Rotating Magnetic Field Range Finder for Drilling Well Separation
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Solution Overview
Problem
Current magnetic field range finder methods for measuring relative distance between drilling wells suffer from increased ellipse uncertainty and cumulative errors, especially in three-dimensional well placements, making it difficult to achieve accurate distance measurements.
Innovation Solution
A rotating magnetic field range finder system comprising a permanent magnet drill collar sub and a downhole sensor tool with tri-axial fluxgate magnetometers and accelerometers, which generates and measures a rotating magnetic field to calculate the separation and direction between the drill bit and the target well, using a 3D image construction method to improve accuracy and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MWD method is used for three-dimensional well placement, then directional and horizontal wells can be achieved, but cumulative errors will exceed tolerances and measurement accuracy will deteriorate
Solution Approach 1:
The patent introduces a magnetic field as an intermediary physical quantity to establish a direct measurement relationship between the drill bit and target well. By using magnetic field intensity measurements and applying the inverse square law, the system calculates relative distance directly without relying on cumulative MWD data, thereby eliminating cumulative errors and improving measurement precision while maintaining reliability
Solution Approach 2:
The patent replaces the mechanical/MWD-based measurement system with a magnetic field-based measurement system. Instead of relying on mechanical sensors and cumulative directional data processing, the system uses magnetic field intensity measurements combined with mathematical modeling to directly determine relative distance, significantly improving measurement accuracy
2Length of stationary object
If permanent magnet is used as magnetic field source, then sensitive distance is farther compared to solenoid or magnetized casing, but measurement distance and reliability need to be improved
Solution Approach 1:
The patent makes the permanent magnet rotate together with the drill bit, creating a dynamic rotating magnetic field. This dynamic configuration allows the magnetic field orientation to change continuously, providing multiple measurement angles and enabling more reliable distance calculations through mathematical modeling and data processing
Solution Approach 2:
The patent changes the orientation parameter of the permanent magnet by rotating it with the drill bit. This parameter change creates a rotating magnetic field with varying intensity and direction, allowing the system to gather measurement data from multiple orientations and improve measurement reliability through comprehensive data analysis
3Measurement precision
If dipole magnetic field distribution is used to calculate distance, then calculation can be performed, but accuracy is affected by drill bit, mud motor permeability and target well interference
Solution Approach 1:
The patent uses two permanent magnets instead of one, creating an excessive magnetic field configuration. This allows the system to measure magnetic field intensity at multiple locations and use mathematical modeling to eliminate the effects of interfering factors, thereby improving distance calculation accuracy despite the presence of magnetic field interference from drill bit, mud motor, and target well
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
The system provides precise and reliable measurements of relative separation and direction between drilling wells, reducing errors and enhancing measurement accuracy, suitable for complex well placements like intersection and horizontal wells, and applicable in various drilling applications such as SAGD and coal-bed methane development.
Implementation Method 1
The permanent magnet drill collar sub...rotates together with the drill bit to generate the rotating magnetic field for providing the magnetic field signal source
Implementation Method 2
the tri-axial fluxgate magnetometer...measuring the rotating magnetic field components at the drill bit position
Implementation Method 3
together with the accelerometer to establishing the Earth's gravity and terrestrial magnetic field coordinates
Data Source
AI summary
A rotating magnetic field range finder for measuring relative distance in drilling, comprising a permanent magnet steel drill collar (1), an underground detector (2) and a ground interface box (3). The permanent magnet steel drill collar (1) is fixed to the rear part of a drill bit and rotates together with the drill bit to generate a rotating magnetic field to provide a magnetic field signal source. The underground detector (2) comprises two tri-axial fluxgates and three accelerometers. The ground interface box (3) is used for processing the obtained data, and powering the underground detector. The permanent magnet steel drill collar (1) is an obliquely arranged one or a perpendicularly-and-parallelly assembled one. A measuring method for magnetic range measurement is also disclosed.