zone of Liaozhong Sag

WANG Jun, WU Kui, FAN Jianhua, WANG Wei, JIN Xiaoyan   

  1. (Tianjin Branch, CNOOC China Limited, Tianjin 300459, China)
  • Online:2019-01-01 Published:1905-07-18

Abstract: Most of the discovered oil reserves in the Bohai Bay basin concentrate in Tan-Lu strike-slip fault zone, but the hydrocarbon origin and its distribution vary significantly in different oilfields. Therefore, it is significant to study hydrocarbon migration in the strike-slip fault zone. Based on the research of development stages, stress characters in derived fractures, and source rocks and reservoirs connected by the derived fractures in Liaozhong-1 strike-slip fault zone of Liaozhong sag, the paper reveals the controls of vertical hydrocarbon migration along fractures on oil genesis and distribution. It is found that the north part of Liaozhong sag is in the early development stage of the strike-slip fracture which has no unified fracture surface and can’t control trap forming, the derived strike-slip fracture only connected with Dongying formation is not very developed and its slip rate is not high, and the oil originates from the source rocks of the third member of Dongying formation and accumulates in the second member of Dongying formation where the oilfield is relatively small; the south and middle parts of Liaozhong sag are in the late development stage of the strike-slip fracture which has a unified fracture surface and can control trap forming, the derived strike-slip fracture connected with Shahejie formation and the overlying strata is widely distributed with the oil originating from the source rocks of Shahejie formation, and the oilfields are relatively large here. Obvious activation of the derived strike-slip fracture in the south part of Liaozhong sag occured during neotectonic period, the derived fracture connected Neogene reservoirs and was active at the late stage, and oil mainly accumulated in the Neogene strata; there was no obvious activation of the derived strike-slip fracture in the middle part of the sag during neotectonic period, the fracture only connected Paleogene strata where oil mainly accumulated.

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