Degraded In Situ Gelable Polymers for Enhanced Oil Recovery
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Solution Overview
Problem
In enhanced oil recovery (EOR) processes, heterogeneity in oil reservoirs leads to non-uniform oil displacement, resulting in high water production and low oil recovery from lower permeability layers, as water injections preferentially enter higher permeability layers, leaving behind oil in bypassed regions.
Innovation Solution
The method involves providing polyacrylamide-based polymers that degrade into reduced molecular weight fragments and crosslink with glyoxal, forming gels in situ within the reservoir, which can be introduced into desired locations to improve oil recovery by enhancing the sweep efficiency and reducing water breakthrough.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If water injection is used for oil recovery, then oil is mobilized from high permeability layers, but water preferentially enters high permeability layers causing non-uniform displacement and high water production
Solution Approach 1:
The patent applies local quality by forming gels specifically in high permeability layers where water preferentially flows. The gelable polymer composition is injected and transforms into a gel structure that locally modifies the permeability of thief zones, creating different flow resistance in different regions of the reservoir. This allows water to be redirected to previously unswept low permeability zones, achieving more uniform sweep efficiency across the reservoir.
Solution Approach 2:
The patent utilizes parameter changes by transforming the physical state of the polymer from soluble to gelated form in situ. The gelable polymer composition maintains low viscosity during injection for easy delivery, then undergoes gelation to increase viscosity and reduce permeability in high permeability zones. This dynamic parameter change allows the system to adapt to different operational requirements at different stages.
2Reliability
If conventional polymer flooding is used, then mobility control is improved, but gel formation occurs prematurely during injection or in unwanted locations
Solution Approach 1:
The patent employs an intermediary mechanism by using a gelable polymer that requires a triggering condition (such as pH change, temperature, or chemical reaction) to initiate gelation. This intermediary step allows the polymer to remain in a transportable state during injection and only form gels when the triggering condition is met in the desired location, providing precise spatial and temporal control over gel formation.
Solution Approach 2:
The patent applies preliminary action by pre-positioning the gelable polymer composition in the reservoir through injection before the actual gelation process occurs. The polymer is delivered to the target zones in advance, and then gelation is initiated under controlled conditions to ensure it occurs in the correct location and time, preventing premature gel formation during injection.
3Productivity
If gelable polymers are injected to control water flow, then sweep efficiency is improved, but the gel structure degrades over time reducing long-term effectiveness
Solution Approach 1:
The patent applies the principle of disposable short-living objects by using biodegradable or transient gel structures that perform their function for a sufficient operational period and then naturally degrade. This approach allows the gel to provide temporary plugging in high permeability zones to redirect water flow, improve sweep efficiency during the critical production phase, and then decompose to restore reservoir permeability for future operations or secondary recovery methods.
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 in situ gelation of degraded polymers increases oil recovery by directing fluids into unswept regions, reducing water production, and stabilizing the gel structure for extended periods, thereby improving the overall efficiency of EOR processes.
Implementation Method 1
contacting said aqueous solution or composition with one or more degradation agents, which degrade said one or more polymers into one or more polymers comprising reduced molecular weight fragments
Implementation Method 2
contacting said aqueous solution or composition with one or more crosslinkers comprising a glyoxal and/or a glyoxalating agent
Implementation Method 3
allowing for or providing conditions at the desired location which permit gelation of the one or more degraded in situ gelable polymers to occur over time
Data Source
AI summary
Methods and compositions comprising one or more degraded in situ gelable polymers are provided. Use of such compositions and methods comprising one or more degraded in situ gelable polymers during enhanced oil recovery may result in an increase in oil production relative to methods and/or compositions which do not comprise one or more degraded in situ gelable polymers.