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四川盆地须家河组蕴含丰富的天然气资源,是西南油田公司天然气勘探和储量增长的主力层系之一。天然气主要储集在大面积展布的须家河组二段、四段和六段共3段大型砂岩储集体中。利用野外露头勘察和井下资料解释,解剖了须家河组单砂体的内部结构和规模,描述了砂体发育特征,剖析了大型砂岩储集体的形成机理。研究发现须家河组砂体单体规模有限、总体数量众多,单砂体之间存在高频切割式、低频切割式、搭接式和孤立式4种叠置方式,纵向上叠置、横向上搭接、空间上叠合连片,形成了“集群式”大规模展布的砂岩储集体。砂岩储集体的这种分布样式决定了须家河组天然气资源总体呈现中低丰度、大范围展布的特征。
The Xujiahe Formation in Sichuan Basin is rich in natural gas resources and is one of the main strata of natural gas exploration and reserve growth in Southwest Oilfield Company. Natural gas is mainly stored in three large sandstone reservoirs in the second, fourth and sixth stages of the Xujiahe Formation, which is widely distributed. Using outcrop investigation and data interpretation, the internal structure and scale of single sand body in Xujiahe Formation were dissected. The characteristics of sand body development were described, and the formation mechanism of large sandstone reservoir was analyzed. It is found that sand bodies in Xujiahe Formation have a limited scale and a large number of sand bodies. There are four kinds of stacking modes of high frequency cutting, low frequency cutting, overlapping and isolation between single sand bodies. On the overlap, spatially superimposed contiguous, forming a “cluster ” large-scale distribution of sandstone reservoirs. This pattern of distribution of sandstone reservoirs determines that the natural gas resources of the Xujiahe Formation generally exhibit medium-low abundance and large-scale distribution.