Pipeline R-O-W management at light speed
B. Carl Kuhnke Director of Business Development Terra Remote Sensing Inc. Sidney, British Columbia, Canada V8L 5Y3 Tel. (250) 656-0931 Fax (250) 656-4604 Website:www.terraremote.com Geographical information has long been seen as a useful adjunct to the core business needs of large corporations. Today, however, technology advances and management requirements are transforming the previously specialized GIS world into a core enterprise function that integrates engineering detail, geospatial information, and strategic planning. This paper examines an industry in explosive growth B oil and gas transmission – and how the application of a new airborne remote sensing technology, LIDAR, can cost-effectively provide the simple, transparent management tools needed to design, build, manage and value the billions of dollars in pipeline infrastructure currently underway. The Need Power crisis. Lights out in Silicon Valley. Cold pools in Palm Springs………. A combination of well-intentioned but badly-implemented utility deregulation, enormous economic growth, and an insatiable North American appetite for new energy capacity has led to a crisis situation, not only in the west, but across North America. National, state and provincial governments are wrestling with the conflicting ideals of environmental stewardship and the need to design and build generation capacity to keep up with demand and prevent the huge economic ramifications that will result from a failure to do so. At the same time, the corporations charged with the responsibility to develop and provide the critical energy supplies must speed the process with not only these priorities in mind, but also stakeholder accountability. They are required to effectively manage and value these increasingly large assets once they are in the ground. As a result, the “Enterprise GIS” is no longer a ‘wish list’ item, but a necessity. Hydrocarbon producers and purveyors are moving to quickly integrate their existing, fractious systems in inventory, design, construction and maintenance, while simultaneously focusing on the bottom line. A fast, simple and cost-effective means to plan new construction and manage existing assets is needed - one that can reduce deployment and reporting costs while providing more and better data for implementing those functions. Two traditional methodologies - aerial photomapping and ground surveys - have proven cumbersome, slow, and expensive. While satellite imagery has recently become ‘en vogue’, even the best one meter resolutions are not sufficient for more than a cursory view of assets from a management perspective. However, sophisticated airborne scanning LIDAR devices integrated with digital imagery and GPS/IMU systems can provide rapid and precise (to 15 cm absolute) x, y and z positioning and detailing, with considerable cost savings. Its ease of integration into any existing GIS brings both strategic and financial benefits. WHAT IS LIDAR ? Quite simply, LIDAR is the use of light to measure distance. Everyone is familiar with the more common acronym RADAR (RAdio Detection And Ranging). LIDAR (LIght Detection And Ranging) is simply a substitution of light's frequency band for slower radio waves in the electromagnetic spectra. Public awareness of this terminology has grown as LIDAR (‘laser’) speed guns have replaced traditional radar guns in traffic speed enforcement. LIDAR simply uses a laser pulse to determine distance by measuring the time it takes for the laser pulse to reflect back from a "ground hit" (or other object). The key to the effective use of LASER/LIDAR in mapping lies not in the light pulse itself, which is a decades-old technology, but in the sophisticated georeferencing algorithms that enable us to know precisely where the target object is in time and space. Current laser technology provides an accuracy of 5 cm or less from an airborne platform. The aircraft’s Inertial Reference or Measurement Unit (IRU/IMU) provides the directional vector of the laser fire. Coupled with a Differential Global Positioning System (DGPS), they provide a position for the laser within 5 -10 cm. Terra has been in the LIDAR business for almost 20 years, having co-developed the world’s first unit to perform airborne coastal bathymetry at efficiencies far exceeding the capabilities of surface vessels. The LARSEN 500 marine LIDAR bathymeter has been performing bathymetry around the world for over 15 years. Based on the time differential of the water surface reflection pulse and the seafloor reflection the airborne scanning bathymeter can collect water depths down to 50 meters at a rate of 50 sq km/hour. Based on an Nd:YAG laser with a wavelength of 1064 nm, it is frequency doubled to also produce a blue-green wavelength signal (532 nm) which penetrates to the ocean floor. The water depth is derived from the time differential of the seabed reflection and the water surface reflection of the infrared signal. (Figure 1). Combine the LIDAR bathymeter with georeferenced imagery flown simultaneously, and the integrated end product provides a powerful tool for coastal management around the world (Figure 2). New Technological Development Continuing technological advances, miniaturization and industry needs have pushed suppliers of LIDAR technology to ‘go faster and smaller’ in their product offerings. Marine bathymeters require a high-energy laser pulse to be able to transit the water column and return some photons to the airborne detectors. This energy requirement dictates a finite limit to the system's Pulse Repetition Frequency, or PRF. The laser systems are quite bulky, consume kilowatts of power and need liquid cooling. Growing terrestrial needs for precise mapping, digital elevation models, and the advent of GIS have demanded more precise measurements from the supplier community. The demands on a terrain LIDAR system are such that low power diode or diode-pumped YAG lasers can fulfill the task. This laser technology permits the very high PRFs needed for the decimeter level terrain detailing. So, too, the requirement for visual imagery to which senior management can easily relate has become an important feature (Figure 3). Many companies have responded by integrating one or more sensors on an airborne platform that can be moved to a