Abstract：There are mainly volcanic and clastic rock reservoirs at Cretaceous in Changling faulted depression, with different physical characteristics. It is shown that oil layers are mainly developed in the shallow sandstone of fan delta plain facies. The gas layers are mainly distributed in the rhyolite and eruptive tuff of overflow and explosion facies under Yingcheng Formation. The clastic rock reservoirs are mainly made of sandstone and characterized by high maturities of composition and middle texture, high contents of rock debris and matrix, and multi-type cemention. Physical properties of the clastic rock reservoirs are not good for production, majority of which are low-porosity and low-permeability reservoirs. Volcanic rock reservoirs are mainly formed by rhyolite in overflow facies and eruptive tuff in explosion facies, with high degree of heterogeneity of porosity and permeability, and many fractures, which may be good reservoir sites owing to the fracture connection cavity. Reservoir lithofacies and diagenesis are mainly characterized with two factors in affecting reservoir development. Sandstone and conglomerate of fan delta plain facies are mainly developed in clastic rock reservoirs, with weak compaction and more pores in Deng Louku Formation. Strong compaction and less or no secondary pores are seen in Yingcheng and Shahezi Formation. Volcanic rock reservoirs are chiefly rhyolite in overflow facies and eruptive tuff in explosion facies, and primary pores and fractures are developed, which is the result of both cooling diagenesis and hydrothermal fluid diagenesis.
2010, Vol. 28 
