Process for extracting dissolved methane from hydropressured aquifers

Abstract

One undeveloped alternative fuel is methane dissolved in ground water. Equipment for extracting methane from ground water is readily available. This Application presents a process to produce and use dissolved natural gas in the United States. The process includes the use of production wells, pumps, gas/water separators, compressors, low pressure gathering lines, and water disposal wells. Dissolved methane is present in virtually every basin now known to produce oil and dry gas. The Great Valley of California alone contains undeveloped dissolved methane resources of about 1,200 trillion cubic feet (TCF). Dry gas production in 150 years was about 10 TCF. The first full scale test of the extraction process was completed on Jul. 7-8, 2010 in California. Laboratory analyses of the gas produced showed that it was equal in heat value (about 940 to 975 BTU per cubic foot) to dry gas produced from the same field.

I claim: 
     
         1 . A method of dissolved natural gas production from wells having a well-bore, casing, tubing, and wellhead, which are drilled into hydropressured, gas-saturated saline aquifers, comprising the steps of:
 (a) pumping hydropressured water and associated dissolved gas to the surface;   (b) separating dissolved gas from produced water with a conventional gas/water separator;   (c) capturing the separated natural gas and compressing it for transport in pipelines;   (d) injecting produced water back into the aquifer from which it was extracted.   
     
     
         2 . The method of  claim 1 , wherein step (a) further comprises:
 (I) completing production wells with slotted casing and gravel filter packs across thick (300 feet to 500 feet) net aquifer sand intervals;   (ii) pumping dissolved gas and water to the surface with positive displacement, rod driven, “top-drive” submersible pumps, or   (iii) utilizing high pressure gas flowing in small diameter “tremie” pipes to lift dissolved gas and water to the surface.   
     
     
         3 . The method of  claim 1 , wherein step (d) further comprises:
 (I) reinjecting produced water into the same hydropressured aquifer to maintain reservoir properties, including porosity and high permeability (1,000 to 3,000 millidarcies) in the aquifer sands or sandstones.   
     
     
         4 . The method of  claim 3 , wherein step (I), by preserving reservoir properties, will allow each production well to produce dissolved natural gas for 30 years or more with no decline in the ratio of gas production to water production. 
     
     
         5 . The method of  claim 4 , wherein dissolved gas concentrations in partially depleted aquifer sands will be replenished within hydropressured aquifers naturally by diffusion, thereby assuring long-term productivity of each dissolved gas production well. Inventor: Gary Farnsworth Player