El Furrial Oil Field: A New Giant in an Old Basin
In 1978, Lagoven, S.A., an affiliate of Petróleos de Venezuela, S.A., started an exploration program aimed at deeper targets on the northern flank of the Eastern Venezuelan basin, where the shallow upper Tertiary section had been explored for more than eight decades. The quality of the seismic data collected was sufficient to give indications of thrust faults with associated structures. From 1978 to 1985, geologic surveying, structural modeling, and interpretation of seismic data were combined to define the first prospect: El Furrial. The discovery well, FUL-1, penetrated 276 m (905 ft) of net oil sand and produced up to 7331 bbl of 26° API oil per day. This is the largest single discovery of medium-gravity oil in the last 25 years in South America. Folding and thrusting of the northern flank of the Eastern Venezuelan basin occurred during the collision of the Caribbean and South American plates. The evolution began at least by the early Paleocene. Cylindrical folds associated with thrusts are aligned in series for a distance of up to 70 km. They constitute a typical foreland overthrusted basin. The reservoir rock is a shallow marine sandstone deposited during the late Oligocene. Gross thickness ranges from 457 to 518 m (1500 to 1700 ft), and porosities range from 11 to 16%. The El Furrial discovery represents an excellent example of the prospectivity of a foreland overthrusted area and also an example of continued successful exploration to pursue deeper objectives in an area already considered mature.
Figures & Tables
The success of Memoir 14 and the worldwide interest shown for data on giant fields prompted AAPG to schedule a symposium on giant fields at the end of each subsequent decade. The 1968-78 symposium was held in Houston, Texas, April 1-4, 1979, and the papers were published in AAPG Memoir 30, December 1980.
The Stavanger Conference "Giant Oil and Gas Fields of the Decade: 1978-1988" was held in Stavanger, Norway, September 9-12, 1990, and is a continuation of the Giants of the Decade series.
Scientific studies and projections of future world energy demand indicate that although alternative-energy fuel sources must be actively pursued and developed, there also must be adequate petroleum supplies to bridge the gap. For the international petroleum industry, the years covered by this conference, 1978-88, were complex. They were years of boom and bust. The world's energy consciousness was boosted sharply by the effects of the 1979 Iranian revolution and the resulting embargo, which sent world oil prices to record heights. Global petroleum exploration soon surged, leading to the industry's all-time drilling high in 1981. Then came the oil price collapse in 1985, and the following years were characterized by falling oil prices and drastic budget cuts for exploration and development.
Although exploration dropped sharply during the latter part of the decade, there was a steady flow of giant oil and gas field discoveries. Using the giant field designation criteria of 500 million bbl of oil recoverable for fields in Asiatic Russia, North Africa, and the Middle East,