Identifying, Correcting, and Allocating Geodetic Systems to Georeferenced Data in Hydrocarbon Exploration by Using High-Resolution Satellite Imagery
- Gabriel Alvarez (Repsol YPF)
- Document ID
- Society of Petroleum Engineers
- Latin American & Caribbean Petroleum Engineering Conference, 15-18 April, Buenos Aires, Argentina
- Publication Date
- Document Type
- Conference Paper
- 2007. Society of Petroleum Engineers
- 7.6 Information Management and Systems
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- 109 since 2007
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Hydrocarbon exploration in Argentina started long before the IGM created a single, high-precision geodetic reference network for the whole country.
For that reason, several geodetic surveys were conducted in every producing basin, which have ever since then supported land surveys, well placement, seismic programs, etc.
Currently, every basin has a huge amount of information referenced to the so-called "local?? geodetic systems, such as Aguaray in the Northwestern Basin, 25 de Mayo in the Cuyo Basin, Quiñi-Huao in the Neuquén Basin, Pampa del Castillo in the San Jorge Basin, and Tapi Aike in the Austral Basin, which differ to a greater or lesser extent from the national Campo Inchauspe datum established by the IGM in 1969 as the official geodetic network.
However, technology development over the last few years and the expansion of satellite positioning systems such as GPS resulted in a new world geodetic order.
Argentina rapidly joined this new geodetic order through the implementation of a new national geodetic system by the IGM, i.e. the so-called POSGAR network (Fig.1), which replaced the old national Campo Inchauspe system. However, this only helped to worsen the data georeferencing issue for oil companies, as a third reference system was added to each basin. Now every basin has a local system, the national system in force until 1997 (Campo Inchauspe), and finally the newly created POSGAR network national satellite system, which is geocentric unlike the former two planimetric datums.
This variety and complexity of reference systems leads to significant inconsistencies and impairs data quality and metric precision.
The objective of this paper is to show a reliable and specific project to standardize all data measured in the local geodetic systems into a single, high-precision system in line with official organizations' standards and linked to a global framework through the South American Geodetic Network SIRGAS for improved consistency, precision, and eventual data quality.
RepsolYPF, through Energicon and Geodatos, densified the above-referred network in the Neuquén, San Jorge and Northwestern basins, from the 127 POSGAR points established by the IGM, which are evenly distributed all over the country. In the Neuquén Basin, efforts focused on the Chos Malal local system (densified and renamed by YPF as Quiñi-Huao datum), the previous national geodetic datum, i.e. Campo Inchauspe 69, and the new national system, i.e. POSGAR 94 spanning the provinces of Neuquén and Mendoza.
Sixty-two (62) vectors with 47 vortexes were measured, of which 39 were existing monuments from the IGM's Leveling Network and POSGAR 94 System Networks, Campo Inchauspe 69, and Chos Malal (Fig. 2). And 8 monuments were built for the Network geometry to have easily accessible points.
The work was designed to provide a planimetric frame in the 3 above-referred systems, an altimetric frame for the zone, system conversion parameters, and geoid-ellipsoid separation.
Three Ashtech dual-frequency receivers with P-code suppression were used to take measurements as they yield L2 with full wavelength. To recognize and locate existing monuments, a Garmin, GPS12 navigator-type receiver was used. Simultaneous observation time for vectors less than 40 km was always longer than 1 hour, while for vectors in excess of 40 km, it was at least an hour and a half.
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