Closed-Loop Geothermal Well Design to Prevent Induced Seismicity
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Solution Overview
Problem
Current geothermal energy extraction methods, such as Enhanced Geothermal Systems (EGS), are region-specific, inefficient due to induced seismicity, fluid contamination, and mineral deposition, limiting the adoption of geothermal technology and reducing overall efficiency.
Innovation Solution
The design of geothermal wells with a borehole structure featuring a first and second portion intersecting at different depths, an outer and inner string, and an annulus with a choke to regulate return flow and maintain surface backpressure above the boiling pressure of the heated fluid, allowing for efficient heat transfer and reduced seismicity risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hydraulic fracturing is used to create fractures in hot dry rock, then geothermal fluid flow is enabled, but induced seismicity and fluid contamination occur
Solution Approach 1:
The patent extracts the harmful fracturing process entirely from the system by using a closed-loop well design that circulates fluid through the formation without requiring hydraulic fracturing. The fluid is injected through an injection well and produced through a separate production well, eliminating the need for high-pressure fracturing operations that cause seismicity and contamination.
Solution Approach 2:
The patent introduces a closed-loop fluid circulation system as an intermediary between the heat source (hot dry rock) and the surface. This intermediary system allows heat transfer through the formation without direct contact between injected fluid and formation fluids, preventing contamination while maintaining productivity.
2Productivity
If high fluid pressures are applied to force fluid through blocked fractures, then fluid flow is maintained, but formation stress increases and seismicity is exacerbated
Solution Approach 1:
The patent removes the need for high-pressure injection by eliminating the fractured pathway dependency. The closed-loop system allows fluid to flow through the formation at much lower pressures since it does not need to force its way through blocked fractures, thereby reducing formation stress and seismicity risks.
3Productivity
If mineral deposition blocks fracture network, then heating efficiency decreases, but system complexity increases to maintain flow
Solution Approach 1:
The patent extracts the fracture network from the system design, replacing it with a closed-loop well configuration. This eliminates the problem of mineral deposition blocking fractures, as the fluid circulates through the formation through the wellbore pathway rather than relying on fractured pathways that are susceptible to blocking.
4Productivity
If EGS technology is deployed in region-specific locations, then geothermal power is generated, but scalability is limited
Solution Approach 1:
The patent creates a universal geothermal extraction system that can be applied to different geological formations regardless of the presence of natural fractures or permeable aquifers. The closed-loop design works with hot dry rock and other formations by injecting fluid through the injection well and producing it through the production well, making the technology scalable beyond region-specific applications.
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 geothermal energy extraction efficiency by preventing induced seismicity, reducing emissions and water consumption, and improving controllability, while maintaining well integrity and reducing operational costs.
Implementation Method 1
the second portion is exposed to the formation for heating a fluid flowing in the second portion
Implementation Method 2
the choke is configured to regulate return flow of the heated fluid to maintain surface backpressure above a boiling pressure of the heated fluid at surface
Data Source
AI summary
A geothermal well includes a borehole formed in a geologic formation. The borehole includes a first portion extending from a first end to a second end and a second portion intersecting the first portion at a first depth. The second portion is exposed to the formation for heating a fluid flowing in the second portion. The well includes an outer string disposed in the first portion where a lower end of the outer string is disposed above the first depth. The well includes an inner string disposed though the outer string and an annulus formed between the inner string and the outer string. The well includes a choke fluidly coupled to at least one of the annulus or the inner string. The choke is configured to regulate return flow of the heated fluid to maintain surface backpressure above a boiling pressure of the heated fluid at surface.