Unsynchronized Electromagnetic Logging via Multi-Frequency Phase Shift
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Solution Overview
Problem
Conventional electromagnetic logging techniques require synchronization between transmitters and receivers, which becomes problematic in deep resistivity measurements with significant spacing between antennas, limiting the accuracy of parameter estimation in earth formations.
Innovation Solution
The method involves using a single receiver to measure relative phase shift and attenuation of electromagnetic signals at different frequencies, where the second frequency is a positive whole number multiple of the first frequency, allowing for parameter estimation without synchronization, and using a multifrequency signal to generate propagation resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If synchronization is used between transmitters and receivers, then measurement accuracy is maintained, but device complexity and operational difficulty increase significantly in deep resistivity measurements
Solution Approach 1:
The patent extracts and eliminates the synchronization requirement from the electromagnetic logging system. By formulating measurement equations that inherently do not depend on synchronized timing between transmitters and receivers, the system removes the complex synchronization subsystem while maintaining measurement accuracy through mathematical relationships between multi-frequency signals
Solution Approach 2:
The patent changes the operational parameters by using multiple frequencies (first frequency and second frequency that is a positive whole number multiple of the first) instead of single frequency operation. This parameter change enables the system to determine formation properties through frequency-dependent attenuation and phase shift relationships without requiring temporal synchronization
2Length of stationary object
If significant spacing is used between antennas for deep resistivity measurements, then measurement depth is improved, but synchronization becomes increasingly problematic
Solution Approach 1:
The patent removes the synchronization dependency from the system, allowing large antenna spacings to be used without the operational difficulties that would otherwise arise. The measurement methodology is fundamentally changed to rely on frequency-domain relationships rather than time-domain synchronization, enabling practical deployment with significantly spaced antennas for deep formation investigation
3Measurement precision
If conventional electromagnetic logging with synchronization is used, then parameter estimation is possible, but the system becomes operationally complex and difficult to implement
Solution Approach 1:
The patent extracts the synchronization requirement from the measurement process, transforming the system from one requiring complex coordinated operation to one that is inherently simpler to implement. The multi-frequency transmission and reception system automatically provides the necessary information through frequency-dependent signal characteristics without requiring synchronized timing operations
Solution Approach 2:
The system uses the natural frequency-dependent attenuation and phase shift characteristics of electromagnetic waves propagating through the formation to self-determine formation parameters. The multi-frequency signals inherently provide reference relationships that eliminate the need for external synchronization mechanisms, making the system self-sufficient and operationally simple
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 enables accurate estimation of formation parameters like resistivity and dielectric constant without the need for synchronization, improving measurement accuracy in deep resistivity logging and reducing complexity in data acquisition.
Implementation Method 1
using at least one transmitter to initiate at a single location in the formation a first electromagnetic signal at a first frequency and a second electromagnetic signal at a second frequency different than the first frequency for propagation through the formation
Implementation Method 2
receiving the first electromagnetic signal propagating through the formation and the second electromagnetic signal propagating through the formation at a single receiver non-collocated with the at least one transmitter
Data Source
AI summary
Methods and apparatus for determining at least one parameter of interest of an earth formation. Methods include using at least one transmitter to initiate at a single location in the formation a first electromagnetic signal at a first frequency and a second electromagnetic signal at a second frequency different than the first frequency for propagation through the formation; receiving the first electromagnetic signal propagating through the formation and the second electromagnetic signal propagating through the formation at a single receiver non-collocated with the at least one transmitter; estimating a relative phase shift of the second electromagnetic signal relative to the first electromagnetic signal; estimating a relative attenuation of the second electromagnetic signal relative to the first electromagnetic signal; using the relative attenuation and the relative phase shift to estimate a parameter of interest of the formation. The receiver may be unsynchronized with respect to the transmitter.