Solid Expandables Repair Prolific Subsea Gas Producer

Abstract

A working window of opportunity only presents itself from April to mid-September in the turbulent Atlantic waters off the northwest coast of Ireland. When this window opened in Spring 2006, Shell E&P Ireland Ltd began operations to evaluate newly acquired assets in the Corrib field dry-gas subsea development. Prior to acquisition, five wells had been placed in suspension, pending construction of the necessary subsea and onshore infrastructure. Shell had previously determined that only three wells were viable candidates for completion during the current season and commenced operations when the S711 semi-submersible arrived on location in April. The clock started ticking on favorable weather and time quickly became a crucial constraint issue. The project hit a critical mark when a leak was discovered in the 9–5/8 in. production casing on one of the early wells entered. With time running out, Shell approached Enventure to engineer a practical solution that was required within a period of six weeks. Possible solutions for recovery were identified and analyzed before the project management team decided on using solid expandable technology. The solution for this well needed to deliver a production casing string that effectively sealed off the hole. To accomplish this requirement with expandable tubulars, Shell decided to use the Enventure system elastomers for the gas-tight integrity, which required qualification. In approximately six weeks, Enventure and Shell planned and implemented the appropriate tests, coordinated logistical maneuvers to expedite expansions to create the test specimen for qualification and successfully installed the actual system in the production well. This paper will discuss the process used to bring the project to fruition within a tight timeframe. Details will include issues considered, ramifications of possible options, challenges of the operating conditions and circumstances and content and results of the qualification program. This paper will also discuss the philosophical approach of generating a workflow to successfully achieve the stated goals in a short amount of time. Introduction In June 2006, Shell encountered a leak in the 9–5/8 in. production casing in one of its West Atlantic, deepwater subsea wells. The dry gas well is capable of producing in excess of 100 million standard cubic feet per day. The leak, identified after taking the well out of suspension, disappointed the project team as progress to run completion and ultimately put the well in production came to an abrupt halt. After eliminating the possibility of it being in the liner lap, the leak was chased to approximately 1,500m (~4,920 ft) using a DLT packer. In order to progress the campaign, Shell temporarily suspended the well to decide whether to attempt to regain integrity of the production casing or put the well in long term suspension for possible abandonment. After putting the well into suspension, management considered the following four options to address the situation:Abandon and re-drill the wellCut and pull the 9–5/8 in. casingUse a tie-back liner solutionInstall a solid expandable cased-hole liner system Because of time restrictions and the lack of equipment availability with three of the options, Shell chose the solid expandable tubular solution that could be tested, delivered and installed in the timeframe and provide the most robust engineering solution. Although Shell had decided on a definitive approach to the casing leak, several issues needed to be addressed before the solid expandable solution could be implemented. The elastomer technology on the expandable liner selected, specifically Enventure 's 7–5/8 x 9–5/8 in. solid expandable system, had been used in similar scenarios1,2,3,4 but was not qualified to Shell standards. Another issue identified was the lack of gas-tight connections for any expandable casing. Also, several load cases were outside the expandable envelope. Shell and Enventure personnel used innovative engineering to confront the obstacles and to successfully resolve the technical challenges.