Low-permeability water-bearing coal reservoir microwave steam explosion permeability-increasing adsorption-reducing method

Abstract

The present invention relates to a method for microwave steam explosion and anti-absorption reduction in low-permeability water-bearing coal reservoirs. The method utilizes ground microwave generators to generate high-power microwaves, transmits them to downhole power dividers through waveguides, and then arranges them in coal reservoirs. The inner port emits microwaves to the coal seam, and the water in the water-bearing pores / cracks of the reservoir will evaporate instantly after being irradiated by high-power microwaves to form a steam explosion. Under the huge pressure of water vapor from the inside to the outside, the pores and fissures of the coal rock expand and penetrate, making the coal seam The gas migration channel is smoother to achieve the purpose of increasing permeability; at the same time, the coal reservoir will heat up rapidly after absorbing microwave energy, which will promote the thermal movement of coalbed gas molecules to get rid of the adsorption and turn into a free state, so as to reduce the adsorption and increase the gas production. . The method has the advantages of simple system, obvious anti-reflection effect and high heating efficiency, and can improve the extraction efficiency of coalbed methane.

Description

technical field [0001] The invention relates to the field of coal bed gas extraction, in particular to a mining technology for increasing the permeability of coal reservoirs and reducing the adsorption. Background technique [0002] As a clean energy source, coalbed methane is an important part of my country's energy composition, but my country's coal reservoirs generally have the characteristics of "three lows and one high" (low pressure of coalbed methane, low permeability, low proportion of conventional fractures formed by hydraulic fracturing, adsorption High capacity), which restricts the development of coalbed methane. Therefore, the key technology for developing coalbed methane in coal reservoirs is how to increase the permeability of coal reservoirs and reduce their adsorption capacity. [0003] In order to improve the permeability of coal reservoirs, hydraulic fracturing is the most commonly used method at present. However, the lack of water resources is a common fea...

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Problems solved by technology

However, the heat of conventional electric heating is slowly transferred from the coal and rock mass at the heating well to the deep, and the thermal efficiency is low, and the coal and rock show more ductility under the action of this slowly changing thermal stress, which has a greater impact on the cracks. Expansion and regeneration are unfavorable; injecting high-pressure water vapor into coal reservoirs can simultaneously achieve the purpose of increasing permeability and reducing absorption, but the dryness control of water vapor is a difficult problem in the industry. Too low dryness will reduce the specific volume, making it economical. The benefit is reduced, and the condensed liquid water will also cause problems such as water lock when it enters the coal reservoir

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