Carabobo Field

[2] The Orinoco Belt holds 90% of the world's extra heavy crude oils, estimated at 256 billion recoverable barrels.

Preliminary exploration ended in 1967, and in 1987, Venezuelan consultant Anibal Martinez determined that the belt extends 285 miles westwards from Puerto Ordaz.

Venezuelan President Hugo Chavez's administration named the four fields from west to east; Boyacá, Junin, Ayacucho, and Carabobo, with 36 licensing blocks.

[5] Due to the nature of extra heavy crudes, the oil produced from the Carabobo field has extremely high viscosities.

As a result, emerging technologies have recently made recoveries high enough to produce the extra heavy crudes economically.

Methods such as immiscible gas injection, polymer flooding, and in situ combustion, better known as fireflooding, have all seen limited success in the Carabobo field.

In 1999, Bognolo reported that biosurfactants not only reduced the viscosity of the Venezuelan heavy crude oils, but also increased their mobility in transport lines.

Currently, the biodegradation of the heavy crudes has become an integral tertiary recovery method in the field, as it is a cost-efficient and eco-friendly way to drive the residual oil trapped in the reservoirs.

Thrust faults associated with the fold belt resulted in the burial of Cretaceous and possibly older source rocks into the thermal window for oil.

After burial, these source rocks were pushed into the thermal window for oil, and began to migrate updip into the Miocene sandstones.

A classic example of long distance migration, the oil from the Upper Cretaceous Querecual formation source rock travelled about 300 kilometers.

[10] In the Carabobo field, the reservoir tar sands are characterized by several depositional sequences of Miocene sandstones and mudstones.

The sands were carried along north flowing rivers of the time period and deposited on the southern margin of the East Venezuela Basin.

[2] Stratigraphy is also a challenge to production, as the pinch out of the Miocene Ofacina formation is characterized by shale barriers caused by the juxtaposition of different mudstone and sandstone facies.

[6] The advancements in horizontal drilling techniques have led to the use of steam assisted gravity drainage in extra heavy oil reservoirs.