Microwave-assisted supercritical carbon dioxide circulation fracturing system and method

Abstract

The invention relates to a microwave-assisted supercritical carbon dioxide cyclic fracturing system and a microwave-assisted supercritical carbon dioxide cyclic fracturing method. The microwave-assisted supercritical carbon dioxide cyclic fracturing system comprises a liquid carbon dioxide tank, a heater, a boosting pump, a fracturing pipe, a return pipe, a three-phase separator, an air compressor and a cooler which form a loop to achieve supercritical carbon dioxide cyclic fracturing, and a fracture network is formed in a coal seam. According to the microwave-assisted supercritical carbon dioxide cyclic fracturing method, the coal seam and carbon dioxide are subjected to microwave heating to ensure that the carbon dioxide is in the supercritical state for a long time, and heat effect of microwave heating is capable of fracturing coal masses, dredging pores and promoting gas desorption. The microwave-assisted supercritical carbon dioxide cyclic fracturing system and the microwave-assisted supercritical carbon dioxide cyclic fracturing method have the advantages that the supercritical carbon dioxide high in diffusivity is capable of going deep into coal mass pores and fractures quite easily as well as dispelling gas; operation costs are reduced effectively and the construction technology is simplified effectively through cyclic fracturing; microwave radiation is combined with supercritical carbon dioxide cyclic fracturing to increase porosity and permeability of the coal seam greatly and promote gas desorption, so that gas extraction effects are improved substantially, and the system and the method are highly practical in the field.

Description

technical field [0001] The invention relates to a microwave-assisted supercritical carbon dioxide circulation fracturing system and method, which belong to the related technical field of underground fracturing in coal mines, and are especially suitable for soft and high-gas coal seams. Background technique [0002] The characteristics of high adsorption, microporosity, and low permeability of coal seams in my country make gas drainage difficult and gas accidents occur frequently. As a mature technology, hydraulic fracturing can effectively improve the drainage effect of coal seam gas. However, the existing hydraulic fracturing technology has a single form of fracture, is difficult to form a fracture network, has poor desorption promotion effect, and poor recovery of fracturing fluid. Microwaves can act on polar molecules such as water in the coal body to produce thermal effects, tear the coal body, dredge pores and promote gas desorption. Supercritical carbon dioxide refers...

AI Technical Summary

Problems solved by technology

Compared with conventional fracturing fluids, supercritical carbon dioxide fracturing fluid has strong permeability and can easily enter the pores and fissures in coal, thereby creating a fracture network. However, maintaining the supercritical state of carbon dioxide in underground coal mines and effectively recovering it has become the key to its application. technical bottleneck

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