Multi-Well Trona Solution Mining for Uniform Dissolution
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Solution Overview
Problem
Current solution mining techniques for trona are inefficient in extracting sodium carbonate and sodium bicarbonate from deep, thin, or low-quality beds, as they require prior mechanical mining and are prone to issues like sodium bicarbonate 'blinding' and channeling, leading to reduced recovery rates and increased costs.
Innovation Solution
A method involving multiple wells in fluid communication, where solvent is injected into a cavity to dissolve trona, with wells switching between injection and production modes to maintain solvent flow and prevent channeling, and using lithological displacement to create a mineral-free surface for uniform dissolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional solution mining techniques are used to extract trona, then extraction can be performed, but recovery rates are reduced due to sodium bicarbonate blinding and channeling
Solution Approach 1:
The patent divides the extraction system into multiple injection wells and production wells arranged in a pattern. This segmentation allows the solvent to be introduced at multiple points simultaneously, preventing channeling and ensuring more uniform dissolution of trona across the mined area, thereby improving recovery rates and extraction stability
Solution Approach 2:
The patent implements periodic switching between injection mode and production mode for each well. This periodic action prevents continuous solvent flow through the same path (channeling) and allows the cavity to be uniformly dissolved from multiple directions over time, improving both recovery rate and extraction reliability
2Productivity
If mechanical mining is used prior to solution mining, then access to deep beds is achieved, but costs increase and previously uneconomical deposits remain unexploitable
Solution Approach 1:
The patent replaces mechanical mining operations with an in-situ solution mining process. By injecting solvent directly into the underground formation to dissolve trona, the method eliminates the need for mechanical excavation, reducing operational costs and enabling extraction from deep beds that would be economically unviable with mechanical mining
Solution Approach 2:
The patent uses hydraulic injection of solvent through multiple wells to dissolve and extract trona from deep underground beds. This hydraulic approach provides access to deep deposits without the high costs associated with mechanical mining equipment and operations
3Productivity
If solvent flow is maintained through continuous injection, then dissolution efficiency is improved, but channeling and non-uniform cavity shapes occur
Solution Approach 1:
The patent segments the solvent injection into multiple separate injection wells rather than using a single continuous injection point. This allows the dissolution front to advance uniformly from multiple directions, maintaining high dissolution efficiency while preventing channeling and producing a more uniform cavity shape
Solution Approach 2:
The patent employs periodic switching between injection and production modes for each well. This periodic action ensures that no single flow path dominates, maintaining efficient dissolution while preventing the formation of irregular cavity shapes and channeling
4Shape
If multiple wells are used in fluid communication, then uniform dissolution is achieved, but device complexity increases
Solution Approach 1:
The patent designs each well to serve dual functions: acting as an injection well during some periods and a production well during other periods. This multi-functionality reduces the need for separate dedicated injection and production wells, thereby achieving uniform dissolution while limiting the increase in device 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 enhances the uniformity of trona dissolution, reduces the formation of undesirable cavity shapes, and minimizes the deposition of insolubles, thereby increasing recovery rates and reducing operational costs by allowing extraction from previously uneconomical deposits.
Implementation Method 1
injecting a solvent into the at least one cavity for the solvent to contact the mineral free face as the solvent flows through the at least one cavity and to dissolve in situ at least a portion of the mineral from the free face into the solvent to form a brine
Implementation Method 2
A method involving multiple wells in fluid communication, where solvent is injected into a cavity to dissolve trona, with wells switching between injection and production modes to maintain solvent flow and prevent channeling
Implementation Method 3
using lithological displacement to create a mineral-free surface for uniform dissolution
Data Source
AI summary
A method for in situ solution mining of a mineral from an underground evaporite stratum using a set of wells in fluid communication with at least one mineral cavity with some wells operated in solvent injection mode and other wells operated in brine production mode and optionally with some inactive wells, comprising switching the operation mode of one or more wells. The evaporite mineral preferably comprises trona. The at least one cavity may be formed by directionally drilled uncased boreholes or by lithological displacement of the evaporite stratum at a weak interface with an underlying insoluble stratum by application of a lifting hydraulic pressure to create an interfacial gap. The extracted brine can be processed to make valuable products such as soda ash and/or any derivatives thereof. This method can provide more uniform dissolution of mineral in the cavity, minimize flow channeling, minimize sodium bicarbonate blinding for solution mining of incongruent trona ore, and/or may avoid uneven deposit of insolubles.