Fracturing fluid cross-linking agent and preparation method and application thereof

Abstract

The invention relates to a fracturing fluid cross-linking agent and a preparation method and application thereof. The cross-linking agent prepared by the invention can rapidly react with dialkyl phosphate, so that gelled fracturing fluid is formed by lower alkanes. The preparation method of the cross-linking agent comprises the following steps: (1) preparing a complex solvent, namely mixing an alcohol and water according to the mass ratio of 1:2-1:4, stirring uniformly, thereby obtaining the complex solvent; (2) sequentially adding the following components in parts by mass into a reaction container: 40-70 parts of the complex solvent, 30-60 parts of a trivalent iron salt and 6-25 parts of a complexing agent, and stirring and reacting at the temperature of 50-70 DEG C for 3-4 hours; and (3) cooling the reaction solution to the temperature of 30 DEG C, adding 2-8 parts of a cross-linking accelerator, uniformly stirring, thereby obtaining the lower alkane anhydrous fracturing fluid cross-linking agent.

Description

technical field [0001] The invention relates to the petroleum field, in particular to a fracturing fluid crosslinking agent and its preparation and application. Background technique [0002] With the deepening of oil and gas reservoir development at home and abroad, especially unconventional reservoirs are becoming the current development hotspot, including tight gas, shale gas and coalbed methane and other unconventional gases are becoming the current and future gas supply and its important components . However, the development of these gas reservoirs faces many special challenges. Water-based fracturing fluids commonly used in low-permeability reservoirs may cause loss of effective fracture half-length due to phase trapping and retention of water injected into the formation. Most tight gas reservoirs (with no original mobile hydrocarbon saturation) are water-wet, exacerbating this problem due to the strong water dispersion coefficient. Therefore, the adoption of low-carb...

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Problems solved by technology

The cross-linking agent used in it is usually ferric salt, trivalent aluminum salt, ferric complex compound, all mentioned ferric or trivalent aluminum as cross-linking agent in U.S. Patent US5571315, US5647900, US5271464, domestic Commonly used oil-based fracturing fluids mainly use sodium metaaluminate, and the commonly used cross-linking agents generally have the following deficiencies in the application process: (1) Directly combining ferric solution with amines or polycarboxylic acids does not affect Combined with the description of the reaction mode; (2) In the process of forming fracturing fluid, it is necessary to add additives such as alkali for adjustment, and the process is cumbersome, which is not conducive to construction

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