Cross-spring pivot rheometer for gel shear strength measurement
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Solution Overview
Problem
Conventional rheometers used to measure gel shear strength of drilling fluids in harsh environments, such as high temperatures and pressures, often fail due to bearing degradation from corrosive substances and particulates, leading to inaccurate viscosity measurements.
Innovation Solution
The use of a cross-spring pivot rheometer apparatus that eliminates the need for conventional ball or roller bearings, employing a cross-spring pivot mechanism to suspend and rotate the bob assembly, which is more resistant to clogging and wear from particulates and corrosive fluids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ball or roller bearings are used to suspend the bob assembly, then the rheometer can achieve precise angular deflection measurement, but the bearings become pitted or gummed up over time due to corrosive substances and particulates, leading to measurement inaccuracy and instrument failure
Solution Approach 1:
The patent removes the conventional ball or roller bearings from the system entirely. Instead, the bob assembly is suspended from the stationary frame using a fiber or wire, which does not suffer from the same corrosion and particulate contamination issues as metal bearings. This extraction of the problematic bearing component eliminates the source of pitting and gumming while maintaining the ability to measure angular deflection precisely through alternative means.
Solution Approach 2:
The patent replaces the mechanical bearing system with a non-mechanical suspension system using a fiber or wire. This substitution eliminates the complex mechanical contact surfaces that are vulnerable to corrosion and particulate damage, while still allowing the bob assembly to rotate and deflect angularly for measurement purposes.
2Device complexity
If conventional bearings are used in the suspension system, then the rheometer structure can be simplified, but the lubrication and condition of bearings become critical for accurate measurement, requiring frequent maintenance in harsh environments
Solution Approach 1:
The patent extracts the bearings from the suspension system, replacing them with a simple fiber or wire suspension. This eliminates the need for lubrication and bearing maintenance while keeping the overall system relatively simple. The fiber suspension requires no lubrication and can operate reliably in corrosive, high-temperature, and high-pressure environments without degradation.
Solution Approach 2:
The fiber or wire used for suspension is a simple, inexpensive component that does not require maintenance. While it may have a limited lifespan in harsh environments, it can be easily replaced without complex procedures, unlike bearings that require disassembly, lubrication, and precision alignment for maintenance.
3Measurement precision
If the rheometer is used to measure gel shear strength under extreme conditions (temperatures exceeding 700°F and pressures exceeding 20,000 psi), then accurate performance evaluation is achieved, but the corrosive substances and particulates accelerate bearing degradation
Solution Approach 1:
The patent removes the bearings that are vulnerable to corrosive substances and particulates from the suspension system. By using a fiber or wire suspension instead, the system can operate in extreme conditions (temperatures exceeding 700°F and pressures exceeding 20,000 psi) without the bearing components that would otherwise be degraded by the harsh environment.
Solution Approach 2:
The patent replaces the mechanical bearing system with a non-mechanical fiber suspension system that is not susceptible to corrosion from acidic substances or damage from particulates. This substitution allows the rheometer to function reliably in extreme downhole conditions where conventional bearings would fail rapidly.
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 solution enables precise and accurate gel shear strength measurements in extreme environments by reducing the likelihood of bearing failure, maintaining instrument functionality and accuracy over time.
Implementation Method 1
a cross-spring pivot coupled to a second end of the bob shaft
Data Source
AI summary
A rheometer apparatus and methods of use are provided. In one embodiment, the rheometer includes a sleeve having an interior space; a cylindrical bob disposed within the interior space of the sleeve and coupled to a first end of a bob shaft; a cross-spring pivot coupled to a second end of the bob shaft; an arm coupled to and projecting radially from the cylindrical bob; and a linear actuator coupled to the arm. In some embodiments, the rheometer apparatus may facilitate more accurate gel shear strength measurements and/or may be correlated with existing rheometer measurements.