Oil & Gas Geology ›› 2016, Vol. 37 ›› Issue (4): 520-527.doi: 10.11743/ogg20160408

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Characteristics and petroleum geological significance of lacustrine forced regressive deposits in the 1st Member of Liushagang Formation in Weixi'nan Sag, Beibuwan Basin

Pei Jianxiang, Dong Guineng, Zhu Qi   

  1. Zhanjiang Company of CNOOC Ltd., Zhanjiang, Guangdong 524057, China
  • Received:2015-01-22 Revised:2016-06-20 Online:2016-08-08 Published:2016-09-06

Abstract: An oblique progradational sequence occurs in the 1st Member of Liushagang Formation in Weixi'nan Sag,Beibuwan Basin.A comprehensive analysis of single well facies,multi-well correlation,and seismic facies based on geological,logging and seismic data reveals that it belongs to lacustrine forced regressive deposits.It is characterized by obvious upward shallowing in respect of singe well facies,vertical overlapping and lateral sequential migration of multi-phase deltas in multi-well correlation,and significant oblique progradation reflection configuration on seismic profiles.Local uplifting of the basement is the main controlling factor for the development of lacustrine forced regression.The identification of the lacustrine forced regressive deposits helped to eliminate the disputes concerning stratigraphic division and correlation of the 3rd Member of Weizhou Formation and the 1st Member of Liushagang Formation in Weixi'nan sag.Meanwhile,it also led to the recognition of lithologic traps such as turbidite,sublacustrine fan,and progradational delta and the discovery of several reservoirs within the lacustrine forced regression system tracts,thus expanding new domains for oil and gas exploration in this sag.

Key words: lacustrine forced regression, deposit, Liushagang Formation, Weixi'nan Sag, Beibuwan Basin

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