Advancement in Casing Leak Repairs and Scab-Off to Restore Well Integrity Through Data Management Techniques

This paper addresses the data management techniques used to identify the optimum casing leak repair methods in Field-A for different leak intensities and scab-off strategies to isolate the leak intervals and restore well integrity. Casing leaks are one of the major well integrity failures which require well intervention to repair and restore production. There are several factors associated to develop a casing leak which include internal wear due to subsequent drilling after setting the casing, exposure to severely corrosive environments specially across poorly cemented intervals, casing metallurgy and design, cementing practices and in some cases due to casing threads damage. Casing leaks are categorized based on the leak intensity, which is measured by the injectivity rate when casing is pressure tested. For this paper, data evaluation techniques were utilized to evaluate different repair methods in the categories of low and high injectivity leaks. The optimum setting depth of cement retainers above the leak zone is also discussed for different casing sizes along with the recommended cement volume to over displace below the cement retainers, and to re-utilize them for subsequent squeeze attempts in case lockup squeeze pressure is not achieved in the first attempt. Comparative analysis of cement versus solids free resins to squeeze low injectivity leaks are also discussed in this paper. The accumulation of comprehensive historical casing leak repair data and arrangement of this data to evaluate the outcome in a quantitative manner results in identifying the best methods and procedures to cure casing leaks in different downhole environments. This data management technique will further optimize the repair operation with the inclusion of additional casing leaks data, and will optimize the time and cost spent in repairing the casing leaks and scabbing-off.