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Roberto Linares1
(1) Ecopetrol, Bucaramanga, Colombia

Abstract: Fractured Reservoirs In Calcareous Rocks Of The Middle Magdalena Basin, Colombia

The Middle Magdalena Basin of Colombia has been explored since the beginning of this century. The most important reservoirs are La Paz Fm. (Eocene), Mugrosa Fm.(Oligocene) and Colorado Fm. (Oligocene).

The hydrocarbon potential of the Cretaceous rocks has also been identified by some wells in La Luna, Rosablanca and Cimarrona Formations. Those wells tested the hydrocarbon potential that remains untouched in the basin for calcareous rocks.

The goal of this study is to identify the fracture framework of the calcareous rocks that will simplify exploitation of fractured reservoirs in the basin. This work integrates outcrop data, radar images, aerial photographs, seismic and well information.

The Cretaceous sediments have been deformed into a variety of map-scale structures in a compressional structural setting, thus providing a series of natural experiments for observing the formation, distribution, and behavior of fractures in these carbonate units.

The structural position plays a great role in the overall fracture character and density in the folded and faulted Cretaceous carbonates of the Middle Magdalena Basin.

Two northeast-striking fracture sets dominate the Rosablanca Formation, a longitudinal and a conjugate set; the latter is more important because it improves the porosity and permeability of the reservoirs. These sets are interpreted as formed during Miocene event of deformation of the Eastern Cordillera. In this way a new insight is given for reducing the exploratory risk of the new prospects interpreted in the basin.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana