Changes

During deposition of the Vaca Muerta Formation, the Neuquén Basin was a triangular shaped retro-arc basin (Figure 3). The unique configuration of this basin along the western margin of South America was directly related to the confluence of a north – northwest rift system truncated by an east – west system developed between crustal terranes forming the basin basement<ref>Ramos, V. A., M. Naipauer, H. A. Leanza, and M. E. Sigismondi, 2020, [https://archives.datapages.com/data/specpubs/memoir121/data/25_aapg-sp2120025.htm An exceptional tectonic setting along the Andean continental margin], ''in'' D. Minisini, M. Fantín, I. L. N., and H. A. Leanza, eds., Integrated geology of unconventionals: The case of the Vaca Muerta play, Argentina: [https://archives.datapages.com/data/alt-browse/aapg-special-volumes/m121.htm AAPG Memoir 121], p. 25–38.</ref>. Combined with variable rates of thermal subsidence throughout the Late Jurassic through Early Cretaceous, the tectonic regimes exerted a first order control on the stratigraphic and sedimentologic variability observed throughout the formation<ref name=Dmngz2020b>Domínguez, R. F., O. Catuneanu, H. M. Reijenstein, R. Notta, and H. W. Posamentier, 2020b, [https://archives.datapages.com/data/specpubs/memoir121/data/163_aapg-sp2120163.htm Sequence stratigraphy and the three-dimensional distribution of organic-rich units], ''in'' D. Minisini, M. Fantín, I. L. Noguera, and H. A. Leanza, eds., Integrated geology of unconventionals: The case of the Vaca Muerta play, Argentina: [https://archives.datapages.com/data/alt-browse/aapg-special-volumes/m121.htm AAPG Memoir 121], p. 163–200.</ref>.

During deposition of the Vaca Muerta Formation, the Neuquén Basin was a triangular shaped retro-arc basin (Figure 3). The unique configuration of this basin along the western margin of South America was directly related to the confluence of a north – northwest rift system truncated by an east – west system developed between crustal terranes forming the basin basement<ref>Ramos, V. A., M. Naipauer, H. A. Leanza, and M. E. Sigismondi, 2020, [https://archives.datapages.com/data/specpubs/memoir121/data/25_aapg-sp2120025.htm An exceptional tectonic setting along the Andean continental margin], ''in'' D. Minisini, M. Fantín, I. L. N., and H. A. Leanza, eds., Integrated geology of unconventionals: The case of the Vaca Muerta play, Argentina: [https://archives.datapages.com/data/alt-browse/aapg-special-volumes/m121.htm AAPG Memoir 121], p. 25–38.</ref>. Combined with variable rates of thermal subsidence throughout the Late Jurassic through Early Cretaceous, the tectonic regimes exerted a first order control on the stratigraphic and sedimentologic variability observed throughout the formation<ref name=Dmngz2020b>Domínguez, R. F., O. Catuneanu, H. M. Reijenstein, R. Notta, and H. W. Posamentier, 2020b, [https://archives.datapages.com/data/specpubs/memoir121/data/163_aapg-sp2120163.htm Sequence stratigraphy and the three-dimensional distribution of organic-rich units], ''in'' D. Minisini, M. Fantín, I. L. Noguera, and H. A. Leanza, eds., Integrated geology of unconventionals: The case of the Vaca Muerta play, Argentina: [https://archives.datapages.com/data/alt-browse/aapg-special-volumes/m121.htm AAPG Memoir 121], p. 163–200.</ref>.

