Proposed Method for Extracting Liquid Gas Would Trap CO2 Deep Underground

A new technique for trapping the greenhouse gas carbon dioxide deep underground could simultaneously be used to release the last remains of natural gas liquids from dwindling reservoirs, reports a new paper in the journal International Journal of Oil, Gas and Coal Technology.

The method, the authors argue, could be used to offset a portion of the environmental impact of burning fossil fuels.

While so-called "fracking" has dominated headlines of late, there are alternatives to obtaining the remaining quantities of hydrocarbons from gas/condensate reservoirs, according to Kashy Aminian of West Virginia University in Morgantown and his colleagues both there and at Kuwait University.

Earlier experiments, the authors explain, suggest that by replacing nitrogen or methane with carbon dioxide to blast out the hydrocarbon stock from depleted reservoirs could be a highly effective method and carry with it the added benefit of trapping, or sequestering, the carbon dioxide underground.

Furthermore, after calculating the economic benefits associated with the enhanced liquid recovery technique, Aminian and his colleagues argue that not only is it technically viable, but financially as well.

The team explains in the study that the mixing of carbon dioxide with the condensate reservoir fluid results in a reduction of the saturation pressure, the liquid drop-out and the compressibility factor, which in turn boosts recovery of useful hydrocarbon while trapping the carbon dioxide within.

Additionally, the team determined that the process works well regardless of the characteristics of the reservoir or even the rate at which the carbon dioxide is injected into the reservoir, finding that the amount that recovered remains just as high.

Moreover, because of the compressibility of the carbon dioxide, they explain that it is possible to squeeze out anywhere from 1.5 to 2 times the volume of reservoir gas for the amount of carbon dioxide pumped in with an additional possibility of pumping in an another 15 percent once once the maximum amount of reservoir liquid has been extracted.