Micro-pore Structure of Diagenetic Facies of Chang 6₃ Reservoir and Distribution of High Quality Reservoir in Banqiao-Heshui Area

Key words: 
• Banqiao-Heshui area /
• high quality reservoir /
• diagenetic facies /
• pore structure /
• log response /

Abstract: Types of diagenetic facies and micro-pore structure characteristics of sandstone components of Chang 6₃ reservoir in Banqiao-Heshui area are systematically studied according to thin section, scanning electron microscope, mercury injection, constant-rate mercury penetration and relative permeability data. Logging response stencil is also established. Moreover, diagenetic facies parallel and planar distribution have been studied. The results show that relationship between quality of diagenetic facies controlled by sedimentary facies, diagenesis and pore structure, especially throat distribution, which is the major factor controlling the reservoir permeability. Reservoirs belonging to hydromica cementation-residual intergranular pore facies and hydromica cementation-feldspar dissolution facies, in which fine or micro-fine throat develops, pore connectivity is good, show the best flow ability and a relatively uniform oil-water percolation. These facies located in flow composite channel turbidite deposition in semi deep lake facies of gravity and oil within pores is easily mined through the throat. Pore throat radius of chlorite cementation facies and hydromica weak ementation dissolution facies is small but uniform distribution, besides this kind of reservoir distributed in the branching channel margin and seepage permeability is middle to poor. Carbonate cementation facies and carbonate+hydromica cementation facies with the worst pore structure mainly developed in the branch between the canal. Due to fine throat and poor pore connectivity, oil enrichment in pore is difficult to pass through fine throat, and recovery ratio of these two kinds of diagenetic facies is very low.