Timely Sealant Intervention Yields Bi-Directional Seal and Facilitates Completion Program Continuance

Abstract The subject well had successfully been drilled and was transitioning into the completion phase when a leak was observed in the 9 7/8" production casing. Diagnostics located the leak at 15, 329 ft MD, just below the liner hanger. Due to the leak, the operator was unable to obtain the required casing tests to continue their completion program. The initial remediation attempt was a 100 bbl cement squeeze, during which injection rates ranged from 2 BPM @ 1740 psi to 4 BPM @ 2780 psi. Following the squeeze, the casing was tested to 4600 psi, and pressure dropped at a rate of 50 psi/minute. The liquid leak rate averaged 11. 4 GPM across varying pressures. Given regulatory and operational constraints, along with a spread cost exceeding 1 MM daily, the operator was left with few options and little time to determine a forward path for the well. A composite bridge plug was set below the suspected leak site with the workstring across the leak depth. Next, a pressure-activated sealant pill was blended and pumped down the 5" drill pipe and up the annulus with an HEC spacer on both sides. This sealant pill was composed of 4 separate blends, which were layered to promote optimal penetration. The annulus was then pressured up via the kill line until forming an initial seal around 1, 500 psi. Once establishing an initial seal, a brief curing period was allowed before continuing to increase pressure in 500 psi increments up to the final pressure of 4600 psi. The sealant was held at this pressure for 2 hours to strengthen before performing 3 pressure cycles to stress and further strengthen the seal. A final 24-hour cure period then followed. After a successful curing period, clean mud was circulated into the well followed by base oil to create an underbalance in the pipe for a 30-minute negative test. This test confirmed that a bidirectional seal had been achieved. The composite bridge plug was subsequently drilled out and the entire wellbore was tested to 4600 psi. After meeting all regulatory requirements, the operator continued with the completion scope. After perforating the zone and installing the gravel pack assembly, the leak site was permanently isolated with the installation of an isolation packer assembly. Based on the constraints described above, alternatives considered included specialized cement blends, which were not immediately available, or a sidetrack operation. Due to the flexibility inherent to an in-situ pressure-activated sealant repair, technicians and sealant were able to be mobilized to the drillship within 24 hours. Additionally, the linear leak characteristics observed were well suited for a pressure activated sealant repair. In comparison to the alternative sidetrack option, the sealant treatment yielded major economic, operational, and HSE advantages.