From Shutdowns to Solutions: Optimizing Island Based Well Intervention Operations in High H2S Environments

Abstract This paper presents the development of a safer and more efficient methodology to perform slickline interventions in high Hydrogen Sulphide (H2S), high-pressure wells located on offshore artificial islands in UAE. Initially, at the end of each run into the wellbore, the only available and safe option to dispose of the sour gas present in the pressure control equipment (PCE) was to bleed off to the island's green burner. The use of the island's green burner is an operation that requires specific wind conditions, both in direction and speed to avoid combustion gases reaching back to the island and/or accomodation. As a result, waiting on weather (WOW) became a frequent occurrence in the day by day. There was an associated and additional safety risk of having the pressurized PCE containing high-H2S hydrocarbons left suspended from the crane for extended durations compromising permanent presence of personnel on the site for both the crane and the Slick Line crew. This significantly impacted operational efficiency, contributing to Monthly NPT due to WOW to bleed off the PCE during well interventions estimated up to 10% of operating time. To mitigate these efficiency and safety challenges, a series of strategies were progressively implemented and evaluated across multiple jobs in the islands. Some strategies initially focused on removing the H2S from the PCE before breaking containment, while others aimed to prevent the presence of H2S in the PCE throughout the entire operation. This paper explains each strategy in detail, including the implementation process and results, supported by schematics to enhance understanding. The goal is to provide a proven and transferable methodology for similar high-risk environments with similar challenges where this solution could be implemented.