"Rejuvenation" of a Very Mature Productive Area: Application of Sequence Stratigraphy, Depositional Facies and Reservoir Architectural Studies in Inactive Old Fields - Dorsal De Huincul - Neuquen Basin, Argentina

D. A. Kokogian and J. R. Vasquez

The project objectives were to define the upside potential and identified drilling locations, both for exploratory and development wells, in Loma Negra-NI-Huincul old fields, inactive due to pressure depletion.

Fields are located in Dorsal de Huincul area (Huincul Range) which is a highly complex structure associated with a major transtensive-transpressive wrench system. Several angular unconformities are very noticeable, having eroded hundreds of meters of the stratigraphic column.

Study was focused on the fluvial-deltaic sediments of the Cuyo Group (Bajocian-Bathonian), the main productive levels in the area. An understanding of the stratigraphic units, visible at outcrop, seismic and well scales, provided the appropriated framework for the analysis. Seismic facies, detailed log and core analysis allowed us to generate paleogeographic maps and predict the reservoir distribution into each individual stratigraphic unit. Fluvial channels overbank, crevasses splay, mouth-bar, interdistributary and delta front facies were recognized. Finally, the integrated model was compared and adjusted with the outcrop data.

As a result of this study, exploratory and development wells were proposed being all of them productive either gas or oil. Several of the new drilled wells found new productive horizons with original reservoir pressure, proving the presence of different tanks predicted by the model. This fact encourages the evaluation of the whole adjacent areas. Summing up, this integrated approach using the best outputs of the geology and geophysics in subsurface as well as in surface has been proved as a powerful tool to explore and reactivate a very mature area.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California