Oil & Gas Geology ›› 2019, Vol. 40 ›› Issue (2): 248-261.doi: 10.11743/ogg20190204

• Petroleum Geology • Previous Articles     Next Articles

Characters of hydrocarbon generation and accumulation of salt-lake facies in Dongpu Sag,Bohai Bay Basin

Xu Tianwu1, Zhang Hong'an2, Li Jidong1, Zhao Wei3   

  1. 1. Exploration and Production Research Institute of Zhongyuan Oilfield Branch Company, SINOPEC, Puyang, Henan 457001, China;
    2. Zhongyuan Oilfield Branch Company, SINOPEC, Puyang, Henan 457001, China;
    3. CNOOC Ener Tech-Drilling & Production Co., Tianjin 300457, China
  • Received:2018-05-17 Revised:2018-12-28 Online:2019-04-28 Published:2019-01-23

Abstract:

Hydrocarbon generation and accumulation in salt lakes are a typical petroleum geological phenomenon in the world,especially in the Mesozoic and Cenozoic continental strata of China.In order to advance research in this field,this paper discusses the research progress of Dongpu Sag in the Bohai Bay Basin,eastern China.The hydrocarbon generation and accumulation characteristics of salt-lake source rocks were analyzed through systematic geological and geochemical studies of source rocks and crude oils,providing clues for future regional deployments of exploration.Results show that the typical salt-lake source rocks were developed spatially in the north of the sag,specifically the lower section of the third member(Es4(U)) and the upper section of the fourth member(Es4(U)) of the Shahejie Formation vertically.Its lithology is shale featuring early hydrocarbon generation and expulsion,with a "double-layered" structure,i.e.the lower layer dominated by organic matters and clay minerals and the upper one dominated by pyrites and calcites.The hydrocarbon accumulation in salt lakes of Dongpu Sag develops along with the growth of both conventional and unconventional petroleum reservoirs.The conventional ones are characterized by "ordered distribution and differential enrichment",while the deve-lopment of unconventional oil and gas reservoirs is closely related to the organic-rich salt-lake source rocks,reflecting the control of organic-rich salt-lake source rocks on hydrocarbon accumulation.It is recommended that further regional exploration should be focused on the two organic-rich source rock areas,the Es4(U) and the Es4(U),and exploration of various petroleum reservoirs should be carried out.These understandings are of referential significance for the geological research of oil and gas and the exploration in other saline lacustrine basins.

Key words: salt lake, saline lacustrine basin, aggregation of organic matter, shale oil and gas, tight oil and gas, Shahejie Formation, Dongpu Sag, Bohai Bay Basin

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