Pseudo Antenna Decoupling for Multisub Resistivity Logging
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Solution Overview
Problem
The complexity of wellbore and formation property measurements due to large spacing and mechanical variance between antennas in logging tools leads to inaccurate interpretation of raw responses, complicating the relation between component signals and formation properties.
Innovation Solution
A method for decoupling component signals from logging tools using pseudo antennas with specific azimuth offsets and attenuation/expansion factors, allowing for accurate determination of wellbore and formation properties by averaging and combining responses from multiple antennas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If large spacing between antennas is used in logging tools, then the tool can cover larger area and detect more formation properties, but the mechanical variance between antennas increases leading to inaccurate interpretation
Solution Approach 1:
The patent applies parameter changes by introducing azimuth offset as a new geometric parameter between transmitter and receiver antennas. Instead of using traditional collocated or simple spaced configurations, the invention specifies particular azimuth offset angles (e.g., 45 degrees) to decouple component signals. This parameter change transforms the antenna geometry to achieve both large spacing for area coverage and accurate component signal separation for measurement precision.
2Adaptability or versatility
If increased spacing between antennas is implemented, then more formation properties can be measured, but the relation between raw responses and formation properties becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-calculating and applying attenuation/expansion factors to compensate for the azimuth offset geometry before signal combination. The system预先 determines the appropriate mathematical factors based on the known azimuth offset angle and applies them to the raw antenna responses. This preliminary processing simplifies the subsequent interpretation by directly yielding decoupled component signals that have a clear relationship with formation properties, rather than leaving the complex geometric relationships to be resolved during data analysis.
3Adaptability or versatility
If mechanical variance between antennas increases due to large spacing, then tool flexibility is improved, but signal decoupling accuracy deteriorates
Solution Approach 1:
The patent addresses this contradiction by changing the geometric parameters to include specific azimuth offset angles that are optimized for signal decoupling. By setting the azimuth offset to specific values (such as 45 degrees), the invention creates a geometric configuration where the mathematical relationships between antenna responses and formation properties become more favorable. This parameter optimization allows the system to tolerate mechanical variance while maintaining decoupling accuracy, as the azimuth offset geometry provides a more robust mathematical foundation for signal separation.
Data Source
AI summary
Methods and systems for decoupling a component signal. A method may include disposing a logging tool in a wellbore, capturing a signal response with the logging tool from a formation, wherein the logging tool includes a first receiver, a second receiver, and a third receiver, averaging the first receiver and the third receiver to generate a first pseudo antenna, generating a second pseudo antenna which includes an azimuth offset, employing an attenuation factor and expansion factor to generate a pseudo collocated antenna. Furthermore combining responses from a transmitter, the first pseudo antenna, the second pseudo antenna, and the pseudo collocated antenna to decouple a component, which may determine the boundaries of a formation from the component. A well measurement system for decoupling a component may include a logging tool, conveyance, and information handling system. The logging tool may include a first downhole tool, a receiver, and a transmitter.