Oil & Gas Geology ›› 2014, Vol. 35 ›› Issue (5): 595-600,608.doi: 10.11743/ogg20140502

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Main controlling factors and models of hydrocarbon accumulation in weak structural belts of oil-rich sags, the Jizhong Depression

Gao Changhai1, Zha Ming1, Ge Shengquan2, Chen Li3, Zhao Xianzheng4, Jin Fengming4   

  1. 1. School of Geosciences, China University of Petroleum, Qingdao, Shandong 266580, China;
    2. PetroChina Tarim Oilfield Company, Korla, Xinjiang 841000, China;
    3. PetroChina Changqing Oilfield Company, Xi’an, Shaanxi 710018, China;
    4. PetroChina Huabei Oilfield Company, Renqiu, Hebei 062552, China
  • Received:2014-01-08 Revised:2014-03-03 Online:2014-10-08 Published:2014-10-17

Abstract:

Weak structural belts in this paper refer to Wenan and Lixian slope zones of the oil-rich sags in Jizhong Depression,where the exploration maturity is low but resource potentials are large and exploration prospects are good.Based on the integrated analysis of geological elements and in combination with physical simulation experiments,the paper illustrates the main controlling factors of hydrocarbon accumulation,reveals hydrocarbon accumulation patterns and establishes hydrocarbon accumulation models,so as to provide theoretical guidance for further oil and gas exploration of the weak structural belt.The result shows that the main controlling factors of hydrocarbon accumulation in weak structural belt are source rock,carrier system and nose structure.Among them,the source rock controlled the distribution range and the enrichment degree of hydrocarbons,the carrier system controlled the horizons of hydrocarbon accumulation and the reservoir types,and the nose structure controlled the hydrocarbon migration direction.Two hydrocarbon accumulation models were established for the weak structural belt based on the configuration relationships between the source rock and the carrier system.One is distal stepwise accumulation model on wide-gentle slope zone,featuring in joint driving of overpressure and buo-yancy,stepwise migration dominated by lateral transportation through sandbody and adjusted vertically by faults,accumulation in multi-layers far from the source rocks.The other is proximal Z-style accumulation model on gentle slope belt,featuring in driving of buoyancy,Z-style migration through vertical adjustment of faults and lateral transportation of sandbo-dies,the accumulation in multiple layers near the source rocks.

Key words: accumulation dynamic, accumulation model, weak structural belt, Jizhong Depression

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