Integrated Reservoir Modeling to Maximize the Value of a Large Sour-Gas Field With High Concentrations of Inerts

The Madison reservoir in LaBarge Field in Wyoming, U.S.A.,<br>is a multi-zone carbonate on the crest of a regionally plunging<br>anticline. It is ~800 ft thick, covers more than 1,000 square<br>miles, includes 4,000 ft of structural closure and holds 22<br>TSCF initial methane in-place. Methane percentage varies<br>from a high of 23% at the crest to a low of 5% near the gaswater<br>contact, with inerts – CO2, N2, H2S and He – making up<br>the remaining gas. ExxonMobil is the only operator producing<br>from LaBarge Madison and has built a dedicated gas plant to<br>monetize the resource. Current production is 700 MMSCF/d<br>(150 MMSCF/d methane) with 16 crestal producers and two<br>downdip injectors re-injecting 60 MMSCF/d acid gas into the<br>Madison aquifer – one of the world’s largest acid gas reinjection<br>projects.