CARTERRA Analyst – Tools to Manage and Live By
Taking advantage of all the data has to offerBy Tamara Gipprich, geophysics graduate student, Colorado School of Mines, Golden, Colo. http://www.mines.edu/
The country of Colombia has been experiencing a problem of theft along their state-controlled (EcoPetrol) gasoline pipelines. Colombia is losing approximately 100 million U.S. dollars annually due to this problem. They have asked Space Imaging (Thornton, Colo.) to assess the feasibility of using the IKONOS satellite to monitor activity along the gasoline infrastructure.
IKONOS imagery, enhanced using techniques from ERDAS Imagine, provides sufficiently high resolution to see within an oil refinery complex and along roads, railroads, and pipelines. The resolution of the imagery is sufficient to identify lineations on the ground, such as rights of way for power lines and scarring of the surface where pipelines have been buried and run underground. Even with the limited spatial and temporal data coverage available for this project, enhanced IKONOS imagery demonstrated the ability to track the pipeline infrastructure. Therefore, if imagery over the entire petroleum infrastructure were repeated at sufficiently close time intervals, there is potential to observe where theft is taking place along pipelines.
|FIGURE 1: A close-up of the region of Barrancabermeja where imagery has been analyzed. Green-colored regions denote oil fields, while the green lines are oil pipelines and the red lines are gas pipelines. The two red boxes show the locations of the IKONOS images of the city and the refinery. Map courtesy of Wood Mackenzie Global Consultants.|
Two sets of IKONOS imagery were used in this study. The first set of imagery consists of two scenes of the city of Barrancabermeja, located north of the capital of Bogotá. The largest oil refinery in the country is located here, and is capable of processing about 150,000 barrels of oil per day (Figure 1).
The imagery of Barrancabermeja is a good starting point for locating the gasoline pipelines that run to and from the refinery, with most running underground. Space Imaging’s IKONOS imagery provides four-meter color resolution and, even better, one-meter panchromatic resolution. A multispectral color image of the city of Barrancabermeja was produced by layering the separate four-meter color bands of red, green, and blue and then pan-sharpening the color image to near one-meter resolution.
Classifications and enhancements were performed on this one-meter color image to determine the best way to detect the pipeline in and around the refinery center. Many versions of classifications were performed in ERDAS Imagine including supervised and unsupervised techniques. The automatic, unsupervised technique with ten classes in ten iterations yielded the best result (Figure 2).
|FIGURE 2: A comparison of the pan-sharpened|
color image and the unsupervised classification showing the refinery center of Barrancabermeja, Colombia. In the classification image, the above-ground pipeline, highlighted in yellow, is easily visible.
|FIGURE 3: A comparison of the color image of the Barrancabermeja region and the same image filtered by edge detection. Features such as roads, fences and pipelines are sharper in the filtered image.|
|FIGURE 4: Final interpreted mosaic of Barrancabermeja region. Red lines denote gas pipelines, green lines are oil pipelines. Dashed lines show where pipeline location has been interpolated or extrapolated. Black lines indicate where the type of pipeline is uncertain.|
|FIGURE 5: A comparison of the color image of the remote region and the same image after brightness inversion and radiometric balancing. The pipeline location is evident in the lower image.|
For more effective detection and delineation of the pipelines, edge-enhancement algorithms were applied to the imagery. The goal was to highlight the edge of the pipelines above ground and the scarring on the surface due to buried pipelines. Figure 3 shows how one of these procedures has helped to define a portion of a pipeline.
The strategy used in this feasibility study was to begin with enhancements and interpretation of the imagery of Barrancabermeja, where above-ground infrastructure is readily identifiable, and, using ancillary information from the Wood Mackenzie petroleum database, to extrapolate the study farther from the refinery where interpretation becomes challenging. Figure 4 shows the layout of the pipeline infrastructure in and around the city of Barrancabermeja, produced from these procedures.
The second set of imagery consists of five contiguous scenes running north-south in a remote region near the province of Sucre. This area is in rougher terrain and contains widespread vegetation. The remote region imagery reveals only one major oil pipeline that runs from Ayachucho to Coveñas.
For the imagery near Sucre, an unsupervised classification of only five classes in seven iterations was used due to the fact that there are fewer surface features to classify within the scenes. Application of edge-detection, radiometric balancing and brightness inversion techniques produced the clear image of a pipeline running through the remote area (Figure 5). In areas of low-lying vegetation such as in the Barrancabermeja region, the detection of pipelines was much easier than in the thick vegetation of this remote region where it is much harder to see surface features.
After locating the gasoline pipeline infrastructure, some strategies could help focus the search for illegal tapping operations. The analysis would concentrate on areas that provide concealment (vegetation and/or rough terrain) next to a pipeline, as well as areas which are remote and relatively far from large populous areas. Transportation of stolen gasoline would require vehicles, most likely trucks or large vans. Unimproved, infrequently traveled remote roads that approach to within at least a few hundred meters of the pipeline would be the most likely avenues used by thieves. Ground scarring near the pipeline would be worth searching for, since the process of uncovering the buried pipeline would produce lighter colored areas (disturbed soil) easily visible in the imagery. A structure or tank, if used to store the gasoline, will likely be concealed by vegetation, or buried.
The limited sample data used in this study did not provide sufficient coverage to observe an incident of theft along the petroleum infrastructure. If the country of Colombia were to install an IKONOS ground station, it would be possible to obtain imagery with more complete coverage of the infrastructure, repeated over time periods of interest, enhancing the potential for successful observation of illegal activity along the pipeline. For surveillance in bad weather or at night, IKONOS would need to be supplemented by radar and/or thermal infrared data from another satellite.
If imagery of the entire pipeline system is available, a baseline using imagery of the pipelines could be collected and examined for known or suspicious areas of theft operations, and then these areas could be investigated by ground teams. Advanced change-detection techniques could then be applied to imagery of these same areas collected later to highlight new and suspicious activities. Clearly, the imagery offers a means of general surveillance of the petroleum infrastructure in Colombia.
Acknowledgements: Professor Terry Young, Head of the Geophysics Department, Colorado School of Mines and Mike Nifong of Space Imaging.
Wood Mackenzie Global Consultants Pathfinder Software
Wood Mackenzie Global Consultants Electronic Book-Upstream Software
Ministerio de Hacienda y Credito Publico: Mapa de la Republica de Colombia (1981), Departamentos de Bolivar Antioquia y Santander, la Ciudad de Barrancabermeja. Escala 1:200.000 Kms.
Ministerio de Minas y Petroleos: Mapa de la Republica de Colombia (1967), Geologia del Cuadrangulo H.11 Barrancabermeja. Escala 1:200.000 Kms. Bogotá, D.E.