Annular pressure distribution under the displacement conditions of shale oil wells
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.
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