Research On The Reservoir Characteristics Of The Chang-3 Member In Xi-259 Well Area Of Chenghao

In this paper, the reservoir microfacies, petrology, physical properties and pore structure characteristics of Chang-3 member reservoir in Xi-259 well area of Chenghao have maken a systematic research, which based on drilling and logging datas, with the core observation and the techniques of casting section, SEM, pore image, conventional pressure mercury, and relative permeability curve experimental. At the same time, reservoir properties have been discussed from the perspective of sedimentation and diagenesis. The conclusions go as following:(1) The Sedimentary facies of Chang-3 member reservoir in Xi-259 well area of Chenghao mainly shows a shallow lacustrine delta front subfacies, which is basically the band Spread in the plane. There are three microfacies:underwater distribution channel, mouth bar, and interdistributory bay.(2) The main lithology of Chang-3 member reservoir in this study area are mainly composed of lithic feldspathic sandstones, which has the characteristics of low composition maturity, medium textural maturity, and sub-round to sub-angular shaped. Interstitial materials are mainly authigenic clay minerals and carbonate minerals that were formed cement. The main types of pore cementation are pore-film cemented and a few of films-pore type cement.(3) Chang-3 member reservoir in Xi-259 well area is a low porosity and low permeability reservoirs, which main reservoir spaces are esidual intergranular pores, followed by dissolution holes. The main throat type is lamellar and curved lamellar, followed by necking-type throat and tube-shaped throat. The connectivity of interporosity is poor, and pore fabric shows fine-middle.(4) The types of diagenesis of in Chang-3 member are compaction, cementation and dissolution, followed by metasomatism and rupture. The compaction and cementation is one of the main reason which make effective reservoir porosity and permeability low; but the dissolution plays an active role on reservoir properties. (5) The ability of Chang-3 reservoir was mainly controlled by sedimentation and diagenesis. Particle size of rock in weaker hydrodynamic deposition is mainly fine, very fine sand, low compositional maturity and medium texture maturity, which is the main reason for low porosity and permeability of reservoir.