Rotating Collar Magnetic Sensing for Dogleg Severity Estimation
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Solution Overview
Problem
Existing automated drilling methods for measuring dogleg severity (DLS) in wellbores require a-priori knowledge of depth and rate of penetration, which are not readily available downhole.
Innovation Solution
A method using a roll-stabilized sensor housing with magnetic field sensors in a rotating collar to measure cross-axial magnetic fields, identifying distortions in these fields to estimate DLS without requiring depth or penetration rate information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If single sensor measurements are used to measure DLS, then measurement capability is improved, but the method requires a-priori knowledge of depth and rate of penetration which are not readily available downhole
Solution Approach 1:
The system uses the drill collar's own rotation to generate the magnetic field measurements. The rotating collar itself serves as the source of the magnetic field distortion that is measured, eliminating the need for external reference frames or a-priori depth information. The measurement system leverages the natural rotational motion already present in the drilling operation.
Solution Approach 2:
The patent replaces mechanical measurement systems (which would require depth tracking and ROP data) with a magnetic field-based measurement system. By using magnetic field sensors to detect distortions in the field generated by rotating magnets in the collar, the system substitutes mechanical/kinematic measurements with magnetic field measurements that can be taken without knowing depth or penetration rate.
2Measurement precision
If accelerometer or magnetometer sets are used to measure DLS, then measurement capability is improved, but device complexity increases due to requiring multiple sensors and a-priori knowledge
Solution Approach 1:
The patent combines the magnetic field generation function and measurement function into a single integrated system. The same rotating collar that is part of the drilling tool also generates the magnetic field and houses the sensors. This merging eliminates the need for separate, independent sensor sets and reduces the complexity of coordinating multiple measurement systems.
Solution Approach 2:
The rotating collar serves multiple functions: it is a structural component of the drilling tool, a source of magnetic field distortion, and a housing for the magnetic field sensors. This multi-functionality reduces the overall device complexity by eliminating the need for dedicated separate measurement components and reducing the number of a-priori parameters that need to be known or measured.
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 accurate estimation of DLS by analyzing distortions in magnetic field measurements, providing a reliable method for determining DLS without relying on depth or penetration rate data.
Implementation Method 1
The sensor housing includes a magnetic field sensor deployed therein. The collar includes at least first and second magnets deployed thereon. The magnetic field sensor makes cross-axial magnetic field measurements while the collar rotates.
Data Source
AI summary
A method for estimating dogleg severity includes rotating the downhole tool in a wellbore. The downhole tool includes a roll stabilized sensor housing deployed in a rotating collar. The collar includes at least first and second magnets deployed thereon. Cross-axial magnetic field measurements are made using a magnetic field sensor deployed in the sensor housing while the collar rotates. A distortion is identified in the magnetic field measurements. The dogleg severity is estimated from the distortion.