Closed-Loop Geothermal System to Reduce Debris and Erosion Risk
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Solution Overview
Problem
Existing geothermal energy generation systems face challenges such as debris accumulation, erosion of rock formations, environmental leakage, and high maintenance costs due to the use of filters, binary cycle power stations, and polymer coating layers.
Innovation Solution
A system with a pressure-tested downhole well loop that includes a common well segment, insulated injection and production pipes, injection and production wells, and lateral sections, all cased in steel and cemented in place, to isolate and circulate a working fluid underground, minimizing contact with rock formations and reducing the risk of erosion and leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If filters are provided along the flow path to remove debris, then the working fluid is protected from carrying debris into machinery, but maintenance cost increases and system complexity increases
Solution Approach 1:
The harmful factor (debris) is extracted from the working fluid by allowing it to settle in the reservoir before circulation begins. The system removes debris at the source rather than filtering it continuously through the system, eliminating the need for filters while maintaining protection of machinery.
2Reliability
If a binary cycle power station is used to protect turbines from debris, then turbines are saved from encountering debris, but pumps still contend with debris and heat loss increases
Solution Approach 1:
The working fluid is allowed to pick up debris and solids during circulation, but this is converted into a benefit by using the fluid's kinetic energy to clean the rock surfaces it flows over. The debris-laden fluid acts as an abrasive cleaning agent that removes scale and deposits from the rock formation, turning a harmful condition into a useful cleaning function.
3Object-affected harmful factors
If flow rate is minimized to prevent erosion of rock surfaces, then rock formation integrity is protected, but residence time underground increases
Solution Approach 1:
The system changes the physical parameters of the working fluid by heating it underground, which alters its viscosity and flow characteristics. The heated fluid can maintain adequate flow rates for heat transfer efficiency while reducing its erosive capability on rock surfaces, as the thermal energy modifies the fluid-rock interaction dynamics.
4Reliability
If polymer coating is applied to seal rock formations, then leakage is prevented, but pressure testing becomes impossible and maintenance cost increases
Solution Approach 1:
The system uses the working fluid itself to seal and protect the rock formations. By controlling the fluid's chemical properties and injection parameters, the fluid creates natural seals at fracture zones and porous areas without requiring external polymer coatings. The fluid serves its primary heat transfer function while simultaneously providing formation protection and leak prevention.
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 debris accumulation, erosion, and environmental leakage, while minimizing maintenance costs and reducing the risk of leaks and pollution, thereby enhancing the efficiency and reliability of geothermal energy generation.
Implementation Method 1
a downhole well loop extending underground into a rock formation and in a heat transfer arrangement with the rock formation
Implementation Method 2
The downhole well loop receives a working fluid capable of undergoing phase change between liquid and gas within the pressure-tested downhole well loop as a result of the heat transferred from the rock formation
Data Source
AI summary
The present disclosure describes a system and a method for generating energy from geothermal sources. The system includes an insulated injection pipe and a common well segment, an injection well and a production well, a first lateral section connected to the injection well and a second lateral section connected to the production well, a multilateral connector joining the first and second lateral sections, the insulated injection pipe coinciding with the common well segment, defining a pressure-tested loop within the rock formation and in a heat transfer arrangement therewith. The loop cased in steel and cemented in place. The loop to receive working fluid capable of undergoing phase change 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.