A detailed investigation of the integrity issues of oil and gas wells in Bohai Oilfield revealed that there is a high proportion of abnormal annular pressure,which poses a huge challenge to the safety of wellbore service.To effectively calculate the maximum bearing capacity of the annulus and control the annulus pressure within an effective safety range,it is necessary to more accurately calculate the effective residual strength of the casing.The corrosion of casing in oil and gas wells in Bohai Oilfield is mainly caused by CO2.This article comprehensively considers the combined effect of casing wear and CO2 corrosion.Based on the use of the"De.Ward model for corrosion rate prediction","long-term corrosion rate prediction model",and"pipe string strength calculation model"that are in line with the characteristics of offshore oil,a calculation method for residual strength after casing wear and corrosion is established.Taking the 2D well with annular pressure self flowing well as an example,The calculation of the residual strength of the casing shows that corrosion is the main factor affecting the overall minimum residual strength of the casing.When wear occurs in the deep middle of the casing,it has an impact on the residual strength of the middle of the casing.This method is of great significance in calculating the residual strength of casing under the dual effects of wear and corrosion,and effectively guides safety production.
bohai oilfieldannular pressurewear of casingcorrosion of casingremaining strength of casing
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