Paleo-Environmental Models, Sequence Stratigraphic Analysis, and Remaining Prospectivity of the Intra-Malmic to Inter-Senonian Interval (Neuquén Basin, Argentina)

IÑIGO, J.F.; VARGAS, R.; NOVARA, E.; PEREIRA, D.M.; CAMBON, I.; PAZOS, P.; SCHWARZ, E.

Congreso; AAPG International Convention and Exhibition; 2019

Proper sequential analysis is essential for the exploration and development of oil and gas fields, especially in conventional plays in highly mature basins such as it is the Neuquén Basin in western Argentina. Reassessed paleoenvironmental models and sequence stratigraphic framework, constitute key elements to define remnant oil and gas fields? prospectivity for the Intra-Malmic to Inter-Senonian stratigraphic interval in the Northeastern Platform of the Neuquén Basin. A methodology that extended through a broad scale of analyses, going from regional seismic interpretation, well log interpretation, to detailed characterization of core and cuttings, was used to define depositional trends and significant stratigraphic surfaces, and to develop paleo-environmental evolution models of the Loma Montosa and Centenario Formations. Limited at its base by a transgressive surface and at its top by the IntraValanginian unconformity, the Loma Montosa Formation is interpreted to represent a mixed carbonatesiliciclastic ramp, with marginal-marine siliciclastic and mixed inner-ramp carbonate grainstones as the main reservoir facies. Several progradational sequences limited by transgressive and/or regressive surfaces are recognized within the unit. The Centenario Formation is limited at its base by a transgressive surface and in its top by the Inter-Senonian unconformity. In the study area, it comprises at least two transgressive-regressive sequences, defined as Lower and Upper Centenario Members. This mixed sandstone-shale succession is interpreted as a marginal marine and fluvial environment where tide- and wave-dominated deltas can be recognized. Stratigraphic traps associated with erosional truncation and lateral facies change constitute the main trapping mechanisms for the large oil fields present in the Rio Colorado Productive Trend.