Experiment Evaluation And Application Of Shale Oil Mobility In Southern Songliao Basin

The shale oil in the Qing 1 Member in the southern part of the Songliao Basin is widely developed and has abundant reserves.However,during the development in recent years,the recovery rate of shale oil in the study area has not been high,and mobility is the key factor affecting the development of shale oil in the southern Songliao Basin.Therefore,it is very meaningful to study the mobility of shale oil in this area.In this article,the basic physical properties of shale oil reservoir cores in the southern Songliao Basin are experimentally studied.Then,based on the traditional theory of spontaneous imbibition and imbibition oil displacement,Using the monitoring of nuclear magnetic resonance technology,the imbibition capacity and oil displacement potential of the reservoir in the study area were evaluated.At the same time,the change law of the pore structure in the core was studied by the nuclear magnetic T₂ spectrum.Finally,the centrifugation experiment under the monitoring of nuclear magnetic resonance is used to study the movable fluid saturation of the core in the study area and the change of fluid content in the pore space corresponding to different throat radii.From the perspective of dynamic development,this paper systematically analyzes the influencing factors of reservoir shale oil mobility in the study area,and conducts multi-scale evaluation on the mobility of shale oil reservoirs in the southern Songliao Basin.The main research results obtained and the understanding of the research area are as follows:（1）The factors affecting the mobility of shale oil in the southern Songliao Basin include pore radius,imbibition capacity,oil displacement potential,distribution of movable fluid,wettability,rock mechanical properties and microstructure of the reservoir.Among them,the pore radius and the distribution of movable fluid are the main factors affecting the mobility of shale oil in the study area.（2）During the spontaneous imbibition process of shale oil reservoirs in the southern Songliao Basin,the liquid first filled the micro-nano pores,and then imbibed into the slightly larger pores.However,the amount of imbibition in the mesopores and macropores is small,and the overall imbibition end time is short,so it is difficult for the liquid to enter the reservoir.Adding a fracturing fluid containing an anti-swelling agent to the reservoir in the study area can prevent clay swelling from blocking pores,which can effectively improve the mobility of shale oil.（3）The ultimate recovery rate of sandy shale and pure shale in the shale oil reservoirs in the southern Songliao Basin is approximately 23%,while the ultimate recovery rate of low-maturity shale is 16.4%.The overall oil recovery is small and the difference is large.When actually exploiting the oil displacement potential,deep reservoirs with higher core recovery factor in sandy shale should be selected for exploitation,which is beneficial to improve the mobility of shale oil and improve the ultimate recovery factor of shale oil.（4）The difference in movable fluid saturation in the shale oil reservoirs in the southern Songliao Basin is relatively small,ranging from 13.8%to 23.4%.Among them,the small pores with throat radius of 0.07μm～0.19μm are the main contributors to the mobility.It is of great significance to improve the development and utilization of shale oil in small pores to improve the mobility of shale oil in the study area.