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.
The Badamyar project is an offshore gas field located 220 km south of Yangon in the Republic of the Union of Myanmar. In February 2017, four gas wells were successfully drilled and completed using horizontal openhole gravel packing in the Badamyar gas field. The downhole completion design adopted was an alternate path technique using filter-cake breaker deployment for effective well cleanup. Initial geomechanical studies performed in the field show that the sands have low mechanical strength; consequently, they are unconsolidated. This was verified with sonic measurement of 120 us/ft (more than 110 us/ft). An active sand control technique was deemed necessary to ensure a robust well completion with longevity for expected gas production. Based on the comparative risk analysis conducted by the operator for various types of sand control and reservoir drainage, a horizontal openhole gravel pack method was selected to complete the four wells. During the well planning stage, the following specific challenges were identified for the installation of the lower completion: Openhole gravel placement method; alpha/beta wave vs. alternate path technique considering low fracture gradient to achieve 100% pack efficiencyEfficient gravel pack carrier fluid for the selected methodExpected long drain hole in a clay sensitive environmentEffective filter-cake cleanup post-gravel packVery fine, poorly consolidated, and immature shaly sands Downhole sand control equipment deployment, gravel pack placement, filter-cake removal, and initial production results have proven the selected gravel pack method to be successful in the Badamyar field. This paper presents the measures taken to address the project challenges during the design and execution phase and the results achieved. The success achieved can be adopted for the completion of high-rate gas wells with similar reservoir conditions in this area and beyond.
During 2012, a single zone low permeability sand in an offshore HPHT gas well in the North Malay Basin was succesfully stimulated with hydraulic fracturing treatment utilizing skid mounted hysdraulic fracturing equipment from a supply vessel. This is the first offshore Malaysia HPHT frac operation peforming treatment from a supply vessel combining with the use of wellhead isolation tool and high temperature hydraulic fracturing fluid. Historical offshore Malaysia fracture treatments were performed with a drilling rig present. The zone is a dry gas sandstone reservoir, 30% CO2, pore pressure of 0.87 psi/ft, fracure gradient of 0.92 psi/ft, permeability of 0.1-0.5 md and temperatures approaching 400 deg. F at 10,000ft TVDSS. The wellhead isolation tool, fracturing fluids were designed to safely establish the viability of HPHT hydraulic fracturing in the North Malaysia Joint Development Area. The intent of the project was to provide proof of economic concept for development of single stacked tight gas sandstone pay intervals with platform based HPHT hydraulic fracturing through a combination of industry standard tchnologies used in other areas of the world, but rarely in Malaysia. Single zone production rates will allow economic development of additional low permeability zones in this well as well as additional wells that were previously deemed marginally economical to develop. While significant uncertainty still exists with regard to the drainage radius and productivity of the single zone, initial results have proven that hydraulic fracturing has connected multiple channels as seen on the log. This has improved the well capacity above productivity established through pre-frac well test and pressure buildup analysis.
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