松辽盆地北部青山口组页岩油形成地质条件及勘探潜力

Geological conditions and exploration potential of shale oil in Qingshankou Formation,Northern Songliao Basin

页岩油气是重要的常规油气接替资源之一。根据页岩油区域地质调查,研究了松辽盆地北部青山口组页岩油形成的地质条件,优选出有利层段,并评估了其勘探潜力。青山口组内部旋回性明显,受湖平面控制富有机质与灰质、粉砂质泥岩交替出现;次级旋回下部暗色泥页岩具有单层厚度大、分布面积广,有机质丰度高等特点,目前尚处于大量生油气阶段;次级旋回上部富含长英质矿物,属于特低孔特低渗性储层,扫描电镜下微孔及微裂缝较为发育,为油气滞留提供了储集空间;青一段泥页岩整体非均质性强,并普遍发育有异常压力,具备形成页岩油的有利地质条件。地球化学分析及等温吸附试验结果表明,青山口组一段相比其他层段含油性最好,并具有一定的含气量,是具有最优勘探潜力的页岩油层系。综合以上地质条件及含油气性研究,确定了青山口组一段页岩油有利层段的空间分布,并通过资源量计算的相关参数赋值,采用概率体积法计算出松辽盆地北部青山口组一段页岩油地质资源量为105.60×108t,勘探潜力巨大。

Shale oil and gas is one of the most important resources to replace the conventional oil and gas .According to regional geological surveying ,the geological conditions of the development of shale oil in northern Songliao Basin were studied in this paper .Also,the favorable target intervals were selected and their potentials of exploration were assessed . The Qingshankou Formation has obvious cyclicity due to the control of lake level change ,with mudstone rich in organic matter and gray matter and silty mudstone appearing alternately .The dark mudstone in the lower subcycle is characterized by large single layer thickness ,broad distribution area and high content of organic matter ,and is still at the stage of hy-drocarbon generation .The upper subcycle is characterized by enrichment of quartz-feldspathic minerals and ultra-low po-rosity and permeability .Many micro pores and cracks are observed in scanning electron microscope ,and they offer reser-voir space for oil and gas.In addition,the shale reservoirs in K1qn1 are heterogeneous and mostly have abnormal pres-sure,thus are favorable for the shale oil accumulation .Geochemical analysis data and isothermal adsorption test of shale interval show that the 1st member of Qingshankou Formation is richest in oil ,and contains some gas .So it has the larget exploration potential for shale oil exploration .Based on the above-mentioned geological conditions and oil-gas-bearing pos-sibility study,the space distribution of favorable reservoir in K 1qn1 is determined,and the OOIP of shale oil is calculated to be 10.56 billion tons by using probability volume method .