Print this pageHigh Resolution 
Petroleum
Systems Analysis: Application to
Los Molles-Lajas Megasequence of Neuquen Basin, Argentina
VELA, MARIANO L., and DAVID A. WAVREK
High resolution petroleum systems analysis is an analytical method whereby a
conventional petroleum system is subdivided according to different organic
source rock facies. In essence, each organic facies will have a unique oil
window as defined by kerogen kinetics analysis and burial history. This study
applies the principle to the Neuquen Basin, which is located in west-central
Argentina. The Middle Jurassic Los Molles-Lajas (Cuyo) Megasequence is a
frontier exploration target that has been proposed in the literature to be a
speculative petroleum system.
This research documents that the Cuyo Megasequence actually contains two
petroleum systems: one source rock facies is dominated by marine organic matter
(associated with turbidite sequences) and the other by nonmarine organic matter
(marsh environments). The Huincul Dorsal defines the hinge line that separate
the two petroleum systems. Kinetic analyses of the different source rock facies
indicate as much as 20 degrees C variation in peak generation temperatures; this
invokes significant differences in the generation/expulsion parameters. The
reservoir/migration conduits are also different: the marine system is composed
of prodelta/turbidite sequences, in contrast to fluvial systems that dominate
the nonmarine sequences. Traps in both systems are combined stratigraphic and
structural, with the latter enhanced by the Oxfordian-Kimmeridgian
transpressional deformation. Despite quite different geologic histories and
kerogen kinetic values, the critical moment for each petroleum system coincides
with the Late Cretaceous. Thus, this paper introduces the concept of high
resolution petroleum system analysis and demonstrates the application to the Los
Molles (marine)-Lajas(!) and Los Molles (nonmarine)-Lajas Petroleum
Systems.