Managing Geological Uncertainties in Oil Generation, Migration and Entrapment in the Pisco Basin, Offshore Peru

Callejon, Angel F.¹, Peter A. Emmet², Robert Hickman³, Tarek Y. Ghazi⁴, Glenn W. Granata⁵, Rolando Bolaños⁶, Maurice Slot⁷ (1) Platte River Associates, Inc, Houston, TX (2) Brazos Valley G&G Services, Cypress, TX (3) Structural Solutions, Sugar Land, TX (4) Gaffney, Cline & Associates, Inc, Houston, TX (5) Granata Geological Consulting, Houston, TX (6) PERUPETRO S.A, Lima, Peru (7) In-Depth Solutions, Nichols Hills,

Under the sponsorship of Perupetro SA a renewed vision of exploration in offshore Peru was accomplished by a multi-discipline team that undertook a comprehensive reinterpreta­tion of the hydrocarbon prospectivity of the offshore basins in Peru. Kinematic reconstruc­tions, thermal maturation models and regional velocity model were essential in building this new framework. The focus of this paper is specifically on the uncertainties on the elements and evolution of the petroleum systems in the Pisco basin.

A solid, new, tectono-stratigraphic correlation scheme across the region suggests the presence of not only Tertiary depocenters, but also thick Cretaceous sediments that may accommodate early Cretaceous source rock. Collected heat flow data is consistent with a regional average of 45 mW/m2 that provide these basins adequate energy for oil generation in the kitchen pods.

The results, after modeling oil generation, using a kinetic approach based on analogous source rocks in South America, suggest that a Tertiary source rock is not viable in most of the studied plays. However, a Cretaceous Muerto Formation is definitely a feasible active source rock for the area, which opens new exploratory opportunities in an area traditionally considered to be a cold barren basin.

Fluid flow of hydrocarbons and a probabilistic estimation of the volumes of hydrocar­bons expelled and available for entrapment highlight areas of interest in this undrilled basin. The evolution of the petroleum system through geological time allowed the explorationists to identify the timing between oil expulsion and the location of the structural and stratigraph­ic plays in the basin.