Methods for enhancing and maintaining heat transfer efficiency between geothermal heat and injection fluid
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Solution Overview
Problem
The permeability of subterranean systems in geothermal operations decreases due to silica and other solids precipitation, leading to reduced flow rates and heat transfer efficiency, requiring higher injection pressures and increased electricity usage.
Innovation Solution
The use of etching agents and scale inhibitors, such as chelants, to create conductive channels and prevent scale formation, combined with intermittent injection and production to enhance fluid flow and heat transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fluid injection is continued without intervention, then geothermal energy production continues, but permeability decreases due to scale formation
Solution Approach 1:
The patent applies preliminary action by injecting etching agents and scale inhibitors into the subterranean system before significant scale formation occurs. These chemicals pre-treat the formation to prevent silica and other solids from precipitating and forming scale, thereby maintaining permeability and preventing the need for later intervention.
Solution Approach 2:
The patent uses etching agents and scale inhibitors as intermediary substances that mediate between the injected fluid and the formation matrix. These intermediaries chemically interact with precipitating solids to prevent scale formation, allowing continuous fluid injection while protecting the formation's permeability.
2Productivity
If injection pressure is increased to maintain flow rate, then flow rate is maintained, but electricity consumption increases
Solution Approach 1:
By preliminarily treating the formation with etching agents that create conductive channels and enlarge pores, the system reduces flow resistance before injection begins. This allows maintenance of designed injection flow rates at lower pressures, reducing electricity consumption for injection equipment.
3Reliability
If scale forms in pore spaces, then permeability decreases, but heat exchange efficiency also diminishes
Solution Approach 1:
The patent employs etching agents as intermediaries that chemically react with silica and other solids to prevent scale formation in pore spaces. By maintaining clean pore channels, these intermediaries simultaneously preserve both permeability for fluid flow and thermal conductivity for heat exchange, preventing dual degradation.
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 increases fluid flow rates, maintains thermal conductivity, and reduces energy consumption by preventing scale formation and enlarging fractures, thereby improving geothermal energy extraction efficiency.
Implementation Method 1
etching agents may be used to create conductive channels within the formation
Implementation Method 2
liquid scale inhibitors and/or solid slow-release scale inhibitors may be used to prevent the formation of scale
Implementation Method 3
allowing it to become heated by the formation
Data Source
AI summary
Methods and compositions for enhancing the flow rate and heat transfer efficiency of wellbores and/or propped fractures for use in geothermal operations are provided. In some embodiments, the methods comprise: injecting an etching agent into an injection inlet of a first wellbore penetrating a first portion of a subterranean formation, wherein the injection inlet is disposed at a first location at or near a surface of the subterranean formation; injecting a working fluid having a first temperature into the injection inlet; allowing at least a portion of the working fluid to flow from the injection inlet to a production outlet of a second wellbore penetrating a second portion of the subterranean formation; and producing the portion of the working fluid out of the production outlet at a first rate and at a second temperature that is higher than the first temperature.