Authors: Diego León Venegas Gutiérrez (presenter), Juan Carlos Llinás, Ecopetrol S.A.
The Fuerte Sur Block is located in the southern Caribbean offshore of Colombia between the Urabá and the Morrosquillo Gulfs. The area of the block has an extension of 278.000 km2, mostly on the current continental slope. A significant percentage of this block is covered by a 3D PSDM seismic cube, which is the main dataset for this project. A handful of wells have been drilled just outside of the study area, including the Uvero-1, Fuerte-1, Morrosquillo-1 and El Bobito-1 drilled on the continental platform in the late 60s and 70s and the Kronos-1, Purple Angel and Gorgon wells drilled recently at the foot of the slope, which resulted in significant gas discoveries that are being currently evaluated.
The studied interval corresponds to the syn-kinematic succession accumulated on top of a distinctive angular unconformity of Pleistocene age that separates it from the pre-kinematic succession that forms the Sinú Offshore Deformed Belt. The syn-kynematic section in the Fuerte Sur area displays a series of narrow depocenters located on the back limbs of predominantly west-verging folds that were being filled by sediments as these structures grew.
The objective of this study was to identify and map seismic horizons that are continuous throughout the entire area in order to generate a chronostratigraphic framework for the syn-kinematic succession, and then to define seismic facies in the interpreted sequences that would help to understand the depositional environments, and therefore, to predict the distribution of reservoir, source and seal rocks.
Five Horizons were interpreted; the lowest one is the angular unconformity, and four additional horizons define the top of the four sequences (TS1 to TS4). In the syn-kinematic sequence of the Sinú Deformed Belt, seismic facies Cbh, Bh, Cbl, Bl and A were identified based on the methodology of Prather (1998), in addition to hemipelagic deposits corresponding to the slope wedge. The sequences TS1 (Lower Pleistocene) and TS2 (Middle Pleistocene) contain the main reservoir intervals (Cbh facies). In TS3 and TS4, there is a predominance of facies Bh and Bl, which are not considered good reservoirs in the area. In the northern part of the block the sequences become shallower and thinner reducing their prospectivity. The intermediate sector of the block, is the most prospective area with seven deep depocenters containing significant sandy facies. To the south, the depocenters are interpreted to be filled mostly with fine sediments. The identified play in the syn-kinematic sequence in the Fuerte Sur block is characterized by stratigraphic traps, where Cbh facies pinch out of near the edges of the “piggy-back” basins of folds developed due to active compressional tectonics at the time of deposition. Main provenance seems to come from the north, where some sequences were not deposited or eroded (TS1 and TS3), and where Cbh facies predominate and onlap in each mini basin.
Diego León Venegas Gutiérrez, Ecopetrol S.A.
Diego earned a BSc in Geology from the Universidad Nacional de Colombia.
In his 18 years of experience in the petroleum industry, he has worked at DEMINEX Colombia for 2 years as a Geologist, and was a consultant for the Instituto Colombiano del Petróleo (ICP) for three and a half years in a project about seal rocks, working in petrography and mapping.
Currently, Diego works as Geologist in Ecopetrol, providing support as interpreter for the geophysics group in acquisition, interpretation, reprocessing and data management. For the last three years he worked in the offshore group, interpreting the 3D seismic of the Sinu Belt, in orther to identify the seismic facies for the syn-kinematic sequences and prospectivity. Previously, he worked in prospetivity for the onshore group in the different basins of Colombia. He is a member of ACGGP.