An Integrated Solution to Repair Multiple Shallow Leaks in Production Tubing – A Unique Single Trip Well Intervention Technique

Abstract

In brownfield developments, prolonging the production life of the wells beyond the 30-year original well design life has been one of the challenges in managing well integrity. This challenge is often compromised by multiple tubing leaks or, in the worst case, by parted tubing caused by metal fatigue, erosion, and corrosion. The issue is often observed in many wells in the S field and usually occurs at a shallow depth between the tubing hanger and subsurface safety valve. The conventional through-tubing repair technique becomes increasingly difficult and ultimately tends to be unsuccessful. Moreover, with the challenge of low oil prices, a simple single-trip system, necessary to reduce costs and increase the success rate, is preferred. Several cost effective approaches to repair production tubing leaks have been available in the market for quite some time. These conventional methods (e.g., stackable slickline straddle, multi-run coiled tubing (CT) conveyed straddle, and tubing patches) come with basic tools, but require difficult manipulation to set and retrieve some of the assemblies, which are permanently installed, that may complicate future well abandonment. For wells with multiple leaks or where the completion tubing has been parted, complete replacement of completion tubing will be the only solution because of the severity of damage. This typically requires a workover rig or snubbing unit at both economically and operationally significant expense. It also typically results in a significant amount time required for well preparation, mobilization, and demobilization of the rig. In addition, the retrieval of this degree of corroded completion is not straightforward because it can come apart piece by piece, which will consume additional time. This paper describes the first customized, through-tubing hanger system installed at the lower master valve (LMV) of its kind. This unique repair method uses a coiled tubing-conveyed swellable packer, a hanging mechanism at the LMV, and through-tubing swellable packer elastomers at both top and bottom of the assembly. A description of the single-trip technology is presented, with a brief description of its engineering development and the installation procedure. The candidate selection process and installation procedure are discussed; information about the economics is provided to demonstrate that this type of repair was economically superior to a rig workover. This paper presents the successful field application of a new well intervention technique to repair multiple shallow leaks in production tubing in S field, an offshore field located in Malaysia. Effective teamwork among various parties through all phases, including engineering design, LMV fabrication, through-tubing hanger customization, swellability laboratory testing, and the execution phase, were key elements to the success of this pioneer project. By demonstrating the operational possibility and a low-cost alternative to an expensive rig workover, this unique technique has created more new opportunities to restore the integrity of shallow leaks and can be run in wells with parted tubing in similar brownfield wells.