Downhole Drill String Vibration Control via Eigenfrequency Avoidance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Severe vibrations in drill strings and bottomhole assemblies during drilling operations lead to reduced rate of penetration, reduced measurement quality, and increased risk of equipment damage, which existing technologies have not adequately addressed.
Innovation Solution
A method for selecting drilling parameters such as string RPM, bit RPM, and weight on bit that vary the excitation frequency to mitigate vibrations, allowing for the identification of modal properties like eigenfrequencies and modal damping without knowing the excitation force, and automatically adjusting operational parameters to avoid resonance-induced damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If drilling parameters are selected without considering vibrations, then drilling operations can proceed without complex monitoring systems, but severe vibrations occur causing reduced rate of penetration, reduced measurement quality, and equipment damage
Solution Approach 1:
The system performs preliminary identification of modal properties (eigenfrequencies, mode shapes, modal damping) of the drill string before severe vibrations occur. By characterizing the drill string's natural frequencies and vibrational modes in advance, the system can predict when dangerous resonance conditions may occur and take preventive action by adjusting drilling parameters to avoid these critical frequencies.
Solution Approach 2:
The system continuously monitors vibrations using sensors and feeds this information back to adjust drilling parameters in real-time. The vibration monitoring system detects early signs of resonant conditions and triggers automatic adjustments to drilling parameters, creating a closed-loop control system that prevents severe vibrations before they cause equipment damage or significantly reduce drilling efficiency.
2Reliability
If vibration monitoring and analysis systems are implemented, then severe vibrations can be detected and prevented, but system complexity and cost increase
Solution Approach 1:
The system uses the drill string's own vibrational responses to automatically identify its modal properties without requiring external excitation devices or complex test setups. By utilizing ambient vibrations and operational data from standard sensors already present in drilling operations, the system performs self-diagnosis and characterization, eliminating the need for separate identification equipment or specialized testing procedures.
Solution Approach 2:
The system transforms complex vibration data into simplified modal parameters (eigenfrequencies, mode shapes, damping ratios) that directly inform drilling parameter selection. By changing the representation of vibration data from raw time-series signals to meaningful modal characteristics, the system provides actionable insights without requiring complex real-time analysis infrastructure, enabling practical implementation with standard computational resources.
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 improves drilling efficiency and reduces equipment damage by effectively reducing or eliminating severe vibrations, enabling more cost-effective and efficient borehole drilling.
Implementation Method 1
measuring vibration-related amplitudes of a drill string due to an applied excitation force using sensors
Implementation Method 2
The resulting amplitudes of vibrations due to one stimulus or multiple stimuli are measured by one or more sensors... varying an excitation frequency of a stimulus applied to the drill string
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method for selecting drilling parameters for drilling a borehole penetrating the earth with a drill string. The method includes: measuring vibration-related amplitudes of the drill string during operation using one or more vibrations sensor to provide amplitude measurements; determining with a downhole processor one or more modal properties comprising one or more eigenfrequencies of the drill string using the amplitude measurements, the determination being made by including any excitation force in a white noise term of a model of the drillstring; and selecting drilling parameters that apply an excitation force at a frequency that avoids a selected range of frequencies that bound the one or more eigenfrequencies using the processor.