After producing for 70 years, a gas well in the Texas Panhandle had severe casing corrosion, resulting in uneven surfaces and a large, irregular hole. The leaking casing had allowed water from an aquifer to kill the well, and the operator wanted a quick, feasible, and effective solution to restore well integrity and production.
The SLB expandable steel patch was the optimal solution. Unlike other technologies, this patch is not pushed out to a predetermined diameter by a cone. Instead, it is expanded by a controlled setting process using an inflatable packer, which ensures that the patch is pushed out to seal effectively against the inside of the casing, irrespective of casing ID.
To help ensure good sealing across the casing surface, a customized patch with swellable elastomer skin was developed to seal the challenging geometry effectively, despite significant casing wear due to severe corrosion. Engineers also calculated that the remaining wall thickness would not withstand the packer inflation pressures typically used to set the patch. Consequently, they adapted the setting procedure to minimize risks of further casing damage.
The patch was set in 12 steps in 2.3 hours and drifted at 5.9 in with the setting tool. The well was successfully pressure tested to 200 psi for 30 min, and production and casing integrity were restored with minimal deferred production. This operation extended the life of the well and enabled the operator to continue gas production.
