| Description |
The mudstone-dominated Early Cretaceous Agrio Formation is the youngest marine source rock interval of the hydrocarbon prolific Neuquén Basin, Argentina, yet its unconventional hydrocarbon potential remains relatively understudied. A northern section of the entire Agrio Formation and a southern composite section of the lower Pilmatué and middle Avilé Members, totaling ∼1,200 m of outcrop, were measured. From these measured sections, programmed pyrolysis, X-ray diffraction (XRD), and thin section analyses were conducted on subsets of 441 samples and a high-resolution facies scheme and depositional model were established. The facies scheme and depositional model indicate distinctly more dynamic sedimentation in the substorm wave base, basinal to outer ramp portion, of this homoclinal ramp than previously described. Characterization of such heterogeneity allows for recognition of stratigraphic packaging and correlative relationships with established updip stratigraphy. Utilizing TOC, S2, and HI value cutoffs, this study identifies discrete stratigraphic packages totaling ~140 m thick within the upper Agua de la Mula and lower Pilmatué Members with the highest source rock potential. Based on regional correlation, source intervals within the Pilmatué Member lie within Retrogradational to Aggradational Parasequence Sets. This study provides a novel integration of macro and microfacies analysis, stratigraphy, and a geochemical analysis to define a new offshore depositional model and source potential of the Agrio Formation. The model presented here provides an analog for carbonate-dominated mudstone successions of interest as unconventional reservoirs worldwide. |
