Gradiometric Ranging Using Magnetic Dipole Transmitters
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional downhole ranging methods are ineffective in accurately determining the position and direction of T-intersecting wellbores due to sensitivity issues and cancellation of magnetic fields, particularly in T-intersection scenarios.
Innovation Solution
A downhole ranging system utilizing magnetic dipole transmitters and receivers that analyze gradiometric data to determine the distance and direction of T-intersecting wellbores by generating an electromagnetic field, measuring the induced magnetic field and its gradient, and using processing circuitry to calculate the relative position, with bucking receivers to eliminate direct signals and enhance sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional coil antennas or electrode sources are used to measure magnetic field amplitude or gradient, then ranging capability is provided, but measurement precision deteriorates in T-intersection scenarios due to field cancellation
Solution Approach 1:
The patent changes the measurement parameter from magnetic field amplitude or first derivative (gradient) to the second derivative (curvature) of the magnetic field. This parameter transformation allows accurate measurement in T-intersection scenarios where conventional methods fail due to field cancellation, as the second derivative remains sensitive to the target casing even when the first derivative becomes zero.
2Measurement precision
If magnetic field gradient is measured to determine range to target casing, then positioning information is obtained, but sensitivity is lost when true T-intersection occurs due to field cancellation at receiver location
Solution Approach 1:
The invention transitions from measuring the first derivative (magnetic field gradient) to measuring the second derivative (curvature) of the magnetic field. This parameter change ensures that measurement sensitivity is maintained in T-intersection scenarios where the first derivative becomes zero due to field cancellation, allowing reliable detection and ranging throughout the entire drilling process.
3Loss of information
If amplitude of induced field is measured to determine target position, then location information is obtained, but measurement precision deteriorates due to strong dependence on casing and formation properties
Solution Approach 1:
The patent measures the second derivative (curvature) of the magnetic field rather than the amplitude or first derivative. This parameter transformation reduces the influence of casing and formation properties on measurement accuracy, as the curvature measurement is less sensitive to variations in these parameters compared to amplitude-based methods.
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 accurate and reliable positioning for well avoidance and intersection applications, maintaining sensitivity in T-intersection scenarios and reducing errors in distance and direction calculations, even at greater distances from the target well.
Implementation Method 1
inducing a current along the target wellbore that results in a magnetic field being radiated from the target wellbore
Implementation Method 2
measuring the magnetic field and its gradient
Data Source
AI summary
A ranging system utilizes gradiometric data to determine the direction to and distance between a first and second well without any knowledge or involvement of the borehole or formation characteristics in order to intersect and/or avoid the second well. In general, this is achieved by deploying a downhole assembly comprising transmitters and receivers having magnetic dipoles, along with bucking receivers positioned between the transmitters and receivers.