Safety Analysis of Carbon Dioxide Injection in AN Oilfield Casing Damage Repair Wells

In order to achieve green and low-carbon transformation, X Oilfield plans to build a CCUS full industry chain demonstration base, among which the AN experimental area is an important support block for CCUS industrial construction. In response to the issue of whether the repaired casing damaged wells in the AN block of X Oilfield can meet the safety requirements for carbon dioxide injection, a post repair safety assessment of casing damaged wells has been conducted. By analyzing the production parameters of gas injection wells in the CCUS experimental area of AN oilfield, conducting research on the performance parameters of casing damage repair processes, and analyzing the location and geological conditions of casing damage, evaluate whether the casing damage repair wells can meet the safety requirements for carbon dioxide injection. In response to the problem of insufficient targeted safety assessment during carbon dioxide injection in the previous scrapping process of casing damaged wells, innovative efforts have been made to conduct integrated analysis of wellbore formation, mechanical analysis of residual strength of pipe strings, analysis of cement ring sealing ability during supercritical carbon dioxide injection, and safety evaluation of sealing after casing damage repair. At present, there are 34 casing damage repair wells in AN test area. According to the current data analysis results, 12 of them meet the subsequent safety production requirements and can be converted to carbon dioxide Injection well to continue production. The remaining 22 wells do not meet the safety requirements and need to be plugged and scrapped to reduce the scrapping rate of casing damage repair wells by 35%. It is recommended to conduct a safety analysis on the conversion of casing damage repair wells to injection before the production of each CCUS experimental area, in order to improve the utilization rate of old wells.