Supercritical carbon dioxide sand-carrying coal seam fracturing device and method

Abstract

The invention relates to a supercritical carbon dioxide sand-carrying coal seam fracturing device and method. The supercritical carbon dioxide sand-carrying coal seam fracturing device comprises a liquid CO2 storage tank, a booster pump, a heating device, a high-pressure ejector and a hole packer, wherein the liquid CO2 storage tank is connected with the high-pressure ejector through the booster pump and the heating device; and the high-pressure ejector is connected with the hole packer and further provided with an ejection medium inlet. According to the invention, supercritical CO2 is used asa fracturing fluid, and the extremely strong diffusivity and solubility of the supercritical CO2 are utilized, so that micro-fractures in a coal seam can be communicated with each other, and the airpermeability of the coal seam is improved. Ceramsite is carried to serve as a propping agent, the fractures formed after fracturing can be kept open, the ceramsite has good flow conductivity, and gascan smoothly pass through the ceramsite in the gas extraction process.

Description

technical field [0001] The invention relates to a coal seam fracturing device and method, in particular to a supercritical carbon dioxide sand-carrying sand fracturing device and method for coal seam fracturing, belonging to the technical field of coal mine safety mining. Background technique [0002] At present, the pressure relief and anti-reflection measures adopted by my country for deep high-stress, low-permeability, and high-gas content coal seams mainly include loosening blasting, high-pressure air blasting, hydraulic fracturing, ultra-high pressure hydraulic slotting, Liquid carbon dioxide fracturing anti-permeability and other technologies, but these technologies have the following problems: [0003] (1): Loosening blasting and high-pressure air blasting consume most of the energy of the explosion on the fragmentation of the coal near the drill hole, so the range of cracks produced by them is very limited. [0004] (2): Ultra-high pressure hydraulic cutting consumes...

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Problems solved by technology

[0003] (1): Loosening blasting and high-pressure air blasting, because most of the explosion energy is consumed in the crushing of coal near the drill hole, the range of cracks produced by them is very limited

[0004] (2): Ultra-high pressure hydraulic cutting consumes a lot of water, requires high pressure, requires high equipment performance, complex process and heavy workload. Although it can relieve pressure and increase permeability of coal, the cutting seam Shallow, the range of influence of loosening and pressure relief formed by it is limited

[0005] (3): When using pure liquid carbon dioxide to fracturing the coal seam, although the cracks open in a large range, the cracks are easy to reclose after the carbon dioxide gas is filtered out. It is easy to freeze under the ground and cause the proppant to agglomerate, which increases the difficulty of smooth sand delivery and may cause sand plugging

In addition, the low temperature generated by liquid carbon dioxide may also cause the water in the coal seam near the orifice to freeze, causing safety hazards in fracturing

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