Defining a Target Interval in the Vaca Muerta Formation, águila Mora Block, Neuquén Basin, Argentina

Depine, Gabriela¹; Buenafama, Pablo; Veldkamp, Jaap; Repol, David; Isaza-Londono, Carolina; and Gardini, Marco
¹[email protected]

The hydrocarbon potential of the Neuquén basin in Argentina has been recognized since the nineteenth century through the presence of seeps. The petroleum systems in the basin are well understood for conventional traps, with almost a century of production since 1918. However, the unconventional hydrocarbon plays are still in their early stages and there are a lot of uncertainties to address. One key challenge for unconventional hydrocarbon exploration is defining a target zone where to land a horizontal well, and/or place the perforations for hydraulic fracturing.

New 3D seismic has been acquired in the águila Mora block, north of the Cortaderas lineament. This area has been affected by Cenozoic magmatism which results in sill intrusions at the level of the Jurassic-Cretaceous reservoir, the Vaca Muerta Formation. The new data allow a detailed mapping of the position of the sills in this sector of the basin. These sills affect 65% of the block, which introduces a new challenge for drilling and stimulating wells.

The presence of sills also disrupts the depositional architecture of the progradational system in the Vaca Muerta Formation. In the southern part of the basin, clinoforms that help determine the continuity of intervals of interest can be regionally mapped in the subsurface. This exercise is key to understand lateral TOC, thickness and lithological variations in the upper section of the Vaca Muerta Formation, which has hydrocarbon potential. This upper section has TOC that ranges between 1-4 wt%, thickness that reach 600 meters, and composition that ranges from marl to calcareous siltstone. In the águila Mora block, even though clinoforms can be inferred, they are difficult to map. Acoustic impedance seismic inversion was successfully used instead of clinoform mapping as an aid to define the target interval in the Upper Vaca Muerta in the block. These observations are calibrated with TOC data from cuttings, and well log information. The seismic inversion turned out to be also useful to map intrusive sills.

Another aspect that was looked into in the águila Mora block is the presence of fault zones. NW-SE oriented faults were previously inferred based on regional understanding of the basin and 2D seismic data sets. Attribute extraction on the new 3D seismic cube corroborates the inferred fault orientation in the area. Understanding the orientation of these structures is important due to its impact on production and drilling orientation.

AAPG Search and Discovery Article #90166©2013 AAPG International Conference & Exhibition, Cartagena, Colombia, 8-11 September 2013