Variability in sediment provenance and distribution has been well established via outcrop observations dating to the early 1900s across the basin. Over the past 20 years, seismic imaging and mapping, as well as petrophysical evaluation and log correlation, has focused upon the intervals observed within the Vaca Muerta in an effort to better define and predict the distribution of the high-quality reservoir units<ref name=Dmngz2020b />. These efforts have resulted in a detailed stratigraphic framework that accounts for the multiple cycles and directions of clinoform geometries observed across the basin (Figure 4). Petrophysical evaluations have suggested that the highest reservoir quality occurs within the mixed siliceous and calcareous organic-rich facies that occur within proximal bottom sets and basal foresets of the progradational clinoform units<ref name=Mnsn>Minisini, D., P. Desjardins, G. Otharán, M. Paz, D. Kietzmann, G. Eberli, C. Zavala, T. Simo, J. H. Macquaker, and C. Heine, 2020, [https://archives.datapages.com/data/specpubs/memoir121/data/201_aapg-sp2120201.htm Sedimentology, depositional model, and implications for reservoir quality], ''in'' D. Minisini, M. Fantín, I. L. Noguera, and H. A. Leanza, eds., Integrated geology of unconventionals: The case of the Vaca Muerta play, Argentina: [https://archives.datapages.com/data/alt-browse/aapg-special-volumes/m121.htm AAPG Memoir 121], p. 201–236.</ref> (Figure 5; Romero-Sarmiento et al., 2017; Tenaglia et al., 2020).

Variability in sediment provenance and distribution has been well established via outcrop observations dating to the early 1900s across the basin. Over the past 20 years, seismic imaging and mapping, as well as petrophysical evaluation and log correlation, has focused upon the intervals observed within the Vaca Muerta in an effort to better define and predict the distribution of the high-quality reservoir units<ref name=Dmngz2020b />. These efforts have resulted in a detailed stratigraphic framework that accounts for the multiple cycles and directions of clinoform geometries observed across the basin (Figure 4). Petrophysical evaluations have suggested that the highest reservoir quality occurs within the mixed siliceous and calcareous organic-rich facies that occur within proximal bottom sets and basal foresets of the progradational clinoform units<ref name=Mnsn>Minisini, D., P. Desjardins, G. Otharán, M. Paz, D. Kietzmann, G. Eberli, C. Zavala, T. Simo, J. H. Macquaker, and C. Heine, 2020, [https://archives.datapages.com/data/specpubs/memoir121/data/201_aapg-sp2120201.htm Sedimentology, depositional model, and implications for reservoir quality], ''in'' D. Minisini, M. Fantín, I. L. Noguera, and H. A. Leanza, eds., Integrated geology of unconventionals: The case of the Vaca Muerta play, Argentina: [https://archives.datapages.com/data/alt-browse/aapg-special-volumes/m121.htm AAPG Memoir 121], p. 201–236.</ref><ref>Romero-Sarmiento, M.-F., S. Ramiro-Ramirez, G. Berthe, M. Fleury, and R. Littke, 2017, Geochemical and petrophysical source rock characterization of the Vaca Muerta Formation, Argentina: Implications for unconventional petroleum resource estimations: International Journal of Coal Geology, v. 184, p. 27-41.</ref><ref>Tenaglia, M., G. P. Eberli, R. J. Weger, L. Rodriguez Blanco, L. E. Rueda Sanchez, and P. K. Swart, 2020, Total organic carbon quantification from wireline logging techniques: A case study in the Vaca Muerta Formation, Argentina: Journal of Petroleum Science and Engineering, v. 194, 107489.</ref> (Figure 5).

Early exploration and development focused almost exclusively upon the organic-rich bottom set intervals described above. Thirty-year EURs from these wells compare favorably with all of the most prolific North American shale plays, with the average 10000 ft lateral well estimated to produce ~ 644,000 BOE combined oil and gas<ref name=Zbrsk /> (Figure 6) proving the Vaca Muerta play as one of the most prolific unconventional resources in the world. However, as acreage across regions containing high-quality bottomset facies was quickly acquired, companies began to evaluate the potential for high quality reservoir units in other parts of the depositional system.

Early exploration and development focused almost exclusively upon the organic-rich bottom set intervals described above. Thirty-year EURs from these wells compare favorably with all of the most prolific North American shale plays, with the average 10000 ft lateral well estimated to produce ~ 644,000 BOE combined oil and gas<ref name=Zbrsk /> (Figure 6) proving the Vaca Muerta play as one of the most prolific unconventional resources in the world. However, as acreage across regions containing high-quality bottomset facies was quickly acquired, companies began to evaluate the potential for high quality reservoir units in other parts of the depositional system.

==See also==

==See also==