Viscosified CO2 Recycling for Enhanced Oil Recovery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current enhanced oil recovery (EOR) techniques using condensed carbon dioxide (CO2) face inefficiencies due to its low viscosity, leading to poor mobility and early breakthrough, resulting in low oil recovery and high CO2 utilization, especially when CO2 is injected into more permeable layers, while less CO2 enters low permeability zones containing recoverable oil.
Innovation Solution
A process involving the recycling of a hydrocarbon-enriched CO2 stream from oil wells without full purification, where thickeners are added to increase the viscosity of the CO2, allowing direct reuse in EOR processes, thereby improving solubility and reducing operational costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If condensed CO2 is used for EOR, then oil recovery can be increased, but the low viscosity of CO2 causes unfavorable mobility ratio leading to viscous fingering and early breakthrough
Solution Approach 1:
The patent changes the physical parameters of CO2 by dissolving polymers, associating polymers, or small associating molecules to increase viscosity from 0.05-0.10 cP to levels comparable to oil (0.5-10 cP), thereby achieving favorable mobility ratio and suppressing viscous fingering while maintaining oil recovery enhancement
Solution Approach 2:
The patent creates a composite system by combining CO2 with polymer solutions or associating molecules, forming a viscosified CO2 mixture that maintains the solvent properties of CO2 while adding viscosity control through the polymer or associating molecule component
2Reliability
If CO2 is purified to >95% purity before adding thickeners, then the CO2 can be recycled in EOR, but the purification and subsequent addition steps are resource-intensive and expensive
Solution Approach 1:
The patent removes the purification step from the CO2 recycling process, allowing direct injection of field-separated CO2 containing light hydrocarbons (C1-C4), thereby eliminating resource-intensive purification operations while maintaining EOR effectiveness through the hydrocarbon-enriched CO2 stream
Solution Approach 2:
The patent enables the CO2 stream to serve itself by directly recycling field-separated CO2 without external purification intervention, using the inherent properties of the recovered CO2 mixed with light hydrocarbons as the injection medium for EOR
3Speed
If condensed CO2 is injected into more permeable layers, then CO2 flow is enhanced, but CO2 preferentially enters high permeability zones while disappointingly small amounts enter low permeability zones containing more recoverable oil
Solution Approach 1:
The patent modifies the viscosity parameter of CO2 by adding polymers or associating molecules, increasing viscosity to match oil viscosity ranges, which slows CO2 flow velocity and enables penetration into low permeability zones that contain additional recoverable oil while still maintaining overall flow efficiency
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
This approach enhances oil recovery by increasing the viscosity of the CO2, reducing early breakthrough, and optimizing CO2 utilization, leading to more efficient and cost-effective EOR operations by utilizing a hydrocarbon-enriched CO2 stream directly in the recycling process.
Implementation Method 1
Attempts to increase the viscosity of condensed CO2 and raise it to a level comparable to that of oil via dissolution of high molecular weight polymers, associating polymers, or small associating molecules
Implementation Method 2
Condensed carbon dioxide (CO2) has been used for 40 years as a profitable EOR technique
Implementation Method 3
it was determined that purification of recovered condensed CO2 prior to recycling the condensed CO2 is not necessary. A condensed CO2 stream from an oil well which also contains some low hydrocarbons can be used directly for CO2 recycling processes
Data Source
AI summary
An efficient and cost-effective process of carbon dioxide recycling in enhanced oil recovery wells or in fracturing wells is provided. The process comprises recovering a hydrocarbon enriched stream of condensed carbon dioxide from and enhanced oil recovery (EOR) well or a fracturing well; adding to said stream one or more thickeners; and directing the thickened stream to the EOR well or fracturing well for recycled usage in EOR.