Swellable Polymer With Cationic Sites For Reservoir Fluid Diversion
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Solution Overview
Problem
Current swellable polymers used in enhanced oil recovery are prone to washout during subsequent water injections, limiting their effectiveness in blocking 'thief zones' and preventing the efficient sweeping of less permeable reservoir regions.
Innovation Solution
Development of crosslinked polymers with cationic sites and a combination of stable and labile crosslinkers, where the cationic sites adsorb to negatively charged surfaces, such as rock formations, to prevent washout and maintain polymer presence within the reservoir.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If swellable polymers are used to block thief zones, then hydrocarbon recovery is enhanced, but the polymers are washed out during subsequent water injections
Solution Approach 1:
The polymer system incorporates cationic sites that provide feedback interaction with negatively charged rock surfaces through adsorption. This adsorption creates a retained polymer layer that responds to the electrostatic environment of the reservoir, preventing washout while maintaining the ability to swell and block thief zones effectively.
Solution Approach 2:
The invention uses a composite polymer structure combining crosslinked polymeric particles with cationic sites. This composite material integrates the swelling capability of crosslinked polymers with the surface-adhesion properties of cationic compounds, creating a material that both blocks thief zones and resists washout through electrostatic adsorption to rock surfaces.
2Ease of operation
If polymers are injected to block thief zones, then water is forced through less permeable regions, but subsequent injections wash out the polymer
Solution Approach 1:
The cationic sites in the polymer provide continuous feedback interaction with the negatively charged rock surfaces. This electrostatic adsorption creates a self-reinforcing mechanism where the polymer remains anchored to the rock, maintaining fluid diversion effectiveness through multiple injection cycles without washout.
Solution Approach 2:
The invention changes the chemical parameter of the polymer by incorporating cationic sites with appropriate charge density and distribution. This parameter modification transforms the polymer from a washout-prone material to one that reliably adheres to rock surfaces, ensuring long-term fluid diversion capability.
3Length of moving object
If highly crosslinked polymer particles are used, then particle size is small for efficient propagation, but the particles require significant energy for injection
Solution Approach 1:
The polymer system employs dynamic crosslinking with both stable and labile crosslinkers. The labile crosslinkers break under the stress of injection, temporarily reducing particle rigidity and energy requirements. After injection, the crosslinks reform or are replaced by stable crosslinks, restoring the particle structure for effective thief zone blocking.
Solution Approach 2:
The invention changes the crosslinking parameter by using a combination of stable and labile crosslinkers in specific ratios. This parameter optimization allows the particles to maintain small size for efficient propagation while reducing the energy barrier for injection through temporary crosslinker breakdown during the injection process.
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 effectively block thief zones, enhancing hydrocarbon recovery by remaining adsorbed to the rock surfaces, reducing polymer loss and improving the long-term effectiveness of water injection methods.
Implementation Method 1
the cationic sites act to adsorb to the surrounding negatively charged surfaces
Implementation Method 2
cationic sites that become accessible on swelling of the polymer and that act to adsorb to the surrounding negatively charged surfaces
Implementation Method 3
the particle to further expand by absorbing additional injection fluid, usually water
Implementation Method 4
On heating to reservoir temperature and/or at a predetermined pH or other stimuli, the reversible (labile) internal crosslinks break, allowing the particle to further expand
Data Source
AI summary
The invention is directed to long lasting crosslinked water-soluble swellable polymers, methods for making same, and their uses. More particularly, the invention relates to a composition comprising expandable polymeric particles having cationic sites as well as labile crosslinkers and stable crosslinkers, said particle mixed with a fluid. A particularly important use is as an injection fluid in petroleum production, where the expandable polymeric particles are injected into a target zones in the reservoirs and when the heat and/or a suitable pH in the reservoir cause degradation of the labile crosslinker and when the particle expands, the cationic sites in the polymer adsorb to negative sites of the rock in the formation, thus diverting water to lower permeability regions and improving oil recovery. However, many other uses are possible.