How Expandable Casing Patches Can Restore Casing Integrity and Enable the Sidetracking of an Old Well

Abstract

This paper describes how an operator restored the casing integrity of a nonproducing well to resume offshore drilling operations by installing four 10¾-in. overlapping expandable steel patches. From 2020 to 2022, the operator scheduled a sidetrack drilling program, Māui A Crestal Infill (MACI), from the Māui A offshore platform, located in the Taranaki Basin of New Zealand. The operations included eight wells targeting the remaining unswept zones within the Māui A structure. During a reentry in a plugged and abandoned well, MA-03, a multifinger caliper log and a failed pressure test indicated a casing leak in the 10¾-in. intermediate casing. The log identified severe longitudinal casing wear with some fully penetrating holes. This lack of integrity prevented the scheduled operations from being performed. Several lost circulation material (LCM) and cement squeeze jobs attempted to seal off the leak but were unsuccessful. A service company proposed a mechanical repair solution to cover the long interval with four 13-m- (42.7-ft)-long customized, overlapping patches. Later, a second caliper was run to check if the cement squeeze jobs had reinforced the area for better patch support. Surprisingly, the zone appeared significantly more damaged, with a complete circumferential casing breach. Thus, the planned solution looked very challenging to implement. A video camera run, additional thinking, modeling, and cooperative engineering led to a complete redesign of the solution. The lengths and positions of the patches were changed, and one of the patches was assigned to serve as an inner reinforcement. The team assembled, deployed, and installed the patches in an accelerated mode. In 10 days, the casing integrity was fully restored, enabling the 8½-in. sidetrack hole to be drilled to total depth. This case is a typical example of how industry practices should evolve regarding the management of casing integrity issues. Remedial cement squeezes are often prioritized over mechanical options, even though mechanical options are now adjustable, much quicker to implement, and likely offer greater success rates.