Resonance-Tuned Drill String Vibration Sub
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Solution Overview
Problem
Drilling through varying rock formations with differing hardness leads to increased wear on drill bits and slower drilling rates due to torsional vibrations and stick-slip phenomena, which cause excessive vibrations and inefficiency in wellbore operations.
Innovation Solution
The drilling system induces vibrations at or near the resonant frequency of the rock formation using acoustic or mechanical stress waves, weakening the rock bonds and improving drill bit penetration efficiency by matching the frequency of the induced vibrations with the rock's resonant frequency, thereby reducing effective rock strength and enhancing drilling speed and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional drilling methods are used without vibration control, then the drill string structure remains simple, but excessive torsional vibrations and stick-slip phenomena occur causing drill bit wear and reduced drilling speed
Solution Approach 1:
The patent applies mechanical vibration by inducing vibrations at or near the resonant frequency of the drill string using a vibration source. This controlled vibration counteracts the harmful stick-slip phenomena and excessive torsional vibrations, allowing for higher drilling speeds without the negative effects of uncontrolled vibrations. The vibration frequency is specifically tuned to match the drill string's resonant frequency to maximize the beneficial effect while minimizing the required vibration amplitude.
Solution Approach 2:
The patent changes the operational parameters of the drill string by operating it at or near its resonant frequency. This parameter change transforms the drill string from a passive structure subject to harmful vibrations into an actively vibrated system where the vibrations are controlled and beneficial. The resonant frequency serves as the key parameter that, when exploited, improves drilling performance while maintaining structural integrity.
2Strength
If drill bits are used in harder rock formations, then drilling through resistant formations becomes possible, but drill bit wear increases and drilling rate decreases due to torsional vibrations
Solution Approach 1:
The patent uses mechanical vibration at resonant frequency to reduce the effective strength of harder rock formations during drilling. The induced vibrations create dynamic loading conditions that facilitate rock fracture and bit penetration, allowing maintain or increase drilling rates even when drilling through harder, more resistant formations that would otherwise cause excessive wear and slow progress.
Solution Approach 2:
The patent employs periodic action by applying vibrations at the resonant frequency of the drill string. This periodic excitation creates cyclic stress patterns in both the drill string and the rock formation, which over time facilitates rock breakdown and maintains drilling efficiency. The periodic nature of the vibration at resonant frequency maximizes the energy transfer to the system while minimizing energy loss to harmful vibrations.
3Force
If the drill string is made of elastic materials to handle torsion, then the drill string can accommodate rotational forces, but excessive torsional vibrations and stick-slip phenomena occur
Solution Approach 1:
The patent applies mechanical vibration to the drill string at its resonant frequency to counteract the harmful torsional vibrations and stick-slip phenomena. By inducing controlled vibrations, the system transforms the elastic properties of the drill string from a source of instability into a mechanism for stable, controlled operation. The resonant vibration creates a dominant frequency pattern that suppresses chaotic torsional oscillations.
Solution Approach 2:
The patent implements feedback by monitoring the vibrations of the drill string and adjusting the vibration source to maintain operation at or near the resonant frequency. This feedback mechanism ensures that the drill string operates in a stable vibrational state, automatically correcting deviations from the optimal frequency and preventing the development of harmful torsional vibrations and stick-slip behavior.
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
This approach reduces the effective rock strength, increases drilling speed, and extends drill bit life by using real-time or pre-programmed resonant frequency determination and continuous vibration adjustment, minimizing wear and vibrations during the drilling process.
Implementation Method 1
The resonant frequency of a subterranean formation being drilled may be determined in real time during drilling (and/or measured or modeled and preprogrammed prior to drilling) and vibrations may be induced in the drill string at or near the determined resonant frequency.
Data Source
AI summary
A drilling system includes a drill string extendable into a wellbore penetrating a subterranean formation. The subterranean formation exhibits a resonant frequency and a drill bit is coupled to a distal end of the drill string. A vibration sub is positioned within the drill string adjacent the drill bit for generating vibration stress waves at the drill bit, and the vibration stress waves exhibit a vibration frequency that approximates the resonant frequency.