Paper No. 4
Presentation Time: 9:45 AM


HERNANDEZ-BILBAO, Eider, Dept. of Geology and Geol. Engineering, Colorado School of Mines, 1516 Illinois St, Golden, CO 80401, HUMPHREY, John, Department of Geology and Geological Engineering, Colorado School of Mines, 1516 Illinois St, Golden, CO 80401 and SONNENBERG, Stephen A., Geology and Geological Engineering, Colorado School of Mines, Dept of Geology and Geological Engineering, Golden, CO 80401,

The Vaca Muerta Formation, Neuquén Basin, Argentina, is an emerging resource play involving shale oil and shale gas in Late Jurassic to Early Cretaceous foreland basin strata. The Vaca Muerta Formation consists of alternating marls and dark organic basinal shales deposited in a gently sloping ramp setting.

Because of the time transgressive nature of this lithostratigraphic unit, in which early Tithonian sediments in the east progressively change to younger Valanginian shales towards the west, a sequence stratigraphic approach is of great importance for gaining a thorough understanding of basin development and for correlating stratigraphic units.

This study combines stratigraphy, sedimentary petrology, mineral characterization, and source rock geochemistry to further understanding of the Vaca Muerta petroleum system. The lower Vaca Muerta shale is defined as a “hot” shale based on source rock geochemical data. Detailed mineralogical interpretation of the facies from available core is tied to elemental and mineralogical data from x-ray fluorescence spectroscopy and x-ray diffractometry. Geochemical parameters of the sediments are used as proxies for depositional redox conditions from the Tithonian to the Valanganian during deposition of the Vaca Muerta Formation.

Through application of trace element analysis, the most favorable paleoredox conditions for organic matter preservation can be established in the study area. Additionally, both XRF elemental data and the stable isotopes of carbon will be used to begin to develop a standard chemostratigraphic profile for the Vaca Muerta.

A good understanding of geochemical and isotopic stratigraphic variability, elemental and mineralogic characteristics, and source rock geochemical parameters help to characterize the best reservoir quality and enable definition of areas with highest organic matter preservation and favorable hydrocarbon potential.