Drilling System Oscillation Prevents Stick-Slip
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Solution Overview
Problem
Conventional drilling operations often lead to undesirable 'steady state' conditions and harmonic motions, such as stick-slip, insufficient hole cleaning, bit whirl, and excessive vibrations, which can result in damage to drillstrings and downhole components, as operators react to these issues after they arise rather than proactively preventing them.
Innovation Solution
The method involves a drilling system where the rotational speed, axial speed, and drilling fluid flow rate are controllably oscillated within predetermined ranges to maintain non-steady state conditions, preventing the formation of undesirable steady state conditions and harmonic motions by varying the energy input into the drilling process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If drilling parameters are kept constant to maintain steady state operation, then drilling stability is improved, but undesirable harmonic motions and vibrations occur leading to equipment damage
Solution Approach 1:
The patent applies periodic action by oscillating drilling parameters (rotational speed, weight on bit, axial speed, drilling fluid flow rate) in a cyclic manner. This periodic variation prevents the system from settling into steady state conditions that generate harmful harmonic motions and vibrations, thereby eliminating bit whirl and drillstring vibrations while maintaining drilling stability.
Solution Approach 2:
The patent implements dynamics by transitioning from static constant drilling parameters to dynamic oscillating parameters. The rotational speed, weight on bit, axial speed, and drilling fluid flow rate are continuously varied within predetermined ranges, creating a dynamic drilling environment that prevents resonance and harmful vibrations while maintaining stable drilling operations.
2Object-affected harmful factors
If drilling parameters are oscillated to prevent steady state conditions, then harmful harmonic motions are reduced, but drilling operation complexity increases
Solution Approach 1:
The patent employs feedback control by continuously monitoring drilling parameters and automatically adjusting them to maintain oscillation within predetermined ranges. The system responds to real-time drilling conditions by modulating rotational speed, weight on bit, axial speed, and drilling fluid flow rate, thereby preventing harmful steady state conditions without requiring complex manual intervention.
Solution Approach 2:
The drilling system performs self-service by automatically oscillating its own parameters to prevent harmful conditions. The system monitors its own state and autonomously adjusts rotational speed, weight on bit, axial speed, and drilling fluid flow rate to maintain non-steady state operation, eliminating the need for external complex control mechanisms.
3Ease of operation
If conventional reactive drilling control is used, then operational simplicity is maintained, but drilling efficiency decreases due to operational delays
Solution Approach 1:
The patent applies preliminary action by proactively oscillating drilling parameters before harmful steady state conditions can develop. Instead of reacting to problems after they occur, the system continuously varies rotational speed, weight on bit, axial speed, and drilling fluid flow rate to prevent bit whirl, vibrations, and other harmful conditions from forming, thereby eliminating operational delays and improving drilling efficiency while maintaining ease of operation.
Data Source
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AI summary
A method for drilling a borehole in an earthen formation comprises (a) providing a drilling system including a drillstring having a longitudinal axis, a bottom-hole assembly coupled to a lower end of the drillstring, and a drill bit coupled to a lower end of the bottom- hole assembly. In addition, the method comprises (b) rotating the drill bit at a rotational speed. Further, the method comprises (c) applying weight-on-bit to the drill bit and advancing the drill bit through the formation to form the borehole. Still further, the method comprises (d) pumping a drilling fluid down the drillstring to the drill bit. The drilling fluid has a flow rate down the drillstring. Moreover, the method comprises (e) oscillating the rotational speed of the drill bit during (c). The method also comprises (f) generating non- steady state conditions in the borehole during (e).