Methods for microbial gas production and use as isotopic tracer

A method of generating methane, the method comprising:

• delivering a first feedstock downhole to a coal reservoir, wherein the first feedstock comprises a molasses desugarized soluble, beet molasses, sugar cane, sugar beet thick juice, sugar beets, alfalfa, corn extract, or a combination thereof;
• generating a first methane using enhanced anaerobic digestion by in-situ micro-organisms within the coal reservoir having a first isotopic signature corresponding to the first feedstock within the coal reservoir, wherein the first feedstock is an energy source for the in-situ micro-organisms;
• analyzing the first methane having the first isotopic signature;
• delivering a second feedstock downhole to the coal reservoir, wherein the second feedstock comprises a molasses desugarized soluble, beet molasses, sugar cane, sugar beet thick juice, sugar beets, alfalfa, corn extract, or a combination thereof, wherein the second feedstock is different from the first feedstock;
• generating a second methane using enhanced anaerobic digestion by in-situ micro-organisms within the coal reservoir having a second isotopic signature corresponding to the second feedstock within the coal reservoir, wherein the second feedstock is an energy source for the in-situ micro-organisms;
• analyzing the second methane having the second isotopic signature;
• differentiating the first methane having the first isotopic signature from the second methane having the second isotopic signature by comparing the first isotopic signature and the second isotopic signature, wherein the first isotopic signature of the first methane and the second isotopic signature of the second methane are isotopically differentiable from a third isotopic signature of a background methane;
• harvesting the first methane and second methane;
• and
• sequestering carbon dioxide within the coal reservoir.