Fractal Antenna Array for Deep Borehole Dielectric Logging
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Solution Overview
Problem
Conventional resistivity and dielectric tools used in earth formations are limited by physical size constraints, compromising their ability to efficiently probe deep into the formations, which is a challenge in hydrocarbon production, geothermal production, and carbon dioxide sequestration.
Innovation Solution
The use of fractal-shaped antenna elements, where a first antenna is connected to a mirror image of itself at a connection point, allowing for improved electromagnetic energy transmission and reception without the need for a large impedance matching network, enabling deeper probing into earth formations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional coil antennas are used in resistivity and dielectric tools, then the tools can measure electrical characteristics of earth formations, but the physical size constraints compromise transmitting efficiency and probing depth
Solution Approach 1:
The patent transitions from conventional planar coil antennas to three-dimensional fractal antenna structures. The fractal geometry embeds multiple antenna elements within a compact volume through recursive patterning, effectively utilizing spatial dimensionality to achieve extended electrical length and improved transmitting efficiency without increasing the overall tool footprint.
Solution Approach 2:
The fractal antenna design implements nesting by placing smaller antenna elements within the structure of larger elements, creating a self-similar pattern where multiple functional units are contained within a compact overall structure. This nested configuration allows the antenna to present an extended electrical length while occupying minimal physical space.
2Power
If fractal-shaped antenna elements are used, then transmitting efficiency and gain are improved, but the antenna design becomes more complex
Solution Approach 1:
The fractal antenna structure serves multiple functions simultaneously: it acts as both the radiating element and its own impedance matching network. The self-similar geometry inherently provides broadband operation and automatic impedance transformation, eliminating the need for separate matching components and reducing overall device complexity despite the intricate antenna shape.
Solution Approach 2:
The patent merges the antenna radiating structure with the impedance matching network into a single integrated fractal geometry. The fractal pattern itself performs the impedance transformation function that would traditionally require separate L-network or Pi-network components, combining multiple functions into one unified structure.
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 configuration provides a wide useful frequency bandwidth and increased gain over prior art antennas, potentially eliminating the need for an impedance matching network, thus allowing for more effective resistivity and dielectric measurements in earth formations.
Implementation Method 1
a first fractal-shaped antenna element disposed on the carrier and configured to at least one of transmit electromagnetic energy into the formation and receive electromagnetic energy from the formation
Data Source
AI summary
An apparatus for estimating a property of an earth formation includes: a carrier configured to be conveyed through a borehole penetrating an earth formation; a first fractal-shaped antenna element disposed on the carrier and configured to at least one of transmit electromagnetic energy into the formation and receive electromagnetic energy from the formation; and a second fractal-shaped antenna element electrically connected to the first fractal-shaped antenna element at a connection and configured to at least one of transmit electromagnetic energy into the formation and receive electromagnetic energy from the formation; wherein the second fractal-shaped antenna element is substantially a mirror image of the first fractal antenna element with respect to a reflection about the connection.