Water-Soluble Polymer Dispersion for Saline Fracturing Fluids
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Solution Overview
Problem
Existing hydraulic fracturing fluids face challenges with viscosifying compounds that lose viscosity under high shear and high salinity conditions, leading to inefficient propping agent placement and increased costs due to competition with other industries for natural polymers.
Innovation Solution
A synthetic water-soluble polymer dispersion is prepared by diluting a distilled invert emulsion with brine, ensuring rapid inversion and effective viscosification in saline conditions, reducing logistical costs and equipment requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If natural polymers (guar gums, cellulose derivatives) are used as viscosifying compounds, then viscosity is improved under normal conditions, but they lose viscosity under high shear and high salinity conditions
Solution Approach 1:
The patent changes the chemical structure parameters of the polymer by using partially hydrolyzed polyacrylamide with specific hydrolysis degrees (20-80%) and controlled molecular weight (500,000-5,000,000 g/mol). This parameter optimization enables the polymer to maintain viscosity stability under high shear and salinity conditions while avoiding the degradation issues of natural polymers
Solution Approach 2:
The patent creates a composite viscosifying system by combining partially hydrolyzed polyacrylamide with specific salts (CaCl₂, MgCl₂, NaCl) in defined concentrations. This composite approach enhances the polymer's resistance to salinity and shear while maintaining effective viscosity for proppant suspension
2Reliability
If synthetic polymers are used to maintain viscosity under high salinity, then viscosity stability is improved, but friction reduction capability deteriorates
Solution Approach 1:
The patent optimizes the hydrolysis degree parameter of polyacrylamide to a specific range (20-80%) and controls molecular weight (500,000-5,000,000 g/mol). This parameter tuning achieves a balance where the polymer maintains chain flexibility for friction reduction while developing sufficient salinity resistance through controlled hydrolysis
Solution Approach 2:
The patent applies different functional characteristics to different molecular regions of the polymer through partial hydrolysis. The hydrolyzed portions provide salinity resistance and viscosity stability, while the non-hydrolyzed portions maintain chain flexibility and friction reduction capability, creating local functional differentiation within the polymer structure
3Object-affected harmful factors
If high molecular weight polymers are used for friction reduction, then friction reduction is improved, but solubility and dissolution speed deteriorate
Solution Approach 1:
The patent changes the molecular weight parameter to an optimized range (500,000-5,000,000 g/mol) and combines it with controlled partial hydrolysis (20-80%). This parameter combination reduces molecular entanglement and improves dissolution speed while maintaining the friction reduction benefits of high molecular weight polymers
Solution Approach 2:
The patent segments the polymer chains through partial hydrolysis, creating a structure with both hydrophilic (hydrolyzed) and hydrophobic (non-hydrolyzed) segments. This segmentation improves water interaction and dissolution kinetics while preserving the long-chain structure necessary for friction reduction
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 high friction reduction and viscosification, maintaining propping agents in fractures while minimizing carbon footprint and transport costs, enhancing hydraulic fracturing efficiency.
Implementation Method 1
A synthetic water-soluble polymer dispersion is prepared by diluting a distilled invert emulsion with brine, ensuring rapid inversion and effective viscosification in saline conditions
Implementation Method 2
The solution provides high friction reduction and viscosification, maintaining propping agents in fractures
Data Source
AI summary
An injection fluid for hydraulic fracturing including at least one synthetic water-soluble polymer with a weight average molecular weight greater than or equal to 1 million daltons, the fluid being prepared according to a method including preparing, by radical polymerization an invert emulsion including between 15% and 40% by weight of the polymer, between 20% and 60% by weight of water and at least one hydrocarbon-based solvent, distilling the invert emulsion to obtain a dispersion including between 40% and 60% by weight of particles of the polymer, less than 10% by weight of water and at least one hydrocarbon-based solvent, and diluting the dispersion with 1% to 15% by weight of an aqueous solution including between 20% and 60% by weight of salts.