Petroleum system modeling in complex tectonic setting; a study case of the Huallaga-Maranon retroforeland basin system, Peru

The present study explores the oil and gas potential of the HuallagaMaranon Andean retroforeland basins in Peru, considering a regional transect which extends from the Eastern Cordillera in the west trough the Huallaga fold-and-thrust belt at the Andean deformation front to the Maranon Basin in the east. The sequential restoration of main tectonic events was derived from previous stratigraphic and structural interpretations revisited with reprocessed seismic lines, and new geochemical, petrographical, geochronological and thermochronological data. The resulting framework was tested in a 2-D Basin and Petroleum System Modeling (BPSM) to check the relationship between burial history, thermal maturity evolution and timing of hydrocarbon generation, expulsion and trapping at regional scale. BPSM suggests that during the Late Cretaceous (ca. 80 Ma) the petroleum generated in the Upper Triassic-Lower Jurassic source rock known as the Aramachay Formation migrated through the Middle-Upper Jurassic Sarayaquillo Formation basal sandstones up to 250 km and accumulated in the southeast of the Maranon Basin. From the Late Miocene, the reactivation of vertical faults favored the migration and accumulation of petroleum in Cretaceous siliciclastic reservoirs which is consistent with the hydrocarbon fields existence in this sector of the basin.In addition, results of modeling show that in the southwest of the Maran similar to on Basin the development of structures during Late Miocene times postdated the generation and expulsion of hydrocarbons calculated for the Aramachay Formation which introduces a risk of synchronization between oil migration and charge. However, part of the generated hydrocarbons during the Late Cretaceous and Cenozoic are partially preserved in Jurassic reservoirs due to the high seal capacity of mudstones of the Sarayaquillo Formation. Such hydrocarbon fluids are redistributed and migrated into structural traps during Miocene times. In addition, the Miocene gas generation and expulsion also will reduce the risk of synchronization with the development of structures. In the Eastern Cordillera, organic-rich levels of the Aramachay Formation are in the late immature to early oil window show the occurrence of organic pores adding hydrocarbon storage capacity, suggesting this unit to be considered as a potential unconventional target in future exploration activities.

Automated summary

This study explores the potential of oil and gas in the Huallaga-Maranon Andean retroforeland basins in Peru and investigates the relationship between hydrocarbon generation, migration, and accumulation. The findings show that the petroleum in this region mainly comes from the Upper Triassic-Lower Jurassic source rock and migrates through the Jurassic sandstones to accumulate in the southeast of the Maranon Basin. In addition, the development of structures during the Late Miocene promotes the migration and accumulation of petroleum, while hydrocarbon generation and expulsion occur mainly in the Cretaceous and Cenozoic periods.