The present invention is directed to the disposal of waste water from subterranean gas-bearing formtions, and, more particularly, to a combination gas-producing and waste-water disposal well wherein the waste water is disposed of in an earth formation underlying the gas-producing earth formation. This invention was made as a result of a contract with the U.S. Department of Energy.
Gas from subterranean gas-bearing earth formations provides a considerable percentage of energy required for satisfying our energy demand. One such source of gas is methane gas from underground coal beds either of the mineable or unmineable type. The coal beds are penetrated by well bores to effect the drainage of methane from the coal bed. The problem associated with producing gas from subterranean earth formations, especially methane from coal beds, is that a considerable amount of contaminant-bearing waste water is produced along with the gas. Disposal of this extracted water has proven to be very difficult due to the need to satisfy environmental standards. The removal of this water away from the well site by tank trucks or pipelines is normally overly expensive.
In the drainage of methane gas from subterranean coal beds, the use of a deep waste-water disposal well in or near the area where several methane gas drainage wells are located has been one approach to disposing of the waste water removed from the coal bed during the production of the methane gas. In such an approach, the water disposal well sufficiently penetrates various earth formations until an earth formation is found that has adequate water absorbing properties to absorb or function at a sink for the water produced from the several gas-producing wells. Inasmuch as this waste-water disposal well is normally spaced among or near the various gas production wells, a waste-water gathering and pumping system is required for transporting the water to the disposal well. While this arrangement is beneficial since it can service more than one production well, and perhaps an entire field, the cost of the surface pumps and piping network collection system for the water represents a considerable expense. As will appear clear upon viewing the description below, the combination gas production and waste-water disposal well of the present invention is a more economical, reliable, and feasible approach than the use of a single waste-water disposal well for the entire gas field.