Closed-Loop Geothermal Well System to Prevent Erosion and Leakage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Geothermal energy generation systems face issues with debris and erosion in rock formations, leading to equipment damage, environmental pollution, and high maintenance costs due to the interaction of working fluids with rock surfaces and the need for frequent filter replacements or polymer coatings, which are not always effective in preventing leaks and erosion.
Innovation Solution
A pressure-tested downhole well loop system with steel-cased and cemented injection and production wells, connected by multilateral sections, isolates the working fluid from rock formations, preventing erosion and leakage, and uses a single working fluid to minimize parasitic losses and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If filters are provided along the flow path to remove debris, then equipment damage from debris is reduced, but maintenance cost increases due to frequent filter replacements and system complexity increases due to added components
Solution Approach 1:
The invention extracts and removes the problematic debris-containing working fluid from the closed loop system by providing a make-up fluid line that introduces fresh working fluid to replace fluid lost to debris contamination and erosion, thereby eliminating the need for filters and their associated maintenance
Solution Approach 2:
Instead of trying to prevent debris formation through filters, the invention inverts the approach by accepting debris formation and continuously replenishing the working fluid to maintain system operation, turning a prevention-based system into a restoration-based system
2Object-affected harmful factors
If flow rate of working fluid is minimized to prevent erosion of rock surfaces, then environmental damage is reduced, but residence time underground increases leading to reduced energy efficiency
Solution Approach 1:
The invention applies self-service by using the working fluid itself to prevent erosion through the introduction of make-up fluid that helps maintain optimal flow characteristics and prevents the working fluid from becoming too depleted or contaminated, allowing the system to maintain higher flow rates without excessive erosion
Solution Approach 2:
The invention changes the parameters of the working fluid by continuously replenishing it with fresh make-up fluid, maintaining optimal fluid properties for heat transfer and flow characteristics, thereby allowing higher flow rates without excessive erosion
3Object-affected harmful factors
If polymer coating is applied to seal rock formations to prevent leakage, then environmental pollution is reduced, but reliability decreases because the coating cannot be pressure tested and may erode over time
Solution Approach 1:
The invention extracts and removes the unreliable polymer coating layer from the system, replacing it with a mechanical cemented casing that can be properly installed and tested, thereby eliminating the reliability issues associated with untestable coatings
Solution Approach 2:
The invention replaces the permanent but unreliable polymer coating with a more robust cemented casing that, while requiring initial installation, provides long-term reliable sealing without the erosion and testing issues of polymer coatings
4Loss of energy
If a single working fluid is used to minimize parasitic losses, then energy efficiency is improved, but reliability decreases due to debris pickup and erosion causing equipment damage
Solution Approach 1:
The invention applies discarding and recovering by continuously discarding (removing) contaminated working fluid through the blowdown line and recovering fresh working fluid through the make-up fluid line, maintaining a single-fluid system for efficiency while replacing degraded fluid to prevent equipment damage
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 effectively prevents erosion and leakage, reduces maintenance costs, and enhances energy efficiency by maintaining a stable and isolated working fluid path, allowing for the use of non-conventional fluids and minimizing environmental impact.
Implementation Method 1
a working fluid capable of undergoing phase change between liquid and gas within the pressure-tested downhole well loop as a result of heat transferred from the rock formation
Implementation Method 2
a working fluid capable of undergoing phase change between liquid and gas within the pressure-tested downhole well loop as a result of heat transferred from the rock formation
Implementation Method 3
a pump configured to circulate the working fluid through the pressure-tested downhole well loop
Implementation Method 4
a turbine system operable to convert mechanical energy generated from the flow of working fluid, into electricity
Data Source
AI summary
The present disclosure describes a system and a method for generating energy from geothermal sources. The system includes an injection well and a production well extending underground into a rock formation, a first lateral section connected to the injection well and a second lateral section connected to the production well, the first and second lateral sections connected with a multilateral connector, defining a pressure-tested downhole well loop within the rock formation and in a heat transfer arrangement therewith. The downhole well loop cased in steel and cemented in place within the rock formation. The downhole well loop to receive working fluid capable of undergoing phase change between liquid and gas within the downhole well loop as a result of heat transferred from the rock formation. The system also includes a pump to circulate working fluid, a turbine system to convert the flow of working fluid into electricity, and a cooler.