Distinctive Well Intervention Integrated Solutions Realizing Idle Well Potential in North Sabah

Abstract The South Furious field located in the Sabah Inboard Basin, in the South China Sea consists of thin, laminated sandstone reservoirs, plagued by sand production. Sand management in the field has been handled through limiting drawdown and downhole sand control. Various downhole sand control technologies have been utilized for newly drilled and recompleted wells, such as, gravel packing, prepacked screens, expandible sand screens, and standalone screens. As the field has been producing since 1979, several of these downhole sand control installations have been found to be ineffective in controlling the sand production and subsequently resulted with a few idle wells, caused by sand filling the tubing and casing, and well integrity. The field is producing under natural depletion with some segments having aquifer support which has resulted in increasing water cuts and decreasing reservoir pressures which further exacerbates the sand production. While some wells retain their potential to flow, economics for recompletion or infill drilling are unattractive when weighing the rig costs against the potential production uplift in these depleted reservoirs. Hence the challenge imposed – how production increase can be achieved with a reasonable enhancement cost. While tubing integrity can be addressed with tubing straddle or patch technology, severe sand inflow with no downhole sand control must be addressed to ensure that production is sustained long enough to provide a return on investment and prevent damage to the surface production system. Due to high unconformity of the sand particle size distribution based on core data, an open cell matrix polymer (OCMP) sand control was deployed. The OCMP allows for deployment within the existing production tubing, to filter and prevent sand infill downhole across a wide range of particle size distributions, which was confirmed through lab sand retention testing. For wells with multiple tubing leaks, a coiled tubing insert string was deployed to straddle long sections of tubing where the leaks have been identified with a reduced number of runs and potential leak paths compared to a wireline deployed straddle system. Nodal Analysis concluded that the use of 1.50″ OD coiled tubing for the insert string was sufficient and would not restrict the production rates. The sub hydrostatic nature of the reservoir requires additional work to deepen the existing gas lift point which is limited by the mandrel depths in the completion. Additionally, if a straddle is to be installed across the tubing, gas lift capability must incorporated into the design to ensure the well is able to unload and produce effectively. A downhole gas lift mandrel with an orifice valve was integrated to the straddle to achieve this while utilizing the existing gas lift supply. Reactivation of the well was achieved without the need for a rig or any heavy intervention unit. South Furious is the first in the region to deploy such a method to address both tubing integrity remediation and gas lift deepening simultaneously and this paper illustrates the design and thought process, realizing the initial remedial concept to solution. This success establishes a strong validation for idle wells restoration candidates in the field in the chase for production enhancement.