Triaxial Antenna Logging Tool Formation Resistivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing logging tools face challenges in accurately measuring formation resistivity and conductivity during drilling, particularly in harsh drilling environments, due to limitations in borehole compensation and gain corrections, which affect the reliability of real-time data collection.
Innovation Solution
A logging-while-drilling tool equipped with a plurality of triaxial antennas that use propagation-style measurements to form impedance matrices, eliminating gain factors and providing borehole-compensated phase shift and attenuation responses, allowing for accurate formation evaluation without a priori assumptions about the formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional logging tools are used in harsh drilling environments, then real-time formation evaluation measurements can be obtained, but measurement accuracy deteriorates due to gain errors and tool orientation variations
Solution Approach 1:
The patent applies feedback by using multiple triaxial antenna measurements to determine actual tool orientation and gain factors, then using this information to correct the formation resistivity and conductivity measurements. The system continuously monitors measurement quality and applies corrections based on the determined parameters, creating a closed-loop measurement system that compensates for environmental disturbances.
Solution Approach 2:
The patent changes the measurement parameters by transitioning from conventional single-antenna resistivity measurements to multi-antenna triaxial measurements. By measuring electromagnetic fields in multiple orientations (x, y, z directions) and at multiple positions, the system obtains sufficient data to solve for both formation properties and tool parameters simultaneously, enabling accurate measurements despite tool orientation variations.
2Reliability
If borehole compensation methods are applied to correct for drilling fluid effects, then formation measurement reliability improves, but device complexity increases due to additional measurements and processing requirements
Solution Approach 1:
The patent applies universality by designing a multi-antenna system that serves multiple functions: it measures formation resistivity and conductivity, determines tool orientation, calculates gain factors, and performs borehole compensation all within a single integrated tool. The triaxial antenna array can operate in different measurement modes, making the device versatile and reducing the need for separate correction tools or procedures.
Solution Approach 2:
The patent merges multiple measurement functions into a single integrated system. Instead of using separate tools for formation evaluation and tool orientation monitoring, the system combines triaxial antenna arrays that simultaneously perform both functions. The same electromagnetic field measurements used for formation evaluation also provide information about tool orientation and drilling fluid effects, consolidating multiple measurement objectives into one unified approach.
3Measurement precision
If triaxial antenna measurements are used to improve formation evaluation accuracy, then measurement precision improves, but the complexity of data processing and analysis increases
Solution Approach 1:
The patent applies segmentation by dividing the complex triaxial measurement data into separate component measurements along the x, y, and z directions. Each directional measurement is processed independently to extract formation properties, and the results are then integrated to provide the complete formation evaluation. This segmented approach simplifies the processing of what would otherwise be an overwhelming amount of three-dimensional electromagnetic field data.
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
Enables precise and reliable measurement of formation resistivity and conductivity, improving data accuracy and extending borehole compensation to triaxial measurements, even in complex anisotropic formations, by compensating for gain errors and tool orientation variations.
Implementation Method 1
A logging-while-drilling tool equipped with a plurality of triaxial antennas that use propagation-style measurements to form impedance matrices
Data Source
Figure 1
Figure 2~3
Figure 4A~4F
AI summary
A logging tool having a plurality of spatially separated antennas is provided and used to make propagation-style measurements in a formation. Tensors are formed using the propagation-style measurements and one or more quantities are computed using the tensors. A formation evaluation is performed using the computed quantities. The formation evaluation determines a formation property or parameter such as horizontal resistivity, vertical resistivity, relative dip, azimuthal dip, bed boundary location, or bed thickness. The computed quantities may include compensated phase shift resistivity, compensated attenuation resistivity, symmetrized phase shift resistivity, symmetrized attenuation resistivity, anti-symmetrized phase shift resistivity, and anti-symmetrized attenuation resistivity. The measurements may be corrected for antenna gain errors and an air calibration may be performed. A zero-dimension inversion may be performed, while drilling, and the determined horizontal resistivity, vertical resistivity, relative dip, and/or azimuthal dip information may be sent to an uphole processor in real-time.