High Pressure Viscometer Magnetic Coupling Seal Friction
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Solution Overview
Problem
Existing high-pressure viscometers face challenges in accurately measuring viscosity under down-hole conditions due to seal friction errors, limited pressure sealing capabilities, and high maintenance requirements, especially when dealing with drilling fluids at high temperatures and pressures.
Innovation Solution
A viscometer design featuring a pressure vessel with a rotor and magnetic coupling, utilizing low-friction ball bearings and a spiral spring to allow angular motion of the bob, which is immersed in the fluid, and a magnetometer to measure rotation, thereby reducing seal friction errors and maintenance needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealed container with seal is used to separate test sample from outside pressurizing fluid, then measurement accuracy is improved by preventing contamination, but measurement precision deteriorates due to friction between seal and shaft
Solution Approach 1:
The patent removes the seal component entirely from the system. Instead of using a seal to separate the test sample from pressurizing fluid, the design allows the sample to be in direct contact with the pressurizing fluid while using a magnetic drive system that eliminates mechanical seals and their associated friction errors.
Solution Approach 2:
The patent replaces the mechanical seal system with a magnetic coupling system. The drive shaft is magnetically coupled to the rotor, eliminating the need for mechanical seals that would otherwise be required to transmit rotation while maintaining pressure containment. This substitution eliminates seal friction and improves measurement precision.
2Ease of operation
If a helical spring assembly is used to support the bob, then rotational motion is achieved, but device complexity and space requirements increase
Solution Approach 1:
The patent removes the helical spring assembly and replaces it with a spiral spring. This simplification maintains the necessary rotational motion capability while reducing the complexity and space requirements of the bob assembly.
Solution Approach 2:
The patent inverts the conventional helical spring design by using a spiral spring configuration. This inversion allows for a more compact arrangement that maintains rotational freedom while reducing overall device complexity and spatial requirements.
3Ease of operation
If jewel bearings are used to support the bob assembly, then low friction operation is achieved, but reliability deteriorates due to fragility and wear
Solution Approach 1:
The patent replaces the expensive and fragile jewel bearings with conventional ball bearings. While ball bearings are not as luxurious as jewel bearings, they are much more durable, reliable, and maintenance-free, achieving the same low-friction operation without the reliability drawbacks of jewel bearings.
4Reliability
If packing is used to dynamically seal the rotating tube, then sealing is achieved, but pressure capability is limited to below 2,000 psi
Solution Approach 1:
The patent removes the dynamic seal packing system entirely. By using a magnetic drive system where the drive shaft is magnetically coupled to the rotor, the design eliminates the need for packing to seal rotating components, thereby removing the pressure limitation associated with packing capabilities.
Solution Approach 2:
The patent replaces the mechanical packing seal system with a magnetic coupling system. This substitution eliminates the pressure limitation of packing while maintaining the necessary sealing function, enabling operation at pressures well above 2,000 psi.
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 design enables accurate viscosity measurement under high-pressure conditions with reduced maintenance, eliminating seal friction errors and ensuring reliable operation at temperatures up to 600°F and pressures of 40,000 psi, while maintaining ease of cleaning and installation.
Implementation Method 1
a magnetic coupling for rotating the rotor
Implementation Method 2
The bob is suspended within the pressure vessel by a pair of low friction ball bearings and bob shaft
Implementation Method 3
A spiral spring permits limited angular motion of the bob shaft
Implementation Method 4
A magnetometer located on the top of the pressure vessel senses the rotation of the magnet
Data Source
AI summary
Viscometer (80) with a rotor (51) rotatable by a coupling magnet (34) and a driving magnet (38) to shear a tested fluid thus imparting torque to a bob (30) mounted on a bob shaft (24) supported via a pair of bob shaft bearings. A spiral spring (70) restricts the rotation of bob shaft (24). Magnetometer (10) measures the angular position of a top magnet (72) connected to the top of bob shaft (24). This angular position information is further converted to the viscosity of the tested fluid.