Surface Torque Stick-Slip Detection via Resonant Filtering
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Solution Overview
Problem
Current methods for detecting downhole torsional vibration (stick-slip) in drilling operations require costly downhole tools and detailed mechanical models of the drillstring configuration, which can be impractical due to the complexity of wellbore profiles and variability in drilling conditions.
Innovation Solution
A method and apparatus for detecting stick-slip using surface sensors to measure torque applied by a top drive system, filtering the data to isolate resonant frequencies, and calculating a surface stick-slip index (SSSI) without the need for downhole tools or detailed mechanical models, utilizing strain, electrical current, or pressure sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If downhole tools with accelerometers or magnetometers are used to measure drill pipe rotation speed, then measurement precision of stick-slip is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses surface torque measurements as an intermediary to indirectly detect downhole stick-slip conditions. Instead of placing sensors downhole, the system measures torque at the surface and uses a mechanical model to infer downhole vibration, eliminating the need for complex downhole measurement tools while maintaining detection capability
Solution Approach 2:
The patent replaces the mechanical sensor system (accelerometers/magnetometers in downhole tools) with a surface-based mechanical measurement system (torque sensors) combined with computational modeling. This substitution moves the measurement point from downhole to surface, simplifying the downhole environment while preserving measurement functionality
2Measurement precision
If downhole tools with telemetry are used to detect and communicate stick-slip, then measurement precision is improved, but loss of time increases due to telemetry delays
Solution Approach 1:
The patent inverts the traditional approach by moving the measurement location from downhole to surface. Instead of measuring downhole and transmitting data up, the system measures torque at the surface where communication infrastructure already exists, eliminating the need for delayed telemetry transmission while maintaining measurement capability through the mechanical model
3Measurement precision
If detailed mechanical models of drillstring configuration are used to estimate stick-slip, then measurement precision is improved, but device complexity and ease of operation worsen due to manual data entry requirements
Solution Approach 1:
The system automatically acquires drillstring configuration data from existing well planning software and rig site databases, eliminating the need for manual data entry. The mechanical model is self-configured using available operational data, reducing operator burden while maintaining measurement precision
Solution Approach 2:
The patent creates a universal system that can operate with various drillstring configurations without requiring custom model setup for each case. The mechanical model adapts to different well conditions using standardized procedures and available data, making the system easy to operate across diverse drilling scenarios
4Device complexity
If surface torque measurements are used to detect stick-slip, then device complexity is reduced, but measurement precision may be affected by torque signal noise
Solution Approach 1:
The system applies bandpass filtering to the torque signal before analysis to pre-remove noise and isolate the frequency range where stick-slip signals occur. This preliminary signal conditioning improves measurement precision by eliminating irrelevant frequency components that would otherwise interfere with detection
Solution Approach 2:
The system uses the mechanical model to establish the expected relationship between surface torque and downhole vibration, then compares actual measurements against this model to identify stick-slip events. This feedback mechanism enhances precision by using the model as a reference to distinguish true stick-slip signals from noise
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
Enables accurate detection of stick-slip severity at the surface, reducing costs and practicality issues by using surface measurements to estimate torsional vibration, allowing for timely mitigating actions without the need for downhole telemetry or detailed mechanical models.
Implementation Method 1
measuring a parameter that is a function of a torque applied to the drillstring by a top drive system over a selected time period, wherein the measuring is performed by at least one surface sensor that produces measurement data including torque values
Implementation Method 2
filtering out measurement data that has a frequency outside a selected frequency band, wherein the selected frequency band includes a resonant frequency of the drillstring
Data Source
AI summary
A method for detecting stick-slip in a drillstring includes (a) measuring a parameter that is a function of a torque applied to the drillstring by a top drive system over a selected time period, the measuring being performed by at least one surface sensor that produces measurement data including torque values over a frequency range; (b) filtering out measurement data that has a frequency outside a selected frequency band, the selected frequency band including a resonant frequency of the drillstring; (c) identifying a minimum and a maximum torque value in the filtered measurement data and determining a difference of these two values; (d) determining a surface stick-slip index by dividing the difference of the maximum and minimum torque values by an average torque value over the selected time period; and (e) displaying the surface stick-slip index on a display.