RF Radiator Frequency Control for Subterranean Heating
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Solution Overview
Problem
Current hydrocarbon resource recovery methods, such as RF heating, face inefficiencies in startup and cost due to uninsulated wellbore conditions and suboptimal frequency adjustments during steam bubble formation, leading to reduced power transfer and increased energy losses.
Innovation Solution
A method involving an RF radiator within a laterally extending wellbore that supplies RF power at a settable frequency, adjusts frequency based on sensed impedance matching values, particularly lowering the frequency when the Voltage Standing Wave Ratio (VSWR) exceeds 2:1, to optimize power transfer and maintain efficient heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If RF heating is applied at a fixed frequency, then the heating process is simple to operate, but power transfer efficiency decreases due to impedance changes during steam bubble formation
Solution Approach 1:
The patent applies dynamics by making the RF frequency adjustable rather than fixed. The system dynamically changes frequency based on real-time impedance measurements during steam bubble formation, optimizing power transfer efficiency at each stage of the heating process while maintaining operational simplicity through automated control.
Solution Approach 2:
The patent implements feedback by continuously monitoring impedance changes during RF heating and using this information to adjust the operating frequency. This closed-loop control ensures optimal power transfer efficiency by adapting to impedance variations caused by steam bubble growth, resolving the contradiction between fixed operation and efficient energy transfer.
2Loss of energy
If frequency is adjusted frequently to maintain optimal power transfer, then power transfer efficiency improves, but system complexity increases
Solution Approach 1:
The patent uses feedback mechanisms to automatically adjust frequency based on impedance measurements, improving power transfer efficiency while managing system complexity through automated control. The feedback loop continuously monitors conditions and makes frequency adjustments without requiring complex manual intervention.
Solution Approach 2:
The system performs self-service by automatically detecting impedance changes and adjusting frequency without external intervention. This autonomous operation optimizes power transfer efficiency while keeping the control system relatively simple, as the RF generator manages its own frequency adjustment based on built-in sensing capabilities.
3Temperature
If RF power is applied to uninsulated wellbore, then heating can be achieved, but energy losses increase due to lack of insulation
Solution Approach 1:
The patent applies parameter changes by adjusting RF frequency in response to changing thermal and electrical conditions in the wellbore. As the steam bubble forms and insulates the wellbore, the system detects impedance changes and adjusts frequency to maintain optimal power transfer, reducing energy losses while achieving effective heating despite the lack of initial insulation.
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 enhances hydrocarbon resource recovery efficiency by managing impedance and steam bubble growth, reducing energy losses and costs, and improving startup efficiency by maintaining optimal power transfer and resonance frequencies.
Implementation Method 1
supplying radio frequency (RF) power at a settable frequency from an RF radiator positioned within the laterally extending wellbore to heat the hydrocarbon resource and start formation of a steam bubble
Implementation Method 2
A 1 kilometer long subterranean RF radiator may include electrical conductors 2000 to 3000 meters long that convey 5 megawatts of power
Implementation Method 3
radio frequency magnetic fields are applied to ferrous piping that includes hydrocarbons. The magnetic fields induction heat the ferrous piping and the hydrocarbons inside are warmed conductively
Data Source
AI summary
A method for heating a hydrocarbon resource in a subterranean formation having a laterally extending wellbore therein may include supplying radio frequency (RF) power at a settable frequency from an RF radiator positioned within the laterally extending wellbore to heat the hydrocarbon resource and start formation of a steam bubble adjacent the laterally extending wellbore while sensing an impedance matching value of the RF radiator. The method may also include lowering the settable frequency at least one time based upon the sensed impedance matching value as the steam bubble grows. The frequency may rise after the steam bubble is formed and induction heating operation occurs.