Oil & Gas Geology ›› 2018, Vol. 39 ›› Issue (1): 20-29.doi: 10.11743/ogg20180103

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Characteristics of S-shaped strike-slip transfer zones and quantitative analysis of their influence on hydrocarbon accumulation in Liaoxi structural belt, Bohai Sea

Liu Yubo1, Huang Xiaobo1, Xu Changgui1, Li Qiang1, Wu Kui1, Yu Yixin2, Zhang Rucai1   

  1. 1. Tianjin Branch, CNOOC Limited, Tianjin 300459, China;
    2. State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum(Beijing), Beijing 102249, China
  • Received:2017-05-14 Revised:2017-09-20 Online:2018-02-28 Published:2018-03-12

Abstract: S-shaped strike-slip transfer zone is widely developed structure in strike-slip strain background.However, previous researches are mainly focused on the classification of strike-slip transfer zones, but its control on hydrocarbon accumulation is poorly understood.Based on 3D seismic data and oil and gas fields analysis, this paper addresses the effects of S-shaped strike-slip transfer zone on hydrocarbon accumulation in the Liaoxi structural belt, Bohai Sea, by using statistical methods.Cenozoic structural deformation of the Liaoxi structural belt is characterized by deformation of NE-trending extension superimposed by NEE-trending dextral strike-slip activities.S-shaped strike-slip transfer zone can be divided into restraining bends and releasing bends.According to different evolution stages, restraining bends can be further divided into 3 subordinate classes, involving transpressional uplifting bend, gentle restraining bend and intense restraining bend.Similarly, releasing bends involve spindle-shaped pull-apart, lazy s-shaped pull-apart and rhomboidal pull-apart.In addition, the strike-slip transfer zones at the end of strike-slip fault zones contain restraining and releasing horsetails.The concept of oil and gas enrichment index (OGEI) is defined, and the positive correlation between master strike-slip fault curvature and intensity of adjusting strike-slip faults is proven.A mathematical model from OGEI is proposed to quantitatively predict oil and gas enrichment.It is a quantitative tool for exploration decision, and has been applied in analysis of LD5-2N oil field successfully.

Key words: oil and gas enrichment index, strike-slip structure, S-shaped strike-slip transfer zone, Liaoxi structural belt, Tanlu fault zone, Bohai Sea

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