Thuan Hoa Nguyen

"Development of a New Technology for Productivity Enhancement of Low Permeable Coal Seam Gas"

Coal seam gas is a type of unconventional resource where it was produced since the 1900s. Unlike conventional gas reservoir where gas freely flows in porous media, coal seam gas adsorbs onto coal seams' micropores. Tight coal seam gas cannot be produced economically due to flow restriction. It was reported that low sorption affinity gas injection can improve near wellbore permeability. Therefore, a new technique is proposed to improve near wellbore productivity in tight coal seams. The new method involves three main steps: low sorption affinity gas injection – gas soaking – flow back.

The new technique mechanism is mainly based on competitive adsorption of the gas mixture which yields a pressure buildup during the soaking period. The increase of pressure allows gases to compress coal matrix and with the combination of methane desorption, permeability increases. Different types of adsorption isotherm will be tested in the project due to the flaws of extended Langmuir isotherm which is popularly used in commercial simulators.

The project success will add in a new way of tight coal seam gas productivity enhancement which might increase the world’s coal seam gas reserve. The new technique can be tested for deep coal seam gas where a magnificent amount of methane is kept.