Characteristics of Diagenesis-Reservoir Facies and Pore Space Evolution of the Second Member of Quantou Formation at Siwujiazi Oilfield, Jilin Province

Based on the analytic data of casting thin section, scanning electron microscope, X-ray diffraction of clay minerals of well core samples at Siwujiazi oilfield, the diageneses, diagenetic sequences and stages of the Second Member of Quantou Formation of the Lower Cretaceous were studied. The study suggests that its reservoir rocks can be divided into 4 types of diagenetic-reservoir facies, i.e. facies A, which has undergone weak cementation and middle compaction and has interparticle pores; facies B, in which calcite cements have been greatly dissolved and secondary dissolution pores have been developed; facies C, which has undergone strong compaction and has micro pores, showing matrix filled in interparticles; facies D, which has undergone early calcite cementation. The characteristics and origin of each diagenesis-reservoir facies are described in detail. Finally the types and evolution of pore space are discussed.