Closed loop energy production from producing geothermal wells
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Solution Overview
Problem
Geothermal power production is limited by low well pressures, heat loss during fluid ascent, corrosion from chemical contaminants, non-condensable gases (NCGs) interference, and inefficiencies in utilizing hot steam due to corrosive elements, leading to reduced power generation and maintenance costs.
Innovation Solution
A system with a downhole heat exchanger (DHX) and artificial lift mechanisms, such as gas injection and submerged pumps, to enhance fluid pressure and temperature, separate NCGs, and manage corrosive elements, utilizing a working fluid to produce thermal or electrical power efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If geothermal brine is produced to surface for power generation, then power can be generated from the thermal energy, but heat is lost during fluid ascent and pressure decreases
Solution Approach 1:
The heat exchanger is installed downhole before the brine reaches the surface, extracting thermal energy from the brine while it is still at high temperature and pressure. This preliminary action prevents the heat loss that would occur during the fluid's ascent to the surface, capturing energy at the optimal moment when the brine is hottest.
2Stress or pressure
If geothermal brine is produced at high pressure for power generation, then sufficient pressure is available for power production, but the amount of fluid that can be produced is limited
Solution Approach 1:
The heat exchanger extracts thermal energy from the brine downhole, allowing the brine to be produced at lower pressures while still providing sufficient thermal energy for power generation. This extraction of thermal energy decouples the requirement for high production pressure from the need for adequate power generation capability, enabling higher fluid production rates.
3Use of energy by moving object
If geothermal brine containing corrosive chemicals is used for power production, then thermal energy can be utilized, but corrosion and scale deposit on downstream equipment requiring expensive maintenance
Solution Approach 1:
The heat exchanger extracts thermal energy from the brine and transfers it to a separate working fluid in a closed loop system. This extraction process isolates the corrosive brine from the downstream power generation equipment, allowing thermal energy utilization while preventing corrosion and scale deposition on turbines and other sensitive components.
4Power
If geothermal steam contains non-condensable gases, then steam can be used for power generation, but NCGs interfere with power production and require expensive separation
Solution Approach 1:
The heat exchanger extracts thermal energy from the steam-brine mixture downhole, separating the thermal energy from the NCG-containing fluid. The working fluid in the closed loop system does not contact the NCGs, eliminating their interference with power generation while still utilizing the thermal energy for turbine operation.
5Temperature
If dry steam is produced from hot geothermal resources, then high temperature energy is available, but corrosive and toxic elements in the steam make it unusable for direct power production
Solution Approach 1:
A working fluid serves as an intermediary between the corrosive dry steam and the power generation equipment. The heat exchanger transfers thermal energy from the steam to the working fluid, which then drives the turbine. This intermediary approach allows utilization of high-temperature steam energy while the working fluid protects the equipment from exposure to corrosive and toxic elements.
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
Increases power production from geothermal reservoirs by accessing higher temperatures, maintaining fluid pressure, isolating corrosive substances, and optimizing energy extraction, thereby enhancing overall geothermal energy utilization and reducing operational expenses.
Implementation Method 1
a heat exchanger disposed within the outer production conduit, the heat exchanger comprising an outer heat exchange conduit and an inner conduit
Implementation Method 2
circulating a working fluid through the outer heat exchange conduit and into the inner conduit
Implementation Method 3
transferring the heat to a separate working fluid at the surface operating in a closed loop
Implementation Method 4
artificial lift mechanisms, such as gas injection and submerged pumps
Implementation Method 5
circulating a working fluid through the outer heat exchange conduit and into the inner conduit by means of a pump
Implementation Method 6
flashing geothermal brine to maximize the quantity and enthalpy of dry steam that can be used in a steam turbine to generate power directly
Data Source
AI summary
Methods and systems for producing thermal or electrical power from geothermal wells. Power is produced from a working fluid circulating in a closed loop within a geothermal well. Geothermal steam or brine at depth transfers heat at higher temperature than at the surface to the working fluid. The working fluid is then used to produce power directly or indirectly. The geothermal production fluid may be stimulated through use of gas lifting or submersible pumps to assist in bringing such fluids to the surface or through the use blockers to encourage the downhole steam advection and brine recirculation through the resource in a connective loop. The working fluid may be compatible with existing direct heat or power generation equipment; i.e., water for flash plants or hydrocarbons/refrigerants for binary plants.