A Simultaneous Seismic Inversion study was executed on the ETE-3D survey, El Turbio Este area, Southern Austral Basin, Santa Cruz province, Argentina. The particularity of this work is that the 3D seismic on which the inversion was executed does not have in situ wells. The exploratory targets studied with this tool are located in the basal section of the Tertiary and belong to the Foreland megasequence called Foreland 2 (Paleocene-Eocene). In general terms, the Foreland 2 megasequence is composed of distal shelf to slope turbiditic deposits. Results of the inversion enable to detect reservoir properties, given the isolated, porous nature of relatively thick sand beds, encased in uniform, massive clays. Due to the absence of wells in the survey, analyses based on this processing were contrasted with bibliographic sources and should be considered primarily qualitative. To build the initial model, the particular absence of boreholes led to introduce the low-frequency component by means of 2D lines that included wells located outside the 3D seismic. Although P and S Impedance are usually the main outputs, the large aperture of angular offsets allowed to generate a reliable Density cube to support seismic porosity estimations. Using the Lambda-Rho vs. Mu-Rho approximation, combining P and S Impedance values improved the discrimination of rock properties, with respect to the AVO analysis (P Velocity vs. S Velocity) and P Impedance vs. S Impedance. Elastic properties of intervals containing the reservoirs were extracted and statistically analyzed to determine background and anomalous populations. P Impedance vs. S Impedance crossplots from well data available in literature show a boundary separating gas-bearing from water-bearing sands. Their equivalent Lambda-Rho vs. Mu-Rho crossplots from the inverted ETE 3D seismic data show a clear, almost vertical separation. In addition to the visual advantages that facilitated interpretations, modeling the data presented in this paper in the Lambda-Mu-Rho space allowed to derive lithological and fluid content approximations to the target reservoris.