Downhole Drill Bit Rotation Control via Spaced Magnetometers
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Solution Overview
Problem
Existing drilling technologies face inefficiencies in transmitting rotational torque to the drill bit due to drag, which is exacerbated by factors like borehole curvature, deformation, and noise from drilling operations, making accurate downhole measurements challenging for determining drill bit wear and drilling direction.
Innovation Solution
The use of magnetometers or accelerometers placed at spaced-apart locations along the drill string to measure field components and determine relative rotation, enabling a data processing system to calculate and reduce drag by adjusting the drill string rotation and torque application near the drill bit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If downhole measurements are taken using traditional strain gages or magnetometers during drilling, then torque and rotation data can be obtained, but measurement precision deteriorates due to noise, shock, and vibrations from drilling operations
Solution Approach 1:
The patent extracts the measurement function from the harsh drilling environment by using magnetometers to measure the Earth's magnetic field rather than directly measuring torque in the noisy environment. The magnetic field measurements are taken downhole but are not affected by drilling vibrations, and the torque is calculated indirectly from the relative rotation between spaced-apart magnetometers, effectively removing the measurement system from the harmful vibrational environment.
Solution Approach 2:
The patent introduces the Earth's magnetic field as an intermediary medium for measurement. Instead of directly measuring torque with strain gages in the noisy drilling environment, magnetometers measure the magnetic field vector, which serves as an intermediary that can be measured accurately even during drilling operations. The relative rotation is then calculated from changes in this intermediary magnetic field measurement.
2Productivity
If the drill string is rotated to transmit torque to the drill bit, then drilling progress is achieved, but drag increases due to borehole curvature, deformation, and stabilizer packing
Solution Approach 1:
The patent implements feedback by continuously measuring the relative rotation between spaced-apart magnetometers along the drill string and using this information to calculate actual torque at the drill bit. This feedback allows operators to monitor drag conditions in real-time and adjust drilling parameters to optimize torque transmission and reduce energy loss to drag.
Solution Approach 2:
The patent replaces direct mechanical torque measurement with a magnetic field-based measurement system. Instead of using mechanical strain gages that are affected by drilling vibrations and drag, magnetometers use the Earth's magnetic field to determine relative rotation, which is then used to calculate torque. This substitution eliminates the direct mechanical connection that transmits drag forces to the measurement system.
3Measurement precision
If separate borehole surveys are conducted when drilling is stopped, then survey accuracy is improved, but productivity decreases due to drilling interruptions
Solution Approach 1:
The patent enables continuous measurement during drilling operations by using magnetometers that can accurately measure the magnetic field even in the presence of drilling vibrations and movements. The spaced-apart magnetometers continuously track relative rotation, providing uninterrupted torque and rotation data without requiring drilling to be stopped, thus maintaining both measurement quality and drilling productivity.
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 method allows for more accurate and efficient control of drill bit rotation, reducing drag and improving torque transmission, thereby enhancing drilling efficiency and preventing issues like stuck drill strings by identifying and mitigating environmental factors contributing to torque loss.
Implementation Method 1
measuring at spaced-apart locations with at least one magnetic field responsive measuring instrument proximate the drill bit, a plurality of components of a magnetic field strength
Implementation Method 2
measuring at spaced-apart locations with at least one gravitational field responsive measuring instrument proximate the drill bit, a plurality of components of a field strength
Data Source
AI summary
An apparatus and method to control the rotation of a downhole drill bit are disclosed. A pair of spaced-apart measuring or survey instruments at the drill string provide data that is analyzed to determine relative rotation between the instruments so that drag affecting the drill bit may be reduced.