Liquid Polymer Inversion for Plug-Free EOR Injection
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Solution Overview
Problem
Existing water-in-oil emulsions of polymers used in enhanced oil recovery (EOR) processes are challenging to invert efficiently and often fail to pass through porous structures, limiting their utility due to slow dissolution and inefficient inversion, especially in the presence of dissolved salts.
Innovation Solution
The method involves preparing inverted polymer solutions by inverting liquid polymer compositions comprising synthetic (co)polymers dispersed in hydrophobic liquids, using emulsifier and inverting surfactants, and diluting them in an aqueous fluid to achieve concentrations of 50 to 15,000 ppm with a filter ratio of 1.5 or less, utilizing in-line mixers for rapid inversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If water-in-oil emulsions are used to deliver polymers, then polymer concentration and mobility control are improved, but inversion efficiency deteriorates and filterability worsens
Solution Approach 1:
The patent applies inversion by transforming the emulsion structure from water-in-oil to oil-in-water configuration. This is achieved by adjusting the surfactant system and phase ratios, allowing the dispersed phase to swap roles. The inverted emulsion structure enables rapid phase separation and efficient polymer release into the aqueous continuous phase, resolving the contradiction between maintaining high polymer concentration and achieving fast inversion kinetics.
Solution Approach 2:
The patent employs parameter changes by modifying surfactant concentration, hydrophobic liquid composition, and emulsion preparation conditions. These parameter adjustments optimize the interfacial tension and phase stability, enabling the emulsion to invert efficiently while maintaining high polymer load. The controlled changes in formulation parameters allow simultaneous achievement of high polymer concentration and rapid inversion.
2Quantity of substance
If water-in-oil emulsions are used, then polymer delivery is improved, but ability to pass through porous structures deteriorates
Solution Approach 1:
By inverting the emulsion from water-in-oil to oil-in-water type, the patent transforms the system's interaction with porous media. The oil-in-water inverted emulsion has an aqueous continuous phase that is compatible with porous rock structures, allowing easy passage. The polymer is delivered effectively while the inverted structure prevents plugging, resolving the contradiction between polymer delivery and injectability.
Solution Approach 2:
The inverted emulsion structure acts as an intermediary vehicle that facilitates polymer delivery without compromising flow through porous structures. The oil-in-water configuration allows the polymer to be transported in a water-compatible form that can pass through reservoir rock pores, then release the polymer effectively at the target location.
3Quantity of substance
If conventional mixing equipment is used for dissolution, then polymer dissolution is achieved, but time consumption and equipment cost increase
Solution Approach 1:
The patent applies preliminary action by pre-dissolving the polymer within the emulsion droplets during emulsion preparation. The polymer is already in solution within the dispersed phase before injection, eliminating the need for subsequent dissolution steps at the injection site. This preliminary dissolution action saves time and eliminates the need for complex mixing equipment at the wellhead.
Solution Approach 2:
The emulsion system provides self-service by maintaining polymer in pre-dissolved form within the dispersed droplets. Upon injection and inversion, the polymer automatically releases into the aqueous phase without requiring external mixing energy or equipment. The system self-regulates the dissolution process through the inversion mechanism, eliminating time loss and equipment costs.
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 inverted polymer solutions exhibit improved injectivity and flow through hydrocarbon-bearing formations without plugging, enhancing hydrocarbon recovery by increasing fluid mobility and oil production efficiency.
Implementation Method 1
using emulsifier and inverting surfactants
Implementation Method 2
liquid polymer compositions comprising synthetic (co)polymers dispersed in hydrophobic liquids
Data Source
AI summary
Provided herein are liquid polymer (LP) compositions comprising a synthetic (co)polymer (e.g., an acrylamide (co)polymer), as well as methods for preparing inverted polymer solutions by inverting these LP compositions in an aqueous fluid. The resulting inverted polymer solutions can have a concentration of a synthetic (co)polymer (e.g., an acrylamide (co)polymer) of from 50 to 15,000 ppm, and a filter ratio of 1.5 or less at 15 psi using a 1.2 μm filter. Also provided are methods of using these inverted polymer solutions in oil and gas operations, including enhanced oil recovery.