Downhole Marking and Sensing for Accurate Rate of Penetration
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Solution Overview
Problem
Traditional methods for measuring the rate of penetration (ROP) of a drill bit in subterranean drilling become less reliable and accurate as the drill string elongates, due to bending, twisting, and buckling, which can cause variations in the measured rate of penetration.
Innovation Solution
A drilling apparatus that includes a marking element and sensors to measure the axial distance and time interval between marking and sensing on the borehole wall, allowing for real-time calculation of ROP, either within the apparatus or along the drill string, using extendable cutters to create recognizable patterns on the borehole wall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If surface-based monitoring of drill string feed rate is used to measure ROP, then the measurement method is simple and cost-effective, but the reliability and accuracy decrease as the borehole elongates due to bending, twisting, stretching, or buckling of the drill string
Solution Approach 1:
The patent replaces the mechanical surface-based drill string feed rate monitoring system with a downhole optical sensing system. The marking element creates physical marks on the borehole wall, and the optical sensor detects these marks to measure ROP directly at the drill bit location, eliminating the mechanical transmission path through the drill string that causes measurement errors.
Solution Approach 2:
The patent introduces a marking element as an intermediary between the drill bit and the sensor. The marking element creates visible marks on the borehole wall that serve as a physical record of the drill bit's position and movement, allowing the sensor to indirectly measure ROP by detecting the timing and position of these marks.
2Productivity
If the drill string is fed into the elongating borehole, then the drilling operation continues, but the drill string experiences increased bending, twisting, stretching, or buckling that causes distortion and varies the ROP from the feed rate
Solution Approach 1:
The patent replaces the mechanical drill string feed rate measurement with an optical measurement system that directly observes the drill bit's interaction with the borehole wall through marking and sensing, eliminating the mechanical distortion issues inherent in long drill string operations.
Solution Approach 2:
The drilling apparatus performs its own measurement by incorporating the marking element and sensor within the same assembly. The system measures its own ROP directly at the source without requiring external surface-based monitoring, enabling self-diagnosis and real-time optimization of drilling parameters.
Data Source
AI summary
A downhole drilling apparatus, passing through a subterranean borehole, may mark an inner wall of the borehole with a marking element. A sensor, spaced axially from the marking element on the drilling apparatus, may subsequently sense the marking as it passes. A rate of penetration of the drilling apparatus may be calculated by dividing an axial distance, between the marking element and the sensor, by a time interval, between when the marking element marks the inner wall and when the marking is sensed by the sensor. Alternately, a second sensor, spaced axially from the first, may also sense the marking. A rate of penetration may then be calculated by dividing an axial distance, between the two sensors, by a time interval, between when the two sensors sense the marking.