Stochastic Play Assessment of the Offshore Basins of Peru

Tarek Ghazi
GeoKnowledge USA, Inc, Houston, TX

In June 2005, Gaffney, Cline and Associates completed a USTDA-funded study for PERUPETRO S.A. on the sequence stratigraphy of the Peruvian Offshore Continental Shelf-Slope. The results of this study included a comprehensive new interpretation of the structural and stratigraphic framework and the generation, migration and entrapment of hydrocarbons within that framework in the offshore parts of the Tumbes, Talara, Sechura, Trujillo, Salaverry and Pisco basins. This work provided fresh insight into existing plays and identified several promising new plays in these basins.

This paper presents a stochastic assessment of yet-to-find resources and the net present value (NPV) of those resources in light of the work described above. Each assessment begins with play element adequacy maps and a composite play map generated with a geographic information system (GIS). Input parameters are extracted from those maps and other tabular data to enable stochastic risk and yet-to-find resource estimates using a commercial software tool. Lastly, stochastic production and cost profiles are combined with product price forecasts and several levels of dry hole tolerance to produce stochastic NPV estimates for each play, which are then aggregated into summary resource and NPV estimates per basin. The results indicate substantial remaining exploration value in all six of the studied basins, especially in those with proven petroleum systems, which include the Tumbes, Talara and Trujillo basins.