Study on numerical analysis method of abnormal pressure formation in annulus A of CO2 injection well

Abstract

With the gradual development of CO₂ drive in oilfield, the existing CO₂ injection wells have A annulus pressure anomalies, and the A annulus pressure anomalies are very likely to cause damage to the wellbore integrity, and there is a greater safety risk to production and the environment. To address the problem of annulus pressure in CO₂ injection wells, a model of pressure equilibrium between tubing and A annulus and a model of mass conservation in the process of A annulus pressure relief have been established, and the effects of different oil jacket differential pressures, annulus liquid levels, leakage hole locations, equivalent diameter of leakage holes, and pressure relief time on the pressure in A annulus have been investigated, so as to form a method of evaluating the degree of leakage in A annulus. This method can provide theoretical guidance for the preliminary diagnosis of annulus with pressure in CO₂ injection wells, and has certain engineering reference significance for the control of annulus pressure in CO₂ injection wells.