Associative Amphoteric Polymer Fracturing Fluid for Proppant Suspension
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Solution Overview
Problem
Current fracturing fluids used in unconventional oil and gas reservoirs face challenges in maintaining proppant suspension due to viscosity issues, especially at high salinity and temperature, leading to increased polymer dosages that are not economically viable and are in competition with other industrial applications, limiting their availability and effectiveness.
Innovation Solution
A novel aqueous fracturing fluid composition incorporating an associative amphoteric polymer of high molecular weight, comprising acrylamide-derived cationic and anionic monomers, and nonionic monomers, which provides superior rheological properties for maintaining proppant suspension with reduced polymer dosage, including the option of adding surfactants to enhance viscosifying properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional fracturing fluids are used to maintain proppant suspension, then viscosity must be increased, but this requires higher polymer dosages that are economically unviable and compete with other industrial applications
Solution Approach 1:
The invention changes the chemical parameters of the polymer by using amphoteric copolymers with both cationic and anionic charge groups, allowing the polymer to interact more effectively with proppant particles through electrostatic interactions, thereby achieving stable suspension at lower concentrations
Solution Approach 2:
The invention uses composite polymer structures combining hydrophilic and hydrophobic segments in amphoteric copolymers, creating a material that can form associative networks in brine environments while maintaining effective proppant suspension at reduced dosages
2Stability of the object's composition
If high viscosity is maintained for proppant suspension, then pumping efficiency decreases, but reducing viscosity compromises proppant placement
Solution Approach 1:
The invention employs polymers that dynamically adjust their conformation and interaction strength based on flow conditions, maintaining extended configurations and strong proppant binding at low shear rates while collapsing to reduced viscosity states at high shear rates during pumping
Solution Approach 2:
The amphoteric copolymers change their electrostatic interactions and chain conformation in response to shear rate variations, enabling the fluid to exhibit high viscosity for suspension stability during static or low-flow conditions and low viscosity for efficient pumping during high-flow injection
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 composition achieves high viscosity at low shear rates for effective proppant suspension and low viscosity at high shear rates for efficient pumping, maintaining proppant placement and reducing the need for high polymer dosages, thus improving the economic viability and performance of fracturing operations.
Implementation Method 1
Water soluble polymers can be used as viscosifying compound. By definition, a compound will be said to be viscosifying when it increases the viscosity of the solutions in which it is dissolved.
Implementation Method 2
the polymer must have a low viscosity at high shear rate so as not to impede the transportation and the pumping of the fluid containing the proppant during the injection of the fracturing fluid
Implementation Method 3
Once injected, this same compound must be able to generate a sufficient viscosity when the shear decreases in order to support the proppant so as to keep it in the fractures
Data Source
AI summary
Fracturing fluid comprising, in solution in water, a proppant and an associative amphoteric polymer, the said polymer having a molecular weight of at least 1 000 000 g/mol and comprising:0.01 to 10 mol % of at least one cationic monomer derived from acrylamide,from 0.09 to 89.99 mol % of at least one anionic monomer,and from 10 to 99 mol % of at least one nonionic water-soluble monomer.Fracturing process using the fluid.