The Research On The Micro-pore Structure And Seepage Characteristics Of Chang 6 Reservoir Of Banqiao-heshui District In Ordos Basin

The Banqiao-Heshui area is a typical oil and gas reservoir with low-permeability.The physical properties of Chang 6 reservoir in this area are poor,and the pore structure is complex.The percolation characteristic in the reservoir is affected by many factors.Since recovery rate is still low after years of exploration and development,this dissertation carried out a systematic and comprehensive analysis of the Chang 6 reservoir in the Banqiao-Heshui area in order to make a deep study of problems mentioned above.Several experiments including casting thin films,scanning electron microscopy,high-pressure mercury intrusion,and constant-rate mercury intrusion have been used to study the microscopic pore structure characteristics of the reservoir.The factors which affecting the pore structure have been also analyzed from different perspectives including physical properties,mineral content,and experimentally obtained characteristic parameters;The study of microscopic seepage characteristics of the reservoir is based on data gained from experiments including nuclear magnetic resonance,oil-water phase seepage,water flooding and other experimental methods.Finally,the reservoir characteristics,micro-pore structure and percolation characteristics of three representative single wells are comprehensively analyzed,and the mechanical coupling effect of the study area is studied.The main research results are as follows:The main type of rocks of Chang 6 reservoir in the Banqiao-Heshui area is lithic arkose sandstone.The physical properties of this reservoir are poor with an average value of porosity is 10.01%and an average value of permeability is 0.22×10^-3?m².Diagenesis,which is mainly destructive diagenesis,has a significant effect on the pore structure of the reservoir.The pore throat types of Chang 6 reservoir in the Banqiao-Heshui area are diverse.The type of pore is mainly feldspar dissolved pores.The main throat types are flake or curved throat.The pore throat characteristics of reservoir is complex and the heterogeneity is strong.The main types of high pressure mercury capillary curve is?,?.The analysis shows that the quality of the reservoir physical properties is affected by a number of characteristic parameters including pore throat radius,sorting coefficient,coefficient of variation and so on.The saturation of mobile fluid in the reservoir is low,and the saturation of irreducible water is high.The interference degree of oil-water flow is large and the displacement efficiency of water is low.The study of microscopic pore throat structure and percolation characteristics of single wells with different pore structures indicates that the superiority of the reservoir is the result of the coupling of multi-factors,in which the degree of throat development and pore throat configuration play a major controlling role.