Fracturing fluid capable of resisting low pH value environment and higher salinity and preparation method thereof

Abstract

The invention relates to a fracturing fluid capable of resisting low pH value environment and higher salinity and a preparation method thereof. Most conventional fracturing fluid can have favorable viscoelasticity only in an alkaline environment, and the natural vegetable glue used under normal conditions is difficulty for crosslinking under acidic conditions. The preparation method comprises the following steps: uniformly mixing a viscoelastic surfactant, an acid and a dispersion pour-point depressant to form a liquid component mixture; and dissolving a water-soluble nonionic polymer thickener at normal temperature, adding the liquid component mixture, and stirring uniformly to obtain the fracturing fluid. Under the condition of not using any crosslinking agent, the vermiform accumulation of the viscoelastic surfactant is utilized to coat the linear high-polymer part inside the viscoelastic surfactant, so that the linear high polymer generates the crosslinking-like effect due to the existence of the viscoelastic surfactant when meeting the acid and shrinking. The fracturing fluid has high viscosity in a neutral environment due to the linear high polymer, and thus, can not have the solid carrying capacity due to greatly lowered viscosity under acidic conditions.

Description

technical field [0001] The invention belongs to the field of fracturing fluid technology, and in particular relates to a fracturing fluid resistant to low pH environment and high salinity and a preparation method thereof. Background technique [0002] Fracturing fluid plays an important role in oil field stimulation measures. Conventional fracturing fluids can only exhibit good viscoelasticity in alkaline environments. However, in some special formation environments for acidification treatment, or in special operating environments such as carbon dioxide injection, it is necessary for the fracturing fluid to work under acidic conditions and high salinity. Generally used natural vegetable gums are relatively difficult to cross-link under acidic conditions. A linear polymer solution that can produce a higher viscosity and has a certain acid resistance cannot work independently because it is difficult to resist high salinity and crosslinking. Viscoelastic surfactants that can...

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to provide a kind of fracturing fluid that can withstand low pH value environment and higher salinity and its preparation method, improve the carrying capacity of acid, and solve the problem of high pH use restriction existing in the prior art