Petroleum Systems And Tectono-Stratigraphic Evolution Of The Madre De Dios Basin And Its Associated Thrustbelt In Peru And Bolivia

Despite the presence of a widespread Late Devonian world-class source rocks (up to 16 % TOC), the Madre de Dios Foreland Basin and associated fold and thrust belt is one of the most under-explored Subandean basins. Detailed biostratigraphic studies have confirmed similarities to the tectonic stratigraphic evolution of the southern Ucayali Basin. Oils and source rock correlations indicate at least three distinct source rocks. These include mixed Type I/II Devonian (Frasnian Famennian) world-class source rock, units from the Mississippian Ambo Group, and the Late Permian Ene Formation. Devonian source rocks have a variable thickness, richness, and regional distribution. Hydrocarbon generation commenced during the late Cretaceous in the deepest part of the basin and has continued to the present time at the basin margin. Several stacked Devonian and Carboniferous reservoir and seal pairs are present. Reservoir quality improves northward and eastward away from the preserved foredeep. The main migration carriers are sandstones interfingered with or overlying the Devonian source rocks. Interbedded Pennsylvanian to Permian evaporites in the carbonate sequence represent the regional seal, which stratigraphically restricts upward hydrocarbon migration Potential stratigraphic traps with good seismic amplitude anomalies are present along the Manu Arch and may also exist along the eastern peripheral bulge. Thrust loading was hindered by the crystalline Madidi Arch, which operated as buttresses for foreland thrust propagation and also inhibited faulting along the poorly developed peripheral bulge. The peripheral bulge may exhibit significant faulting and could be the site of potential structural traps as the arch plunges northwestward and turned westward. Progressive eastward migration of the oil kitchen is associated with episodic thrust sheet propagation and coeval molasse deposition. The fold and thrustbelt petroleum system is more complex and may involve younger Permo- Carboniferous source rocks. Peak oil generation took place prior to the Quechua Phase of Andean deformation in subthrust synclines kitchens. As a result, most of the structures are charged with gas and condensate. North of the Madidi Arch, there is potential for additional oil kitchens in subthrust synclines. Because of the complex duplex style, large thrust displacement, and intricate paleo-burial history documented in the Candamo-1X well, reservoir quality is a crucial issue for liquid hydrocarbons. However, reservoir quality may improve north of the Madidi Arch where is preserved along the frontal thrusts that carry older units in the hanging wall. Good pressure seals in the Cretaceous Chonta Formation and Lower Tertiary shales are also documented in the Candamo-1X discovery as well as in the Camisea trend.