Hydrolyzable Cross-linked Polymers for Enhanced Oil Recovery
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Solution Overview
Problem
Current enhanced oil recovery methods face challenges with poor sweep efficiency due to differences in water and oil mobility, and permeability variations in oil reservoirs, leading to reduced oil recovery rates as existing polymers degrade under shear and temperature stress.
Innovation Solution
Development of water-soluble, shear-resistant, high molecular weight polymers with hydrolyzable cross-linked monomer units that maintain viscosity after injection into subterranean formations by hydrolyzing and increasing viscosity over time, enhancing mobility control and recovery efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high molecular weight water soluble polymers are used to improve sweep efficiency, then viscosity increases and sweep efficiency improves, but the polymers undergo molecular weight breakdown and degradation due to temperature and shear stress
Solution Approach 1:
The polymer is pre-crosslinked with hydrolyzable crosslinkers before injection to provide initial shear resistance during injection, then the crosslinks hydrolyze in situ to provide long-term stability and viscosity maintenance in the reservoir
Solution Approach 2:
The polymer structure undergoes parameter changes through hydrolysis of the crosslinked monomer units, transforming from a temporarily crosslinked state during injection to a hydrolyzed state in the reservoir, changing the polymer's physical properties to match reservoir conditions
2Strength
If polymer concentration is increased to maintain viscosity under shear stress, then shear resistance improves, but the polymer degrades faster under oxidative stress and physical force
Solution Approach 1:
The invention creates a composite polymer structure combining linear polymer chains with crosslinked monomer units, where the crosslinked units provide shear resistance while the overall structure remains resistant to oxidative degradation and mechanical breakdown
3Productivity
If water is injected to displace oil, then oil recovery begins, but water channels through high permeability zones bypassing oil in low permeability zones due to mobility differences
Solution Approach 1:
The polymer changes its viscosity parameter in response to reservoir conditions, increasing viscosity after hydrolysis to match oil mobility and improve displacement efficiency across varying permeability zones
Solution Approach 2:
The polymer automatically adjusts its viscosity through in-situ hydrolysis of crosslinked monomer units, self-regulating its flow characteristics to optimize sweep efficiency without external control
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 increase viscosity within the reservoir, improving sweep efficiency and secondary/tertiary oil recovery rates by maintaining stability under shear and temperature conditions, leading to higher oil displacement and recovery.
Implementation Method 1
the hydrolyzable cross-linked monomer units are hydrolyzed to produce an aqueous flooding fluid after hydrolysis having a viscosity that is about the same or higher than a viscosity of the aqueous fluid prior to injection
Data Source
AI summary
Disclosed herein are water-soluble polymers comprising hydrolyzable cross-linked monomer units, and methods for recovering hydrocarbon fluids from a subterranean formation using the water-soluble polymers.