Drilling Weight-on-Bit Control Using Surface Hookload Modeling
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Solution Overview
Problem
Current methods for controlling drilling weight on bit, especially in deviated or horizontal wells, are inefficient due to wellbore friction and tortuosity, leading to reduced penetration rates and increased costs, as they rely on expensive downhole sensors or manual adjustments based on surface hookload trends.
Innovation Solution
A method and system that estimate and control downhole weight on bit using real-time surface data processing and optimization, constructing drill-string and wellbore models, acquiring surface tension data, and calibrating friction coefficient-depth distribution without requiring downhole calibration, allowing for automated weight control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If downhole sensors are used to measure actual weight on bit, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses surface hookload measurements as an intermediary to indirectly determine downhole weight on bit. Instead of placing sensors downhole, the system measures hookload at the surface and uses friction models to calculate the relationship between surface measurements and downhole conditions, thereby avoiding complex downhole equipment while maintaining measurement capability
Solution Approach 2:
The patent replaces physical downhole sensors with a computational model-based system. By using mechanical principles (friction models, force balance equations) and surface measurements, the system substitutes the need for downhole measurement devices with a software-based calculation approach
2Device complexity
If manual adjustment based on surface hookload trends is used, then device complexity is reduced, but productivity decreases due to slower response time
Solution Approach 1:
The patent implements an automated feedback control system that continuously monitors surface hookload measurements, compares them with friction model predictions, calculates the actual weight on bit, and automatically adjusts drilling parameters to maintain optimal weight on bit. This closed-loop feedback mechanism eliminates manual intervention delays while keeping the system relatively simple
Solution Approach 2:
The system performs self-adjustment by automatically calculating the required weight on bit corrections based on surface measurements and friction models, then autonomously modifying drilling parameters without requiring continuous human intervention, thereby maintaining productivity while keeping operations straightforward
3Measurement precision
If friction models are calibrated using downhole data, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent performs preliminary calibration of friction models using historical or representative data before actual drilling operations. This advance calibration establishes the friction model parameters needed for real-time weight on bit calculations, eliminating the need for complex downhole calibration equipment during drilling while maintaining model accuracy
Solution Approach 2:
The system uses surface hookload measurements as a copy or proxy for downhole conditions. By calibrating friction models against surface data that correlates with downhole states, the system creates an accurate representation of downhole weight on bit without requiring direct downhole measurement equipment for calibration
Data Source
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AI summary
A method and system for automatically controlling drilling weight-on-bit for using a drill-string to drill along a wellbore is described.