Objectives:

The main unit to be developed will be the Rayoso Formation, bearing a general characterization of overlying and underlying units. The area under study is limited the Colorado River to the north, a folded belt to the west, the Huincul ridge to the south, and the basin margin to the east. Should the possibility of enhancing the work’s scope arise during the process, further definitions will be sought after within the Neuquén Group.

Transects: Four regional transects representing the subsurface have been planned:

• T01, from the folded belt close to Filo Morado heading towards Auca Mahuida, El Santiagueño, ending in the Vaca Mahuida area.

• T02, from the folded belt close to Cortadera Sur heading towards Sierra Chata, Aguada San Roque, La Amarga Chica, ending in Medanito area.

• T03, from the folded belt close to Las Tacanas heading towards Mangrullo, Meseta de Buena Esperanza, Loma Barrosa, ending in Centenario or Cerro Manrique.

• T04, joining southwards,  from Puesto Hernandez, heading towards Los Toldos, La Escalonada, Aguada San Roque, La Calera, Loma La Lata, ending in Sierra Barrosa or Senillosa.

The transects will be studied from different points of view:

• Lithologic characterization, geometry identification, interpretation of the sedimentary environment and stratigraphic relationships using the available information (cuttings, electric and seismic profiles as per the work scales) to draft a paleogeographic pattern of the Rayoso Formation.

• Regional hydraulic characterization: which units could function as seals and which as reservoirs.

• General water characterization in main aquifers.

• Identification of stratigraphic relationship according to the units in each sector (Troncoso, La Tosca, Rayoso)

Neuquen Group:

• Definition of main areas and delimitation of under groups or formations.

• Characterization as per the seal or reservoir’s nature within an aquifer system

Team:

Juan Reynaldi

Pluspetrol

Lorena Zabala

YPF

Carlos Echevarría

Pampa Energía

• Transect 1, which is 550km long and runs in a SW-NE direction, depicts the folded belt and the Cretaceous-Paleogene foreland geology of the onshore Austral Basin, heading east to the offshore, where the main gas fields are located, and where we can see the Lower Cretaceous wedging against the Río Chico Ridge, the overlapping of geological units by Upper Cretaceous and Paleogene deposits, and the geometry of Jurassic hemigrabens belonging to different stages of the Serie Tobífera which are mostly developed on ancient lineaments of the metamorphic basement. To the east, the transition to the West Malvinas Basin can be observed, which begins with the thickening of the lower sequences of the Lower Cretaceous; then, shifting towards the mid-sector, where the Jurassic extension is represented by significant sediments thickening assigned to the Serie Tobífera. In the last section, we can observe the Jurassic and Lower Cretaceous wedging against the Malvinas High, the presence of a prograding sequence from the Middle to Upper Cretaceous heading west, and significant discordancies related to the Springhill base on the Cretaceous/Tertiary boundary.

• Transect 2, which is 570km long and runs in a NNW-SSE direction, begins on the Rio Chico Ridge shifting southwards onto the West Malvinas Basin, where the different progradings of the Tertiary platform and the thickening of the lower sequences of the Cretaceous can be seen; then, shifting southwards onto the mid-sector where the Jurassic extension is mostly developed on ancient lineaments of Paleozoic basements and is then filled with significant sediments thickening assigned to the Serie Tobífera. In the last section, we can observe the transition to a post-Eocene flexural basin, featuring thickened Cenozoic deposits. The south boundary is made up by the deformation front of the folded and faulted belt of the Banco de Burdwood, which constitutes the boundary between the South American plate and the Scottia Sea plate.

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Diego Rojas Arce TotalEnergies