Crosslinked acid sand fracturing acid liquor

Abstract

The invention relates to crosslinked acid sand fracturing acid liquor, comprising the following components in percentage by weight: 0.7% of thickening agent, 1.5% of cross-linking agent, 1.5% of corrosion inhibitor, 0.5% of surfactant, 0.15% of stabilizing agent, 20% of hydrochloric acid and 75.65% of water, wherein the thickening agent consists of the following components by weight percent: 6.61% of methacrylamidoethyltrimethylamine hydrochloride, 3.22% of acrylamide, 1.25% of acrylic acid, 9.52% of 2-acrylamide-2-methylpropanesulfonic acid, 6.15% of sodium hydroxide and 73.25% of deionized water; and the cross-linking agent consists of the following components in percentage by weight: 1% of zirconium oxychloride, 80% of formaldehyde and 19% of glyoxal. The crosslinked acid sand fracturing acid liquor can be cross-linked in 20% hydrochloric acid, the temperature resistance reaches 100 DEG C, the constant of reaction rate of acid-rock is 1.3744*10-6 (mol/cm<3>)(1-m)*(cm/s), and the viscosity of the gel-breaking liquid is less than 10 mPa.s.

Description

Technical field [0001] The invention relates to a method for improving single-well production of oil low-permeability and high-filling dolomite natural gas reservoirs, which can be cross-linked under high temperature and strong acid conditions, has good rheological properties to ensure sand carrying, and can be broken and returned in time after fracturing The discharged cross-linked acid is added with sand fracturing acid. Background technique [0002] Aiming at high-filling Type III dolomite reservoirs, in order to further increase the production of a single well, a cross-linked acid sand-carrying fracturing technology that relies on the dual effects of acid dissolution and sand fracturing has been carried out. This technology can delay the reaction rate of acid rock, increase the length of acid-etched fractures, and improve fracture conductivity. [0003] At present, although the performance of conventional sand-added fracturing fluid systems can meet the requirements of reservo...

AI Technical Summary

Problems solved by technology

[0003] At present, although the performance of conventional sand-added fracturing fluid systems can meet the requirements of reservoir stimulation technology, most of them are alkaline fracturing fluids, CO 2 The fracturing fluid system can only cross-link under weak acidity

[0004] The cross-linked thickening acid used in the past can be cross-linked under strong acid conditions, but the viscosity after cross-linking is low, generally only about 20mPa·s, and multivalent metal ions or acetaldehyde are used as cross-linking agents. However, because the initially developed gelling acid is very sensitive to shearing, has poor high temperature stability, and is difficult to break the gel in residual acid, this acid system has not been widely used.

In recent years, relevant foreign companies have developed high-efficiency acid-acid systems (the names of each company are different) and corresponding technologies on the basis of this acid solution, and have applied them on site, but they are only used in ordinary acidizing fracturing construction. Its performance cannot meet the technical requirements of sand fracturing construction