辽河坳陷东部凹陷沙三段页岩油气成藏地质条件

Accumulation Conditions of Shale Oil and Gas in Member 3 of the Shahejie Formation in the Eastern Sag of Liaohe Depression

从辽河坳陷东部凹陷的构造演化入手，通过对沙三段页岩的沉积地质背景、地球化学特征、储集特征及含气性特征等方面分析页岩油气的成藏条件，初步探讨了辽河坳陷东部凹陷沙三段页岩油气的成藏模式，并优选出页岩油气的勘探有利区。结果表明：东部凹陷沙三段发育一套湖相暗色页岩，页岩厚度较大，一般介于100～500m之间；有机碳含量在0．1％～6％之间，平均值达2．91％；有机质热成熟度Ro值较低，平均值为0．6％，属于低成熟一成熟有机质；储集空间以粒间孔和溶蚀孔为主，石英、碳酸盐类等脆性矿物含量较高，具有一定的脆性；页岩的含气性较好，等温吸附测试表明吸附气量在0．65～5．11m3／t之间，平均为2．32m3／t。通过页岩油气成藏条件多因素叠加法，认为北部的牛居一长滩洼陷和南部的驾掌寺一二界沟洼陷是东部凹陷沙三段页岩油气勘探有利区。

Based on the shale sedimentary background, geochemical characteristics, reservoir characteristics and gas content etc. ,we analyse the formation conditions of shale oil and gas and the reservoir forming pat- tern,and select the favorable exploration area. The results show that the thickness of member 3 in the stud- y area is large,commonly between 100-500m. The organic carbon mass fraction is in the range of 0.1%-6% with an average of 2.91%. Thermal maturity of organic matter is low with an average value of 0.6 %. The reservoir space is mainly inter-granular pore and dissolved pore. The brittle mineral content is high such as quartz and carbonate rocks, so it has certain fragility. Furthermore, the results of isothermal absorption show that shale has high performances of gas absorption, and the total gas content is 0. 65-5.11m3/t, with an average value of 2.32%. Finally,through the multi-factors superposition method of shale oil and gas ac- cumulation conditions,we believe the Niuju-Changtan subsag in the north and south of Jiazhangsi-Erjiegou subsag is a favorable area for oil and gas exploration in the Eastern Sag of Liaohe Depression.