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 creation of crossbores when drilling in areas with unknown underground utility installations, leading to increased job time and cost due to the need for post-drilling inspections using cameras and wireless data transmission systems that lack real-time capabilities.
Innovation Solution
A system utilizing tracer wires for power line communication (PLC) to power and transmit data to an observation device, such as a camera, during the pullback of the drill string, enabling real-time downhole observation and identification of crossbores.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If post-drilling inspections are performed using cameras and wireless data transmission systems, then crossbores can be detected, but job time and cost increase due to lack of real-time capabilities
Solution Approach 1:
The observation device is attached to the drill string before drilling begins, and data transmission capabilities are established in advance through tracer wires embedded in the utility line. This allows real-time monitoring during drilling operations, eliminating the need for post-drilling inspections and reducing job time while maintaining reliable crossbore detection.
2Loss of time
If real-time observation during pullback is implemented, then crossbores can be immediately identified, but system complexity increases due to additional components
Solution Approach 1:
The tracer wires serve multiple functions: they provide structural support for the utility line, enable real-time data transmission from the observation device, and facilitate power delivery. By making the tracer wires multi-functional, the system achieves real-time monitoring without adding significant complexity, as the wires already present in the utility line are utilized for data transmission.
3Loss of information
If tracer wires are used for power line communication, then real-time data transmission is enabled, but energy loss increases due to electrical resistance
Solution Approach 1:
The system uses the tracer wires as an intermediary medium for both mechanical support and electrical communication. By utilizing existing tracer wires rather than adding separate communication cables, the system enables data transmission while minimizing additional energy loss, as the electrical resistance of the tracer wires is already accounted for in the original utility line design.
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 detection of crossbores, reducing job time and cost by allowing immediate identification and marking of crossbores during the drilling process without the need for additional post-drilling operations.
Implementation Method 1
A controller on the drilling rig is configured to transmit drilling data to a remote location using power line communication (PLC) techniques over the tracer wire
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.