Temperature-Stable Electrolytic Hydrogel for Hydraulic Fracturing
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Solution Overview
Problem
Current hydrogels used in hydraulic fracturing for unconventional oil and gas production lack sufficient temperature stability and resistance to saline water, leading to viscosity degradation and reduced effectiveness in high-temperature environments.
Innovation Solution
A temperature-stable hydrogel is developed, containing electrolyte-containing water and a crosslinked copolymer with specific structural units, including ethylenically unsaturated phosphonic acid, sulfonic acid, and amide derivatives, which maintains viscosity and elasticity even at temperatures up to 250°C and in saline conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional hydrogels are used in hydraulic fracturing, then they can provide viscosity and elasticity for proppant transport, but they degrade at high temperatures above 110°C
Solution Approach 1:
The patent changes the chemical parameters of the hydrogel by incorporating thermally stable copolymers with specific functional groups (carboxyl, hydroxyl, amide, sulfonate, phosphate) and controlling molecular weight and crosslinking density. This allows the hydrogel to maintain viscosity and elasticity at temperatures up to 250°C while retaining proppant transport capability
Solution Approach 2:
The patent creates a composite hydrogel system combining multiple polymer components with complementary properties. The copolymer blend includes hydrophobic and hydrophilic segments that work synergistically to provide both thermal stability and viscoelasticity, resolving the contradiction between temperature resistance and functional reliability
2Strength
If polysaccharide-based polymers are used to increase viscosity, then they can improve sand transport, but they have limited temperature stability up to only about 110°C
Solution Approach 1:
The patent modifies the chemical structure by selecting copolymers with specific functional groups (carboxyl, hydroxyl, amide, sulfonate, phosphate) and controlling molecular weight parameters. These parameter changes enable the polymer to resist thermal degradation while maintaining sufficient viscosity for proppant suspension and transport at elevated temperatures
3Temperature
If synthetic polymers based on acrylamide are used, then they exhibit improved temperature stability, but they are sensitive to saline waters and show reduced viscosity
Solution Approach 1:
The patent introduces local chemical functionality through specific functional groups (carboxyl, hydroxyl, amide, sulfonate, phosphate) distributed throughout the polymer chain. These local chemical features provide salt tolerance by creating electrostatic repulsion and hydration shells that prevent polymer collapse in saline environments, while maintaining the overall temperature stability of the acrylamide backbone
Solution Approach 2:
The patent creates a composite polymer system combining acrylamide-based copolymers with complementary functional groups. This composite structure integrates the thermal stability of the acrylamide backbone with the salt tolerance provided by ionizable functional groups, resolving both temperature and salinity sensitivity simultaneously
4Strength
If cross-linking is increased to improve gel strength, then viscosity increases, but temperature stability decreases due to degradation at high temperatures
Solution Approach 1:
The patent optimizes crosslinking parameters by selecting appropriate crosslinking agents and controlling crosslinking density. The use of thermally stable copolymer structures with specific functional groups allows for effective crosslinking at lower temperatures while maintaining gel strength, and the crosslinked network resists thermal degradation at high temperatures due to the stability of the copolymer backbone
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 hydrogel provides stable viscosity and effective transport of proppants at elevated temperatures and in saline environments, enhancing the efficiency of hydraulic fracturing processes.
Implementation Method 1
a copolymer cross-linked with polyvalent metal ions
Implementation Method 2
The gels must exhibit shear-thinning properties for effective transport of the support materials
Implementation Method 3
the electrolyte content in the hydrogel is between 0.075 and 25 wt.%, based on the total mass of the hydrogels
Data Source
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AI summary
The invention relates to a temperature-stable hydrogel comprising electrolytic water and a copolymer cross-linked to multivalent metal ions. The invention is characterized in that the copolymer contains at least structural units which are derived at up to 0.005-20 wgt.-% from an ethylenically unsaturated phosphonic acid and alkali metal salts thereof and/or ammonia salts, up to 5-40 wgt.-% from an ethylenically unsaturated sulfuric acid and alkali metal salts thereof and/or ammonia salts and up to 5-94.995 wgt.-% from an amide of an ethylenically unsaturated carboxylic acid selected from the group of acrylamide, methacrylamide and/or C1-C4 alkyl derivatives, wherein the percentages are based on the total mass of the monomers used during copolymerization, that the multivalent metal ions for cross-linking of the copolymers belong to the groups IIIA, IVB, VB, VIIB and/or VIIIB of the periodic system of elements, and that the electrolyte content of the hydrogel equals between 0.075 and 25 wgt.-% based on the total mass of the hydrogel. The electrolytic hydrogel can preferably be used for hydraulic fracturing of crude oil or natural gas deposits and for reservoir stimulating of underground waters and is characterized by a very good resistance to saline waters.