Passive Arm Reduces Jamming in Bi-Directional Well Logging
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Solution Overview
Problem
Borehole imager tools often jam or stick when encountering obstructions while moving in one direction, preventing effective data collection and tool movement in subterranean formations.
Innovation Solution
A passive arm is integrated into the linkage system of downhole tools to reduce or eliminate jamming by allowing the tool to move freely in both directions, using a passive arm that redirects obstructions away from the primary arm and pad, ensuring consistent contact with the borehole wall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional linkage is used to press pads against the borehole wall, then the pad can be extended against the wall, but the linkage may stick or jam when encountering obstructions while moving in the opposite direction
Solution Approach 1:
A passive arm is introduced as an intermediary component between the obstruction and the primary linkage system. The passive arm contacts obstructions first and redirects the forces, preventing direct transmission of jamming forces to the pad-actuating linkage. This mediator absorbs and redirects harmful forces before they can affect the critical measurement function.
Solution Approach 2:
The linkage system is segmented into multiple independent components: the primary arm for pad actuation and the passive arm for obstruction management. By dividing the system into separate functional segments, the passive arm can handle obstruction forces independently without interfering with the pad actuation mechanism, preventing jamming while maintaining measurement capability.
2Strength
If the linkage encounters an obstruction, then the pad may be protected from damage, but the tool may jam and stop moving in the opposite direction
Solution Approach 1:
The passive arm serves as a mediator that intercepts obstruction forces before they can block the primary linkage movement. It redirects these forces along an alternative path that does not interfere with the tool's ability to move through the borehole, thus maintaining productivity while still providing pad protection.
Solution Approach 2:
The passive arm converts the harmful effect of obstructions (which would normally cause jamming) into a beneficial force distribution pattern. By redirecting obstruction forces through the passive arm, the system transforms potential jamming events into controlled force transmissions that protect the pad while allowing continued tool movement.
3Strength
If the linkage is designed to be robust against obstructions, then the pad can withstand forces, but the complexity of the linkage increases
Solution Approach 1:
The robust force resistance function is segmented from the pad actuation function. The passive arm handles force resistance from obstructions, while the primary linkage maintains its simpler design for pad actuation. This segmentation allows each component to be optimized for its specific function without unnecessary complexity.
Solution Approach 2:
The passive arm acts as an intermediary force-bearing structure that protects the primary linkage from excessive forces. By placing this intermediary element in the force path, the primary linkage can remain simpler while still achieving robust overall force resistance through the combined system.
Data Source
AI summary
A downhole tool may comprise a tool body that is a structural support for the downhole tool, an upper arm attached at one end to the tool body, a pad attached at an opposite end of the upper arm, a lower arm attached at one end to a sliding block and attached to the pad at an opposite end of the lower arm, and a passive arm connected to the lower arm and the tool body. A method may comprise disposing a downhole tool into a borehole, applying a force to a passive arm, applying a second force from the passive arm to the lower arm in response to the force applied to the passive arm, and moving the lower arm and the passive arm in a longitudinal direction along an axis of the downhole tool.