A Strategic Approach to Significant Cost Reduction Through Advanced Souring Forecasting Modelling and High-Pressure Bioreactors in H2S Production Management

Abstract

Abstract Microbial oilfield reservoir souring, characterised by the contamination of hydrogen sulfide (H2S) in production fluids, continues to pose significant challenges to operators worldwide. Understanding the likelihood and severity of sour gas production throughout the life of any oilfield asset involves computer modelling and quantitative laboratory-based simulation studies. Where significant sulfide generation is forecast, low sulfate water injection may be considered, often in conjunction with a scale mitigation treatment strategy. In some cases however, significant microbial activity in the downhole formation is limited due to extreme environmental conditions, restricting the geomicrobiological generation of sulfide species. This paper will present output data from souring forecasting and modelling analysis of a high-pressure, high-temperature West African offshore asset, using the DynamicTVS© model. In addition, data from high-pressure bioreactor studies, designed to evaluate microbiological sulfide generation under high-pressure and high-temperature conditions, will be shared to support the conclusions that microbial souring would be negligible under simulated reservoir conditions. More than 10 years on, the asset modelled remains ‘sweet’ following years of observed injection water breakthrough from all production wells, and the Operator continues to focus on relatively low-cost monitoring and chemical control of problematic biofouling at the topsides facilities.