HDD Pullback Camera Using PLC Tracer Wires for Crossbore Detection
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Solution Overview
Problem
Horizontal directional drilling (HDD) systems face challenges in confirming the absence of crossbores during underground utility installations, leading to increased job time and cost due to limited positional accuracy and the need for time-consuming video monitoring and wireless data transmission.
Innovation Solution
A method and system utilizing power line communication (PLC) over insulated tracer wires to power and transmit real-time video data from a camera attached to the drill string, allowing for immediate identification of crossbores during the pullback operation, reducing the need for extensive camera cable deployment and post-installation tracing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional HDD drilling is performed without real-time monitoring, then drilling speed is maintained, but crossbores cannot be identified until after installation requiring time-consuming verification
Solution Approach 1:
The patent implements real-time feedback by transmitting video images from the drill head back to the surface through PLC modulators coupled to the drill string. This allows operators to immediately see what the drill head is encountering and identify crossbores during the drilling operation itself, rather than discovering them after utility installation is complete.
Solution Approach 2:
The system performs preliminary detection of crossbores during the drilling operation before utility installation occurs. By using the drill string as a communication medium to transmit video data in real-time, the system identifies obstacles ahead of time, allowing operators to take preventive action before the utility line is installed in the wrong location.
2Loss of information
If extensive camera cable deployment is used for downhole observation, then real-time video transmission is achieved, but cable management complexity and post-installation tracing requirements increase
Solution Approach 1:
The patent makes the drill string serve multiple functions: it not only drills through the ground but also acts as a communication medium for transmitting video data and electrical power to the downhole camera. By coupling PLC modulators to the drill string, the system eliminates the need for separate camera cables, as the existing drill string infrastructure is utilized for dual purposes of mechanical drilling and electrical/data transmission.
Solution Approach 2:
The drill string serves itself by providing both the mechanical drilling function and the electrical communication function. Rather than requiring external cable infrastructure, the drill string's own metallic structure is used as the transmission medium for power and data, making the system self-sufficient and eliminating complex cable management requirements.
3Device complexity
If wireless data transmission is used for downhole observation, then cable management is simplified, but transmission reliability and real-time feedback capability are reduced
Solution Approach 1:
The drill string is utilized for multiple purposes simultaneously: mechanical drilling, electrical power transmission, and data communication. By coupling PLC modulators to the drill string, the system achieves reliable wired communication without the complexity of separate cable deployment, maintaining transmission reliability while simplifying the overall system architecture.
4Measurement precision
If positional accuracy is increased to avoid crossbores, then drilling precision is improved, but drilling time and operational complexity increase
Solution Approach 1:
Real-time video feedback from the downhole camera allows operators to immediately see the drill head's position relative to underground utilities and make instantaneous steering adjustments. This eliminates the need for overly conservative drilling paths that would be required without visual feedback, maintaining high positional accuracy while minimizing drilling time.
Solution Approach 2:
The patent replaces complex mechanical steering systems with advanced steering mechanisms that utilize real-time video feedback for precise control. By substituting mechanical guesswork with visual information, the system achieves high positional accuracy without requiring excessively slow or complex mechanical steering operations.
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 real-time downhole observation and identification of crossbores, reducing drilling time and costs by providing immediate feedback and eliminating the need for extensive cable management and post-installation tracing processes.
Implementation Method 1
power line communication (PLC) over insulated tracer wires to power and transmit real-time video data from a camera attached to the drill string
Data Source
AI summary
A horizontal directional drilling method includes operation of a HDD machine to power a drill string terminating at a drill head to create an underground borehole extending at least partially horizontally between an entry point and an exit point. A utility line and a pair of insulated wires are attached to the drill string at the exit point. An observation device is also attached to the drill string, and the observation device is connected with an uphole module via power line communication (PLC) over the pair of insulated wires. The horizontal directional drilling machine performs a pullback of the drill string, with the utility line, the pair of insulated wires, and the observation device connected thereto, back toward the entry point. Data from the observation device are displayed on the uphole module during pullback of the drill string.