Reservoir Characteristics And Oil Accumulation Factors Research Of Chang 9 In Huanxian-Zhengning Area Ordos Basin

Huanxian-Zhengning area where has a low structure is as some nose-shaped uplifts on north-west dip monocline.The sedimentary systems of chang9 of Huanxian-Zhengning area is delta deposition.The south-west part of study area develops delta front facies and north-east part of study area develops shallow lacustrine facies.The reservoir condition is poor in the study area,main porosity is 6%~14%,the average is 10.55%,mainly permeability is0.001 m D~2mD,average is 0.306 mD,it belongs to low permeability and low porosity reservoirs.Lithology is mainly arkose,a few of lithical arkose.The main reason for the densification of the reservoir is mainly due to the strong compaction effect and the influence of the cementation.The contact mode of mineral particles presents the shape of the point and line.A large number of primary intergranular pores were lost,mainly due to the pore filling of calcite and zeolite.A large number of primary intergranular pores were lost,mainly due to the pore filling of calcite and zeolite.A large number of intergranular pore preservation because chlorite film development,improve the compressive capacity of mineral particles.A little of lithic intragranular dissolved pores and feldspathic intragranular dissolved pores Improve the quality of reservoir.The thick sand body,larger particle size sand,chlorite content close to 5%,is the standard of high quality reservoir.chang 9 reservoir have large-scale distributary channel sandstone.It provides favorable conditions for the high quality reservoirs.Dissolved pore and fracture provide storage spaces and migration channel.High-quality hydrocarbon source rock is the main control factors of reservoir-forming.