Process of sustaining methane production in a subterranean carbonaceous medium

A process of stimulating and maintaining an activity of a microbial consortia within a subterranean solid carbonaceous medium to produce methane, the process comprising the steps of:

• A. dosing a first nutrient composition into the subterranean solid carbonaceous medium;
• B. monitoring generation of methane in the subterranean solid carbonaceous medium;
• C. dosing a second nutrient composition into the subterranean solid carbonaceous medium based upon the results of step (B);
• and
• D. repeating steps (B) and (C) and, if required,
• E. dosing a further nutrient composition into the subterranean solid carbonaceous medium based upon the results of step (D),
• wherein step (B) measures a parameter associated with generation of methane, wherein the second nutrient composition is closed after the generation of methane has dropped to less than 90% of a peak methane generation parameter, and wherein the peak methane generation parameter monitored over a given monitoring/incubation period (B) is one or more of:
• i. a peak rate of methane production per unit nitrogen (Mr/N)n resulting from a nitrogen concentration added in the second (Nc)2 or subsequent (Nc)n nutrient composition dosages is higher than a peak rate of methane production per unit nitrogen (Mr/N)1 observed for the initial nutritional composition dosage (Nc)1, wherein n is an integer equal to a dose of 2 or greater;
• ii. a peak rate of methane production per unit nitrogen (Mr/N)n resulting from the nitrogen concentration added in a second (Nc)2 or subsequent (Nc)n nutrient composition dosages is higher than a peak rate of methane production per unit nitrogen (Mr/N) observed for an initial nutritional composition dosage, than had the second or subsequent dosages the same or higher nitrogen concentration (Nc)n than the initial nitrogen dosage concentration (Nc)1, wherein n is an integer equal to a dose of 2 or greater;
• iii. a peak average daily % contribution to a sample methane composition over a sampling period (ave)1>(ave)n, 1 wherein n is an integer equal to a dose of 2 or greater;
• iv. peak mole of methane generated per volume of methane gas, where (moles/unit volume methane gas)>(moles/unit volume methane gas)n, 1 wherein n is an integer equal to a dose of 2 or greater;
• and
• v. average amount of methane generated during the period.