Sour Gas Production: Moving From Conventional to Advanced Environmentally Friendly Schemes

Abstract

Abstract For decades to come, gas will be the energy source of choice to meet increasing demand. Oil and gas operators, who have already developed those fields the easiest and the cheapest to produce, will have to develop fields with much higher acid gas content in the future, as forty per cent of the remaining (natural or associated) gas reserves are sour, totaling over 350 Tcf with over 10% H2S, and almost 700 Tcf with over 10% CO2, with both these components present most of the time. Future sour gas sustainable developments will have to deal with three major challenges: additional costs associated to the production and separation of large quantities of acid gases, more ambitious objectives to reduce green house gases emissions, and global and durable saturation of the sulfur market. This leads to the development of more energy efficient technologies for acid gas separation and more generally to new gas production schemes. Acid gas cycling for Enhanced Oil Recovery or acid gas disposal by reinjection offers a promising alternative to avoid costly sulfur production and reduce CO2 emissions to the atmosphere when producing these large very sour gas reserves. However, acid gas injection requires the qualification of a suitable and well known geological formation and there are some drawbacks and constraints related to the surface facilities that will be discussed in the paper. The paper also presents the necessary evolutions of the production / treatment technologies, and the new solutions under development or already developed and proven by Total and its partners, to cope with these new environment and constraints. They include environmentally friendly methods to store sulfur, as well as energy efficient processes to separate acid gases from sour gas, such as the cryogenic separation process well adapted to acid gas injection schemes, and new solvent processes for enhanced sweetening performances.