Recovering from Integrity Loss in Compromised Completion with Coiled Tubing Abandonment Techniques

Abstract An operator wanted to sidetrack a well but faced several compounding issues. The production tubing was irretrievable, the tubing below the hanger was cut, and the tubing/casing annulus pressure envelope was compromised. Coiled tubing (CT) was introduced in a multirun plug and abandonment operation with a thru-tubing inflatable packer and cement to shut off the lower zone and reestablish hermeticity between the tubing and casing. The solution reestablished well integrity for sidetrack drilling. Given the loss of hermeticity between the tubing and casing, CT leveraged inflatable packers and hole punches in the tubing to control the placement of cement and reestablish integrity downhole. Two sets of hole punches allowed controlled circulation of fluids behind the tubing, between two production packers. CT set an inflatable packer which ensured that the cement could be squeezed into the annulus. The second inflatable packer was set near the cement plug to isolate it from the compromised hanger and pressure test the plug through CT without pressurizing the entire completion. The packers were successfully placed using tag-and-flag correlation which ensured depth control of the packer and cement. Uncontaminated cement was squeezed through the initial packer and squeezed behind the tubing through the lower punch. Careful volumetric analysis eliminated suicide squeeze: a failure mode where cement falls through the upper punch back onto the CT packer. The use of the second packer enabled testing of the new plug by bypassing the communication between the tubing and casing at the hanger. Setting of this second packer presented a unique challenge because recognizing final anchoring pressure drop signature is difficult when there is a small volume between the bottom of the packer and the top of cement. This required fine control and monitoring of inflation pump rates and critical pressure signatures. The pressure test using the second packer validated the integrity of the cement plug and zonal isolation as per the objective. The project met regulatory requirements—this includes having a column of 50 m of cement—prevented the loss of the well, and eliminated the need to drill a new well. In total, this saved the operator 30 days of new well drilling and associated environmental footprint and enabled a more cost-effective and sustainable infill drilling. The operator was out of conventional options, even if they chose to abandon the well. CT provided one last opportunity to recover from the situation. The out-of-the-box solution to reestablish annular hermeticity downhole is a first for the operator worldwide. The solution brought side tracking back on the table and eliminated loss of the well. The successful execution of the project highlights the importance of innovative solutions in overcoming well integrity challenges.