Down-hole Drill Face Orientation via Magnetic Field Sensing
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Solution Overview
Problem
Current borehole drilling techniques face challenges in precision and accuracy, particularly when drilling under obstacles like railroad tracks or rivers, due to the complexity and cost of down-hole systems and limitations in determining drill bit and bent sub orientation.
Innovation Solution
A self-contained down-hole system using dual concentric drill rods with permanent magnets and sensors to control the drill face orientation and determine drilling direction, employing gravity and magnetic field data for precise horizontal path tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a down-hole motor with hydraulic drive system and electrical signaling infrastructure is used to control drill face orientation, then drilling direction control is achieved, but system cost and complexity increase significantly
Solution Approach 1:
The patent extracts the magnetic field sensing capability from complex down-hole electrical systems and uses it to determine drill face orientation. By utilizing the Earth's magnetic field and permanent magnets attached to the drill rod, the system obtains orientation data without requiring complex hydraulic motors and electrical signaling infrastructure down-hole.
Solution Approach 2:
The patent replaces the mechanical-hydraulic control system with a magnetic sensing system. Instead of using hydraulic motors and electrical signals to control and measure drill face orientation, the system uses magnetic field interactions between permanent magnets on the drill rod and sensors at the surface to determine orientation non-contactively.
2Power
If conventional dual coaxial drill rods with screw connections are used, then drilling power transmission is achieved, but determination of bent sub orientation becomes difficult due to unknown relative orientations
Solution Approach 1:
The patent introduces permanent magnets as an intermediary element attached to the bent sub or drill rod. These magnets create a magnetic field that serves as a reference, allowing the orientation of the bent sub to be determined relative to the drill rod axis without requiring precise mechanical alignment or knowledge of screw connection orientations.
Solution Approach 2:
The patent uses magnetic field distribution patterns (analogous to color changes) to encode orientation information. By analyzing the spatial distribution of the magnetic field generated by permanent magnets on the drill rod, the system can determine the relative orientation of the bent sub regardless of mechanical connection uncertainties.
3Measurement precision
If walk over electromagnetic transmitter systems are used to determine drill location and orientation, then basic measurement capability is provided, but vertical range is limited and accessibility requirements restrict usage
Solution Approach 1:
The patent replaces the walk-over electromagnetic transmitter system with a magnetic field sensing system that operates through the drill rod structure itself. Permanent magnets on the drill rod create a magnetic field that can be detected by sensors at the surface, eliminating the need for physical access to the drill location and extending operational range.
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 enhances drilling precision and accuracy by allowing simultaneous determination of drill face orientation, azimuth, and inclination, enabling the borehole to follow a prescribed path under obstacles with increased reliability and reduced operational costs.
Implementation Method 1
The down hole portion of the drilling apparatus includes a pair of permanent magnets mounted on an outer drilling rod
Implementation Method 2
employing gravity and magnetic field data for precise horizontal path tracking
Implementation Method 3
The apparatus is configured to control the roll angle of the outer drill rod to a known angle with respect to the borehole high side direction using gravity and magnetic field data
Data Source
AI summary
The present invention is directed to tracking a borehole drilling direction and magnetic azimuth and orienting the tool face which controls the direction of drilling in a generally horizontal path between a specified borehole entry point and a predetermined exit location. The generally horizontal path may be disposed under a geographic obstacle such a river, a highway, a railroad, or an airport runway wherein the ground above the borehole is difficult or impossible to access.