Patent ID: 8522868

Claim:
A method for converting oil in a subterranean light-crude oil reservoir to methane gas and extracting said methane gas comprising the steps of: (a) identifying a subterranean light-crude oil reservoir; (b) obtaining a microbial community sample from the bottomhole of a well in said reservoir, said sample is collected in the bottomhole of said well and maintained at the bottomhole temperature and the bottomhole pressure while being brought to the surface of said well; (c) transferring said sample obtained from said bottomhole to a reservoir simulator that is an anaerobic chamber, said sample being maintained under bottomhole temperature and pressure conditions that substantially mimic natural conditions of said reservoir; (d) testing said sample by incubating said sample in at least one candidate liquid nutrient substrate medium formulation including said oil in said reservoir simulator, said sample being maintained under bottomhole temperature and pressure conditions that substantially mimic natural conditions of said reservoir; (e) determining a targeted regime for said reservoir based on positive growth of methane-producing microbes from said microbial community sample in said liquid nutrient substrate medium formulation, said sample being maintained under bottomhole temperature and pressure conditions that substantially mimic natural conditions of said reservoir; (f) injecting said reservoir with a nutrient substrate medium formulation that provided positive growth in step (e) of method-producing microbes thereby enabling the conversion of trapped oil into methane gas; (g) monitoring said reservoir; and (h) extracting said methane gas from said reservoir.