Downhole Transient Resistivity Measurement Inversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current transient electromagnetic (EM) measurement techniques, such as deep transient logging while drilling (LWD), face challenges in reducing the time required for data inversion, especially for real-time inversion during LWD operations, due to the time-consuming numerical modeling of synthetic transient signals.
Innovation Solution
A method and apparatus that transform measured time domain transient electromagnetic (TEM) signals into frequency domain signals using a Fourier transform, allowing for the application of inversion techniques to estimate formation parameters, which reduces calculation time and improves efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If numerical modeling of synthetic transient signals is performed using inverse Fourier transform of frequency-dependent signals, then measurement precision is maintained, but processing time increases significantly
Solution Approach 1:
The patent inverts the conventional processing approach by transforming measured time-domain TEM signals into frequency-domain signals using Fourier transform, rather than transforming synthetic frequency-domain signals into time-domain signals. This allows direct application of frequency-domain inversion techniques to measured data, eliminating the time-consuming inverse Fourier transform step while maintaining measurement accuracy.
2Productivity
If real-time inversion is performed during LWD operations, then productivity is improved, but calculation complexity increases due to time-consuming numerical modeling
Solution Approach 1:
The patent changes the domain parameter from time-domain to frequency-domain processing. By applying Fourier transform to convert measured time-domain TEM signals into frequency-domain signals, the inversion problem is transformed into a form that can be solved more efficiently using frequency-domain techniques, reducing computational complexity for real-time applications.
3Speed
If shorter time intervals are used for signal measurement, then processing speed increases, but signal accuracy may be compromised
Solution Approach 1:
The patent transitions from time-domain to frequency-domain analysis, adding a dimensional transformation to the measurement process. This allows the use of shorter measurement time intervals because the Fourier transform efficiently captures signal characteristics in the frequency domain, maintaining accuracy while enabling faster processing.
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 significantly reduces the processing time for applying modeling and inversion algorithms, enabling the use of shorter time intervals for accurate frequency signal recovery, thus enhancing the speed and accuracy of formation property estimation during LWD operations.
Implementation Method 1
transmitting an electromagnetic pulse from the transmitter into the formation and measuring a time domain transient electromagnetic (TEM) signal
Data Source
AI summary
A method of processing electromagnetic signal data includes: disposing a downhole tool in a borehole in an earth formation, the downhole tool including at least one electromagnetic transmitter; performing a downhole electromagnetic operation, the operation including transmitting an electromagnetic pulse from the transmitter into the formation and measuring a time domain transient electromagnetic (TEM) signal over a selected time interval following a transmitter turn-off time; transforming the measured time domain TEM signal into a frequency domain TEM signal measured; and applying an inversion technique to the transformed frequency domain TEM signal to estimate one or more formation parameters.