A low-damage nitrogen foam fracturing fluid for weakly water-bearing coalbed methane wells

Abstract

The invention provides a low-damage nitrogen foam fracturing liquid for a weak water-bearing coal-bed gas well and a preparation method thereof. The gas phase of the foam fracturing liquid is nitrogen, the liquid phase of the foam fracturing liquid is an additive solution, and the foam mass is 60 to 80 percent. The foam fracturing liquid is prepared from the following components in percentage by mass: 0.5 to 1.5 percent of a foaming agent, 0.3 to 0.7 percent of a foam stabilizing agent, 0.2 to 0.6 percent of a clay stabilizing agent, 0.1 to 1.0 percent of an auxiliary desorption agent and 96.2to 98.9 percent of water. The foaming agent is mainly an anionic surfactant; the foam stabilizing agent is mainly an amphoteric surfactant; the clay stabilizing agent is mainly an organic solvent; the auxiliary desorption agent is mainly a fluorocarbon surfactant. The foam fracturing liquid does not contain a macromolecular additive, has good temperature resistance and shearing resistance, high sand suspending capacity, good coal powder dispersing performance and negative damage to a coal rock core, and has a great significance to efficient development of weak water-bearing coal-bed gas and reservoir protection.

Description

technical field [0001] The invention relates to the technical field of unconventional coalbed gas exploitation, and in particular to a low-damage nitrogen foam fracturing fluid for coalbed gas wells with weak water content. Background technique [0002] The geological type in eastern Yunnan and western Guizhou is unique, and coalbed methane resources are abundant, with predicted reserves of 49117.9×10 8 m 3 , accounting for 13% of the country's coalbed methane resources, is a large coalbed methane gas-rich area. Coalbed methane exploration in this area has made significant breakthroughs this year, showing huge potential for development. Coalbed methane exploration and trial production operations have been carried out in more than a hundred wells in multiple blocks, and some areas have obtained good industrial gas flow. Eastern Yunnan and western Guizhou will be an important area for the next step of national CBM development. [0003] The coal reservoirs in this area have ...

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Problems solved by technology

[0003] The coal reservoirs in this area have the characteristics of low temperature, weak water content, and developed structural coal. In the early test mining experiments, various fracturing fluids such as clear water fracturing fluid and linear gel fracturing fluid were used for fracturing construction. The results are not satisfactory. According to the analysis, it is believed that the entry of a large amount of liquid water and additives has caused damage to the reservoir, resulting in poor stimulation effects.

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