Paleogeography During The Aptian – Albian In The Neiva Subbasin (Upper Magdalena Basin, Colombia)

The tectonic and stratigraphic evolution of the upper Magdalena valley and adjacent Colombian areas took place in several structural and sedimentary episodes. The original Jurassic back-arc extensional basin in the area has been modified during several periods of compression, oblique slip, and elevation since the late Cretaceous to the present. A complex structural geometry and sedimentation has been developed in this basin, and maturation, migration, lithostratigraphic histories are significantly diverses in different sub-areas. A good comprehension of depositional environments , sedimentology and reservoir quality evolution during the Aptian-Albian is a key factor for the hydrocarbon exploration in the Upper Magdalena Basin. Since the clastic Aptian-Albian reservoirs (Alpujarra and Caballos Fms) are considered the main target in the area , the study was focussed on a regional paleogeographic mapping integrating all the available field and well information. It appears that the marine Aptian-Albian sediments was deposited overlying a Triassic- Jurassic basement on two main sedimentary cycles. The Alpujarra and Caballos reservoirs with a deepening marine environment to the North were influenced by clastics supplying coming from two existing paleo-highs: the Proto Central Cordillera to the West and the Garzon Massif to the East of the studied area. The reservoirs properties are considerably degraded to the South and the East of Neiva Subbasin.