Friction Reducing Copolymers for Hydraulic Fracturing
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Solution Overview
Problem
Current friction-reducing polymers used in hydraulic fracturing have limited effectiveness in high salinity media, particularly in the presence of divalent cations, and are often obtained through environmentally detrimental and costly methods.
Innovation Solution
Development of High Viscosity Friction Reducers (HVFR) polymers comprising polyacrylamide combined with zwitterionic, cationic, and anionic entities, along with physical and chemical ligands, which are synthesized using controlled radical polymerization in aqueous media, providing enhanced viscosity and friction reduction properties while being environmentally friendly and cost-effective.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional friction-reducing polymers are used in high salinity media, then friction reduction is achieved, but the polymers display limited friction reduction properties and lose viscosity in high salinity media, particularly in the presence of divalent cations
Solution Approach 1:
The patent changes the chemical composition parameters of the polymer by incorporating zwitterionic monomers (such as carboxymethylbetaine and sulfobetaine) alongside acrylamide units. This compositional parameter change enables the polymer to maintain its viscosity and friction reduction properties in high salinity media containing divalent cations, directly resolving the contradiction between achieving friction reduction and maintaining reliability in saline conditions
Solution Approach 2:
The patent creates a composite polymer structure combining multiple monomer types (acrylamide, carboxymethylbetaine, sulfobetaine) into a single copolymer. This composite material approach allows the polymer to exhibit both friction reduction capability and viscosity stability in high salinity media, as the different monomer units work synergistically to maintain performance under challenging conditions
2Loss of energy
If oil/water emulsion free radical polymerization methods are used to prepare HVFR polymers, then friction reduction and high viscosity properties are achieved, but the methods are costly and non-environmentally friendly
Solution Approach 1:
The patent extracts and eliminates the harmful components (organic solvents and emulsifiers) from the polymerization process by using aqueous solution polymerization instead of oil/water emulsion methods. This allows the production of HVFR polymers with the same friction reduction capability but without the environmental harm and high costs associated with conventional emulsion methods
Solution Approach 2:
The patent substitutes the mechanical/emulsion-based polymerization system with a solution-based chemical polymerization system. By using water as the sole medium and avoiding emulsifiers, the process replaces the complex emulsion mechanism with a simpler, more environmentally friendly solution polymerization approach that reduces manufacturing costs and environmental impact
3Productivity
If bulk free-radical polymerization or oil/water emulsion polymerization is used, then polymer synthesis is achieved, but quantitative monomer conversion is poor and environmental harm is caused
Solution Approach 1:
The patent replaces emulsion polymerization with solution polymerization in aqueous media, eliminating the need for organic solvents and emulsifiers. This substitution achieves complete monomer conversion while avoiding environmental harm, as water is used as the sole medium and no harmful chemicals are required for the polymerization process
Solution Approach 2:
The patent uses water as a disposable, environmentally benign medium for polymerization instead of expensive and harmful organic solvents. The aqueous solution can be easily disposed of or recycled without environmental concern, and the method achieves complete monomer conversion, improving productivity while eliminating environmental harm
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 polymers exhibit improved resistance to saline media, higher viscoelastic properties, and competitive performance, allowing for efficient proppant transport and reduced energy loss during hydraulic fracturing, while being easier to store, transport, and apply.
Implementation Method 1
Friction-reducing polymers included in the fluid suppress the turbulence and allow to reach higher fluid flow rate at a fixed pumping pressure
Implementation Method 2
The suspending properties of the fluid are related to its viscosity and higher viscosities are need for transporting higher proppant concentrations
Implementation Method 3
Development of High Viscosity Friction Reducers (HVFR) polymers... which are synthesized using controlled radical polymerization in aqueous media
Data Source
AI summary
A friction reducer comprising a copolymer of acrylamide, an anionic monomer, a zwitterionic monomer or a cationic monomer, a physical ligand or a chemical ligand, wherein the acrylamide amounts to at least 50% (w/w) of the total monomer content. The friction reducer is useful in hydraulic fracturing operations and is obtained by controlled radical polymerization at a temperature between 30° C. and 70° C. using iodine as polymerization control agent.