High potential, undeveloped, deep Cretaceous reservoirs in Lake Maracaibo Basin

Abstract

The Lake Maracaibo Basin contains one of the world’s richest petroleum source rocks, the upper Cenomanian to upper Campanian organic rich shales of the La Luna formation (Hedberg and Sass, 1937). It has produced more than 30 billion bbl of oil mostly from Miocene/Eocene sandstone reservoirs and with total mean resources of 656 million barrels of oil-MMBO (USGS March 2017), it still contains ~40 billion bbl of estimated oil reserves. The Early Cretaceous (Aptian/Albian) Cogollo Group carbonates initially produced oil in the northern part (Mara/La Paz fields). It has been developed in the west, onshore and offshore parts of the Basin. These carbonate formations of the Cogollo Group, which comprises Apon, Lisure and Maracas formations, are currently the main producers in the Shell/PDVSA West Urdaneta field where detailed modern studies and analysis have been conducted in the last 15 years. During the evaluation for the re-development of a group of mature fields (sandstone Eocene reservoirs) in the Central part of Lake Maracaibo, attention was paid to a set of old isolated (sparse) deep wells which had penetrated, tested and some even produced oil from the Cogollo Group carbonates. The integrated evaluation of 3D seismic, log correlation, modern petrophysical evaluation and production data of these selected deep wells, led to identifying several Cretaceous prospective zones, suitable for future drilling to produce from carbonates of Apon, Lisure and Maracas formations. The most prolific areas are expected to be towards paleostructure highs. A combination of matrix porosity and fractures reinforces the attractiveness of these areas. The density of subsurface data (3D seismic, well logs, etc) will allow to manage associated subsurface risk, and based on the relative location of these zones to existing infrastructure and shallower producers, these resources could be moved quickly into development.

AAPG Datapages/Search and Discovery Article #90330©2018 AAPG Hedberg: Geology of Middle America – the Gulf of Mexico, Yucatan, Caribbean, Grenada and Tobago Basins and Their Margins “Integration of the geology of the area from the southern onshore of North America to the northern onshore of South America”, Siguenza, Guadalajara, Spain, July 2-5, 2018