Overrunning Clutch Drill Assembly for Stick-Slip Vibration Mitigation
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Solution Overview
Problem
Conventional drill bits with PDC cutters are prone to failure due to torsional vibration, particularly stick-slip, which causes chatter and repeated impacts, and existing solutions require increasing bit speed or reducing weight on bit, which are undesirable.
Innovation Solution
An inline torsional vibration mitigation system comprising an overrunning clutch assembly and a torsional dampener assembly is used to decouple the drill string from the bottom hole assembly during over-speed conditions and dampen rotational impacts, respectively, using a mechanical mechanism without electronic controls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PDC cutters and inserts are used for continuous loading drilling, then drilling efficiency is improved, but the cutters are subject to failure under vibration and impact forces
Solution Approach 1:
The patent applies beforehand cushioning by introducing a torsional vibration mitigation system that includes a dampener and overrunning clutch assembly positioned above the PDC bit. This system proactively absorbs and dissipates torsional vibrations and impact forces before they reach the PDC cutters, preventing cutter failure while maintaining continuous loading drilling efficiency
2Use of energy by moving object
If stick-slip torsional vibration occurs, then the drill string winds up and stores potential energy, but the drill bit breaks free violently and over speeds causing chatter and impacts
Solution Approach 1:
The patent applies the intermediary principle by introducing a torsional vibration mitigation system that acts as a mediator between the drill string and the PDC bit. The overrunning clutch assembly and dampener serve as intermediary components that absorb and dissipate torsional vibrations and impact forces, preventing the violent break-free motion and chatter while allowing the drill string to continue rotating
3Object-affected harmful factors
If bit speed is increased or weight on bit is reduced to address stick-slip, then torsional vibration is mitigated, but drilling parameters must be altered which reduces efficiency
Solution Approach 1:
The patent applies segmentation by dividing the drilling system into distinct functional zones: the drill string rotation zone, the torsional vibration mitigation zone (with overrunning clutch and dampener), and the bit drilling zone. This segmentation allows the drill string to rotate at optimal speeds for productivity while the mitigation system handles vibration control, eliminating the need to compromise drilling parameters
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 system effectively reduces torsional vibrations by altering natural frequencies and damping rotational impacts, thereby protecting the drill bit and drill string from damage without altering drilling parameters.
Implementation Method 1
an overrunning clutch assembly and a torsional dampener assembly are used to decouple the drill string from the bottom hole assembly during over-speed conditions
Implementation Method 2
a torsional dampener assembly is used to decouple the drill string from the bottom hole assembly during over-speed conditions and dampen rotational impacts
Data Source
Figure 1
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AI summary
An assembly for inclusion between a drill bit and a drill string, the assembly having an overrunning clutch mechanism that disengages the drill bit from the drill string during the "slip" portion of a stick-slip cycle to allow the drill bit to freely rotate faster than the drill string. The assembly further includes a rotational vibration dampener operatively connected between the overrunning clutch and the drill bit. The vibration dampener may include a fluid chamber with viscous fluid or restrictions to fluid flow to effect dampening. During normal operation, the one-way overrunning clutch remains engaged to transfer torque between the drill string and bit, while the torsional damper is in its maximum displaced position to transfer the load. During slip, the drill bit is disengaged until its speed is lower than the drill string speed. Torsional vibration dampener dampens sudden impulse force of the overrunning clutch re-engaging.