CARBON-ISOTOPE STUDY OF METHANE PRODUCTION IN A TOWN GAS-STORAGE RESERVOIR

Methane production in town gas (45-50% H-2, 20-25% CH4, 8-12% CO2, 7-12% CO, 6-10% N2) stored in an underground aquifer proceeds by reduction of CO2 and CO with considerable H-2 consumption, leading to significant loss of volume, and, in the extreme, to unacceptable alteration of combustion properties. Use of carbon isotope analysis has enabled a detailed description to be given of all the processes occurring in the reservoir. The reactions could be separated from actual losses of hydrogen, which were hardly distinguishable by chemical analysis only. Combined chemical and isotope analyses proved to be effective for the study of underground gas reservoirs.