Polymer acidic cross-linking agent and preparation method thereof

Abstract

The invention provides a polymer acidic cross-linking agent, which is prepared from the following raw materials in percentage by weight: 20-30% of a complexing agent, 0.1-5% of nanoparticles with core-shell structure, 5-10% of a zirconium compound, 1-3% of a stabilizer, 3-5% of a corrosion inhibitor and the balance of deionized water, wherein the nanoparticles with the core-shell structure take sulfide-loaded amorphous alumina as a core and oligomeric chitosan as a shell material, and the particle size of the nanoparticles is 50-500 nm. According to the cross-linking agent, the problem of more residues after gel breaking of a zirconium cross-linking agent is remarkably improved, the flowback rate is remarkably increased, and the damage to a reservoir is remarkably reduced.

Description

technical field [0001] The invention relates to the technical field of low-permeability oil field fracturing construction liquids, in particular to a crosslinking agent for acid fracturing and a preparation method thereof. Background technique [0002] The guar gum fracturing fluid system has low water insoluble matter, high viscosity, good temperature and shear resistance, and strong sand-carrying ability, which can meet the fracturing operations of different well depths and scales, and has been widely used after development. However, with the further exploration and development of the oilfield, the physical properties of the formation are becoming more and more complex, and the characteristics of low pressure and low permeability are becoming more and more prominent. In particular, clastic gas reservoirs have strong heterogeneity, high clay mineral content, low pressure coefficient, and flowback. Difficult, the requirements for fracturing technology and fracturing fluid ar...

AI Technical Summary

Problems solved by technology

[0005] There are boron-based, titanium-based and zirconium-based cross-linking agents in the prior art. The boron-based cross-linking agent acts on non-ionic galactomannan such as guar gum and its derivatives, and the formed jelly can withstand a temperature of 50-70 ℃, and the formed boron jelly has good viscoelasticity, high viscosity of suspended sand, and wide crosslinking ratio and range. It is only suitable for crosslinking systems under neutral or alkaline conditions, and the high temperature resistant type is poor, only suitable for 3000 medium shallow well

Ti-based and zirconium-based cross-linking agents are less used, low friction, longer delayed cross-linking time, high temperature resistance and shear resistance, and the jelly formed by titanium-based and zirconium-based cross-linking agents and thickeners is very Stable, so it has great advantages in high-temperature deep well construction, but its gel breaking is not complete, causing great damage to the reservoir after construction, low flowback rate, and low production after fracturing construction

[0006] Due to the molecular structure of the guar gum series thickener, the crosslinked guar gum gel is easily hydrolyzed in an acidic environment, and the viscosity is quickly reduced, which affects the performance of the fracturing fluid; although the guar gum series thickener The use of boron-based cross-linking agents under alkaline conditions has good cross-linking performance, and can meet the fracturing of different well depths and construction scales. However, zirconium-based or titanium-based cross-linking agents are usually used in acidic environments. Guar gum fracturing fluid has high residue content after gel breaking and incomplete flowback. The above reasons greatly limit the application of guar gum series in acidic environment

Images