Permanent Electromagnet Sensor for Reverse Cementing Debris Management
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Solution Overview
Problem
Magnetic particle accumulation on downhole sensors during reverse cementing operations inhibits their ability to accurately detect cement intrusion, leading to potential failures in controlling cement flow.
Innovation Solution
A Hall effect sensor assembly coupled with a permanent electromagnet and a computing device that modulates the magnetic field by temporarily neutralizing it at designated intervals to clear accumulated magnetic debris, allowing the slurry to wash away particulates and maintain sensor functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a permanent electromagnet is used to detect magnetic particles in cementing fluid, then detection capability is improved, but magnetic particle accumulation on the sensor occurs leading to function inhibition
Solution Approach 1:
The patent applies periodic reversal of the electromagnet's magnetic field polarity to prevent magnetic particle accumulation. The controller periodically reverses the polarity of the electromagnet, causing accumulated magnetic particles to be dislodged and flushed away by the cementing fluid flow, thus maintaining sensor reliability while preserving detection capability
Solution Approach 2:
The patent converts the harmful effect of magnetic particle accumulation into a beneficial cleaning mechanism. By intentionally allowing particles to accumulate and then using polarity reversal to suddenly dislodge them, the system transforms the accumulation problem into a self-cleaning function that maintains sensor performance
2Measurement precision
If the permanent electromagnet's magnetic field is continuously active, then detection accuracy is maintained, but magnetic debris accumulates on the sensor
Solution Approach 1:
The system periodically interrupts the continuous magnetic field by reversing polarity at set intervals. This periodic action prevents continuous accumulation of magnetic debris while maintaining sufficient detection accuracy during the active phases, balancing measurement precision with debris prevention
3Reliability
If the magnetic field is temporarily neutralized to clear magnetic debris, then sensor functionality is maintained, but detection is interrupted during the neutralization period
Solution Approach 1:
The patent uses brief, partial neutralization periods for cleaning rather than extended interruptions. The polarity reversal duration is optimized to be just long enough to dislodge accumulated particles without creating significant detection gaps, minimizing time loss while maintaining sensor functionality
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
Ensures continuous accurate detection of cement slurry presence, preventing premature cement intrusion and ensuring effective control of cementing operations by regularly clearing magnetic debris from the sensor.
Implementation Method 1
A sensor coupled with a permanent electromagnet on the inner or outer diameter of the casing may detect when the cementing fluids reach the bottom of the wellbore
Implementation Method 2
The slurry may comprise magnetic particles detectable by the sensor
Implementation Method 3
A Hall effect sensor assembly may be utilized to detect a Hall effect of a cementing slurry
Data Source
AI summary
In some embodiments, a method for reducing magnetic debris accumulation on a downhole sensor within a tubular conveyed in a borehole comprises supplying a voltage to temporarily neutralize a magnetic field of a permanent electromagnet proximate to the downhole sensor and removing magnetic debris on the downhole sensor via a flow of a first fluid in the tubular while the magnetic field is neutralized.