Supercritical carbon dioxide positive and negative pressure interaction combined gas extraction system and gas extraction method

Abstract

The invention discloses a supercritical carbon dioxide positive and negative pressure interaction combined gas extraction system. The system comprises a plurality of negative pressure holes evenly formed in a coal seam wall, and positive pressure holes are formed in areas defined by adjacent negative pressure holes. An extraction pipe is arranged in each negative pressure hole, extends out of a negative pressure hole sealing device and is connected with a negative pressure branch pipe, and the negative pressure branch pipes are connected with a negative pressure main pipe; a fracturing pipe and a carbon fiber quartz electric heating pipe are arranged in each positive pressure hole, each fracturing pipe extends out of a positive pressure hole packer, and the fracturing pipes are connected with a positive pressure main pipe; the positive pressure main pipe is connected with a gas storage tank, and a heating box, a booster pump and a pressure release valve are arranged on the positive pressure main pipe between the gas storage tank and the fracturing pipe in series. The invention further discloses a corresponding gas extraction method. The energy utilization rate is high, the supercritical state of carbon dioxide can be kept for a long time, and efficient gas extraction is achieved under the interaction of positive pressure and negative pressure.

Description

technical field [0001] The invention relates to the technical field of coal mine gas drainage. Background technique [0002] Coal mine gas extraction is an important guarantee for safe production in coal mines, and it is also a need for recovery and utilization of gas. my country's coal seams have the characteristics of high gas adsorption and low permeability, which lead to difficulties in gas extraction and frequent gas accidents. At present, the commonly used gas drainage method needs to arrange dense gas drainage boreholes, which requires a lot of manpower and material resources, and the negative pressure value of a single hole is low. However, hydraulic fracturing technology has poor desorption promotion effect and cannot fundamentally solve the problems of low coal seam permeability and low coal seam gas extraction rate in my country. [0003] Supercritical carbon dioxide refers to a state in which carbon dioxide is heated and pressurized above the critical point (Tc...

AI Technical Summary

Problems solved by technology

[0005] Coal seams are easier to absorb microwave energy than carbon dioxide, and microwaves have good penetrating properties, so microwave energy is mainly used to heat coal seams, and can heat coal seams far away from positive pressure holes. Energy cannot be concentrated in supercritical carbon dioxide, resulting in useless work The phenomenon of more useful work and less work

[0006] The existing positive and negative pressure gas drainage technology has the following defects: intensive drilling is required to ensure the positive and negative pressure drainage effect, which increases the cost of gas extraction

Images