Temperature-Sensitive Viscoelastic Fracturing Fluids for Formation Protection
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Solution Overview
Problem
Current fracturing fluids face challenges such as high leak-off rates, high costs, slow viscosity recovery, and damage to subterranean formations due to the use of high-concentration polymer and surfactant systems, which hinder efficient hydrocarbon recovery and proppant transport.
Innovation Solution
A fracturing fluid composition with a hydrophobically associative polymer (HAP) and a surfactant having a critical solution temperature (CST) between 30° C. and 150° C., allowing for temperature-sensitive viscosity and reduced surfactant levels, enabling efficient hydration, proppant transport, and minimized formation damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-concentration polymer systems are used to achieve sufficient fluid viscosity for proppant transport, then proppant carrying capability is improved, but formation damage and residual gel plugging increase
Solution Approach 1:
The patent changes the chemical nature of the viscosity-providing agent from high-molecular-weight polymers to low-molecular-weight viscoelastic surfactants. This parameter change allows achieving the same or better viscosity at much lower concentrations, thereby reducing formation damage while maintaining proppant transport capability
Solution Approach 2:
The patent uses composite micellar structures formed by viscoelastic surfactants that self-assemble into worm-like micelles. These micellar networks provide the necessary viscosity and elasticity without requiring high concentrations of individual components, thus avoiding formation damage associated with traditional polymer systems
2Object-affected harmful factors
If viscoelastic surfactant systems are used to reduce polymer concentration and formation damage, then formation damage is reduced, but leak-off rate increases
Solution Approach 1:
The patent modifies the chemical structure of surfactant molecules to include both hydrophilic and hydrophobic segments, creating viscoelastic surfactants that can form structured micellar networks. This structural parameter change enables the fluid to achieve both low formation damage and controlled leak-off rate by balancing surfactant concentration and micellar network strength
3Object-affected harmful factors
If conventional VES systems are used to achieve low formation damage, then formation damage is reduced, but viscosity recovery time after high shear increases
Solution Approach 1:
The patent changes the molecular architecture of the surfactant to create viscoelastic surfactants with optimal hydrophilic-lipophilic balance. This parameter optimization enables rapid micelle reformation and viscosity recovery after shear degradation, reducing the time loss while maintaining low formation damage characteristics
Solution Approach 2:
The patent utilizes the dynamic self-assembly and disassembly properties of viscoelastic surfactant micelles. The micellar networks can rapidly reorganize after shear stress is removed, providing fast viscosity recovery. This dynamic behavior allows the fluid to adapt its viscosity in real-time without permanent damage to the formation
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 solution provides a cost-effective, rapidly hydratable fracturing fluid with improved proppant transport properties and reduced damage to subterranean formations, maintaining stability at high shear rates and temperatures, facilitating efficient hydrocarbon recovery.
Implementation Method 1
Viscoelastic surfactant molecules, when present at a sufficient concentration, can aggregate into overlapping worm- or rod-like micelles, which confer the necessary viscosity to the fluid to carry the proppant during fracturing
Implementation Method 2
a surfactant having a critical solution temperature (CST) of between about 30° C. and 150° C., wherein the viscosity of the fracturing fluid composition is temperature sensitive
Implementation Method 3
One class of polymers which interact particularly strongly with surfactants is the class of hydrophobically modified water-soluble polymers. Since contact between the hydrophobic groups and water is unfavorable, these polymers have a strong tendency to self-associate and/or to associate with surfactants
Data Source
AI summary
The present invention is directed to fracturing fluids having temperature-sensitive viscosities. The fracturing fluids may include a mixture of a hydrophobically associative polymer (HAP) and a surfactant in an aqueous medium, wherein the surfactant imparts a critical solution temperature (CST) to the fluid. The fluid is more viscous at temperatures lower than the CST as compared to temperatures above the CST.