The El Portn field, located in the Neuqun basin, belongs to one of the largest oil and gas trends of Argentina. Fields in the area produce oil from middle Cretaceous fluvial and eolian porous sandstones at about 600 m (1968 ft) below sea level. The field structure is described as a triangle zone located in front of the Neuqun fold and thrust belt that was formed during the Andean orogeny by a combination of tight detachment folds and fault-propagation folding. The structure has a basal detachment through the contact between the evaporites of the Auquilco Formation and the shales of the Vaca Muerta Formation. The upper detachment corresponds to the salt layers of the Huitrn Formation. The structure was reactivated by basement fault inversion that produced tightening of the preexisting geometry and backthrusts that increased the structural complexity.

A three-dimensional (3-D) structural model has been constructed using 3-D seismic data and well information to plan new horizontal wells in steeply dipping to overturned limbs, through 50–60 m (164–196 ft) of productive reservoir avoiding pilot and sidetrack wells. The results of the modeling have made the company consider as a priority the 3-D structural model-building procedure for the development of fields located in fold and thrust belts.