Acid esters coordination directional glue crushing method

Abstract

The invention discloses an acid esters coordination directional glue crushing method which belongs to the technical field of fracturing technique in production of an oil field, and comprises the steps of adding acid in prepad fluid and adding ester in sand carrying liquid. As for the acid esters coordination directional glue crushing method, not only is the sand carrying capability of the sand carrying liquid not influenced, but also the acid releasing speed and the acid releasing capability can be controlled reasonably, so that the environment of pH less than or equal to 7.5 can be created for polyhydroxy-alcohol system fracturing liquid, therefore, polyhydroxy-alcohol system jelly is hydrated completely and a glue returning phenomenon can not be caused.

Description

technical field [0001] The invention relates to a method for breaking the gel of a polyhydric alcohol system fracturing fluid used for realizing low-permeability oil well reservoir reconstruction in the fracturing process of oilfield production, in particular to a method for directional gel breaking with an ester compound. Background technique [0002] Fracturing is one of the important measures to increase oil production. The process is to use the viscoelastic gel to carry the proppant into the formation fractures to prevent the closure of the fractures, thereby increasing the porosity and permeability of the rock formation. According to the construction process, the fracturing fluid is divided into three parts, pre-fluid, sand-carrying fluid and displacement fluid. The main function of the pre-fluid is to generate fractures, the main function of the sand-carrying fluid is to use viscoelastic gel to bring the proppant into the formation, and the displacement fluid is to en...

AI Technical Summary

Problems solved by technology

However, directly dispersing ammonium persulfate in the hydrogel will inevitably cause local concentration of the breaker, which will affect the breaking efficiency and the sand-carrying ability of the sand-carrying fluid; Surface-based breakers are expensive to produce and have low release efficiency

Moreover, this gel breaker uses oxidation to degrade the galactomannan in the fracturing fluid, destroying the C-O-C bond and causing the polysaccharide thickener gel to break, while the polyhydric alcohol gel system C-O-B-O-C It is invalid and cannot make it completely break the glue

[0005] (2) For the jelly with boron as the crosslinking center, in the gel breaking process of hydration under acidic conditions, the direct addition of acid substances will destroy the jelly in a short time, resulting in the loss of the sand-carrying ability of the sand-carrying fluid

Moreover, the continuous hydrolysis of this boron-based cross-linking agent to free B will trigger the cross-linking reaction again, resulting in the phenomenon of "returning glue".

[0006] (3) Biological enzyme is a special protein that can degrade polysaccharide colloids; but it has no effect on polyhydric alcohol system jelly

[0007] (4) Some organic esters will also be hydrolyzed to generate acid in the presence of water, and then break the gel of the fracturing fluid, but the gel breaking of esters is slow, and it is difficult to ensure the timely release of proppant