Movable Piston Viscometer for High-Pressure Drilling Fluids
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Solution Overview
Problem
Existing high-pressure viscometers fail to accurately measure the viscosity of high-density drilling muds due to magnetic interference and cannot test corrosive samples, and they require frequent maintenance.
Innovation Solution
A high-pressure viscometer design featuring a pressure vessel with a movable piston assembly that separates the test sample from the pressurization fluid, using a magnetic coupling to transfer torque without direct contact, ensuring seal integrity and allowing for accurate viscosity measurements under extreme conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a magnet is used to rotate the rotor in the test sample, then the rotor can be rotated without direct mechanical contact, but the test sample cannot be accurately measured when it contains hematite or is corrosive due to magnetic attraction or chemical reaction
Solution Approach 1:
A piston assembly with a central bore acts as an intermediary barrier between the magnet and the test sample. The piston allows the shaft to pass through and transmit rotation while preventing direct contact between the magnet and test sample, thereby eliminating magnetic interference with hematite-containing samples and preventing corrosion reactions
Solution Approach 2:
The pressure vessel is segmented into separate chambers by the piston assembly. The magnet is positioned in one chamber while the test sample is in another chamber, allowing independent positioning and preventing harmful interactions while maintaining the rotational function through the central bore
2Measurement precision
If a sealed piston is used to prevent test sample contact with the magnet, then measurement accuracy is improved, but the device complexity increases due to the need for a rotating shaft through the piston
Solution Approach 1:
The piston assembly serves multiple functions simultaneously: it acts as a seal to prevent test sample leakage, provides a barrier to prevent magnetic interference and corrosion, and allows rotational transmission through its central bore. This multi-functionality reduces the need for additional separate components
3Device complexity
If direct contact between pressurization fluid and test sample is allowed, then device simplicity is maintained, but seal integrity under high temperature and pressure conditions deteriorates
Solution Approach 1:
The piston assembly acts as an intermediary barrier between the pressurization fluid and test sample, allowing each to be contained in separate chambers. This prevents contamination and maintains seal integrity under high temperature and pressure conditions while still allowing the system to function
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
The design allows for accurate viscosity measurements of drilling fluids under down-hole conditions without magnetic interference, supports testing of high-density and corrosive samples, and requires minimal maintenance while maintaining industry standards of accuracy and durability.
Implementation Method 1
a magnetic coupling for rotating the rotor. Suspended within the rotor is a bob capable of angular motion about the longitudinal axis of the rotor
Implementation Method 2
A magnet is secured on top of the bob shaft. A magnetometer located on the top of the pressure vessel senses the rotation of the magnet
Implementation Method 3
A spiral spring permits limited angular motion of the bob shaft
Data Source
AI summary
Viscometer (150) with a rotor (108) connecting a magnet holder (62) which penetrates a sealed movable piston (96) and rotatable by a coupling magnet (58) and a driving magnet (64) to shear a tested fluid thus imparting torque to a bob (42) mounted on a bob shaft (30) supported via a pair of bob shaft bearings. A spiral spring (140) restricts the rotation of bob shaft (30). Magnetometer (10) measures the angular position of a top magnet (142) connected to the top of bob shaft (30). This angular position information is further converted to the viscosity of the tested fluid.