Oil & Gas Geology ›› 2018, Vol. 39 ›› Issue (4): 811-822.doi: 10.11743/ogg20180418

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Lateral variation of sequence stratigraphic architecture on passive continental margin and its enlightenment: A case from the Middle Miocene in Pearl River Mouth Basin in 13.8 Ma

Xu Shaohua1,2, He Min3, Pang Xiong3, Chen Weitao3, Wang Yingmin4, Zhuo Haiteng4, Qin Chunyu2   

  1. 1. Chongqing Key Laboratory of Complicated Oil and Gas Field Exploration and Development, Chongqing University of Science and Technology, Chongqing 401331, China;
    2. State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum(Beijing), Beijing 102249, China;
    3. Shenzhen Branch of COONC Ltd., Guangdong, Guangzhou 510240, China;
    4. Ocean College, Zhejiang University, Hangzhou, Zhejiang 310058, China
  • Received:2017-05-19 Revised:2018-06-01 Online:2018-08-28 Published:2018-07-23

Abstract: Current construction of sequence stratigraphic framework is mainly based on the analysis of stratigraphic superposition patterns near the estuary,with their lateral variation in the sedimentary body neglected.So the division standards of system tracts are restricted by the range of sedimentary bodies,and the sequence stratigraphic division scheme is not unique.As a result,it's difficult to carry out stratigraphic correlation in a larger scope in a sag. The study took a case of Pearl River Mouth Basin clinoform in 13.8 Ma(belongs to the Middle Miocene),and elaborated the characteristics of sequence boundary(SB),and the lateral variations of stratigraphic superposition patterns in Falling Stage System Tract(FSST)and Low stand System Tract (LST),through combination analysis of well and seismic data.The results show that a series of onlapping strata, which can be laterally tracked and correlated with LST progradation systems on seismic sections,should be named as LST rather than TST.Based on the principle of regional isochronous correlation,the definition of LST should be revised as a set of strata that are developed in the early of base-level rising cycle,marked by accommodation increasing rate being lower than the sediment supply rate,and contain lateral equivalent beds.While the definition of HST is revised as a set of strata that are formed in the late of base-level rising cycle,marked by the accommodation increasing rate being less than the sediment supply rate,and include a set of lateral equivalent beds. Meanwhile,the TST is defined as a set of strata with facies marker of the accommodation increasing rate being greater than the sediment supply rate and the lateral equivalents of LST and HST being excluded.Thus we proposed that the reconstruction of sequence stratigraphy framework should take estuary,shelf and deep water as an integrated whole,looking for the unique facies marker of each system tract,and carrying out systematic comparison and checking in three-dimensional space,rather than factitiously splitting a sedimentary system and then establish sequence stratigraphic frameworks separately.

Key words: lateral variation, system tract, seismic stratigraphy, sequence stratigraphy, Pearl River Mouth Basin

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