Dr. MarianA Olivo
Affiliated researcher
Dr. Mariana S. Olivo obtained a BSc in Geology (2010) from the National University of La Plata, Argentina. Later, she worked as a PhD student at the Centro de Investigaciones Geológicas (CIG, CONICET – National University of La Plata) where she developed her PhD studies on sedimentology and sequence stratigraphy of continental and marginal-marine depositional systems (Lower Cretaceous, Neuquén Basin, Argentina). She received her PhD degree in Natural Sciences (2016) at the National University of La Plata. Currently, Mariana has a postdoctoral position in the Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires at the University of Buenos Aires, where she analyzes multiscale sedimentological heterogeneities of fluvial tight-gas sandstones from the Neuquén Basin (Argentina), evaluating its impact on the reservoir properties. Her stay in PetroLab was sponsored by the Ministry of Foreign Affairs of the State of Israel. Currently, Mariana holds a graduate teaching assistant position in Geomorphology (since 2011) and Sedimentology chairs (since 2016) at the National University of La Plata (Argentina). Mariana is a member of the AAPG and IAS. She likes photography and enjoys doing yoga.
Research at PetroLab
Sedimentary heterogeneities in a fluvial-estuarine reservoir analog: an example from outcrops of the Mulichinco Formation, Neuquén Basin, Argentina
An integrated stratigraphic, sedimentological and petrophysical analysis is presented to document the variety of sedimentary heterogeneities scales that can occur in a fluvial–estuarine reservoir analog. In this context, outcrops of the Mulichinco Formation (Neuquén Basin, Argentina) were investigated combining architectural analysis, vertical and lateral facies organization, and reservoir properties distributions in different channel-body types. Six main facies associations have been defined: gravelly–sandy to sandy braided channels, meandering channels, floodplain deposits, tidally influenced terminal channels, and subtidal to intertidal plains deposits, which we interpret the deposition in a proximal to distal fluvial and inner estuarine systems. Sequence stratigraphic analysis suggest the fluvial–estuarine succession evolved from a lower to an upper interval representative of low to high accommodation versus sediment supply ratios, respectively. Variations in accommodation and spatial changes from on-to off-axis locations within the fluvial system might performed as large-scale controls in stratigraphic and spatial variations of channel-deposits proportions and connectedness, which decreases vertically and horizontally towards the N and SE. Moreover, these trends could be overprinted by the avulsion influence. Distribution and preservation-style of fines within the channels define different intra-channel-body compartments controlled by distinct allogenic and autogenic processes. Cross-bedded sandstones represent the facies with the greatest reservoir quality, but they record the widest range in petrophysical values and textural variations, which represent unfavourable potential facies-scale reservoir compartments and barriers. Finally, variations in cement mineralogy would be the first-order control for permeability distribution and reservoir quality separation throughout the different channel units, since clay-rich cements contain the highest values of microporosity and permeability. Therefore, primary depositional processes followed by diagenesis strongly controlled the sandstone properties as reservoir. This work provides a characterization for stratigraphic-to pore-scale sedimentary heterogeneities and may contribute to the improvement of predictive models for exploration and development strategy of fluvial–inner estuarine reservoirs.