Method to enhance microbial gas production from unconventional reservoirs and kerogen deposits

Abstract

A biostimulation method comprising injecting sulfur dioxide into water producing H + , SO 2 , SO 3 = , HSO 3 − , dithionous acid (H 2 S 2 O 4 ), and other sulfur intermediate reduction products in sulfurous acid, and then applying the sulfurous acid at the oxidation reduction potential required to biostimulate either aerobic or anaerobic organisms at the active margins of the black shale and coal bed deposits at a pH sufficient to reduce bicarbonate and carbonate buildup to a) increase CO 2 production to drive the production of methane by chemoautotrophic assimilation of CO 2 by hydrogen consuming methanogens, b) increase porosity and flows through the black shale and coal bed deposits, and c) provide SO 2 , SO 3 − , HSO 3 − , and dithionous acid (H 2 S 2 O 4 ) and other sulfur intermediate reduction products to provide soluble nutrients with bicarbonates and carbonate conducive to the growth of microbial consortia under either aerobic or anaerobic conditions to stimulate syntrophic bacteria and methanogenic archaea to produce methane.

1 . A biostimulation method of natural microbial populations active at margins of black shale and coal bed deposits where the organic matter has hydrologic flows there through consisting of:
 a. injecting sulfur dioxide into water producing H + , dissolved SO 2 , SO 3   − , HSO 3   − , dithionous acid (H 2 S 2 O 4 ), and sulfur intermediate reduction products all referred to as sulfurous acid, and   b. applying the sulfurous acid to the black shale and coal bed deposits and adjusting the oxidation potential of the sulfurous acid either:
 i. with the addition of oxygen and additional acid to effectuate a downhole acidic pH and an oxidation reduction potential of between −50 and −150 mV to create an oxidizing solution to provide aerobic conditions to stimulate aerobic microbial consortia to produce methane; or 
 ii. without the addition of additional oxygen and additional acid to effectuate a downhole acidic pH and an oxidation reduction potential of between +50 and −100 mV to create a reducing solution to provide anaerobic conditions to stimulate anaerobic syntrophic bacteria and methanogenic archaea microbial consortia to produce methane; the sulfurous acid applied sufficiently to: 
 ci. reduce bicarbonate and carbonate buildup to produce CO 2 , which drives the production of methane by chemoautotrophic assimilation of CO 2  by hydrogen consuming methanogens, 
 cii. increase porosity and flows through the black shale and coal bed deposits, and 
 ciii. provide dissolved SO 2 , SO 3   = , HSO 3   − , and dithionous acid (H 2 S 2 O 4 ) and sulfur intermediate reduction products to produce soluble bicarbonates and carbonate nutrients at the oxidation reduction potential conducive to the growth of microbial consortia to produce methane. 
   
     
     
         2 . (canceled) 
     
     
         3 . The biostimulation method according to  claim 1 , further comprising adding supplemental nutrients to the sulfurous acid. 
     
     
         4 . The biostimulation method according to  claim 1 , further comprising adding syntrophic bacteria and/or cyanobacteria and methanogenic archaea to the sulfurous acid to inoculate the black shale and coal bed deposits microbial consortia.