Successful Implementation of Resin Based Isolation Plug RBIP in Annulusto Restore Lost Well Integrity. A Case Study from South of Pakistan

摘要

Exposure of production annulus with formation fluids due to tubing-casing communication is unfavorablescenario throughout well's life cycle. The communication paths are always susceptible to aggravate with thepassage of time, eventually resulting in complete loss of well integrity due to failure of one of the integralwell barriers and potentially causing major risk and hazards to environment and personnel. Accurate andmost efficient actions are therefore required on war-foot basis to restore lost integrity. DST of an exploratory well in South Pakistan revealed the corrosiveness of reservoir fluid (26 % CO2),therefore, completed with chrome material. Well remained shut-in due to plant capacity constraints. Soonafter well commissioning, pressurized annulus was reported. Initial investigation depicted hydrocarbonsin annulus, however, Distributed Temperature Sensing (DTS) was later used to accurately locate the leakpath. Conventional remedial options including tubing patch and work-over were ruled out due to extremereservoir parameters and associated high cost as well as production curtailment. Placement of Resin-BasedIsolation Plug (RBIP) in annulus was found to be the most feasible option to restore well integrity. Coiled tubing conveyed DTS was carried out in shut-in and flowing conditions that confirmed depth ofleak path in completion string. Main reason of implementing this diagnostic technique was the unavailabilityof conventional logging tools compatible with high temperatures. DTS was run in conjunction withcorrelating tool (CCL) for precise depth determination with respect to completion jewelry. After exploringpros and cons of conventional remedial techniques, treatment through annulus was the only remedial optionleft to block the leakage path in completion string therefore, placement of RBIP on top of leak point wasplanned. This plug, once solidifies, restricts tubing movement due to thermal effects when exposed toproduction loads. Therefore, extensive stress analysis was essential to evaluate the integrity of anchoredcompletion due to plug under various production loads throughout the well's lifecycle. With all possible riskscritically assessed, RBIP along with bridging spacers was successfully poured in annulus during rig lessoperation. Well was kept in flowing conditions towards plant to avoid production curtailment throughoutthe operations. Currently, well is flowing, maintaining the necessary feed at plant and fulfilling country'sgas demands with well integrity intact. Tubing-Casing communication and pressurized annulus has become common problem and playssignificant role in maintaining the reputation and progress of E&P companies. Conventional methodsare readily available to rectify such problems however, there are scenarios where wellbore conditions /parameters and economic feasibility may restrain their implementation. RBIP is a new technique in restoringwell integrity through annulus and is successfully implemented for the first time not only in PakistanPetroleum Limited (PPL) but in Pakistan.