The goal is to develop a low cost, easy to use ground penetrating radar (GPR) instrument for locating natural gas pipes and leaks with commercialization potential. The work will result in the development of a preproduction prototype instrument.
Geophysical Survey Systems, Inc. (GSSI) – project management and research product
North Salem, NH 03073
There is a limited arsenal of tools available for pipe detection. However, the diversity of techniques shows that each has advantages and shortcomings. For example, only GPR can claim to reliably detect nonmetallic pipes, but may fail to detect pipes in some soils. The main categories of pipe detection tools in common use include: Pulsed Induction (Inductive Line Location, Inductive Line Tracer, Conductive Line Tracer, Passive Line Tracer); Magnetic Locators; EM Locators; Resistivity Methods and GPR Pipe Detection.
GPR has a long and sometimes checkered history of pipe detection. Although it is perhaps the best general pipe locator available, it is often mistakenly assumed to be a silver bullet. In fact, GPR has difficulty in highly conductive clay and silty soils. Sometimes clutter from other objects can obscure pipes. And most commonly, subtleties in processing and interpretation mean that less skilled surveyors may fail to detect pipes that would otherwise be clearly resolved. This means that GPR can never be 100% successful at locating pipes. However, expanding GPR's capabilities into full 3D images has made detection much more robust, and interpretation much simpler. This means that GPR is really now entering into a new phase of capability, making it far more versatile than ever before.
A primary need in the gas pipeline area, as expressed by industry stakeholders, is the ability to accurately detect underground utilities. The GPR method developed under this project provides a lightweight, easy to use system with the capability to detect and display underground utilities, as well as predicted depths, in real time. This, along with the post processing capability of the system, offers the potential to reduce the costs and efforts associated with the accurate location of utilities whether for the purpose of pipeline location for excavations or for prevention of unintentional damage to utilities from third party excavation. By making location easier and cheaper to accomplish, the overall reliability of the nation's natural gas infrastructure is enhanced and the reliability of the delivery of gas to the nation's consumers is increased.
This work has developed a lightweight, easy to use ground penetrating radar (GPR) system for tracking metal/non-metal pipes. A pre-production prototype instrument whose production cost and ease of use should fit important market niches has been developed and tested . It is a portable tool which is swept back and forth like a metal detector and which indicates when it goes over a target (metal, plastic, concrete, etc.) and the depth of the detection. In this way the user can simply walk around looking for targets and by “connecting the dots” follow pipes in real time. This is the first tool that locates metal and non-metal pipes in real time and maps their location.
As is commonly known, GPR is no silver bullet; in heavy clay soils, small deep pipes are often impossible to see. The laws of physics limit the penetration depths based on soil conductivity. Since pipes can be successfully located regardless of pipe composition and crossing angle in most soils, this could be an important addition to the arsenal of pipe locators. Typically, a six inch pipe three feet down is easily tracked using this device. In the best Florida soils, a six inch pipe can be targeted more than 20 feet down. In the worst Houston clays, depth of detection may be limited to two feet. The user can follow the pipe as he walks along, distinguishing its depth from other pipes that either cross or are running alongside and can tell when the pipe bends or branches and, most importantly, locate places where it may be broken.
The Pipe Location/Leak Detection Tool prototype developed under this project includes the following features: 1) lightweight deployment (armature, antenna and backpack), 2) small, low power system controller (compact user interface, easy data manipulation), 3) positioning systems (Gyro, GPS, Accelerometers), 4) data compression algorithms, real-time signal and image processing (audio feedback, feature extraction, target recognition, new graphic data interfaces) and 5) holds the potential to serve as a leak detection device in addition to pipe location capabilities
Work under this project has been completed. Final evaluation of the results of testing of the system as a natural gas pipeline leak detector have not yet been finalized due to delays in excavation of potential leak sites found using the device to validate system findings. Overall project results will be provided in project final report scheduled for completion by early Spring 2005. Research performer continues to work on reduction in system weight and overall costs and is evaluating the potential commercial market for the project.