Geometry and Kinematic Evolution of The Matachines Oil Fields, Magdalena Valley(Colombia)

Located in the Upper Magdalena Valley (Colombian Andes), these two fields Matachin Norte (MN) and Matachin Sur (MS) are compartmented along strike by an anastomosing system of thrust faults and in depth by a complex interplay of fault splays. The complex tectonic evolution of the Magdalena Valley encompasses Mesozoic Rifting, followed by successive inversions with main pulses during the Late Paleocene/Early-Eocene and Mid-Miocene. The Espinal High, located bellow The Matachines fields, is a basement high formed during these inversions. The 3D structural model reveals that in MN the main trap is the Monicongo Anticline, an open to gentle asymmetric fold at the footwall of a westward verging thrust fault (The Venganza Thrust -VT). MS is more complex. It corresponds to a west-verging break-backward imbricate system of fault-propagation folds decapitated by the VT. This system disappears along strike and in depth, as it merges northwestward with the VT. Discrepancies of structural relief across both oil fields reveal a major control by a deep rooted inverted fault in the rise of the Espinal High beneath MA and RV. Seismic interpretation, forward modeling and cross-section restoration showed that the tectonic evolution of the area commenced with the uplift of the Espinal High. As the deeper structures controlling this basement high do not cut the Mid-Eocene unconformity, it is presumed that it was created between the Paleocene and Early Eocene, predating the main Andean compressional event. This methodology allows the development of operational plans and builds new locations and exploitation strategies for these fields.