Methods of enhancing biogenic production of methane from hydrocarbon-bearing formations
The present invention describes methods of identifying stimulants for the biogenic production of methane in hydrocarbon-bearing formations. Methods involve the use of microbial nucleic acid sequence information for the determination of gene products that are enzymes in a variety of pathways involved in the conversion of hydrocarbons to methane. Enzymes and stimulants identified by invention methods can be used in processes for enhancing biogenic methane production, for example, by addition to coal seams and coalbed methane wells.
1. A process for enhancing biogenic production of methane in a hydrocarbon-bearing formation, said method comprising
determining the presence of one or more gene products of a nucleic acid sequence from one or more microorganisms derived from the hydrocarbon-bearing formation, wherein said gene product is an enzyme in a pathway involved in the conversion of a hydrocarbon to methane selected from the group consisting of: peroxidases, phenol oxidases, alcohol oxidases, laccases, hydrolases, glycosyl hydrolases, esterases, etherases, oxidases, nitrogenases, cellulases, amylases, glucanaeses, pullulanases, reductases, dismutases, oxygenases, monooxygenases, dioxygenases, catalases, hydrogenases, carboxylases, and methyl reductases; or an enzyme involved in homoacetogenesis, methanogenesis, acetoclastic methanogenesis or CO2-reducing methanogenesis;
introducing into the formation a substrate, reactant, or co-factor that is a stimulant for the enzyme;
thereby enhancing biogenic production of methane in the hydrocarbon-bearing formation in comparison with production in the absence of the stimulant.
2. The process according to claim 1 , wherein said enzyme is present in an existing microorganism in said hydrocarbon-bearing formation.
3. The process according to claim 1 , wherein said enzyme is introduced into said hydrocarbon-bearing formation.
4. The process according to claim 3 , wherein said enzyme is introduced by introducing a microorganism expressing said enzyme into said hydrocarbon-bearing formation.
5. The process according to claim 4 , wherein said microorganism expressing said enzyme is a recombinant microorganism prepared by modifying a microorganism derived from said hydrocarbon-bearing formation.
6. The process according to claim 4 , wherein said microorganism expressing said enzyme is a synthetic microorganism.
7. The process of claim 1 wherein said enzyme is a bacterial enzyme or an archaecal enzyme capable of converting a hydrocarbon to a product selected from the group consisting of: hydrogen, carbon dioxide, acetate, formate, methanol, methylamine, and a methanogenic substrate.
8. A process according to claim 1 , wherein said hydrocarbon-bearing formation is selected from the group consisting of coal, peat, lignite, oil shale, oil formation, traditional black oil, viscous oil, oils sands and tar sands.
9. A process according to claim 1 wherein said enzyme is selected from the group consisting of oxygenases, monooxygenases, and dioxygenases.
10. A process according to claim 1 wherein said substrate, reactant or co-factor is oxygen.
11. The process according to claim 1 wherein the enzyme is selected from the group consisting of one or more of: oxygenases, monooxygenases, and dioxygenases.
12. The process according to claim 1 wherein the stimulant is a defined microbial assemblage.
13. The process according to claim 1 wherein the stimulant is introduced into the formation by injection.
14. The process according to claim 1 wherein the stimulant is introduced into the formation by adding the stimulant to recovered formation water and re-introducing the formation water into the formation.