Refracturing method and system

Abstract

The invention discloses a refracturing method and system, and belongs to the field of coal bed gas mining. The refracturing method and system are used for conducting refracturing on a coal bed. The refracturing method comprises the following steps that anti-swelling liquid is injected into a primary fracture system formed by primary fracturing of the coal bed; plugging agents are injected into a primary perforated interval of the coal bed so as to plug the primary fracture system, and the primary perforated interval is formed in the primary fracturing process of the coal bed; perforated operation is conducted on the coal bed and a roof of the coal bed, and a secondary perforated interval is formed; and fracturing liquid and propping agents are injected into the secondary perforated interval, and a secondary fracture system is formed in the coal bed. According to the refracturing method and system, by injecting the anti-swelling liquid into the primary fracture system formed through the primary fracturing of the coal bed and injecting the plugging agents into the primary perforated interval of the coal bed so as to plug the primary fracture system, the fracture systems formed through refracturing are easier to extend and expand to areas without fractures, and accordingly the gas production and the recovery ratio of the coal bed are guaranteed.

Description

technical field [0001] The invention relates to the field of coal bed gas exploitation, in particular to a repeated fracturing method and system. Background technique [0002] Coalbed methane is hydrocarbon gas adsorbed on the surface of coal matrix particles, and it is an associated mineral resource of coal. With the continuous advancement of mining technology, coalbed methane can also be collected while mining coal mines. In practical applications, in order to exploit coalbed methane, coal seams can be fractured, that is, fracturing fluid is injected into the coal seam under high pressure to form cracks in the coal seam, and then proppant is injected into the formed cracks to prevent The fractures close to eventually form a fracture system in the coal seam. However, due to the high Poisson's ratio and low Young's modulus of the coal seam, the fracture system formed after coal seam fracturing is likely to have a large height and many branches. Such a fracture system is of...

AI Technical Summary

Problems solved by technology

[0006] In order to solve the problem that the quality of the fracture system formed by repeated fracturing in the prior art is poor, and the gas production rate and recovery rate of the coal seam cannot be effectively improved, the embodiment of the present invention provides a method and system for repeated fracturing

Images