Inversión geoestadística aplicada a la caracterización de reservorios de areniscas fluviales en la Cuenca del Golfo San Jorge, Argentina

In the Golfo San Jorge Basin, Argentina, the main traditional reservoirs are fluvial sandstones which usually fall below seismic tuning frequency. Using high technology added to the proved workflow improves the detection and follow-up of reservoirs, proven and new ones. After the traditional seismic structural interpretation of faults and horizons with the help of attributes, the seismic reservoir characterization was aimed with the processing and analysis of a Seismic Geostatistical inversion. Using this technique we improved the knowledge of the emplacement, behavior and occurrence of the reservoir sand bodies, opening new zones and determining the drilling development planning. The seismic time thickness of the reservoirs, sand probability and effective porosity maps for each separate layer were generated and interpreted at the end of the sequence workflow. This method has demonstrated to be very confident, not only for development of well locations, but also to drill mid to high risk wells (mainly in stratigraphical traps) and add a new dimension in the decision tree of determining the sands occurrence. The Geostatistical Inversion has proven to provide subtle details and quantification of uncertainty. This procedure works like putting together three worlds more closely, the Geophysical, the Petrophysical and the Geological. The ability to go from one place to any other in a cube of seismic with the accuracy of the well logs, even though in a Geostatistical way, is considered one of the most positive answers to the problem of thin layers.