Novel active water fracturing fluid for fracturing of coal bed gas well

Abstract

The invention relates to a fracturing fluid for the fracturing construction of coal bed gas well. In general, a coal bed gas well cannot be put into operation before the fracturing construction. Owing to the characteristics of small harm, low cost, convenient preparation and the like, the active water is extensively applied to the fracturing construction of coal bed gas well. The typical active water fracturing fluid is generally prepared from clear water, anti-swelling agent (typically potassium chloride) and cleanup additive (typically complex of surfactants, typical cleanup additive for oil field is D-60 and HP-8, etc.) based on certain proportions. The active water fracturing fluid shows, when being used for the fracturing construction, the defects of high frictional resistance and no dispersion effect on coal dusts generated in the process of the fracturing construction. The active water fracturing fluid according to the invention is prepared in a manner of adding the typical active water fracturing fluid with drag-reducing agent (anionic or nonionic polyacrylamide) and coal dust dispersing agent (lignosulfonate, such as sodium lignin sulfonate) based on the mass percents as below: 1%-2% of potassium chloride, 0.02% to 0.06% of drag-reducing agent and 0.01% to 0.03% of dispersing agent. The fracturing fluid according to the invention has the characteristics of simple formula, the effect of reducing frictional resistance of construction tubular columns and uniformly dispersing coal dusts, small harm to coal bed and easy flowback.

Description

technical field [0001] The invention relates to the technical field of coalbed gas well fracturing and production stimulation, and is a fracturing fluid, in particular to a novel active water fracturing fluid with the functions of anti-swelling, reducing resistance and dispersing coal powder for coalbed gas well fracturing construction. Background technique [0002] Coalbed methane reservoirs are characterized by low porosity and permeability, and low natural production capacity. Fracturing is often required to obtain industrial production and realize economical mining. Fracturing fluid is the working fluid in the process of fracturing construction, which plays the role of creating fractures and carrying proppant into the formation. Commonly used fracturing fluids for coalbed methane well fracturing operations include: active water fracturing fluid, linear gel fracturing fluid, cross-linked gel fracturing fluid (including viscoelastic surfactant fracturing fluid) and foam fr...

AI Technical Summary

Problems solved by technology

The commonly used active water fracturing fluid is generally composed of water, anti-swelling agent (commonly used potassium chloride) and drainage aid (usually a compound of surfactants, commonly used drainage aids in oil fields include D-60 and HP-8, etc.) Prepared according to a certain ratio, the active water fracturing fluid exhibits the following defects during fracturing construction: (1) high frictional resistance, which limits the construction displacement, thereby limiting the construction scale and affecting the fracturing effect; (2) It has no dispersing effect on the pulverized coal produced during the fracturing construction, which makes the pulverized coal easy to form agglomerates, blocks the fracturing crack channel, makes the construction pump pressure fluctuate greatly, and increases the difficulty of construction. The pulverized coal produced is discharged and produced after fracturing During the process, the pump is easy to get stuck, increasing the number of pump inspections and increasing the mining cost of coalbed methane wells

The active water fracturing fluid prepared by the coal powder dispersant and anti-swelling agent (such as potassium chloride) can disperse coal powder, but it has no drag-reducing effect