Produced water management represents a significant financial burden for operators, sometimes requiring them to drill wells just to dispose of the water. The APS Project in Ecuador was preparing to plug and abandon several wells, when a decision was made to repurpose some of them for injection instead—either for produced water disposal or reservoir pressure maintenance. Because the injection zone was deeper than some open perforations, it was necessary to isolate the perforations from the high-pressure, high-rate water injection without losing access to lower sections of the wells.
Minimizing rig time and costs was a key consideration for the Production Engineering & Execution Team. Therefore, instead of a conventional cement squeeze, SLB recommended its expandable steel patch, a permanent solution to repair a zone of damaged tubing or casing, shut off unwanted perforations, or perform other remedial functions. Expanded downhole with an inflatable packer, the internal casing patch creates a high-pressure inner lining with minimal loss of diameter. It is made of high‑quality stainless steel and uses a profiled sealing system that is applied and cured in a controlled environment during manufacturing, employing different materials based on the application requirements—unlike the field-applied epoxy resin used by some providers.
The expandable casing patch provides a robust long-term seal across old perforations—even in irregular bores. The patches can withstand high-pressure injection, which can break down or fracture squeezed cement or injected resin. They are resilient even in the face of the thermal cycling inherent to injection stoppages and restarts. Installation is faster and has a higher probability of first-time success, whereas cement squeezes must often be repeated. The patches also significantly reduce environmental impact.
Average installation time per patch was 53 h versus 135 h for a squeeze operation, saving 82 h—more than 60%—of rig time per well. Based on a daily diesel consumption of 909 L [200 galUK] on average, this well integrity technology saved more than 3,100 L of fuel and avoided 8,348 kg* of CO2e emissions per well. Eliminating the 2,300 kg of cement that would have been used per well during a squeeze campaign decreased embodied CO2e by about 921 kg** per well.
Waste generated by a casing patch installation is limited to the single packer element used to expand the patch. A cement squeeze, on the other hand, often requires mixing cement in excess of the requirement and then disposing of the cement circulated to surface when the cement is drilled out downhole to regain access below the squeeze depth. An average of 1,340 kg of cement is wasted per well, while the packer element weighs only about 80 kg—a net waste reduction of 12,600 kg across 10 wells.
The conversion from producer to injector complied with all regulatory and technical requirements, while controlling costs. The SLB team in Ecuador has been recognized with Punto Verde certifications for its sustainable practices.
* Using an emissions factor of 2.68787 kg CO2e per liter of 100% mineral diesel per the UK Government Greenhouse Gas Conversion Factors for Company Reporting, 2020
** Based on 860 kg of embedded CO2e per metric ton of cement per Mineral Products Association (MPA) Fact Sheet 18: Embodied CO2e of UK cement, additions and cementitious material and 3.02 kg of CO2e per kg of stainless steel, as listed in the Inventory of Carbon & Energy database (ICE DB V3.0 - 10 Nov 2019)
