Coal bed methane hydrofracture method

Abstract

The invention relates to a coal bed methane hydrofracture method. Active water fracturing fluid is used as prepad fluid and displacing fluid, carboxymethyl guanidine gum fracturing fluid is used as sand-carrying fluid, four kinds of quartz sand different in particle size range are used as propping agents, the 100-mesh-to-70-mesh mealy sand and the 70-mesh-to-40-mesh fine sand serve as the propping agents in the prepad fluid, the 40-mesh-to-20-mesh medium sand and the 20-mesh-to-14-mesh coarse sand serve as the propping agents in the sand-carrying fluid, and the proportions of the added sand which is different in particle size and serves as the propping agents are different. The concentrations of clay stabilizers KCL in the active water fracturing fluid and the carboxymethyl guanidine gum fracturing fluid are determined according to the GR average value, represented with the API unit, of fractured objective layer section logging data. By means of the coal bed methane hydrofracture method, the coal bed methane production increasing effect is improved to a great extent, and the preparing cost of the fracturing fluid is reduced to the maximum degree while swelling is effectively prevented.

Description

technical field [0001] The invention relates to a hydraulic fracturing method for mining coal bed gas, belonging to the technical field of hydraulic fracturing of coal bed gas wells. Background technique [0002] Coalbed methane is an unconventional natural gas resource with great resource potential and low development degree in my country. The total resources of coalbed methane with a buried depth of more than 2000m in the country are 32.86×10 12 m 3 . The low-cost and high-efficiency mining of coalbed methane can not only solve the pollution and safety problems caused by coal mine production, but also make up for the shortage of conventional energy development and utilization. However, due to the characteristics of low saturation, low permeability, and low pressure in my country's coalbed methane reservoirs, it is necessary to take certain measures to increase production in order to realize the commercial development of coalbed methane, and the most commonly used streng...

AI Technical Summary

Problems solved by technology

However, there are also deficiencies in actual construction: ①The sand-carrying capacity is poor, especially when it is used as a sand-carrying liquid to carry medium-coarse sand and other large-grained sand; ②High friction limits the construction displacement and construction scale, affecting the overall Fracturing effect

However, there are also disadvantages in actual construction and application: ①The cost is relatively high; ②When used as pre-fluid for joint creation, the joint height is not easy to control, and the joint height will be greatly expanded during large-displacement construction

[0015] In the actual construction process, the application concentration of the clay stabilizer KCL is usually an empirical value, which cannot achieve an economical and effective anti-swelling effect

If the applied concentration is low, the stabilization effect will be poor; if the concentration is too high, the overall fracturing cost will increase accordingly

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