Sensor Transportation Wheel Bearing Lubrication
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Solution Overview
Problem
Wireline logging tools face challenges in descending deviated wellbores due to high friction in wheel bearing assemblies, leading to inefficient and inaccurate data collection, particularly in deep and angled wells, where the tool often experiences stop-start movement and increased risk of cable failure.
Innovation Solution
A sensor transportation apparatus with a wheel bearing system that includes a tungsten carbide wear surface and a lubrication delivery system using a bellows formation to maintain lubricant pressure higher than ambient wellbore pressure, reducing static and dynamic friction and ensuring smooth operation in deviated wells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard wheel bearing assemblies are used in logging tools, then the device complexity is low, but the friction is high causing stop-start movement in deviated wells
Solution Approach 1:
The patent changes the material parameter of the wear surface from standard steel to tungsten carbide, increasing hardness and reducing friction. This material parameter change enables smooth operation in deviated wells by significantly reducing the coefficient of friction between the wheel and wellbore wall.
Solution Approach 2:
The patent introduces a lubrication system as an intermediary between the bearing components. The lubricant reduces direct contact friction between moving parts, and the magnetic particle contaminant removal system acts as an intermediary to prevent abrasive particles from increasing friction and causing stop-start movement.
2Use of energy by moving object
If gravity-driven descent is used in deviated wells, then the energy consumption is low, but the cable tension varies causing overshoots
Solution Approach 1:
The patent implements a feedback control system where cable tension is continuously monitored and used to control the winch operation. When the logging tool approaches the target depth or when excessive tension is detected, the winch automatically adjusts or stops, preventing overshoots and ensuring accurate depth placement while maintaining energy-efficient gravity-driven descent.
3Stress or pressure
If conventional lubrication systems are used, then the device complexity is low, but the lubricant pressure cannot overcome wellbore ambient pressure
Solution Approach 1:
The patent employs a hydraulic pressure system where lubricant is pumped under pressure to overcome the wellbore ambient pressure and maintain adequate lubrication film thickness in the bearing assembly. This hydraulic approach enables the lubricant to be forced into high-pressure zones, ensuring continuous lubrication even in deep deviated wells.
Solution Approach 2:
The patent replaces traditional mechanical spring-loaded or gravity-based lubrication systems with a pump-driven hydraulic system. This substitution enables precise control of lubricant pressure, allowing the system to overcome wellbore ambient pressure and maintain adequate lubrication under high-stress conditions.
4Length of stationary object
If wireline logging is performed in deep wells, then the exploration capability is improved, but the cable length increases causing elastic behavior
Solution Approach 1:
The patent uses cable tension monitoring as a feedback mechanism to detect and compensate for elastic cable behavior. As the cable stretches under tension during descent, the increased tension is detected and used to control winch speed, maintaining constant descent velocity despite cable elasticity. This feedback control ensures stable operation in deep wells where cable length and elastic effects are significant.
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 apparatus reduces frictional resistance, allowing for efficient gravity-driven descent of logging tools in deviated wells, maintaining constant cable tension, and enhancing data accuracy by minimizing 'overshoots and reducing the risk of cable failure.
Implementation Method 1
a shaft seal to prevent or reduce debris from the wellbore entering the bearing, wherein a sealing lip of the shaft seal is sealingly engaged with a wear surface
Implementation Method 2
a lubrication delivery system to provide a lubricant to the bearing at a pressure which is greater than ambient wellbore pressure
Implementation Method 3
the lubrication system comprises: a bellows formation
Implementation Method 4
A sensor package, also known as a 'logging tool' or 'tool-string' is then lowered into the wellbore and descends under gravity to the target depth
Data Source
AI summary
A sensor transportation apparatus for conveying a sensor assembly through a wellbore comprises at least one engagement structure to connect the sensor transportation apparatus to the sensor assembly, at least one axle, a bearing connected to the axle, and a wheel connected to the bearing and provided with a shaft seal to prevent or reduce debris from the wellbore entering the bearing, and a lubrication delivery system to provide a lubricant to the bearing at a pressure which is greater than ambient wellbore pressure. The lubrication system comprises a bellows formation, and the apparatus comprises a housing to contain the lubricant, the housing in fluid communication with the bearing, the bellows formation sealingly mounted to the housing with at least a portion of the bellows received within the housing.