Analyses suggest that carbon dioxide (CO2) can be injected into depleted gas reservoirs to
enhance methane (CH4) recovery for periods on the order of 10 years, while simultaneously
sequestering large amounts of CO2. Simulations applicable to the Rio Vista Gas Field in
California show that mixing between CO2 and CH4 is slow relative to repressurization, and
that vertical density stratification favors enhanced gas recovery.

Analyses suggest that carbon dioxide (CO {sub 2}) can be injected into depleted gas
reservoirs to enhance methane (CH {sub 4}) recovery for periods on the order of 10 years,
while simultaneously sequestering large amounts of CO {sub 2}. Simulations applicable to
the Rio Vista Gas Field in California show that mixing between CO {sub 2} and CH {sub 4} is
slow relative to repressurization, and that vertical density stratification favors enhanced gas
recovery.