In 2015, hydrogen sulfide (H₂S) was encountered in the Etame Marine Permit (EMP), offshore Gabon. Its presence causes a significant risk to production volumes. Therefore, understanding its origin and primary areal distribution could open up cost-effective remediation opportunities.

 This study provides a likely geological concept for the H₂S origin and distribution in the EMP area and a three-dimensional basin model of the H₂S generation, migration, concentrations, and basinal distribution. It tries to unravel the H₂S charge mechanism of the reservoir (i.e., changes of concentrations within the fields). However, the objective of this paper is not intended to predict future H₂S behavior during the production phase.

 It was determined that organic sulfur compounds in the lacustrine hydrocarbon source rocks were the likely source for the H₂S. The most probable generation process is thermal cracking of organic sulfur compounds within the source rocks. Pathways for the migration of H₂S were provided mainly by extensional fault systems that are likely to have influenced the H₂S distribution in the sandstone reservoir.

 Cost-effective remediation opportunities could include reservoir management through careful placement of additional infill wells and/or designing “fit for purpose” crude sweetening project (CSP) solutions like central CSP platform, or the use of scavengers.