A linear gel fracturing fluid for automatic gel breaking in reservoirs and its preparation method

Abstract

The invention discloses a linear gel fracturing fluid for automatically breaking a reservoir in shale gas fracturing and a preparation method thereof. The linear gel fracturing fluid is formed through self-assembly of an anionic hydrophobic associated polymer and a thermally-unstable cationic surfactant. According to the technical scheme, the method comprises the following steps: (1) copolymerizing dodecylmaleimide serving as a hydrophobic monomer and acrylamide to obtain the anionic hydrophobic associated polymer; (2) reacting long-carbon-chain tertiary amine with CO2 to prepare a thermally-unstable ammonium bicarbonate cationic surfactant; (3) adding a thermally-unstable surfactant of 100 to 600mg.L<-1> with a hydrophobic associated polymer solution slightly lower than a critical association concentration to form the linear gel fracturing fluid for automatically breaking the reservoir. The linear gel fracturing fluid for automatically breaking the reservoir has high proppant carrying capacity in the ground and a shaft; the thermally-unstable surfactant is decomposed in the reservoir, and the linear gel fracturing fluid plays a role in automatic breaking, so that damage to the reservoir is reduced; the linear gel fracturing fluid has a wide application prospect in shale gas fracturing.

Description

technical field [0001] The invention relates to a linear glue fracturing fluid for automatically breaking glue in reservoirs for shale gas fracturing and a preparation method thereof. Background technique [0002] Due to the characteristics of low porosity and low permeability of shale gas reservoirs, exploration and development are difficult, and most shale gas wells need reservoir reconstruction to obtain ideal production. At present, foreign countries mainly use mixed fracturing fluids formed by slick water, linear gel and jelly fracturing fluids for volume fracturing. However, most of the commonly used linear gel fracturing fluids are formulated with guar gum, which has a high content of guar gum residues, making it difficult to completely break the gel and cause great damage to the reservoir. [0003] Therefore, the present invention provides a linear gel fracturing fluid for automatic gel breaking of reservoirs and a preparation method thereof. The linear glue fractu...

AI Technical Summary

Problems solved by technology

However, most of the commonly used linear fracturing fluids are formulated with guar gum, which has a high content of guar gum residue, making it difficult to completely break the gel and cause great damage to the reservoir