CO2-Philic Capsules for Density and Viscosity Control
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Solution Overview
Problem
Carbon dioxide flooding for enhanced oil recovery faces challenges such as gravity override, viscous fingering, and reservoir geology heterogeneities, which limit oil recovery efficiency due to the low density and viscosity of carbon dioxide, and the instability of surfactant-induced foams.
Innovation Solution
A capsule-based carbon dioxide system is developed, where functionalized capsules containing a dense liquid are dispersed in supercritical carbon dioxide, increasing density and viscosity, and functionalized with carbon dioxide-philic compounds to enhance oil recovery by improving sweep efficiency and reducing early breakthrough.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carbon dioxide is injected for enhanced oil recovery, then oil recovery is improved, but gravity override occurs due to density differences causing poor recovery in lower reservoir portions
Solution Approach 1:
The patent changes the physical parameters of carbon dioxide by converting it to a supercritical state and blending it with heavier hydrocarbons, thereby increasing its density to match or exceed reservoir fluid density and eliminate gravity override
Solution Approach 2:
The patent creates a composite carbon dioxide mixture by blending supercritical CO2 with heavier hydrocarbon components, forming a density-matched injectate that maintains uniform distribution throughout the reservoir
2Productivity
If carbon dioxide is injected for enhanced oil recovery, then oil recovery is improved, but viscous fingering occurs due to low viscosity causing early breakthrough and poor sweep efficiency
Solution Approach 1:
The patent changes the viscosity parameter of carbon dioxide by transforming it to a supercritical state and blending with heavier hydrocarbons, increasing viscosity to improve mobility ratio and eliminate viscous fingering
Solution Approach 2:
The patent creates a composite carbon dioxide mixture with adjusted viscosity characteristics by combining supercritical CO2 with heavier hydrocarbon components, achieving optimal mobility control
3Stability of the object's composition
If surfactants are used to create foam for mobility control, then viscosity is improved, but density challenge remains unresolved and long-term stability is difficult to maintain
Solution Approach 1:
The patent changes the fundamental physical state and composition parameters of the injectate by using supercritical carbon dioxide blended with heavier hydrocarbons, achieving both density matching and viscosity improvement without relying on surfactant foams
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 capsule-based system achieves more uniform reservoir flooding, reduces viscous fingering, and increases oil recovery by enhancing the density and viscosity of carbon dioxide, thereby improving sweep efficiency and overall oil recovery.
Implementation Method 1
The capsules are functionalized by adding a carbon dioxide-philic compound to the outer side of the capsule wall. A dispersion is then prepared by adding the functionalized capsules to supercritical carbon dioxide such that a stable dispersion of capsules in supercritical carbon dioxide is achieved.
Implementation Method 2
A capsule based carbon dioxide system addresses the density challenge by delivering a substantial amount of a dense liquid, such as water or heavy filler.
Data Source
AI summary
This invention generally relates to the field of oil recovery from reservoirs. More specifically, it relates to the recovery of oil from sandstone and carbonate reservoirs using a process for preparing a dispersion of capsules for use downhole including the steps of providing capsules containing a dense liquid, each capsule having a capsule wall defining an inner area, the capsule wall having an outer side. The capsules are functionalized by adding a carbon dioxide-philic compound to the outer side of the capsule wall. A dispersion is then prepared by adding the functionalized capsules to supercritical carbon dioxide such that a stable dispersion of capsules in supercritical carbon dioxide is achieved.