Seismic Characterization of Ultra Matures Oil Fields: Improving the Capacity of Prediction, Study in Lote X - Talara Basin, NW Peru

Jose Castillo
Petrobras Energia Peru

In this paper we aim to develop technical issues involved with 3D seismic interpretation methodology and its applicability in mature fields in a case study on Talara Basin, Block X, which produces since 1911 and where over 5.000 wells were drilled. The Talara basin is considered as a fore-arc, located in the NW Peruvian active margin, it is characterized by structural and stratigraphic complexity, moderate degree of digenesis which implies poor porosity-permeability in reservoirs. The age of the reservoirs ranges from the Paleozoic to Eocene. The subsurface interpretation control was mainly driven by well geology. In the last five years a great effort to join well information and seismic data was performed.

The most important contributions provided by these seismic interpretations may be designated as:

· Structural model for main producing formations: Mogollon, Ostrea-Echino and Helico sandstones.
· Modeling of more than 120 normal faults, identifying the main patterns and roles in the petroleum accumulations, age of different fault systems (Pre–Talara and reactivations).
· Identifying of structural features such as rotation of blocks, local dip changes (not seen by wells). Intensity of faulting events.

· Stratigraphic variations between Ostrea-Echino reservoirs.
· Identification of Ypresian unconformity – Base of Talara group and stratigraphic relationships of the formations involved, like as angularity and new criteria for stratigraphic correlation and compartmentalization of reservoirs in Ostrea Formation.
· Relationships between main faults and production trends in Mogollon (fractured reservoir).
· Identification for drilling opportunities in new significant prospective areas behind Carrizo, Coyonitas and La Tuna fields.

The extraction of RMS seismic amplitude in Ostrea and Helico reservoirs show a reasonable correlating with production trends. The integrated study on the south area of Block X involves mentioned geophysical interpretation, well geology, stratigraphy, petrophysics and reservoir engineering in order to support a recovery program with over 800 wells focusing in better exploring of those reservoirs.

AAPG Search and Discovery Article #90185 © AAPG Geoscience Technology Workshop, Revisiting Reservoir Quality Issues in Unconventional and Conventional Resources, Austin, Texas, November 12-13, 2013