Abstract:
Proper handling of produced sour gas is a big challenge for operating companies due to the serious
environmental and technical problems caused by H2S. Among various sour gas processing methods,
reinjection into reservoirs is a cost-effective and environmentally-friendly technique that not only
enhances oil recovery but also allows underground storage of H2S. The high safety requirements for
working with toxic H2 S have suppressed extensive experimental studies, hence sour gas injection
has not been adequately investigated and implemented in laboratory compared to other enhanced oil
recovery (EOR) methods. Existing studies show that sour gas injection with high H2S content can bring
about higher incremental oil recovery than CO2 or CH4 injection due to the highly miscible nature
of H2S with a significant reduction of minimum miscibility pressure (MMP) and interfacial tension.
Mineral dissolution as well as sulfur and asphaltene precipitation might occur as consequences of
sour gas induced reactions, thus causing technical challenges such as low injectivity, formation damage,
and poor sweep efficiency, but contrary observations were also reported. In addition, the economics of
sour gas injection for EOR depends on several critical factors, such as H2 S content in crude oil, sulfur
price, and environmental impact. Overall, sour gas EOR presents far more challenges than other EOR
methods, deserving full-fledged and in-depth investigations. This review comprehensively assessed
the performance of the sour gas EOR method by integrating the results of laboratory experiments,
simulation, field test studies, and economic analysis.