CO2 EOR Mobility Control With Surfactant-Amine Gelation
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Solution Overview
Problem
Existing CO2 injection methods for enhanced oil recovery (EOR) in subterranean formations face inefficiencies due to CO2 gravity override and poor areal sweep, leading to unswept low-permeability zones and incomplete oil recovery.
Innovation Solution
Inject a mixture of an anionic surfactant and amine with low viscosity into a high-permeability zone, followed by CO2 injection to increase viscosity and reduce CO2 mobility, then stimulate hydrocarbon flow from low-permeability zones using CO2 injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CO2 is injected into the subterranean formation, then oil recovery is enhanced, but CO2 gravity override occurs reducing recovery at lower parts of the reservoir
Solution Approach 1:
The patent changes the physical-chemical parameters of the injection fluid by combining CO2 with surfactant and amine components. This creates a composition that forms gel structures, fundamentally altering the mobility and density characteristics of the injected phase to prevent gravity override while maintaining oil displacement capability.
Solution Approach 2:
The patent uses a composite injection system combining CO2 with surfactant and amine components. This composite creates gel structures in situ that increase viscosity and reduce mobility, allowing CO2 to be retained in the upper zones rather than overriding to lower parts of the reservoir, thereby improving vertical sweep efficiency.
2Productivity
If CO2 is injected into the subterranean formation, then oil displacement is achieved, but poor areal sweep occurs leaving less permeable zones unswept
Solution Approach 1:
The patent modifies the rheological parameters of the injected fluid by forming gel structures through surfactant-amine-CO2 interactions. This increases viscosity and reduces mobility, causing the injection front to advance more uniformly across the reservoir area rather than channeling through high-permeability pathways, thereby improving areal sweep coverage.
3Productivity
If a mixture of anionic surfactant and amine is injected into the high-permeability zone, then CO2 mobility is reduced, but the mixture viscosity must be maintained below 0.01 Pa·s for effective injection
Solution Approach 1:
The patent applies preliminary action by injecting the surfactant and amine mixture into the formation before CO2 injection. This pre-treatment allows the gel-forming components to be in place and activated by subsequent CO2, creating the desired mobility control without requiring the initial mixture to have high viscosity that would impede injection.
Solution Approach 2:
The patent employs dynamic viscosity control where the mixture viscosity remains low (<0.01 Pa·s) during injection for ease of delivery, then transforms to a higher viscosity gel state after CO2 activation. This dynamic property change allows the system to satisfy both injection requirements and mobility control requirements at different stages of the 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
Enhances oil recovery by reducing CO2 mobility in high-permeability zones and stimulating hydrocarbon flow from unswept low-permeability zones, improving overall recovery efficiency.
Implementation Method 1
injecting a mixture comprising an anionic surfactant and an amine through a wellbore into a high-permeability zone, and then injecting CO2 through the wellbore into the high-permeability zone to increase a viscosity of the mixture in the high-permeability zone
Data Source
AI summary
A mixture of an anionic surfactant and an amine is injected into a high permeability zone of a subterranean formation. Gaseous CO2 is injected through the wellbore into the high permeability zone to increase the viscosity of the injected mixture to prevent gravity override of the injected CO2. After increasing the viscosity of the mixture, CO2 is injected through the wellbore into a low permeability zone to recover the hydrocarbons.