Abstract:

Reservoir rocks in Bashijiqike Fm outcrop are mostly of medium-grained lithic sandstone, dominated by the secondary dissolved micropores, strong-medium cementation, and weak-medium dissolved diagenetic facies. There are three genetic types of sand bodies in the Bashijiqike Fm, including sandy-braided channel sand bodies in the braided-delta plain in the 2nd member of Bashijiqike Fm, gravel-braided channel sand bodies in the braided-delta plain in the 1st member of Bashijiqike Fm,and fan delta reservoir sand bodies in the 3rd member of the Fm. On the basis of reservoir sand bodies' prototype-model, the reservoirs' architectural structure of Bashijiqike Fm outcrop can be divided into 6-grade hierarchical interfaces and 6-grade hierarchical entities, and the framework structure is of “building block” pattern. Single sand body occurs generally as tabular mass or wide lens.By contrasting with those in the subsurface,sand bodies in the outcrop area might be a little bit coarser,with higher cement content,and worse reservoir quality.The obvious differences between them might be caused by the epidiagenesis in the outcrop.

Key words: Cretaceous, reservoir characteristics, Bashijiqike Fm, Kuqa depression