oa Unexpected Occurrence of H2S in Fluids from a Deep Offshore Field, Gom, Usa

Unexpected H2S was detected in fluids from downhole sampling. The presence of more than 100 ppm of H2S was a significant issue, as no H2S had been detected during exploration and appraisal campaigns, and no specific infrastructure for H2S management was included on the production platform. As a result, a comprehensive study was initiated to understand the source of this H2S and determine if and what contingency scenarios should be developed. This geochemical investigation showed that DBM is likely to have generated temperatures sufficient for induced TSR reaction using the barite and hydrocarbons from the oil-based mud or reservoir fluid. To the best of our knowledge this is the first time that H2S occurrence is attributed to be DBM induced by drilling operations and the presence of barite, leading to localized accumulation.