Ultrasonic Caliper Borehole Shape Estimation
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Solution Overview
Problem
Current methods for identifying borehole shapes, particularly those with keyseats, are inaccurate due to presuming circular or elliptical shapes, leading to erroneous center and shape characterization.
Innovation Solution
A system and method utilizing ultrasonic caliper measurements and weighted circle fitting with tool-eccentric penalization to accurately identify keyseats and characterize borehole shapes, accounting for distorted measurements and tool offset.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional circle fitting algorithms are used to characterize borehole shape, then the processing is simple and fast, but the measurement precision deteriorates when keyseats are present
Solution Approach 1:
The algorithm segments the borehole cross-section into multiple radial measurements from the tool center to the borehole wall. By dividing the continuous borehole shape into discrete radial segments, the algorithm can identify keyseat features as localized deviations in specific segments while maintaining overall circular/elliptical fitting, thus improving measurement precision without requiring completely complex new methodologies
Solution Approach 2:
The algorithm performs preliminary identification of keyseat features by detecting radial measurements that significantly deviate from the fitted circle or ellipse before final shape characterization. This preliminary detection allows the system to flag and handle keyseat regions specially, improving overall accuracy by addressing distortions early in the processing sequence
2Reliability
If the borehole is presumed to be circular or elliptical, then the center determination is straightforward, but the reliability deteriorates when keyseats distort the shape
Solution Approach 1:
The algorithm uses iterative feedback where the fitted circle or ellipse is continuously refined based on residual errors between measured radial points and the fitted shape. Keyseat-induced deviations generate feedback signals that allow the algorithm to adjust the center position and shape parameters iteratively, improving reliability of center estimation even in the presence of distortions
Solution Approach 2:
The algorithm changes parameters by transitioning from simple circular fitting to elliptical fitting, and further to modified fitting models that account for localized keyseat distortions. By adjusting fitting parameters and model complexity adaptively, the system maintains reliable center determination while accommodating shape variations caused by keyseats
3Measurement precision
If acoustic pulses are emitted to measure borehole shape, then non-contact measurement is achieved, but measurement precision deteriorates due to tool offset from borehole center
Solution Approach 1:
The system replaces mechanical contact-based centering mechanisms with acoustic field-based measurement and computational center determination. By using acoustic pulse travel time measurements from multiple transducers and computationally determining the center that best fits all measurements, the system achieves high precision standoff measurement without complex mechanical tool positioning
Solution Approach 2:
The acoustic transducers serve multiple functions: they emit acoustic pulses for measurement, receive reflected echoes, and their spatial arrangement provides geometric constraints for center determination. This multi-functionality allows the same device components to perform both measurement and positioning reference functions, improving precision without adding separate positioning mechanisms
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
Provides high-accuracy and robust tool center estimation, enabling reliable borehole characterization and improved drilling operations by accurately modeling borehole shapes and keyseat locations.
Implementation Method 1
transmitting an acoustic pressure pulse with the transducer and recording the reflected echo
Implementation Method 2
transmitting an acoustic pressure pulse with the transducer and recording the reflected echo
Data Source
AI summary
A method for identifying a shape of a borehole may comprise disposing a measurement assembly into the borehole, transmitting a pressure pulse from the at least one transducer, recording the echo with the at least one transducer producing data points based at least in part on the echo to determine a distance from an inner wall of the borehole to the measurement assembly; performing a kurtosis on the data points; comparing a result of the kurtosis to a pre-determined threshold; and producing one or more repositioning results based at least in part on the comparing the result of the kurtosis to the pre-determined threshold. A system may comprise a measurement assembly which may include at least one transducer connected to the measurement assembly and an information handling system.