AbstractIn this study, we summarize data on the location and scale of proven and probable sour gas resources and compare with size and location of oil fields. This provides an indication of the location and scale of opportunities to gain further experience in the application of CCS. This by using captured carbon dioxide (CO2) from sour gas resources, which are presently undeveloped or underdeveloped, for carbon dioxide enhanced oil recovery (CO2-EOR). Currently there are globally many undeveloped or underdeveloped sour gas accumulations containing a significant fraction of CO2. The high CO2 content between 15% and 80%, as well as in some cases the addition of hydrogen sulfide (H2S), severely limits the economic and environmental viability of sour gas resources. Globally a total resource of around 4 trillion m3 of net hydrocarbon gas and 15000 MT of associated CO2 has been identified. This was done by summing individual undeveloped and underdeveloped fields with ultimate recoverable proven and probable resources larger than 14 billion m3 each of net hydrocarbon gas and CO2 content between 15% and 80%.Development of these fields could be enabled by the availability of a cost effective gas separation method such as the Controlled Freeze ZoneTM (CFZ) technology, and of viable CO2 enhanced oil recovery opportunities (CO2-EOR) to reduce the cost of CO2 capture, transportation and storage.Sour gas resources have been mapped globally using the IHS fields and reservoirs database from 2009. The largest concentrations of sour gas are located in SE Asia & NW Australia, Central USA, Middle East and North Africa. In the USA, Middle East and North Africa, which are oil rich, there is significant potential for CO2-EOR opportunities. The relative absence of significant oil accumulations in SE Asia & NW Australia will in many cases require the storage of CO2 in saline aquifers, as is planned for the Gorgon field in Australia.The challenges of developing natural gas fields with a high CO2 content can be best illustrated by ExxonMobil’s development of the LaBarge field. This field, located in SW Wyoming, USA, was discovered in 1963, but production was delayed until 1986 because of the challenging gas composition of 65% carbon dioxide, 21% methane, 7% nitrogen, 5% hydrogen sulfide, and 0.6% helium. It is the lowest hydrocarbon content natural gas commercially produced in the world. Currently the majority of the recovered CO2 is transported and sold to EOR operators.Additionally, construction of a commercial demonstration facility for ExxonMobil’s Controlled Freeze Zone™ (CFZ) gas treatment technology has been completed at Shute Creek, Wyoming. The CFZ™ technology allows the single step separation of CO2 and other contaminants from a natural gas stream without the use of solvents or absorbents.