Heat extraction method for liquid dominated geothermal reservoirs
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Solution Overview
Problem
Geothermal systems face inefficiencies due to temperature reduction in the geothermal reservoir surrounding the wellbore, leading to reduced heat production over time, and there is a need for methods to enhance steady heat production.
Innovation Solution
A closed-loop geothermal system with a bidirectional fluid conduit and a downhole pump is used to draw geothermal fluid into a wellbore, maintaining temperature through convective heat transfer and controlling the operation to prevent exceeding the downhole pump's maximum operating temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If heat is extracted from the geothermal reservoir using conventional systems, then heat production is achieved initially, but the temperature of the geothermal reservoir cools over time reducing efficiency
Solution Approach 1:
The system alternates between extraction phases (removing heat from the reservoir) and injection phases (introducing hot geothermal fluid back into the reservoir). This periodic cycling maintains reservoir temperature by allowing heat to replenish during injection periods, thereby sustaining efficient heat production over time rather than continuously depleting the reservoir.
Solution Approach 2:
The system recovers and reinjects geothermal fluid that has been cooled after heat extraction. Instead of discarding this cooled fluid, it is injected back into the reservoir where it serves as a heat carrier, allowing the reservoir to transfer heat back to the working fluid during subsequent extraction cycles, thus maintaining thermal energy in the system.
2Productivity
If a downhole pump is used to draw geothermal fluid into the wellbore, then heat transfer efficiency is enhanced, but the pump may degrade if exposed to excessive temperatures
Solution Approach 1:
The downhole pump operates intermittently rather than continuously, alternating between pumping phases and idle phases. During idle periods, the pump is not exposed to high-temperature geothermal fluid, allowing it to cool down and preventing thermal degradation. This periodic operation maintains high heat transfer rates when pumping occurs while protecting the pump from excessive temperature exposure.
Solution Approach 2:
The system prepares the geothermal fluid by allowing it to cool slightly before introducing it to the downhole pump during extraction phases. This preliminary cooling action ensures the fluid temperature is within the pump's operational limits before contact, preventing thermal damage while still enabling effective heat transfer during the pumping operation.
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 system maintains high levels of heat transfer to the surface by managing temperature and pressure, enhancing heat extraction efficiency while preventing pump degradation.
Implementation Method 1
extracting heat, using the closed-loop geothermal system circulating a working fluid, from the drawn geothermal fluid within the first downhole portion
Implementation Method 2
maintaining temperature through convective heat transfer
Implementation Method 3
a pump configured to draw geothermal fluid into the first downhole portion of the wellbore
Data Source
AI summary
Methods and systems for extracting geothermal energy are disclosed. The method may include inserting a closed-loop geothermal system into a wellbore penetrating a geothermal reservoir, where the closed-loop geothermal system comprises a fluid conduit, and a downhole end of the fluid conduit is disposed in a first downhole portion of the wellbore, disposing a pump with a fluid inlet positioned within the first downhole portion, and drawing, using the pump, geothermal fluid into the first downhole portion of the wellbore. The method may further include extracting heat, using the closed-loop geothermal system circulating a working fluid, from the drawn geothermal fluid within the first downhole portion and transporting the extracted heat to a primary heat utilization facility disposed on the surface of the earth.