Summary

Shell Oil Exploration and Production has been exploring and appraising the Vaca Muerta unconventional play in the Sierras Blancas and Cruz de Lorena blocks of the Neuquen Basin, Argentina since 2012. The Vaca Muerta play is immature in comparison to North American unconventional counterparts, and does not benefit from the learning that accompanies intense development activity. For example, there are currently ~4,900 producing and permitted wells in the Eagle Ford whereas, there are 566 wells in the Vaca Muerta play (most of these are vertical wells YPF's Loma La Lata block), and only ~80 of those horizontal wells.

To accelerate our assessment of commerciality, we chose a de-risking approach that strives to be more predictive and incorporates lessons learned from other unconventional plays. A key de-risking component is the availability high quality 3D seismic data. We have employed a focused data acquisition strategy that includes log, geochemistry, geomechanics, core, PLT, and microseismic data on select pads in order to facilitate a detailed understanding of vertical and lateral distribution of rock and reservoir properties. We are able to create rock types using learnings from our data acquisition program at the core and log scale and translate them into the seismic scale. With the use of seismic inversion techniques, we can predict vertical and lateral reservoir properties away from the well bore.

After completing 9 horizontal wells, with 2 of these wells in the top 5 producers of the Neuquén basin, we have developed and calibrated a predictive subsurface model for the Vaca Muerta play within the oil window. The integration and interpretation of well and seismic data indicates a potential dual layer development. The lower layer is present through our acreage with minimal lateral and vertical variation in properties. This reservoir has a large hydrocarbon storage capacity, however long term production behavior is still to be understood due to its geomechanical properties. The best producing well of the basin is located in this layer. The upper layer has significantly more vertical and lateral variation characterized by carbonate-marl cycles with relatively lower storage compared to the lower layer but with more favorable geomechanical properties. Given these learnings, this predictive subsurface model is key to the Vaca Muerta continuing successful de-risking and development planning.

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