Surface Control System for Adaptive Downhole WOB Estimation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for estimating weight on bit (WOB) and torque on bit (TOB) during directional drilling are unreliable, leading to incorrect mechanical specific energy (MSE) calculations and potential damage to downhole equipment due to sudden weight spikes, as they rely on assumptions that do not account for frictional forces and reactive torque in horizontal wells.
Innovation Solution
A system that uses determined relationships between downhole measurement data and surface measurement data to estimate WOB and TOB, employing a bottom hole assembly (BHA) to measure differential pressure and WOB, and a surface controller to implement coefficients for accurate estimation and control, preventing sudden increases in downhole WOB.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If hookload signal is used to estimate weight on bit during directional drilling, then the estimation method is simple, but the estimation accuracy deteriorates due to frictional forces and reactive torque
Solution Approach 1:
The patent introduces an intermediary computational model that processes multiple surface measurements (hookload, torque, differential pressure) through calculated relationships to derive accurate downhole weight on bit. This intermediary processing layer transforms simple surface measurements into precise downhole conditions by accounting for frictional forces and reactive torque through mathematical relationships.
Solution Approach 2:
The patent changes the parameters used for weight on bit estimation by incorporating multiple surface measurements (hookload, torque, differential pressure) and their calculated relationships rather than relying on a single hookload signal. This parameter transformation allows accurate determination of downhole conditions by considering the complex interactions of forces in directional drilling.
2Measurement precision
If mud motor differential pressure is used to estimate weight on bit in directional sections, then the estimation accounts for downhole conditions, but it fails to identify when the bit has exceeded its physical load limit
Solution Approach 1:
The patent implements feedback by continuously monitoring multiple surface measurements (hookload, torque, differential pressure) and their calculated relationships, comparing these against known bit physical limits. This feedback mechanism provides real-time identification when the bit has exceeded its physical load limit, enabling timely intervention to prevent equipment damage.
Solution Approach 2:
The patent takes preliminary action by establishing predetermined relationships and thresholds for bit load limits before drilling operations begin. These pre-established criteria enable the system to reliably identify when the bit approaches or exceeds its physical capacity, allowing preventive measures to be taken before damage occurs.
3Productivity
If current weight on bit estimation is used in autodrillers during directional drilling, then the control system operates continuously, but the control accuracy deteriorates due to incorrect weight on bit estimates
Solution Approach 1:
The patent introduces an intermediary computational framework that processes multiple surface measurements through calculated relationships to produce accurate weight on bit estimates for autodriller control. This intermediary processing ensures continuous operation while maintaining high accuracy by accounting for frictional forces and reactive torque through mathematical relationships.
Solution Approach 2:
The patent transforms the parameters fed into the autodriller control system by incorporating multiple surface measurements (hookload, torque, differential pressure) and their calculated relationships, replacing the incorrect single-parameter hookload-based estimates. This parameter transformation enables both continuous operation and high control accuracy.
4Ease of operation
If frictional forces at sticking points are not accounted for, then the drill string can be lowered easily, but sudden weight spikes occur causing equipment damage
Solution Approach 1:
The patent implements feedback by continuously monitoring surface measurements and their calculated relationships to detect the buildup of frictional forces at sticking points. This feedback enables real-time detection of conditions leading to sudden weight spikes, allowing the system to take corrective action before equipment damage occurs.
Solution Approach 2:
The patent applies preliminary anti-action by using the calculated relationships to predict and prevent sudden weight spikes before they occur. By monitoring the interplay between hookload, torque, and differential pressure, the system can identify developing frictional forces and take preventive measures to avoid the harmful effects of sudden weight increases.
Data Source
AI summary
A drilling rig apparatus is disclosed for improving autodriller control during directional drilling. A BHA determines a relationship between downhole WOB and downhole differential pressure and sends the relationship to a surface controller. The relationships may be sent on a set periodic basis or dynamically in response to the relationships over time differing from each other above a threshold amount. The surface controller estimates downhole WOB by inputting surface differential pressure into a formula implementing the relationship from downhole. The estimated downhole WOB is input into the autodriller for control and is used to estimate MSE. Downhole WOB, either estimated or actual values, may further be used to determine a ratio between downhole WOB and surface-determined WOB values. If the ratio falls below zero in comparison to a prior ratio, then a slack-off rate is adjusted until the ratio reaches zero or a positive value again.