Ranging While Drilling Using Dynamic Magnetic Hot Spots
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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 well casing, which disrupts production and cannot be applied to wells already in service, and struggle to accurately detect the relative position and orientation of the casing to the drillstring at distances greater than a few meters.
Innovation Solution
A system and method that induces a dynamic magnetic hot spot on the casing using rotating magnets and an array of magnetometers in the drillstring, combined with phase-locked loops to enhance signal-to-noise ratio, allowing detection of the casing's magnetic field and estimation of relative distance and direction, even at distances of up to 10 meters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pre-polarization of the well casing is performed to enable passive ranging, then ranging capability is improved, but production is interrupted and the method cannot be applied to wells already in service
Solution Approach 1:
The patent applies preliminary action by pre-polarizing the well casing during the construction phase before the well is put into production. This allows the casing to have the necessary magnetic properties for passive ranging while avoiding interruption of production in existing wells. The polarization is performed once during construction, and the well can then be operated continuously without further interruptions for ranging purposes.
2Ease of operation
If passive ranging is performed at distances greater than a few meters, then drilling flexibility is improved, but detection accuracy deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the magnetic moment of the casing through controlled pre-polarization during construction. By adjusting the polarization parameters to create a stronger magnetic moment in the casing, the system extends the effective ranging distance to greater than a few meters while maintaining sufficient detection accuracy. This allows drilling flexibility to be improved without sacrificing measurement precision.
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 non-disruptive passive ranging during drilling, allowing for precise steering of the drill bit along a desired path relative to an existing well, improving the efficiency and accuracy of hydrocarbon extraction techniques like SAGD.
Implementation Method 1
A magnetic field source on the drillstring rotates to induce a magnetic moment in a nearby casing string
Implementation Method 2
A magnetometer on the drillstring measures a magnetic field produced by the induced magnetic moment
Data Source
Figure 1
Figure 2~3
Figure 4A~4B
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.