Study On Reservoir Heterogeneity And Waterout Characteristics Of Chang 3 Reservoir In X73 Oil Area

The Chang 3 low permeability reservoir in the X73 oil area is located in Xifeng Oilfield in the middle of the Shanbei Slope of Ordos Basin.Research area is put into production in October2018,starting in June 2019,built into a large number of production stages,the early failure for reservoir natural energy development,as of August 2020,reservoir has entered high water cut period,a production decline is accelerated,the phenomenon such as moisture content is higher,at the same time there are some issue such as difference of regional water,the water injection development effect.In view of the problems and contradictions existing in the development of the study area,it is considered that the reservoir heterogeneity is the main cause of these problems.Based on the geological background of the study area and guided by the knowledge of sedimentology,tectonic geology,geophysics,logging geology and reservoir engineering,this paper divides the study reservoir into five sub-layers,namely,Chang 31~1,Chang 31~2,Chang 31~3,Chang 32~1 and 32~2.Based on core observation,particle size analysis and logging curve characteristics,Chang 3 reservoir can be divided into four microfacies:underwater distributary channel,channel flank,interdistributary bay and estuarine bar.The influencing factors of reservoir heterogeneity are revealed,and the depositional environment and diagenesis are the main controlling factors of reservoir heterogeneity.On the basis of geological research,the heterogeneity parameters of the reservoir and the study of the barrier and interlayer are obtained quantitatively,and the heterogeneity characteristics of the study area are clarified from the aspects of microcosmic,intra-layer,interlayer and plane.The water injection development effect is evaluated from five aspects:water cut and recovery degree,water injection utilization rate,production decline law,recovery factor and formation energy.The characteristics of water flooding in the study area are defined,and the geological factors causing water flooding in oil Wells are analyzed.It is considered that the strong heterogeneity of fractures and reservoirs is the main controlling factor for the degree and characteristics of water flooding in this area,and the sedimentary microfacies,microstructure,bedding and interlayer are the second.Continuously deepen the understanding and research of reservoir heterogeneity and its dynamic changes,and clearly understand reservoir heterogeneity and water-flooded characteristics as well as the distribution location of water-flooded layers,which is of great significance for formulating reasonable development technology policies,improving the effect of water flooding development,and maintaining stable and high production of reservoirs.