New Exploration Ideas Leading to Discoveries and Unlocking New Potential in a Mature Oil Province: The T2 Unit, Llanos Basin, Colombia

Abstract

Abstract

Exploration in the Apiay-Ariari Province of the Colombian Llanos Basin started in the 1940s and led to the discovery of the Castilla and Chichimene Fields by Chevron in 1970s and the Apiay-Suria Fields by Ecopetrol in 1980s, which produce from the Upper Cretaceous K1 & K2 Units, and the Upper Cretaceous-Early Tertiary T2 interval. Recently, a comprehensive study that revisited the play concept for the T2 Unit resulted in heavy oil discoveries in the vicinity of these producing fields.

The initial exploration targeted the structural highs in anticlines associated to the tectonic inversion of normal faults from the Cretaceous. We revised the geological framework and well datasets were utilized to analyze and interpret the stratigraphy and structural framework of the area.

Our model, validated by drilling, indicates that: a) the T2 sandstone interval in this area consists of Upper Cretaceous to Eocene rocks with major unconformities in between, and with remarkable thickness variations across inverted fault trends; b) a large stratigraphic trap was charged with oil that was biodegraded during the Oligocene; c) the recent tectonic events that generated the inversion of the existing normal faults breached the older traps, creating anticlines filled beyond the spill points, where the trap limits remain to be tested.

The implementation of our new geologic model concepts has already added around 3.0 billion barrels (OOIP) in the area. We strongly believe that these volumes can be significantly increased along this prolific heavy oil trend.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016