| Shale oil and gas has become a hot spot of oil and gas exploration and development in China,which is of strategic significance to ensure energy security and optimize energy structure.The 7th member of Yanchang Formation in Ordos Basin is rich in shale oil resources,but shale oil reservoirs have low porosity and low permeability,complex pore structure,and low crude oil natural productivity.In order to achieve effective development of shale oil,large-scale horizontal well fracturing technology is adopted to improve crude oil productivity.Spontaneous imbibition exists in many key stages such as volume fracturing and water injection development,which has become one of the important factors affecting the crude oil productivity of shale reservoir.In this paper,the pore structure characterization and physical property test of shale oil reservoir samples in Chang 7 member are carried out,and the migration and storage capacity of the reservoir are analyzed combined with the filling experiment.The effects of reservoir physical properties and pore structure on spontaneous imbibition of shale oil reservoirs were analyzed by spontaneous imbibition experiment and NMR T2 spectrum response to monitor fluid migration process,and the control effect of source-reservoir configuration on imbibition was clarified.The results show that the microscopic pore structure of Chang 7 shale oil reservoir is complex,mainly composed of small pores and medium pores.The source-reservoir interbedded samples have poor reservoir capacity and imbibition capacity,mainly develop small pores,poor pore connectivity,and small pores have a high contribution to imbibition.Shale oil reservoir imbibition is less affected by porosity,permeability and clay content,mainly controlled by wettability,reservoir quality factor and pore throat ratio.The greater the reservoir quality factor is,the closer the wettability is to water and humidity,and the greater the pore throat ratio is,the better the imbibition effect is. |
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