An offshore platform located in the Santa Clara field off the coast of California was being abandoned. The wells were experiencing pressure and gas bubbles in the C and D annuli behind the 9-5/8” and 13-3/8” casings.
The 9-5/8” was cemented in the 13-3/8” casing, and the 13-3/8” casing itself was cemented inside an 18-5/8” casing of its own. The customer needed a tool that could do two things effectively – be deployed through the 9-5/8” on drill pipe and set a plug that would shut off gas migration in both annuli for a permanent abandonment out of the 18-5/8”.
The customer had made three previous attempts at abandonment and was looking for a more cost-effective solution for successfully shutting off all gas migration in the annuli. We took an existing BiSN tool and redesigned its deployment method to accomplish the customer’s specific needs. BiSN’s Bismuth-based alloy plugs are non-porous and non-corrosive and they expand into the casing to create a gas-tight seal. In total, using a BiSN plug leads to millions of dollars of savings that operators traditionally need to spend on costly section milling.
The tools needed to be deployed through the 9-5/8” casing on drill pipe. In order to make a 5 ft plug in the pipe’s 18-5/8” annulus, a certain amount of BiSN alloy needs to be deployed. Traditionally, this would be done by casting it directly onto the outside of the heater itself.
