Sensor Transport Wheels for Gravity-Based Borehole Centralization
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Solution Overview
Problem
Existing wireline logging tools face challenges in descending deviated wells due to high friction and drag forces, leading to delays and potential data inaccuracies, as conventional centralizers fail to effectively centralize the tool string in varying wellbore diameters and deviations.
Innovation Solution
A device comprising wheels and an eccentric weight configuration that ensures the tool string's longitudinal axis coincides with the wellbore axis, using gravity and magnetic forces to maintain contact with the wellbore wall, reducing friction and ensuring accurate data acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional centralizers are used to centralize the tool string, then the tool string can be positioned in the wellbore, but high friction and drag forces occur in deviated wells causing descent delays
Solution Approach 1:
The patent replaces conventional mechanical centralizers that create high friction with a gravity-based system using an eccentric weight. The eccentric weight positioned below the tool string utilizes gravitational force to maintain centralization through the tool's own weight, eliminating the need for friction-based mechanical centralizers and enabling smooth descent in deviated wells.
Solution Approach 2:
The eccentric weight is positioned in advance below the tool string to create a gravity-driven centralization effect before descent begins. This preliminary gravitational positioning ensures the tool string maintains central alignment throughout descent without requiring active mechanical intervention during the process.
2Reliability
If mechanical centralizers are used to maintain tool string position, then centralization is achieved, but additional force and complexity are required
Solution Approach 1:
The tool string uses its own weight through the eccentric weight configuration to achieve and maintain centralization. The gravitational force acting on the eccentric mass automatically positions the tool string centrally in the wellbore without requiring external power sources, complex control systems, or additional mechanical components.
3Productivity
If the tool string descends in deviated wells without proper centralization, then descent speed is maintained, but data acquisition accuracy deteriorates
Solution Approach 1:
The eccentric weight acts as a counterbalancing mass positioned below the tool string to offset gravitational effects that would cause the tool to drift toward the wellbore wall in deviated sections. This gravitational counterbalancing ensures the tool string remains centrally positioned for accurate data acquisition while maintaining efficient descent speed.
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 device provides stable and accurate centralization of the tool string in both deviated and vertical sections of the wellbore, reducing rolling friction and maintaining data quality without additional power input, thus enhancing operational efficiency and reducing costs.
Implementation Method 1
the at least one eccentric weight is positioned so that a centre of mass of the combined device and sensor assembly is offset in the radial direction from the longitudinal axis of the sensor assembly by a second radial distance that is greater than the first radial distance, to orient the device and sensor assembly by gravity during use in a most stable position
Implementation Method 2
reducing rolling friction and maintaining data quality
Data Source
AI summary
A device for transporting a sensor assembly down a bore of a known diameter comprises a pair of wheels offset in a radial direction by a first radial distance from a longitudinal axis of the sensor assembly and at least one eccentric weight. The first radial distance and a lateral distance between the wheels and a diameter of the wheels configures the device so that, in use, a longitudinal axis of the sensor assembly is substantially coincident with a longitudinal axis of the bore when the wheels are in contact with a wall of the bore. The at least one eccentric weight is positioned so that a centre of mass of the combined device and sensor assembly is offset in the radial direction from the longitudinal axis of the sensor assembly by a second radial distance that is greater than the first radial distance to orient the device and sensor assembly by gravity in a most stable position with the rotational axis of the wheels and the centre of mass below the longitudinal axis of the sensor assembly with the wheels in contact with a low side of the wall of the bore.