川西须家河组泥页岩气成藏条件与勘探潜力

POOLING CONDITIONS AND EXPLORATION PROSPECT OF SHALE GAS IN XUJIAHE FORMATION IN WESTERN SICHUAN DEPRESSION

四川盆地川西坳陷上三叠统须家河组具备泥页岩气藏形成的地质条件,其泥页岩厚度大,分布广;有机质丰度高、母质类型好、成熟到过成熟,概略计算资源量为8.4×1012～33.5×1012m3,为第四次全国资源评价同一地区常规天然气聚集资源量的3.8～15.3倍,川西坳陷泥页岩气具有广阔的勘探前景,有望成为该区天然气资源接替的新类型。目前在对上三叠统的钻探中,须家河组泥页岩普遍表现出超高压和活跃的气显示,在砂、泥岩频繁互层段已经获得工业气流。川西致密砂岩气藏勘探技术可直接为泥页岩气勘探服务,同时还需要发展钻探深层泥页岩气藏的水平井钻井、完井技术和泥页岩储层改造技术。

The Upper Triassic Xujiahe formation in the western Sichuan depression is characterized by large thickness and extensive distribution of shale,high abundance of organic matter,favorable types of kerogen,and mature to over mature source rocks,thus it has the geologic conditions for the formation of shale gas pools. The estimated resource volume of shale gas is 8.4 to 33.5 TCM,which is 3.8 to 15.3 times larger than that of conventional gas volume estimates obtained in the fourth round of resource assessment. Exploration prospect of shale gas in the western Sichuan depression is bright and shale gas is possible of contributing to the replacement of gas resources in the study area. Drilling results reveal that ultra-high pressure and gas shows are common in the shale in the Upper Triassic Xujiahe formation,and industrial gas flows have been tested in the interbeded thin sandstone and shale. Exploration techniques of tight sand gas in the western Sichuan depression can be applied directly to exploration of shale gas. In addition,new horizontal drilling and completion technologies and shale reservoir modification techniques should be developed for drilling and exploiting deep shale gas.