Journal of Petroleum Geology, Vol.10,
No.2, pp. 125-134, 1987
©Copyright 2000 Scientific Press,
Ltd.
THE ORINOCO OIL BELT, VENEZUELA
Aníbal R. Martinez*
* Apartado 50 514, Caracas 1 050A,
Venezuela.
Abstract
The Orinoco Oil Belt of Venezuela is a very
extensive, non-discrete, crude-oil producing area located along
the southern third of the Maturin (Eastern Venezuela) basin,
north of the Orinoco River and the Guayana Shield. It extends due
westwards from Puerto Ordaz for 460km; the main producing areas,
defined on the basis of productivity and magnitude of crude oil
in-place, cover 13,600 sq. km. There are no significant surface
indications of petroleum anywhere in the Belt. The first well
drilled was La Canoa- 1 in 1936, initiating a stage of
exploration which ended in 1967 with publication of a preliminary
evaluation of the potential reserves; the Ministry of Energy and
Mines, then of Mines and Hydrocarbons, and the State oil company
Corporación Venezolana del Petréleo (CVP) completed a second
stage of exploration in 1977; Petróleos de Venezuela and its
operating companies then drilled 669 wells in five years
(1979-83) totalling 643,000 m with 5.5MM**m of logs, and shot
15,000 km of seismic lines at a cost of $US 615 MM, an effort
conservatively estimated as having taken 2,500 man-years. The
main producing areas are, from east to west, Cerro Negro, Pao,
Hamaca, San Diego, Zuata, and Machete. Petroleum characterisation
in the Belt is based on the study and analysis of 288 samples.
Viscosity (dynamic) of the crude oils at reservoir conditions
ranges from 2,000 to 7,000 mPa.s(cp)+. Production rates
average 25cu.m/d (160 b/d), increasing fourfold after steam
stimulation. At the end of 1985, production was 13,000 cu. m/d
(80, 000 b/d)+, from the Cerro Negro and Hamaca main producing
areas. Operating costs are similar to those in other heavy-crude
oil fields in the basin. The volume of crude oil in-place is
estimated to be 187.8 B cu. m (1,181 B brls), which makes the
Orinoco Oil Belt the largest crude oil accumulation in the world.
Proved reserves are 4.161B cu. m (26.170 B brls), and unproved
reserves 14,822 B cu. m (93,230 B brls). Investigative activities
are underway, particularly in the Cerro Negro and San Diego
producing areas.