Uphole negative-pressure advancing-type cryogenic fluid injection segmented cyclic fracturing method

Abstract

The invention discloses an uphole negative-pressure advancing-type cryogenic fluid injection segmented cyclic fracturing method. According to the method, firstly, water jet slotting equipment is adopted for arranging three fracture areas; water is injected through a water injection pipe so that hydraulic plugging devices can be filled up to form three hermetic fracturing chambers, the three hermetic fracturing chambers are put in a negative-pressure state, and the cryogenic fluid is injected in the hermetic fracturing chambers to fill the hermetic fracturing chambers in sequence and conduct cold shock fracturing on the fracture areas in the three hermetic fracturing chambers; as the cryogenic fluid in the hermetic fracturing chambers is heated up and gasified under the influence of terrestrial heat, a safety relief valve is opened to exhaust the phase-change gas after gas pressure inside a cryogenic fluid exhaust pipe exceeds an opening threshold value of the safety relief valve, thusthe gas pressure inside the cryogenic fluid exhaust pipe and all the hermetic fracturing chambers is lowered, and through the repetitive cycle, the hermetic fracturing chambers are subject to multipletimes of fracturing under gas expansion force. By means of the method, rapid injection of the cryogenic fluid and the fracturing effect on coal and rock mass can be effectively guaranteed, and pollution to the surrounding environment can also be avoided.

Description

technical field [0001] The invention relates to an upward drilling negative pressure advancing type injection low-temperature fluid staged cycle fracturing method, which belongs to the technical field of coal and rock mass anti-permeability. Background technique [0002] China is rich in coalbed methane resources, with great development potential, and the recoverable resources are about 10.87×10 12 m 3 In the next 10 to 20 years, China's coalbed methane production will increase significantly, and it will play an increasingly important role in making up for the shortage of conventional oil and gas production. With the increase of mining depth, the content and pressure of CBM in the coal seam gradually increase, the permeability of the coal seam gradually decreases, and the gas disasters such as CBM explosion and coal and gas outburst are also becoming more and more serious. CBM extraction is essential. Through investigation, it is found that the current coalbed methane drai...

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Problems solved by technology

[0004] Through investigation, it is found that the existing low-temperature fluid injection technology is injection under pressure, and the maximum injection pressure can reach 20MPa, which will significantly inhibit the contact between the low-temperature fluid and the reservoir surface, thereby greatly weakening the temperature difference between the low-temperature fluid and the reservoir. thermal stress caused by

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