project quickly and inexpensively. Some firms, Terra included, chose a helicopter platform that provides a combination of versatility and low cost, with a specific target market of linear corridors (Figure 4). Others have selected fixed wing aircraft flying at higher altitudes for the mapping of large urban or rural areas. In all cases, the LIDAR sensors now feature pulse repetition frequencies in the order of 5000 - 25,000 Hz, permitting the collection of up to one million data points per minute. This presents its own software challenges for data acquisition and processing, all of which are manageable in today’s technology environment. Today’s GIS has to support a wide range of clients and is challenged by diverse management demands. Typically, management needs a combination of data outputs that satisfies not only engineering design and maintenance, but also strategic planning, all for the same asset or set of assets. Ten years ago this would have been technically unthinkable, cost-prohibitive, or both. Today it is not only a technical reality, but also a cost-effective investment that brings more to the bottom line. A typical sensor suite for these applications will involve a terrain scanning LIDAR, digital imagers and DGPS/IRU. The scanning laser, firing through a scanning mirror that paints a swath up to 60° in width, returning the ‘hits’ from everything underneath. It ‘builds’ a three dimensional numerical model of the area, completely and precisely georeferenced (Figure 5). The digital imagers, video and frame are simultaneously imaging the terrain in the visible and I/R spectrums, providing the ability to "armchair quarterback" the assets from the desktop without resorting to expensive and timeconsuming field surveys. The same planimetric mapping and elevation data previously employed can be provided faster and less expensively. What’s more, they can be integrated with true visuals of the corridor, provided through the ortho-rectification of digital camera data, much the same as the outputs from the photogrammetry process. The differences with this new mapping technology are striking. First, processing can begin immediately, often before the data acquisition project is complete. Digital data sets can be transmitted over the internet effectively or burned to CD-ROMs and expressed back to a processing base (the client receives an immense advantage here over traditional methods, with data acquisition and processing times often many times less than conventional aerial photography/photogrammetry). Second, the specific helicopter platform can vary its speed to provide a denser data set along the corridor, as per client specifications. For example, if stream crossings are a particular sensitivity, or if compressor stations are most critical for engineering or maintenance needs, the platform can hover or move slowly to pick up the density needed. Finally, the outputs of the process are readily sleevable into any off-the-shelf or custom GIS. Imagery can be provided in tiff, jpeg, dwg (AutoCad) or any other format, and the data sets themselves are transferable to any system. Most firms, including Terra, use a combination of proprietary software algorithms and commercial image processing software to turn the data into imagery suitable for either the end users, or mapping outputs suitable for immediate integration into a GIS. Case Study: Williams Gas Pipelines Williams Gas Pipelines delivers over 16 % of the natural gas in the United States of America through its 27,000 mile (and growing!) gas transmission system. As the power crisis in the west heated up, literally, it investigated alternative technologies to deliver its mapping needs for FERC, state and county regulatory purposes. As regulatory agencies shed their traditional “hurdle” image and began actively encouraging new capacity, Williams needed to ensure that time bottlenecks didn’t surface in its own ability to conform, design, build and operate. Key issues for the company were corridor mapping accuracy, precise elevation data, and “speed to build”. It also needed a better handle on its own right-of-way from the standpoints of encroachment, liability and ongoing regulatory compliance. Design and upgrading issues were becoming increasingly important, as existing rights-of-way also often offer the best opportunities for increased capacity. A proposed gas transmission pipeline along an existing 60 mile long corridor needed to be mapped and submitted to regulatory authorities within weeks. Included was an alternate 8 mile routing for the new line. Legacy mapping was not up to par, and both ground and traditional aerial survey methodologies could not come close to meeting critical path deadlines for design and construction. Terra assessed the needs with Williams and configured a sensor package that could resolve all of the issues. The terrain scanning laser (LIDAR) produced the bare earth ground DEM (Figure 6) and vegetation profiles for corridor management. High resolution digital imagery provided precise capture of the entire right-of-way, and a half-mile buffer zone for alternate routings (Figure 7). TRSI’s CAD group also produced planimetry options for maintenance purposes – actual georeferenced imagery overlaid on existing legacy data (Figure 8). TRSI’s system was mobilized and flew the entire corridor in a 2 day period. Processing began immediately on return and the full digital elevation model (to 6 inch vertical accuracy) along with seamless ortho-mosaic imagery of the entire 68 miles was delivered to the client within four weeks of mobilization. Summary LIDAR systems are a fast, precise and cost-effective means to acquire, process and deliver critical geospatial data for energy supply. Their flexibility and data output format provide the additional advantage of being able to easily populate the enterprise GIS database for further manipulation by, or for, the end user. Geographical Information Systems are no longer simply useful corporate appendages for geospatial data sets. They are becoming a core focus within large corporations for long term strategic thinking. Senior management can, and should use the available information to realize substantial cost savings for the management of significant assets. Figure Legend
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