Changes

The current play concept consists in landing the horizontal wells in the proximal bottomsets and lower foresets, which are the depositional sectors with the highest hydrocarbon storage potential and easiest fracture growth (i.e., larger stimulated rock volume). The rocks in these sectors show the best reservoir characteristics (TOC >2%, av. 5%; porosity >8%, av. 11%; clay <40%, av. 10–20%; water saturation <50%, av. 20%), the most adequate geomechanical properties (Young’s Modulus <4 Mpsi, low Poisson Ratio ~0.25, and homogeneous rock units exhibiting interfaces with weak geomechanical contrasts), and a thick vertical stack (av. 30–40 m) of lithofacies with the aforementioned characteristics ([[:file:M125-VacaMuerta-Figure16.jpeg|16A]] and window I and II in ([[:file:M125-VacaMuerta-Figure16.jpeg|Figure 16B]]). Although the distal bottomsets register the highest TOC, they are not a preferred landing zone because (with respect to proximal bottomsets) porosity is lower, clay is higher, ash beds have the highest recurrence, concretions and sills are more numerous, and landing zones are thinner (([[:file:M125-VacaMuerta-Figure16.jpeg|Figure 16A]]). With this concept in mind, at least two landing zones have been fully de-risked and are producing in factory mode in the development phase (lower Unit 1 and lower Unit 2), and other six landing zones have been tested with production logging tool (PLT) data showing encouraging results ([[:file:M125-VacaMuerta-Figure5.jpeg|Figure 5]]). All current successful landing zones are in the Embayment area where hydrocarbon potential is the highest and wells produce high-quality low-sulfur oils and gas condensates.

The current play concept consists in landing the horizontal wells in the proximal bottomsets and lower foresets, which are the depositional sectors with the highest hydrocarbon storage potential and easiest fracture growth (i.e., larger stimulated rock volume). The rocks in these sectors show the best reservoir characteristics (TOC >2%, av. 5%; porosity >8%, av. 11%; clay <40%, av. 10–20%; water saturation <50%, av. 20%), the most adequate geomechanical properties (Young’s Modulus <4 Mpsi, low Poisson Ratio ~0.25, and homogeneous rock units exhibiting interfaces with weak geomechanical contrasts), and a thick vertical stack (av. 30–40 m) of lithofacies with the aforementioned characteristics ([[:file:M125-VacaMuerta-Figure16.jpeg|16A]] and window I and II in ([[:file:M125-VacaMuerta-Figure16.jpeg|Figure 16B]]). Although the distal bottomsets register the highest TOC, they are not a preferred landing zone because (with respect to proximal bottomsets) porosity is lower, clay is higher, ash beds have the highest recurrence, concretions and sills are more numerous, and landing zones are thinner (([[:file:M125-VacaMuerta-Figure16.jpeg|Figure 16A]]). With this concept in mind, at least two landing zones have been fully de-risked and are producing in factory mode in the development phase (lower Unit 1 and lower Unit 2), and other six landing zones have been tested with production logging tool (PLT) data showing encouraging results ([[:file:M125-VacaMuerta-Figure5.jpeg|Figure 5]]). All current successful landing zones are in the Embayment area where hydrocarbon potential is the highest and wells produce high-quality low-sulfur oils and gas condensates.

[[file:M125-VacaMuerta-Figure16.jpeg|center|framed|{{figure number|16}}Left: conceptual sketch generalizing trends of independent proxies in the bottomsets and foresets of the Vaca Muerta–Quintuco system. