Coaxial Mode Converter Array for Uniform RF Heating
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Solution Overview
Problem
Existing systems for RF heating of hydrocarbons in oil wells, such as resonant antennas and triaxial antennas, are ineffective for long horizontal wells and suffer from energy loss and poor control over energy distribution, limiting their ability to heat hydrocarbons uniformly and efficiently.
Innovation Solution
A coaxial array of mode converters along a radio frequency transmission line within the well, which disturbs the differential mode of signal propagation to induce currents and electromagnetic fields, allowing for uniform heating along long lengths of horizontal, vertical, or slant wells by distributing RF power effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If resonant antennas are used for RF heating, then heating can be achieved in a localized area, but the antenna length is limited to a few meters and only a limited portion of the reservoir can be heated
Solution Approach 1:
The patent divides the single resonant antenna into multiple smaller resonant antenna segments arranged in an array along the wellbore. Each segment operates independently at resonant frequency, allowing the overall system to cover a much longer vertical extent while maintaining the benefits of resonant heating at each location. This segmentation resolves the contradiction by enabling both localized efficient heating and extended coverage.
Solution Approach 2:
The patent transitions from a horizontal antenna configuration to a vertical array of antenna segments along the wellbore. This dimensional change allows the system to exploit the vertical dimension of the wellbore to achieve extended heating coverage without requiring each individual antenna element to be excessively long, thus resolving the length limitation while maintaining heating effectiveness.
2Length of moving object
If triaxial antennas are used for distributed heating along horizontal wells, then heating can be distributed over long distances, but energy loss increases and control over energy distribution deteriorates
Solution Approach 1:
The patent employs multiple localized resonant antenna segments rather than a single continuous distributed antenna. Each segment is optimized for local resonant operation, concentrating energy efficiently in its immediate vicinity. This local optimization approach reduces overall energy loss compared to distributed antennas while maintaining extended heating coverage through the array configuration.
Solution Approach 2:
The patent replaces the continuous distributed antenna system with discrete resonant segments that operate independently. This substitution allows for better control of energy distribution, as each segment can be individually optimized and controlled, reducing energy loss and improving control over the heating profile along the wellbore.
3Use of energy by stationary object
If conventional antennas are used, then RF energy can be transmitted to the wellbase, but uniform heating along long horizontal wells cannot be achieved
Solution Approach 1:
The patent segments the heating system into multiple vertically-distributed resonant antenna elements along the wellbore. This segmentation allows RF energy to be transmitted efficiently to each segment while achieving uniform heating along the entire wellbore length, as each segment contributes to the overall temperature distribution. The segmented approach resolves the contradiction by enabling both efficient energy transmission and uniform temperature composition.
Solution Approach 2:
The patent creates a series of resonant antenna segments that operate at the same resonant frequency, establishing an equipotential condition for RF energy distribution along the wellbore. This equipotential operation ensures uniform energy transmission and heating characteristics across all segments, achieving stable and uniform temperature distribution while maintaining efficient energy transmission.
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 solution enables efficient and controlled heating of high-viscosity hydrocarbons over long distances, increasing oil well productivity by achieving moderate and uniform temperature distribution, reducing energy expenditure, and allowing for the effective recovery of heavy oils without the need for large water consumption.
Implementation Method 1
the at least one mode converter being suitable for providing, in the presence of an RF signal along the coaxial transmission line, a disturbance of the differential mode of propagation of the signal along the coaxial transmission line and inducing a current in the external conductor of the coaxial transmission line and an electromagnetic field in the surrounding area which causes the hydrocarbons inside the reservoir to heat up
Implementation Method 2
RF heating of high-viscosity hydrocarbons in situ by means of an antenna comprising a coaxial array of mode converters
Data Source
AI summary
The present invention relates to a system for facilitating the extraction of hydrocarbons, in particular extraction by RF heating of high-viscosity hydrocarbons in situ by means of an antenna comprising a coaxial array of mode converters.