First Offshore Coiled Tubing Intervention Using a Catenary System in the Gulf of Mexico

Abstract

Coiled tubing (CT) operated from a floating anchored vessel (FAV) was developed for well intervention in offshore locations where crane limitations and deck loading constrains imposes various limitations on the ability to perform workover operations. This tailor-made solution involves the operation of a CT unit with the tubing reel located on a FAV and the injector head positioned on the offshore platform. Today, CT operations supported by a FAV are routinely performed in several countries, including Malaysia, Gabon, Tunisia, Brunei, Angola and the North Sea. The first CT operation supported with a vessel in the Gulf of Mexico was successfully performed in a non-producing well which had been shut-in for nine months due to compatibility issues with the structure for temporary installing service equipment and and the limited availability of jack-up platforms to provide a deck area for positioning CT equipment. As result of this successful operation, a new perspective of CT rigless interventions was adopted in offshore Mexico, thus allowing the operator to improve equipment utilization for both CT units and workover rigs, in order to maximize oil production. This paper details the analysis, execution and evaluation of the first CT operation from a FAV in offshore Mexico, which includes equipment selection, sea condition and weather-related studies, contingency planning, personnel competency and training requirements, and logistical considerations, among other technical factors that were critical in the implementation of such project. As well, the benefits that were realized by the operator regarding production enhancement and operational cost reduction are covered.