A kind of fracturing fluid composite crosslinking agent, preparation method and application thereof

Abstract

The invention relates to a compound cross-linking agent, which comprises, by weight, 0.5-5% of inorganic aluminium salt, 1.0-10% of inorganic zircon salt, 2-15% of glacial acetic acid, 0-1% of EDTA and / or EDTA disodium salt and the balance water. The invention also provides a preparation method and an application of the cross-linking agent. A fracturing fluid prepared from the cross-linking agent can resist temperature of 140 DEG C and can continuously shear for 120 min under conditions of 140 DEG C and 170l / s. Viscosity can be maintained above 100 mPa.s, and viscosity can be restored after high shear. Crosslinking time can be adjusted. The cross-linking agent is beneficial to promote uniform sand mulling and reduce wellbore friction. The cross-linking agent has flexibility and controllability. The fracturing fluid can be used for thorough gel breaking, gel breaking time is 3h, viscosity of a gel breaking solution is less than 2mPa.s, and damage to stratum is little. Meanwhile, pH value of the polymer fracturing fluid is 3-4, and the polymer fracturing fluid can be used for cellulose sensitivity stratum.

Description

technical field [0001] The invention relates to a fracturing fluid composite crosslinking agent, a preparation method and an application thereof, belonging to the field of exploration and development of oil and gas fields. Background technique [0002] Hydraulic fracturing is an important technical measure for increasing production of oil and gas wells and increasing injection of water injection wells. The performance of fracturing fluid is an important factor affecting the fracturing effect. According to the fracturing fluid preparation materials and liquid properties, the fracturing fluid can be divided into water-based fracturing fluid, oil-based fracturing fluid, emulsion fracturing fluid, foam fracturing fluid, acid-based fracturing fluid, alcohol-based fracturing fluid, etc. . Among them, water-based fracturing fluid is formulated with water as a solvent and various additives (such as thickeners, cross-linking agents, gel breakers, pH regulators, bactericides, clay s...

AI Technical Summary

Problems solved by technology

Natural vegetable gum and its modified fracturing fluids are currently the most used fracturing fluids, which have outstanding high temperature resistance and shear resistance, but generally have the defects of high water insoluble content, large residues, and great damage to formations

At the same time, most plant gums belong to galactomannan, and guar gum and its hydroxypropylated or carboxymethylated derivatives are commonly used. However, in recent years, the price of guar gum has risen rapidly, fluctuated greatly, and supply and demand are unstable. Increase the cost of natural vegetable gum fracturing fluids, therefore, it is necessary to develop alternative fracturing fluids

Surfactant fracturing fluid has high cost and poor temperature resistance

Synthetic polymer fracturing fluid has the advantages of low cost and stability, low water-insoluble content, no residue (low residue), and little damage to the formation, but it usually has the following disadvantages: poor temperature resistance and shear resistance, Delayed cross-linking time is insufficient, gel breaking time is greater than 4 hours and the gel breaking is not complete, resulting in significant adsorption damage, etc.

However, few cross-linking agents appearing in domestic and foreign patents or literatures meet the three conditions of delay, high temperature and low damage at the same time. Even if they can be achieved, the synthesis process is generally more complicated.