库车坳陷中、下侏罗统煤系烃源岩排烃特征及资源潜力评价

库车坳陷侏罗系致密砂岩油气藏的勘探日趋重要,其主力烃源岩排烃特征及资源潜力的研究亟待加强。根据排烃门限理论,笔者利用生烃潜力法研究库车坳陷中、下侏罗统煤系烃源岩在不同地质历史时期的排烃特征,并对其资源潜力进行评价。研究表明:库车坳陷中、下侏罗统煤系烃源岩Ⅱ型有机质的排烃门限为0.7%,Ⅲ型有机质的排烃门限为0.8%。该套烃源岩的主要排烃期为康村组和库车组沉积期,属于晚期排烃,地质历史时期主要有3个排烃中心,即克拉苏地区、大北地区及迪那—依南地区。总排烃量和总远景资源量分别为887.06×108t和47.02×108t,其中石油与天然气的远景资源量分别为22.96×108t和3.02×1012 m3。综合分析后认为,侏罗系致密砂岩油气藏以中、下侏罗统煤系烃源岩为主力供烃源岩,具有良好的资源前景。

Hydrocarbon Expulsion for Middle-Lower Jurassic Coal Measures and Evaluation of Potential Resource in Kuqa Depression

Since tight sand gas is playing an important role in the gas exploration in the Kuqa depression,it is necessary to well understand hydrocarbon expulsion of source rock and to evaluate the resource potential.In this paper,the hydrocarbon expulsion processes for the middle-lower Jurassic coal measures at different times are discussed by using hydrocarbon-expulsion threshold theory,and the resource potential of these source rocks is also evaluated.The results show that the thermal maturity for the hydrocarbon expulsion thresholds of type Ⅱ and III organic matters in the middle-lower Jurassic coal measures is 0.7%(RO) and 0.8%(RO),respectively.The main period of hydrocarbon expulsion for the middle-lower Jurassic coal measures is corresponding to Kangcun and Kuche Period,which belongs to typical late hydrocarbon expulsion.Three centers of hydrocarbon expulsion in the geological period are located in the regions of Kelasu,Dabei and Dina-Yinan,respectively.The total quantity of hydrocarbon expulsion and is 887.06×108t.The total resources are 47.02×108t,with oil resource of 22.96×108t and gas resource of 3.02×1012m3.Thus,the middle-lower Jurassic coal measures make great contribution to tight sand gas reservoirs in the Kuqa depression,associated with good resource prospect.