Water-Diluted CO2 Injection for Coal Seam Storage Without Swelling

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Solution Overview

Problem

Conventional methods for sequestering CO2 in coal seams cause swelling and damage to the formation due to the injection of pure CO2, leading to loss of connectivity and inefficiency.

Innovation Solution

Injecting CO2 diluted within water or an incompressible fluid into coal seams, utilizing water as a filter to adsorb CO2 and control its concentration, thereby preventing swelling and maintaining formation integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If pure CO2 is injected into coal seams, then CO2 sequestration capacity is improved, but the coal seam swells and loses connectivity, damaging the formation

Engineering Contradiction:

ImproveCO2 sequestration capacityVSAvoidformation connectivity

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

Water is introduced as an intermediary substance to deliver CO2 into the coal seam. The CO2 is dissolved in water at controlled concentrations (typically 1-10% by volume) and injected through the water medium, which prevents direct contact between high-concentration CO2 and the coal matrix, thereby avoiding swelling while still enabling CO2 adsorption onto the coal surface

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The concentration of CO2 in the injected fluid is changed from pure (100%) to diluted (1-10% in water). This parameter change in CO2 concentration allows the coal seam to adsorb CO2 gradually without experiencing the rapid pressure and volume changes that cause swelling and loss of connectivity

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If pure CO2 is injected into coal seams, then CO2 storage amount is increased, but the coal seam swells and subsequently loses connectivity

Engineering Contradiction:

ImproveCO2 storage amountVSAvoidcoal seam structure

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

Water serves as a protective intermediary that mediates between the CO2 source and the coal seam. By dissolving CO2 in water and injecting the solution, the water buffer prevents direct high-concentration CO2 exposure to the coal structure, maintaining coal seam stability while achieving CO2 storage through adsorption onto the coal surface

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The partial pressure of CO2 in the injected fluid is controlled by adjusting the CO2 concentration in water. This parameter control ensures that CO2 is delivered at rates and concentrations that the coal seam can accommodate without structural changes, maintaining stability while achieving storage objectives

Inventive Principle:

Principle #35Parameter changes

3Quantity of substance

If CO2 is condensed for injection, then CO2 concentration is increased, but energy and capital costs increase significantly

Engineering Contradiction:

ImproveCO2 concentrationVSAvoidenergy cost

Core Design Contradiction:

Quantity of substanceVSUse of energy by moving object

Solution Approach 1:

Instead of changing CO2 from gaseous to liquid phase through condensation (which requires significant energy), the invention changes the concentration parameter by dissolving CO2 in water to create a diluted solution. This alternative parameter change achieves CO2 delivery without the high energy costs of phase change, while still enabling effective CO2 sequestration through adsorption

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses hydraulic injection (water-based fluid injection) instead of pneumatic injection of compressed or condensed CO2. By utilizing water as the injection medium, the system avoids the energy-intensive compression and condensation steps required for pure CO2 injection, reducing both energy and capital costs while maintaining effective CO2 delivery

Inventive Principle:

Principle #29Pneumatics and hydraulics

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 allows for effective sequestration of CO2 within connected fractures without damaging the subterranean formation, enhancing the capacity and efficiency of CO2 storage while allowing for the recovery of methane.

Implementation Method 1

absorbing or adsorbing CO2 gas into water to form a CO2 solution gas mixture stream, wherein the CO2 gas may be directly captured by the water from atmospheric air

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

portions of the dissolved CO2 within the solution gas mixture stream may be adsorbed or absorbed by the coal seam

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 3

This may move methane embedded within the coal seam away from an injector or a face of the coal seam towards a collector

Methodology Applied

Scientific EffectPressure gradient-driven flow: Pressure Gradient

Data Source

PatentUS12385374B2Methods and systems for greenhouse gas capture and sequestration

Publication Date: 2025.08.12 CARBON GEOCYCLE INC

AI summary

Injecting CO2 that is diluted within water, into a coal seam, which allows for the sequestering and control of downhole CO2 within connected fractures without damaging the subterranean formation.