Downhole Motor Stall Detection via Index Calculation

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Solution Overview

Problem

Conventional drilling operations lack real-time detection and prevention of downhole motor stalls, leading to potential damage and failure of the mud motor, especially in directional drilling where stress and temperature limits are frequently exceeded.

Innovation Solution

A drilling system equipped with sensors and a computing system that calculates a motor stall index based on RPM, surface torque, flow rate, and standpipe pressure indices to detect motor stalls and automatically adjust operations to prevent or correct the stall.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If real-time detection and prevention of downhole motor stalls is implemented, then reliability of the mud motor is improved, but device complexity increases due to addition of sensors and computing systems

Engineering Contradiction:
Improvemud motor reliabilityVSAvoiddrilling system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system performs preliminary detection of motor stall conditions by continuously monitoring drilling parameters and computing a motor stall index before actual stall occurs. This allows preemptive action to be taken to prevent motor damage, improving reliability while the complexity is managed through automated early warning systems

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements feedback control by continuously measuring drilling parameters (RPM, torque, flow rate, standpipe pressure), computing a motor stall index, and using this feedback to detect and prevent motor stalls. The feedback loop enables real-time adjustments to drilling operations to maintain motor reliability

Inventive Principle:
Principle #23Feedback

2Measurement precision

If multiple sensors and computing systems are added to detect motor stalls, then measurement precision of motor status is improved, but device complexity increases

Engineering Contradiction:
Improvemotor stall detection precisionVSAvoidsensor and control system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The computing system performs multiple functions: it processes data from multiple sensors, computes the motor stall index, detects stall conditions, and can trigger preventive actions. This multi-functionality consolidates what would otherwise require separate systems into a single integrated computing platform, improving measurement precision without proportionally increasing complexity

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system merges multiple sensor inputs (RPM, torque, flow rate, standpipe pressure) and processing functions into a unified motor stall detection system. By combining these elements into an integrated system that computes a single motor stall index, the patent achieves high measurement precision while managing overall system complexity through consolidation

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3784864B1Downhole motor stall detection
Publication Date: 2023.10.11 NAT OILWELL VARCO LP
  • EP3784864B1 patent drawingFigure 1
  • EP3784864B1 patent drawingFigure 2
  • EP3784864B1 patent drawingFigure 3

AI summary

A drilling system includes a drill string, a plurality of sensors, and a computing system. The drill string includes a downhole motor. The sensors are coupled to the drill string. The computing system is coupled to the sensors. The computing system is configured to compute, based on measurements provided by the sensors, a motor stall index, and to determine, by comparing the motor stall index to a motor stall threshold, whether the downhole motor has stalled. The computing system is also configured to, responsive to a determination that the downhole motor has stalled, adjust operation of the drill string to restart the downhole motor.