Method of low-temperature gas-assisted coalbed methane fracturing technology

Abstract

The invention relates to the field of oil and natural gas prospecting and exploitation, and provides a method of low-temperature gas-assisted coalbed methane fracturing technology. According to the method, by the aid of ultralow temperature characteristics of liquid nitrogen, cold shock transformation and ice formation are performed on a coalbed, ice blockage is caused to high-permeability channels (such as fractures), and effect of inorganic harmless dissoluble flowback fluid loss additives, even fracturing diverters and the like is achieved, so that the purpose of improving conventional coalbed methane fracturing technology is achieved. The method of the fracturing technology is suitable for primary fracturing of coalbed methane wells non-fractured or with natural fractures existing at the well bottoms, as well as refracturing of coalbed methane wells already fractured but low in productivity.

Description

technical field [0001] The invention relates to the field of petroleum and natural gas exploration and development, in particular to a coal bed gas fracturing process. Background technique [0002] Coalbed methane, as an important unconventional natural gas resource, is increasingly valued by countries all over the world. Compared with conventional oil and gas reservoirs, coal rocks have the characteristics of low strength, low elastic modulus, low permeability, high Poisson's ratio, well-developed cleats, easy fracture, anisotropy, and severe heterogeneity. Coalbed methane is mainly stored on the inner surface of coal matrix pores in an adsorbed state, and only a small amount is stored in a free state in coal cleats and other fractures. The output of coalbed methane must go through the process of analysis, diffusion and seepage. [0003] Because the permeability of coal seams is generally very low, in order to increase the production capacity of CBM, artificial stimulation...

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Problems solved by technology

[0011] At present, pure liquid nitrogen and liquid CO have been proposed and applied at home and abroad. 2 Fracturing or auxiliary coal bed gas fracturing process, mainly using liquid nitrogen and liquid CO 2 It has the advantages of gasification expansion, energy enhancement and drainage, gas Jamin effect to reduce filtration loss, and inert gas has little damage to the formation, etc., which is suitable for liquid nitrogen and liquid CO 2 The use of low temperature characteristics has not attracted attention

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