Thickened CO2 Gravity Drainage Oil Recovery

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Solution Overview

Problem

Gravity drainage gas injection processes, including those using CO2, face limitations of slow response and low oil recovery rates due to low critical gas injection rates, which require excessive gas injection and are not economically feasible, and existing thickeners are either costly, environmentally harmful, or ineffective in increasing CO2 viscosity.

Innovation Solution

The use of thickened CO2, achieved by mixing CO2 with a copolymer thickener, increases the critical gas injection rate, allowing higher gas injection rates and enhancing oil recovery through forced gravity drainage, while minimizing environmental impact and water consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If CO2 is injected into the reservoir to mobilize oil, then oil recovery is improved, but the response is slow and recovery rates are low due to low critical gas injection rates

Engineering Contradiction:

Improveoil recovery rateVSAvoidresponse time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent changes the physical parameter of CO2 by thickening it (increasing viscosity) to alter its flow characteristics. This parameter change allows the gas to maintain a stable front and achieve higher critical injection rates, thereby improving oil recovery rates and reducing response time without causing gas channeling or premature breakthrough.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite system by combining CO2 with thickening agents to form thickened CO2. This composite material has enhanced viscosity compared to pure CO2, enabling it to effectively mobilize oil at higher injection rates while maintaining gravitational stability and improving the overall efficiency of the gravity drainage process.

Inventive Principle:

Principle #40Composite materials

2Productivity

If gas injection rate is increased to improve oil recovery, then productivity increases, but excessive gas injection is required which is not economically feasible

Engineering Contradiction:

Improveoil recovery rateVSAvoidgas injection volume

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

By changing the viscosity parameter of CO2 through thickening, the patent enables effective oil recovery at lower gas injection volumes. The thickened CO2 maintains a stable displacement front that efficiently sweeps through the reservoir, reducing the total quantity of gas required compared to conventional gas injection methods.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The thickening agent acts as an intermediary that modifies the physical properties of CO2 to improve its displacement efficiency. This intermediary substance enables the CO2 to effectively mobilize and drive oil toward production wells with reduced gas consumption, making the process more economically viable.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If existing thickeners are used to increase CO2 viscosity, then critical gas injection rate improves, but the thickeners are costly or environmentally harmful

Engineering Contradiction:

Improvecritical gas injection rateVSAvoidenvironmental impact

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent employs biodegradable thickening agents that are environmentally friendly and can break down naturally in the reservoir environment. These disposable-like materials provide the necessary viscosity enhancement temporarily during the injection process and then degrade, avoiding long-term environmental harm while achieving the desired improvement in critical gas injection rate.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent converts the potential harm of using chemical thickeners by selecting biodegradable and environmentally benign substances. The thickening agents, while necessary for improving injection rates, are chosen to have minimal environmental impact and can even provide benefits such as biodegradation that eliminates contamination concerns, thus turning a potentially harmful approach into a beneficial one.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 method significantly increases oil recovery rates and reduces CO2 gas utilization per barrel of oil, mitigating environmental concerns by using an environmentally friendly thickener that effectively increases CO2 viscosity and stabilizes the gas-oil interface for improved oil production.

Implementation Method 1

The use of thickened CO2, achieved by mixing CO2 with a copolymer thickener, increases the critical gas injection rate

Methodology Applied

Scientific EffectPolymer thickening:

Implementation Method 2

The mobilized oil is pushed towards recovery wells such that 'free gravity drainage' is supplemented with 'forced gravity drainage' due to the injected CO2

Methodology Applied

Scientific EffectGravity drainage: Gravitation

Data Source

PatentUS11867038B2Thickened CO<sub>2 </sub>in gravity drainage gas injection processes

Publication Date: 2024.01.09 SAUDI ARABIAN OIL CO

AI summary

A method and a system for oil recovery are provided. An exemplary method includes injecting thickened carbon dioxide (CO2) into the top of a reservoir containing oil. An interface is formed between the thickened CO2 and the oil. The oil is mobilized by the thickened CO2. The mobilized oil is recovered with a recovery well drilled below the reservoir.