Oil & Gas Geology ›› 2016, Vol. 37 ›› Issue (5): 644-652.doi: 10.11743/ogg20160504

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Characterization and genesis of fault-controlled karst reservoirs in Ordovician carbonate karst slope of Tahe oilfield,Tarim Basin

Han Changcheng1, Lin Chengyan1, Lu Xinbian2, Ren Lihua1, Wei Ting3, Zhang Xianguo1, Duan Hongzhen4   

  1. 1. School of Geosciences, China University of Petroleum, Qingdao, Shandong 266580, China;
    2. Northwest Oilfield Company, SINOPEC, Urumqi, Xinjiang 830011, China;
    3. Shixi Oil Production Plant, Xinjiang Oilfield Company, PetroChina, Karamay, Xinjiang 834000, China;
    4. CNPC Logging Qinghai Business Division, Dunhuang, Gansu 736202, China
  • Received:2015-11-09 Revised:2016-05-07 Online:2016-10-08 Published:2016-11-07

Abstract: The internal karst reservoirs in the slope area of Tahe oilfield,Tarim Basin have attracted more and more attention as further exploration and development were carried out in the weathering crust karst reservoirs in the buried hills of the main blocks in the field.It is generally agreed that faults control the formation and distribution of karst reservoirs.Based on reservoir classification,the paper analyzed control effect of faults upon karst reservoirs and their distribution and discussed forming mechanism and evolving characteristics of the reservoirs through study of core,thin sections,logging and drilling as well as seismic data.A coupling relationship between extent and phases of development of faults and karst reservoirs was revealed during the analyses.Multi-phased and inherited faults of grade Ⅱ and Ⅲ-1 seemed to have a more prominent controlling effect upon the karst reservoirs.Horizontally,the reservoirs distributed as belts along faults; and vertically,they were observed to occur within intervals 0-50 m or 100-150 m below the top of the Ordovician Yijianfang Formation.The paper also suggested that these reservoirs were formed mainly by meteoric water dissolution,TSR (Thermochemical Sulfate Reduction),hydrothermal dissolution,and hybrid dissolution.The Early Hercynian was believed to be the main stage for the development of the fault-controlled karst reservoirs in the field.

Key words: fault-controlled karst reservoir, slope zone, fault zone, Ordovician, Tahe oilfield

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