Alternating CO2 and Hydrocarbon Injection for EOR

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Solution Overview

Problem

Current CO2 Enhanced Oil Recovery (EOR) methods face challenges such as gravity segregation and water shielding, leading to inefficient oil recovery and suboptimal CO2 storage due to uneven CO2 sweep in subterranean formations, with existing methods utilizing only a small fraction of storage capacity.

Innovation Solution

The method involves alternating between injecting a pure CO2 composition and a CO2-hydrocarbon composition, with the hydrocarbon altering the viscosity and density to enhance miscibility with residual oil, thereby increasing the swept area and optimizing CO2 storage by stabilizing the CO2 plume.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If CO2 is injected into the formation for EOR, then oil recovery is enhanced, but gravity segregation occurs causing CO2 to bypass oil zones

Engineering Contradiction:

Improveoil recoveryVSAvoidCO2 distribution uniformity

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The patent applies periodic action by alternating between injecting CO2 and injecting water in a cyclic manner. This periodic injection pattern prevents CO2 from continuously rising due to gravity segregation, as the water injection periods redistribute the CO2 and maintain more uniform contact with oil zones throughout the formation, thereby enhancing oil recovery while improving CO2 distribution stability.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

Water acts as an intermediary substance in this patent. By injecting water alternately with CO2, the water serves as a mediator that redistributes the CO2 phase and prevents it from bypassing oil zones through gravity segregation. The water injection periods help maintain pressure and ensure more uniform CO2 contact with residual oil, resolving the contradiction between oil recovery enhancement and CO2 distribution uniformity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If CO2 is injected into the formation, then oil recovery is enhanced, but water shielding prevents CO2 from contacting in-place oil

Engineering Contradiction:

Improveoil recoveryVSAvoidwater shielding effect

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The alternating injection of CO2 and water in periodic cycles helps overcome water shielding effects. During CO2 injection periods, the gas contacts oil zones, while subsequent water injection periods displace mobile water away from oil zones and redistribute CO2, thereby reducing the water shielding effect and enhancing CO2-oil contact for improved oil recovery.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

Water injection is performed as a preliminary action before CO2 injection in alternating cycles. This preliminary water injection displaces mobile water from oil zones, reducing the water shielding effect before CO2 is introduced, thereby facilitating better CO2 contact with in-place oil and enhancing oil recovery.

Inventive Principle:

Principle #10Preliminary action

3Quantity of substance

If supercritical CO2 is injected into deep storage sites, then CO2 storage capacity is increased, but uneven sweep leads to fingering and loss of storage volume

Engineering Contradiction:

ImproveCO2 storage capacityVSAvoidCO2 plume uniformity

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent applies periodic action by alternating CO2 injection with water injection in cyclic patterns. This periodic alternation prevents the formation of unstable CO2 fingers by periodically redistributing the CO2 plume through water injection, thereby maintaining more uniform CO2 distribution throughout the storage formation and maximizing usable storage volume.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

Water serves as an intermediary that stabilizes the CO2 plume during storage. By periodically injecting water, it acts as a mediator that redistributes CO2 and prevents fingering, thereby improving CO2 plume uniformity while maintaining high storage capacity in the formation.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 swept area and optimizing CO2 storage, allowing for higher recovery factors and more efficient use of storage sites, with the potential to recover valuable hydrocarbons and achieve near-zero CO2 emissions.

Implementation Method 1

the hydrocarbon altering the viscosity and density to enhance miscibility with residual oil

Methodology Applied

Scientific EffectViscosity alteration:

Implementation Method 2

the hydrocarbon altering the viscosity and density to enhance miscibility with residual oil

Methodology Applied

Scientific EffectDensity alteration:

Implementation Method 3

optimizing CO2 storage by stabilizing the CO2 plume

Methodology Applied

Scientific EffectPlume stabilization:

Data Source

PatentUS10024149B2Method for CO<sub>2 </sub>EOR and storage and use thereof

Publication Date: 2018.07.17 EQUINOR ENERGY AS

AI summary

A method of Enhanced Oil Recovery from oil zones in a subterranean geological formation, and from oil zones. The method including: a first injecting step of injecting a first composition including CO2 into the subterranean geological formation for a period of time; a second injecting step of injecting a second composition including CO2 and a hydrocarbon into the subterranean geological formation for a period of time, wherein the first composition and the second composition are different; and extracting oil from the subterranean geological formation.