Pile Sea Region Mesozoic Clastic Reservoir Characteristics And Evaluation

On the basis of core observation, thin section arbitration, and scanning electron microscope and x-diffraction analysis, the diagenesis, reservoir space and controlling factor of detrital reservoir of Mesozoic in Zhuanghai area are researched. The results indicated that the reservoir sandbodies of alluvial fan, fan delta, fluvial and delta were developed in Mesozoic group in Jiyang Depression. The clastic reservoirs mainly went through strong compaction, cementation, metasomasis and dissolution. It has been found by the analysis of reservoir characteristics and its control factors of clastic reservoirs that solution pores and fractures are main reservoir spaces, under the control of sedimentary process, diagenesis and tectonic process, several secondary pores zones were developed on the round of unconformable surfaces, and the best secondary pores were developed on the top of Mesozoic. The sedimentation, tectonization and diagenesis control the porosity and permeability of clastic reservoirs, and the sedimentation is the most important control factor, among other things, the porosity and permeability of delta sandbody is the highest, the porosity and permeability of fluvial sandbody takes second place, and the porosity and permeability of alluvial fan, fan delta and shore-shallow lake is poor. The influence of tectonization on clastic reservoirs includes the fault activities and unconformities. A great deal of fractures were formed because of fault moving, and the porosity and permeability of reservoirs locating about 100m under unconformity interfaces increases obviously. Dissolution were controlled by both sedimentation and tectonization, and the converted degree on reservoirs is close relative to sedimentary facies and the distance from unconformity interfaces. Comprehensive considering the control of sedimentation, tectonization and diagenesis on reservoirs, the clastic reservoirs are divided into four categories, of which, I is the type of high porosity and medium permeability, II₁ and II₂ are the type of medium porosity and low permeability, II₃ is the type of low porosity and permeability, and III and IV are the type of the lower porosity and permeability.