Crosslinked Polymer Hydrogel for High-Temperature Fracturing Fluids
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Solution Overview
Problem
Current water-based fracturing fluids face challenges with high initial viscosity, high thickener concentration, large construction friction resistance, poor temperature-resistance, and poor sand-carrying performance at high temperatures, while also relying on crosslinking agents that require post-treatment and pose supply security risks and environmental concerns due to water consumption.
Innovation Solution
A crosslinked polymer formed through the reaction between polymer starting materials and 2,4,6-trihalogen-1,3,5-triazine, which creates a hydrogel with improved stability and sand-carrying performance, suitable for use in fracturing fluids, and can be recycled without the need for removing boron or zirconium, using a variety of water sources and polymer materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional crosslinking agents (boron, zirconium, titanium) are used to prepare fracturing fluids, then the fluids achieve high initial viscosity and thickener concentration, but they exhibit large construction friction resistance and poor temperature-resistance performance
Solution Approach 1:
The patent changes the chemical parameters of the crosslinking agent from traditional boron/zirconium/titanium compounds to epichlorohydrin, and modifies the polymer structure by introducing carboxymethyl and hydroxylpropyl groups. This parameter change results in a crosslinked guar gum with improved temperature resistance while maintaining viscosity, directly resolving the contradiction between strength and reliability under high temperature conditions.
2Reliability
If guar gum is used as the thickener in fracturing fluids, then the fluids achieve good sand-carrying performance, but the supply security is at high risk and the price is high
Solution Approach 1:
The patent introduces specific functional groups (carboxymethyl and hydroxylpropyl) at local positions on the guar gum molecule structure. This local modification enhances the sand-carrying performance through improved rheological properties while allowing the use of alternative guar sources, thereby improving supply security without sacrificing the critical sand-carrying capability.
3Strength
If epichlorohydrin is used as the crosslinking agent to prepare crosslinked guar gum, then a relatively high degree of crosslinking is achieved, but the solubility of the prepared crosslinked guar gum is not high in water
Solution Approach 1:
The patent optimizes the molar ratio of epichlorohydrin to guar gum and controls the crosslinking reaction conditions (pH, temperature, reaction time) to achieve a balanced degree of crosslinking. By introducing hydrophilic carboxymethyl and hydroxylpropyl groups, the patent maintains water solubility even at high crosslinking degrees, resolving the contradiction between crosslinking strength and solubility stability.
4Reliability
If traditional fracturing fluids are used, then sand suspension is maintained, but friction resistance is large and post-treatment is required for crosslinking agent removal
Solution Approach 1:
The patent employs epichlorohydrin crosslinked guar gum that can be easily broken down and removed from the fracturing fluid after use. The crosslinked structure provides sufficient sand suspension during the fracturing process, but the gel can be degraded by standard breakers, eliminating the need for complex post-treatment to remove persistent crosslinking agents like boron or zirconium.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The crosslinked polymer hydrogel exhibits enhanced sand-carrying performance at high temperatures, reduces friction resistance, and allows for the recycling of fracturing flowback fluid, lowering operational costs and environmental impact while maintaining effective sand suspension and viscosity control.
Implementation Method 1
A crosslinked polymer formed through the reaction between polymer starting materials and 2,4,6-trihalogen-1,3,5-triazine
Data Source
AI summary
The invention provides a crosslinked polymer, a hydrogel, a water-based fracturing fluid comprising the same, and methods of making and using thereof. The crosslinked polymer of the invention is represented by formula (I), wherein * denotes a combining site with a polymer starting material and *′ denotes an optional combining site with the polymer starting material, wherein the combining sites denoted by * and *′ may be located in the same polymer molecule, or in different polymer molecules, but there are at least two combining sites located in different polymer molecules; X1 and X2, which may be the same or different, are independently an oxy (—O—) or imino (—NH—) group; X3 is an oxy (—O—) or imino (—NH—) group when *′ denotes a combining site with the polymer starting material, or X3 is a halogen, NH2 or OH when *′ isn't a combining site with the polymer starting material. The crosslinked polymer of the invention can be used in water-based fracturing fluid, in personal care products, household care products and pet care products, in reusable hydraulic fracturing flowback fluid, in gel explosives or in fire extinguishing mortar.