Challenges in Managing Surface Controlled Subsurface Safety Valve SCSSV Integrity Issue in Gas Field, Offshore Malaysia

Abstract

Surface Controlled Subsurface Safety Valves (SCSSV) is a critical completion accessory to maintain the Safe Operation Envelope (SOE) of the well and ensuring the production sustainability. In PCSB, it is a requirement that SCSSVs are tested on specific periods to ensure this safety device meet the acceptance requirement as per company guideline. Monitoring and maintaining the SCSSVs is proven to be challenging for E1 gas fields, located in Offshore Malaysia. Wells in E1 field, recently transferred operatorship, is an aging field producing since August 1982. The wells are equipped with Wireline Retrievable SCSSV (WRSCSSV). Within few months after operating this well, few cases of SCSSVs inoperability were encountered, resulted in significant gas production loss from E1. The main problems with SCSSV are: Control line hydraulic pressure unable to build up and maintain, hence unable to flow the well as SCSSV unable to open. Abnormal hydraulic return observed. E11 wells tripped due to Wellhead Control Panel Hydraulic pressure header hit low-ow trip setpoint. Inoperable after well close in, indication of control line leak. Immediate action taken to rectify include retrieving the WRSCSSV and installing redressed old WRSCSSV, injecting and displacing of Pressure Activated Sealant through control line to patch leak point. Root Cause Failure Analysis (RCFA) conducted on the wells identified preliminary factors that lead to E1 SCSSV issues: Frequent SCSSV cycling with high control line pressure in depleted well pressure (Frequent well tripping and monthly Corrosion Inhibitor batching activity requires close in and opening of SCSSV). Non-compatible SCSSV elastomeric parts with production & CI batching chemical. Wear & tear and corrosion due to valve age (manufactured in 1982 & 1985). Worn out seal bore of BP-6 landing nipple. Short term solution such as reviewing the recommended hydraulic line opening pressure, downhole visual inspection, pressure activated sealant and caliper survey to confirm BP-6 Landing Nipple seal bore damage, Swellable Packer/O-ring (External) and re-dress using non-upgraded Elastomers (Internal) had been planned. Contingency for subsurface controlled SSV and replacement using new WRSCSSV had been put in place as long-term solution. This paper describes operator experience in managing the challenges in maintaining SCSSV operability, diagnostic and solution recommended to avoid production deferment due to this issue.