Summary

In the last four years, shale oil and gas play exploration activity in the Vaca Muerta Formation, Neuquén Basin, Argentina; has increased rapidly from a couple of drilled exploration wells in 2010 to more than 135 wells up to December 2014. This large amount of wells drilled in this short term, led to the necessity of a strong play characterization program that included seismic reprocessing, well log data acquisition, core acquisition and interpretation, micro seismic acquisition programs and a highly detailed geological modelling workflow. One of the key issues regarding the productivity behaviour of the wells drilled for this type of play, are among others, the mechanical properties of the formation. In this paper, the estimation of such as properties are done by integrating the data from a simultaneous AVO inversion with a rock mechanic template calibrated with production and log data.

The main objective of this work is the characterization of the exploration shale oil play, Vaca Muerta formation from a geomechanical point of view. The study began with the estimation of the dynamic Poisson's ratio and Young Moduli in the exploratory wells, calibrated in the lab using core samples of this formation. In order to obtain a complete suite of elastic properties, the Lamé constants (?? and µ?) were estimated. The integration of these elastic properties enables to build a rock mechanis template (RMT), where different fields within this template were defined regarding organic richness and mechanical behaviour of the unit. Finally, the conclusions showed that the most fragile and organically rich field of the template, matched with the best production zone.

Once the analysis on wells was concluded, the same workflow was applied to 3D seismic (using a simultaneous inversion result), to obtain volumes of predicted geomechanical properties. The RMT and its fields defined in wells were applied to the seismic volume, in order to obtain a three-dimensional evaluation of those fields. This integration helped to define a new exploratory strategy in the study area.

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