CO2-EOR Miscibility Management via Light End Depletion
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Solution Overview
Problem
Current methods for CO2-EOR miscibility management in oil reservoirs require pressurization to high pressures, making the process operationally demanding when the bubble point pressure and CO2-MMP are both high, as they necessitate significant water injection before CO2 flooding can commence, and there is a lack of effective methods to lower the CO2-crude oil MMP.
Innovation Solution
A method involving determining a depletion pressure to reduce the CO2-MMP by liberating light ends from the crude oil, thereby reducing the bubble point pressure and MMP, allowing CO2 injection at pressures lower than the native CO2-MMP, facilitating more efficient and less demanding CO2 flooding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reservoir pressure is pressurized to high levels (above CO2-MMP) to achieve miscibility, then oil recovery efficiency is improved, but operational complexity and water injection requirements increase significantly
Solution Approach 1:
The patent applies preliminary action by depleting light ends from crude oil before CO2 injection. This pre-treatment modifies the oil composition to lower the CO2-MMP, allowing miscibility to be achieved at reduced pressures. The light end depletion is performed in advance through controlled production or separation processes, transforming the oil properties before the main CO2 flooding operation begins.
Solution Approach 2:
The patent utilizes parameter changes by modifying the crude oil composition parameters (specifically light ends content) to alter the CO2-MMP. By changing the chemical composition parameter of the oil through light end removal, the pressure parameter required for miscibility is reduced from high levels to more manageable levels, resolving the contradiction between recovery efficiency and operational complexity.
2Reliability
If significant water injection is performed to raise reservoir pressure above CO2-MMP, then miscibility is achieved, but the process becomes operationally demanding and costly
Solution Approach 1:
The patent applies preliminary action by depleting light ends from crude oil before CO2 injection. This pre-treatment modifies the oil composition to lower the CO2-MMP, allowing miscibility to be achieved at reduced pressures. The light end depletion is performed in advance through controlled production or separation processes, transforming the oil properties before the main CO2 flooding operation begins.
Solution Approach 2:
The patent utilizes parameter changes by modifying the crude oil composition parameters (specifically light ends content) to alter the CO2-MMP. By changing the chemical composition parameter of the oil through light end removal, the pressure parameter required for miscibility is reduced from high levels to more manageable levels, resolving the contradiction between recovery efficiency and operational complexity.
3Reliability
If reservoir pressure is maintained above bubble point pressure to ensure CO2-MMP, then miscibility is guaranteed, but operational flexibility and economic efficiency decrease
Solution Approach 1:
The patent applies preliminary action by depleting light ends from crude oil before CO2 injection. This pre-treatment modifies the oil composition to lower the CO2-MMP, allowing miscibility to be achieved at reduced pressures. The light end depletion is performed in advance through controlled production or separation processes, transforming the oil properties before the main CO2 flooding operation begins.
Solution Approach 2:
The patent utilizes parameter changes by modifying the crude oil composition parameters (specifically light ends content) to alter the CO2-MMP. By changing the chemical composition parameter of the oil through light end removal, the pressure parameter required for miscibility is reduced from high levels to more manageable levels, resolving the contradiction between recovery efficiency and operational complexity.
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 optimizes CO2 miscibility management, reducing operational demands and enhancing oil recovery by injecting CO2 at pressures lower than conventional methods, thus lowering the CO2-MMP and bubble point pressure, making the process more economical and efficient.
Implementation Method 1
carbon dioxide extracts crude oil components by vaporizing gas drive. During this mechanism, lighter components (mostly C1) of the crude oil are extracted into the CO2 vapor phase.
Implementation Method 2
Miscibility of CO2 with oil results in reduction in oil viscosity and causes oil swelling. Both of these effects lead to enhanced oil recovery from the formation.
Implementation Method 3
depleting the pressure of the reservoir from an initial reservoir pressure to the determined depletion pressure, thus providing the lights-depleted crude oil
Data Source
AI summary
A method of recovering crude oil from a reservoir by: determining a depletion pressure for providing a lights-depleted crude oil comprising a reduced amount of light ends including methane, nitrogen, carbon dioxide (CO2), or a combination thereof and having a CO2 multi contact Minimum Miscibility Pressure (CO2-MMP) below a CO2-MMP of a native crude oil, wherein the native crude oil is crude oil extracted from the reservoir prior to primary oil recovery therefrom; depleting the pressure of the reservoir from an initial reservoir pressure to the determined depletion pressure, thus providing the lights-depleted crude oil; repressurizing the reservoir to an operating pressure for recovering the lights-depleted crude oil from the reservoir via carbon dioxide (CO2) injection; injecting CO2 into the reservoir via at least one injection well; and recovering at least a portion of the lights-depleted crude oil from the reservoir via at least one production well.