Oil & Gas Geology ›› 2012, Vol. 33 ›› Issue (1): 30-36.doi: 10.11743/ogg20120104

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Mesozoic bottom boundary unconformity and its significance for hydrocarbon exploration in the Yakela faulted uplift, Tarim Basin

Luo Xiaolong1,2,3, Tang Liangjie1,2, Xie Daqing4, Luo Shuanghan5, Jiang Huashan4, Yang Yong1,2, Chen Xuyun4   

  1. 1. State Key Laboratory for Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China;
    2. Basin & Reservoir Research Center, China University of Petroleum, Beijing 102249, China;
    3. School of Geosciences, Yangtze University, Jingzhou, Hubei 434023, China;
    4. SINOPEC Northwestern Oilfield Company, Urumqi, Xinjiang 830011, China;
    5. The Second Production Plant, PetroChina Xinjiang Oilfield Company, Karamay, Xinjiang 834008, China
  • Received:2011-08-23 Revised:2011-12-10 Online:2012-02-28 Published:2012-03-22

Abstract:

Mesozoic bottom boundary in Yakela Faulted upliftt is an important unconformity developed for a long geologic time,and its overlying and underlying formations are quite different in deformation manner.Based on interpretation of 3D seismic data in the Yakela faulted uplift,combining with well data,regional geology and regional strata distribution characteristics,the types of unconformities related to this reflector can be divided into nonconformity,truncation unconformity,overlap unconformity and karst unconformity according to their formation mechanisms and main factors controlling geometry.The nonconformities mainly occur in the eastern and western parts,where the pre-Mesozoic deposits were denuded completely.The monocline area,fold area and fault-fold area of truncation unconformity exsit in the middle and western parts of the Yakela faulted uplift from west to east.The overlap unconformity distributes along south climb of the Yakela faulted upliftt.The karst unconformity mainly distributes in the central and western parts,where the upper Palaeozoic was eroded completely and carbonates expose.The unconformities are of great significance for hydrocarbon accumulation as they can act as migration pathway,improve reservoir conditions and create lots of traps.Comprehensive analysis of the characteristics and distribution patterns of various unconformities in this area reveals that they are the results of tectonic deformations strong in the east and weak in the west of the Yakela faulted uplift.

Key words: Mesozoic bottom boundary, unconformity, trap, Yakela faulted uplift, Tarim Basin

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