Approximately 40% of current global natural gas resources have high H2S and CO2 concentrations. The H2S concentration in Middle East gas reservoirs can potentially reach up to 30 mol%. H2S is toxic; therefore, the produced natural gas must be treated and sweetened. In this high H2S environment, a membrane technology that can remove the bulk of H2S from produced natural gas will reduce the load on the amine treatment and sulfur recovery unit operations downstream in gas processing facilities. Bulk removal of acid gases with membrane technology will lower SO2 emissions through a reduction in flaring, elemental sulfur production from sulfur recovery units, and reduce unit delivery costs for the life of the field.

Since 1984, Schlumberger has deployed cellulose triacetate polymeric membranes for CO2 removal in gas processing and EOR applications. In collaboration with a major oil and gas exploration and production company, our membrane science research team is testing cellulose tri-acetate acid gas removal membranes to characterize separation performance under a variety of process conditions. The team deployed a pilot system capable of testing gas with 25% H2S in the USA. These membranes will separate both acid gas components, CO2, and H2S from the feed gas and retain hydrocarbons in the residue gas sent to the amine system for further processing. Low-pressure acid gas permeate can be reinjected into the reservoir for enhanced oil recovery or sequestration.

Initial laboratory testing and predictive modeling of the membranes, completed with an American academic research institution, have shown promising results for bulk H2S removal. Pilot system testing data will further de-risk and validate the feasibility of technology deployment and facilitate economic modeling of this technology's business impact. We will present the results of the testing to date which will form the basis of the observations and conclusions of the paper.

This paper will also present a case study to show the business impact of deploying a hybrid system (membranes + amine) in comparison to a conventional amine system.

After testing, operators will have satisfactory information available to review alternative processing facility concepts and re-evaluate the economics of ultra-sour gas field development projects.