Preparation and application of low-hydrocarbon anhydrous fracturing fluid crosslinking agent for unconventional reservoirs

Abstract

The invention relates to preparation and application of a low-hydrocarbon anhydrous fracturing fluid crosslinking agent for unconventional reservoirs. The crosslinking agent is mainly composed of the following substances in parts by mass: 15-35 parts of main agent, 2-4 parts of phase-transfer catalyst, 7-12 parts of crosslinking accelerator and 40-58 parts of deionized water. The preparation of the crosslinking agent comprises the following steps: adding a certain proportion of deionized water into a reaction vessel, and heating to 60-70 DEG C; adding the phase-transfer catalyst and main agent, and stirring to perform homogeneous reaction; and cooling to room temperature, finally adding the crosslinking accelerator, and stirring to react for 15 minutes. The anhydrous fracturing fluid crosslinking agent has the advantages of high crosslinking speed with the gelatinizer and high gel stability; and the fracturing fluid system has high temperature resistance and shear resistance, and has ideal fracturing effects on high-temperature reservoirs.

Description

technical field [0001] The invention belongs to the field of petroleum exploitation, and in particular relates to a low-carbon hydrocarbon anhydrous fracturing fluid crosslinking agent suitable for unconventional reservoirs and its preparation and application. Background technique [0002] In recent years, with the rapid development of my country's economy, the contradiction between supply and demand of oil and gas has intensified, and the import of crude oil has increased year by year. However, conventional oil and gas resources are facing the problem of severe reduction or even depletion of production capacity, which makes shale gas, coal bed methane, tight oil and gas and other unconventional oil and gas resources more and more valued by countries all over the world. The core technology for the development of unconventional oil and gas reservoirs is fracturing, and the fracturing fluid system is the key to the successful implementation of fracturing, so it is particularly...

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Problems solved by technology

[0004] Fe 3+ 、Al 3+ Metal salt is used as the main agent, usually using trivalent aluminum salt or ferric salt as the cross-linking agent to cross-link with dialkyl phosphate, the cross-linking process is very slow, the operation is cumbersome, difficult to control, and the solubility Slow, poor stability, and particularly high requirements for fracturing construction

[0005] Chinese patent CN104498017A discloses a fracturing fluid cross-linking agent and its preparation and application, but the temperature resistance and sand-carrying ability of the fracturing fluid prepared by this cross-linking agent have not been improved, and the temperature resistance is only 90°C. Not suitable for medium and high temperature oil fields and ultra-deep complex wells

Moreover, its cross-linking agent components are complex, the preparation is cumbersome, and alcohol and water are used as mixed solvents

[0006] In the prior art, aluminum sulfate is also used as a cross-linking agent. Although the by-product is sulfuric acid with good stability, which is beneficial to improving the temperature resistance of oil-based fracturing fluids, the cross-linking process is two steps, which is complicated and Cross-linking time exceeding two hours is not instructive for practical application in the field

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