Method for producing natural gas in organism coal bed

Abstract

The invention discloses a method for producing natural gas in an organism coal bed, comprising the following steps: a filling well is used for filling a nutrient solution or the nutrient solution and microorganism into the coal bed, simultaneously one or a plurality of circulation wells are used for extracting liquid in the coal bed and sending the liquid into the filling well, and by adjusting the filling pressure of the filling well and the extracting pressure of the circulation well, the height of water can be kept to be relatively constant, thus realizing the stable circulation of the nutrient solution; and when the contents of nutrients in water samples extracted from the circulation well all be more than 10% of the water samples in the filling well, filling and circulating are stopped, the well is closed for a while, and the atmospheric pressure of a borehole is monitored; and when the atmospheric pressure of the borehole achieves 10-20psi, the producing of gas begins. In the method, the nutrients filled in the coal bed can be mixed sufficiently by utilizing the multi-well and circulation technology, the filling quantity is reduced greatly, simultaneously, the gas production process of the microorganism can be efficiently activated and promoted, the largest-scale gas production efficiency can be realized, and the environmental pollution can be avoided.

Description

technical field [0001] The invention relates to the combined field of clean energy and biotechnology, in particular to the technology of producing methane (natural gas) gas from various carbon-containing media (such as various types of coal) by using biochemical means and on-site engineering implementation method of cycle operation. Background technique [0002] Most coal seams in the world (including bituminous coal, semi-bituminous coal, lignite, peat, etc.) usually contain methane gas. Coal bed methane is generally produced through pyrolysis or biomethanation processes. Studies have shown that about 30-90% of coalbed methane (the specific ratio depends on the geological structure and region) is produced by biological processes, and this type of methane is also called biological coalbed natural gas (abbreviated as biological coalbed methane). Biological coal seam natural gas is produced by the methane generation reaction caused by the coal formation process or the intrusi...

AI Technical Summary

Problems solved by technology

This method has many defects: 1. The rate of adding nutrient solution is slow, which depends entirely on the volume that can be accommodated by the coal seam porosity around the well, and the gas production cycle is long; 2. The range and volume of nutrient solution contacting coal are small, which limits Total gas production; 3. It is easy to gather in a small area to cause a large number of microorganisms to multiply, consume nutrients but produce little or no biological coalbed methane; 4. The surge of biomass will block the coal seam gap and reduce the liquid transmission rate, thereby further affecting Gas production efficiency; 5. The pumping method gathers high-concentration nutrient solution in a small area, and relies on concentration gradient diffusion to realize the propagation and migration of nutrients in the coal seam. This process takes a long time and will have a negative impact on the water quality of the coal seam in the short term , if the water body is connected with drinking water, it will directly affect the environment and human health; 6. After the injection method is completed, the injection well is called a gas production well, and the injected nutrient solution will form and maintain a well around the well. High water level, the pressure generated will inhibit the collection of the produced coalbed methane, so the water level in the well needs to be pumped down to achieve gas production during gas production, and the coalbed water pumped to the surface in this way still has the added nutrients Chemical components, discharge on the surface will cause surface water and soil pollution, and if it is treated, it will significantly increase the cost of gas production

It can be seen that the "injection and pumping" method for bio-coalbed methane development has significant shortcomings in terms of actual effect, large-scale gas production and environmental protection

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