Ranging While Drilling Using Rotating Magnets
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Solution Overview
Problem
Existing passive ranging techniques for drilling near existing wells are limited by the need for pre-polarization of the casing, which disrupts well operations and cannot be applied to wells already in service, and they rely on magnetic 'hot spots' that are not always present, making it difficult to accurately locate the casing without interrupting production.
Innovation Solution
A system that induces a dynamic magnetic hot spot on the casing using rotating magnets and magnetometers in the drillstring, combined with phase-locked loops, to detect the magnetic field and infer the relative position and orientation of the casing, allowing for accurate ranging without pre-polarization and enabling detection at distances of at least 10 meters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pre-polarization of the casing is performed to enable passive ranging, then magnetic hot spots are created for detection, but well operations must be interrupted and production is disrupted
Solution Approach 1:
The patent applies preliminary action by pre-polarizing the casing during the well construction phase before the well goes into production. This allows the magnetic hot spots to be created in advance, enabling passive ranging operations to proceed without interrupting production. The polarization is performed as part of the initial well setup rather than as a separate intervention later.
Solution Approach 2:
The patent introduces dynamics by using rotating magnets on the drillstring to dynamically generate magnetic fields that induce alternating magnetic moments in the casing. This dynamic approach creates detectable magnetic signatures without requiring static pre-polarization, allowing ranging operations to proceed while maintaining well production continuity.
2Measurement precision
If pre-polarization is performed to create magnetic hot spots, then casing can be detected, but the technique cannot be applied to wells already in service
Solution Approach 1:
The patent applies dynamics by using rotating magnets to generate time-varying magnetic fields that induce alternating magnetic moments in the casing. This dynamic induction works on both pre-polarized and non-polarized casings, making the technique universally applicable to all wells regardless of their service status or initial magnetic state.
Solution Approach 2:
The patent changes the magnetic field parameters by using rotating magnets to create time-varying fields with specific frequencies and orientations. This allows the system to detect casings through induced magnetic moments without relying on the static pre-polarization state, thereby expanding applicability to wells already in service.
3Length of stationary object
If rotating magnets are used to induce dynamic magnetic hot spots, then casing can be detected at greater distances, but the system complexity increases
Solution Approach 1:
The patent applies universality by using the rotating magnets and magnetometers for multiple functions: they serve both as the magnetic field source and as the detection sensors. This multi-functionality reduces the need for separate specialized components, thereby limiting the increase in system complexity despite the extended detection distance capability.
Solution Approach 2:
The patent uses the casing itself as an intermediary element. The rotating magnets induce magnetic moments in the casing, which then acts as a secondary source that enhances the magnetic signal for detection. This intermediary approach allows detection at greater distances without requiring directly more powerful magnets or complex sensor arrays.
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 reliable and precise directional drilling near existing wells without interrupting well operations, allowing for the detection of the casing at greater distances and orientations, improving the accuracy and efficiency of drilling operations.
Implementation Method 1
A magnetic source on the drillstring induces a magnetic moment in a nearby casing string
Implementation Method 2
A magnetometer on the drillstring measures a magnetic field from the induced magnetic moment
Data Source
AI summary
An improved system and method for ranging while drilling, in effect, induces a dynamic hot spot on the casing of a nearby well. The induced hot spot acts as a magnetic source that can be reliably detected from within the drillstring and in such a manner as to infer the relative position and orientation of the casing to the drillstring. At least some disclosed method embodiments employ one or more rotating magnets in the drillstring, an array of at least two magnetometers in the drillstring and one or more phase-locked loops that are used to enhance the signal to noise ratio of the magnetic signal scattered off of the casing from the rotating magnetic field. The rotating magnet or magnets may be magnetic dipoles or magnetic multipoles, and may be modulated to enable the use of multiple magnetic field sources.