Drilling Assembly Stick-Slip Vibration Removal
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Solution Overview
Problem
Drilling operations face challenges with 'stick-slip' oscillations due to frictional torque, which can damage drilling assemblies and reduce drilling efficiency, as existing methods struggle to accurately measure and adjust frictional torque in real-time.
Innovation Solution
A control system that includes a drilling controller, online system identification element, and system states observer, utilizing models of the drilling assembly to determine frictional torque and generate control signals to controllable elements, such as the top drive and hook assembly, to maintain optimal drilling parameters and avoid stick-slip oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If real-time frictional torque measurement and adjustment is implemented, then stick-slip oscillations are prevented and drilling efficiency is improved, but device complexity and control system requirements increase
Solution Approach 1:
The patent implements a closed-loop feedback control system that continuously monitors drilling parameters (rotational speed, torque, weight on bit) and adjusts the top drive output in real-time to prevent stick-slip oscillations. The system uses measured parameters to generate control signals that maintain optimal drilling conditions, directly resolving the contradiction by enabling real-time frictional torque compensation through automated feedback control.
Solution Approach 2:
The patent replaces direct mechanical measurement of frictional torque with an electronic control system that uses sensors and processors to calculate and compensate for frictional effects. Instead of mechanical torque sensors downhole, the system uses surface-based electronic measurement and control algorithms to achieve the same effect, reducing device complexity while maintaining productivity.
2Reliability
If downhole components are protected from stick-slip damage, then component lifespan is extended, but control system complexity and real-time adjustment requirements increase
Solution Approach 1:
The patent applies preliminary anti-action by predicting and preventing stick-slip oscillations before they occur. The control system uses measured drilling parameters to calculate impending stick-slip conditions and adjusts the top drive output in advance to avoid the harmful oscillations, thereby protecting downhole components from damage while managing control complexity through proactive rather than reactive control.
3Speed
If optimal drilling parameters are maintained through real-time control, then drilling speed and efficiency are improved, but measurement and control precision requirements increase
Solution Approach 1:
The patent uses an intermediary approach by introducing a control algorithm that acts as a mediator between measured drilling parameters and top drive control. Instead of directly measuring difficult-to-obtain frictional torque values, the system uses readily available measurements (rotational speed, torque, weight on bit) as intermediaries to calculate and control frictional effects, reducing measurement precision requirements while maintaining optimal drilling 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 system effectively determines and adjusts for frictional torque in real-time, preventing stick-slip oscillations and maintaining desired drilling speeds, thereby extending the lifespan of downhole components and improving drilling efficiency.
Implementation Method 1
determine a frictional torque value for the drill bit... determining the frictional torque acting on the drill bit may comprise determining the frictional torque based on the control signal, a measurement from a sensor within the drilling assembly, and an estimated downhole condition value
Data Source
AI summary
An example method for removal of stick-slip vibrations may comprise receiving a command directed to a controllable element of a drilling assembly. A smooth trajectory profile may be generated based, at least in part, on the command. A frictional torque value for a drill bit of the drilling assembly may be determined. The example method may further include generating a control signal based, at least in part, on the trajectory profile, the frictional torque value, and a model of the drilling assembly, and transmitting the control signal to the controllable element.