Oil & Gas Geology ›› 2008, Vol. 29 ›› Issue (2): 159-166.doi: 10.11743/ogg20080202

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Property differences and genetic mechanisms of hydrocarbon in each oil unit of the Carboniferous in Tazhong-4 oilfield

Jiang Zhenxue1,2, Yang Jun1,2, Pang Xiongqi1,2, Yang Haijun3, Li Zhuo1,2   

  1. 1. Basin & Reservoir Research Center, China University of Petroleum, Beijing 102249, China;
    2. State Key Laboratory of Petroleum Resource and Prospecting, China University of Petroleum, Beijing 102249, China;
    3. Research Institute of Exploration and Development, Tarim Oilfield Branch Company, CNPC, Korla, Xinjiang 841000, China
  • Received:2008-03-03 Online:2008-04-24 Published:2012-01-16

Abstract:

The three oil units of the Carboniferous in Tazhong-4 oilfield feature in a hydrocarbon distribution of gas-bearing formation being clipped between oil-bearing formations.The Carboniferous reservoirs in Tazhong-4 oilfield were formed mainly in two stages,the earlier oil-charging stage and the later gas-charging stage.By combining the oil and gas charging times with the analysis of mudstone compressive strength,fluid residual pressure and normal pressure on fault surface in different periods,and the relationship among these three parameters,it is suggested that the fault cutting through the three units were open in the late Hercynian,leading to accumulation of oil and gas in the Unit C and C;while in the Himalayan period,fluid residual pressure of Unit C was greater than the normal pressure on fault surface,resulting in late accumulation of gas in the Unit C rather than Unit C.Moreover,the gas charged in C unit could not migrate upward through the fault into Unit C due to the large thickness of the upper shale interval.The analysis of the whole process of the pooling in the Carbonife-rous reservoirs in Tazhong-4 oilfield indicates that the western section of the central fault-horst zone is favorable for finding secondary oil pools in Unit C and C.

Key words: fault transport system, fault sealing property, genetic mechanism, Tazhong-4 oilfield, Tarim Basin

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