During the displacement process,dynamic fluid exchange occurs between the fluid in the wellbore and the surrounding formation fluid,leading to changes in the composition of the annular flu-id and subsequently causing variations in annular pressure.Existing models for calculating annular pressure cannot accurately predict pressure distribution based on displacement conditions.Therefore,this study establishes a novel model for calculating annular pressure in shale oil wells under displace-ment conditions.Through numerical simulation analysis of various influencing factors on annular pres-sure distribution,the results indicate:① Maintaining a constant flow rate of annular fluid entering the formation,increasing the flow rate of formation fluid entering the annulus results in a reduction of an-nular pressure by approximately 1.19 MPa/L;② An inflection point will appear on the annular pres-sure distribution curve,and the inflection point position is consistent with the displacement point posi-tion;③ With the increase of shale oil density of formation fluid,the annular pressure increases by ap-proximately 0.034 MPa/(kg·m-3).The results of this study can provide some theoretical reference for problems such as displacement,leakage and overflow in drilling in complex formations.
维普
万方数据