Borehole Geometry Estimation via Iterative Sector Displacement
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Solution Overview
Problem
Existing methods for estimating borehole geometry during drilling are limited by assumptions of elliptical shapes and fail to accurately account for lateral movement of the drilling unit, leading to inaccurate geometry calculations.
Innovation Solution
A method and apparatus that utilize multiple transducers to perform borehole caliper measurements, dividing the borehole cross-section into sectors, calculating representative radii, and iteratively adjusting measurements based on displacement vectors to estimate the borehole geometry, capable of handling arbitrary shapes and lateral motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional methods assume elliptical borehole geometry, then the calculation process is simplified, but the measurement precision deteriorates because arbitrary borehole shapes cannot be accurately represented
Solution Approach 1:
The borehole cross-section is divided into multiple sectors, with each sector's geometry independently determined by representative radius points. This segmentation allows the method to handle arbitrary borehole shapes without requiring a global geometric assumption, thereby improving measurement precision while keeping each local calculation simple.
Solution Approach 2:
The method dynamically adjusts the representative radius points and displacement vectors based on actual measurement data from multiple transducers. Instead of using a fixed elliptical model, the geometry adapts to the actual borehole shape, resolving the contradiction between computational simplicity and geometric accuracy.
2Ease of operation
If standoff measurements are taken without accounting for lateral movement, then the measurement process is simpler, but the measurement precision deteriorates due to unknown BHA center trajectory
Solution Approach 1:
The method uses feedback from multiple transducer measurements to iteratively determine the displacement vector and adjust the representative radius points. By continuously refining the BHA center position based on measurement inconsistencies, the system achieves high measurement precision without requiring prior knowledge of the lateral movement trajectory.
Solution Approach 2:
Instead of directly tracking the physical BHA center position, the method creates a mathematical model (copy) of the BHA center trajectory through iterative calculation of displacement vectors. This virtual model allows accurate compensation for lateral movement without requiring direct physical measurement of the center position.
3Measurement precision
If multiple transducers are used to perform caliper measurements at multiple times, then the borehole geometry estimation precision is improved, but the device complexity and measurement time increase
Solution Approach 1:
The borehole cross-section is divided into multiple sectors, with each sector independently analyzed using measurements from available transducers. This segmentation allows the system to achieve high geometry estimation precision without requiring a complete set of transducers at every measurement time, thereby reducing device complexity.
Solution Approach 2:
The method uses representative radius points sampled at selected angular positions rather than requiring continuous measurement coverage. This partial action approach achieves sufficient geometry estimation precision with fewer transducers and measurement points, reducing both device complexity and measurement time.
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 allows for precise estimation of arbitrary borehole geometry, accurately accounting for lateral motion and tool position, providing a robust and flexible solution that does not assume elliptical shapes, suitable for real-time drilling applications.
Implementation Method 1
Each transducer measures the distance (i.e., standoff) from itself to the borehole wall in the direction of the acoustic waves
Data Source
AI summary
Disclosed is a method for estimating a geometry of a borehole penetrating the earth. The method includes: performing a plurality of borehole caliper measurements with N transducers at a plurality of times, wherein for each time a measurement set comprises measurements made by the N transducers at that time; dividing a cross-section of the borehole into S sectors; obtaining an estimate of the borehole geometry by connecting representative radius points in adjacent sectors; displacing each measurement set according to a displacement vector related to an offset of each measurement set from the estimated geometry if the displacement vector exceeds a selection criterion; iterating the obtaining an estimate of the borehole geometry and the displacing each measurement set based on a latest displacement vector; and providing a latest obtained estimate as the geometry of the borehole when all of the displacement vectors no longer exceed the selection criterion for the displacing.