川中地区香四段气水分布特征及成因机理

Distribution rule and formation mechanism of gas and water in Layer 4 of Xiangxi Group of the centeral area in Sichuan, China

川中地区上三叠统香溪群第四段(香四段)为具低孔、低渗的致密碎屑岩储层。香四段气水层集中发育于中下部,气水分布态势严格受岩性控制,构造起伏对气水分布起辅助作用,非常规岩性-构造气藏与岩性气藏并存。气水分布关系因所处区域位置或构造带不同而有明显差异,相对稳定的斜坡区有利于岩性圈闭聚气成藏,而局部构造高部位有利于岩性-构造圈闭聚气成藏。

Layer 4 in Upper Triassic Xiangxi Group （T3x^4） of the central area in Sichuan has low porosity and permeability. The physical character of the reservoir is bad. The gas and water layers develop in the middle and lower parts of T3x^4. The gas and water distribution is controlled by lithology, and the structural change only has the assistant function. The unconventional lithologystructural gas reservior and lithology gas reservior are coexistent. The gas-water distribution relation has differences in different regions or different structural belts. The relative steady slope regions are favorable for oil and gas accumulation by the lithology trap,and the high-steep structural parts of the central area in Sichuan are favorable for the oil and gas accumulation by lithology-structural trap. So, the distribution rule and formation mechanism of gas and water in Layer 4 of the Xiangxi Group can be explained in reason.