Rotating Magnet Borehole Proximity Measurement
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Solution Overview
Problem
Current methods for determining the distance to a pre-existing wellbore during drilling operations are inaccurate due to limitations in passive ranging techniques, such as interference from the Earth's magnetic field and residual magnetism in the casing, which can result in significant errors in drilling precision.
Innovation Solution
An apparatus and method using a rotating magnet in the drilling tool to induce a primary magnetic field in the pre-existing wellbore, with a stationary sensor detecting the secondary magnetic field to calculate the distance between the two boreholes, effectively separating the signal from the Earth's magnetic field noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If passive ranging techniques using Earth's magnetic field are used to determine distance to pre-existing wellbore, then the measurement can be performed without accessing the pre-existing well, but the accuracy is limited due to interference from Earth's magnetic field and residual magnetism in the casing
Solution Approach 1:
The patent applies periodic action by rotating the magnet in the drilling tool to generate a time-varying magnetic field. This rotating magnetic field induces a corresponding time-varying magnetic field in the magnetic object within the pre-existing wellbore casing. The periodic nature of this interaction allows the system to distinguish the induced signal from static interference sources like Earth's magnetic field and residual magnetism, thereby improving measurement accuracy while maintaining the advantage of non-contact measurement.
2Measurement precision
If a rotating magnet is used to induce a primary magnetic field in the pre-existing wellbore, then accurate distance measurements can be obtained, but the device complexity increases due to the need for rotation mechanisms and signal separation systems
Solution Approach 1:
The patent employs an intermediary approach by introducing a magnetic object within the pre-existing wellbore casing as a mediator. The rotating magnet in the drilling tool generates a primary magnetic field that induces a secondary magnetic field in this intermediate magnetic object. The sensor then detects this induced secondary field rather than directly measuring the primary field. This intermediary mechanism simplifies the overall system by allowing the use of standard rotation and sensing components while achieving accurate distance measurements through the induced field interaction.
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 approach enhances drilling precision by providing accurate distance measurements between boreholes, reducing errors and improving the safety and efficiency of drilling operations, especially in challenging conditions like blowouts or secondary recovery operations.
Implementation Method 1
a magnet on a drilling tool that rotates in the second borehole to induce a primary magnetic field in a magnetic object in the first borehole
Data Source
AI summary
In one aspect an apparatus for determining a distance between a first borehole and a second borehole during drilling of the second borehole is disclosed that in one embodiment includes a magnet on a drilling tool that rotates in the second borehole to induce a primary magnetic field in a magnetic object in the first borehole, a substantially stationary sensor on the drilling tool that detects a secondary magnetic field from the magnetic object responsive to the induced primary magnetic field, and a controller that determines the distance between the first borehole and the second borehole from the detected magnetic field. In another aspect a method of determining a distance between a first borehole and a second borehole, the in one embodiment includes inducing a primary magnetic field in a magnetic object in the first borehole using a rotating magnet in the second borehole, detecting a secondary magnetic field from the magnetic object responsive to the induced primary magnetic field using a substantially stationary sensor in the second borehole, and determining the distance between the first borehole and the second borehole from the detected magnetic field.