Coal Seam CO2 Sequestration Using Water-Diluted Injection
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Solution Overview
Problem
Conventional methods for sequestering CO2 in coal seams cause swelling and damage to the formation due to injecting pure CO2, making them economically unviable and ineffective for further sequestration.
Innovation Solution
Injecting CO2 diluted within water or an incompressible fluid into coal seams, utilizing the water as a filter to absorb CO2 and control its concentration, thereby preventing swelling and enhancing sequestration efficiency.
Engineering Contradictions & Design Principles
Engineering 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
Solution Approach 1:
Water is introduced as an intermediary substance to deliver CO2 to the coal seam. The CO2 is dissolved in water at controlled concentrations (typically 1-10% by volume) and injected through the aqueous medium. This intermediary approach allows CO2 to be transported and released gradually without the direct contact effects of pure CO2 injection, preventing coal swelling while maintaining sequestration capacity.
Solution Approach 2:
The concentration of CO2 in the injected fluid is changed from 100% (pure CO2) to a diluted state (1-10% CO2 dissolved in water). This parameter change in CO2 concentration fundamentally alters the interaction with the coal seam, preventing excessive pressure buildup and swelling while still enabling effective CO2 storage through gradual saturation of the coal matrix.
2Quantity of substance
If pure CO2 is injected into coal seams, then CO2 storage amount is increased, but the coal seam swells and subsequent sequestration is prevented
Solution Approach 1:
The injection process uses periodic cycles of CO2 dissolution in water followed by injection into the coal seam. Rather than continuous pure CO2 injection causing immediate saturation and swelling, the periodic introduction of CO2 through aqueous solutions allows for controlled, incremental storage that maintains coal seam porosity and connectivity for ongoing sequestration operations.
Solution Approach 2:
By changing the physical state and concentration parameters of CO2 delivery (from pure gas to diluted aqueous solution), the system enables continuous sequestration operations. The diluted CO2 in water prevents rapid saturation, maintaining the coal seam's ability to accept additional CO2 over extended periods.
3Quantity of substance
If CO2 is condensed for injection, then storage efficiency is improved, but energy and capital costs increase significantly
Solution Approach 1:
The system utilizes the natural solubility of CO2 in water to achieve storage without requiring external energy input for condensation. CO2 dissolves in water under ambient or near-ambient conditions, and the aqueous solution is then injected into the coal seam where CO2 is released and stored. This self-service approach eliminates the energy-intensive condensation step while maintaining effective storage efficiency.
Solution Approach 2:
The invention employs hydraulic injection of CO2-saturated water into the coal seam, utilizing fluid pressure dynamics rather than gas compression and condensation. The CO2 is transported in dissolved form within the aqueous phase and injected under controlled pressure, avoiding the need for expensive and energy-intensive CO2 condensation equipment and processes.
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 and pores without damaging the coal seam, enabling efficient capture and control of CO2 while minimizing energy and capital costs.
Implementation Method 1
absorbing or adsorbing CO2 gas into water to form a CO2 solution gas mixture stream
Implementation Method 2
portions of the dissolved CO2 within the solution gas mixture stream may be adsorbed or absorbed by the coal seam
Data Source
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.