On an unmanned platform in a remote brownfield offshore Asia, about 60% of the wells are sour wells with extremely high H2S levels, which present grave HSE risks and threaten asset integrity as well as regulatory compliance. H2S removal is a vital part of gas processing, and the operator required a cost- and space-efficient turnkey solution for H2S mitigation, including design, execution, and maintenance services.
After a thorough analysis, SLB proposed a consolidated approach using its gas sweetening unit, which includes a two-phase separator, adsorbent beds, and liquid H2S scavengers to remove any H2S that may be present in the liquid stream from the separators. The fast-reacting SELECT S™ hydrogen sulfide removal adsorbents recommended use engineered metal oxide chemistry with enhanced porosity control for improved activity.
The sour natural gas feed flows through the adsorbent bed, where the H2S reacts with the media. Product consumption depends only on the amount of H2S that passes through, economically matching the need for H2S removal with variations in system flow conditions. Fast reaction time leads to smaller system sizes—a critical consideration on space-constrained offshore facilities—and lower capex. Moreover, the compact system requires fewer support vessels during installation, which reduces emissions. SLB also provides media handling and disposal services.
Using an optimized integrated solution from a single supplier eliminated the challenges of dealing with multiple entities and further lowered capex. In addition, extended bed-life warranties ensure less frequent adsorbent changeouts, enhancing operational efficiency and necessitating fewer trips by maintenance crews. The resulting time and cost savings can be significant on unmanned platforms; fewer trips also reduce the carbon footprint of platform operations. H2S content in the outlet gas is <1 ppm.
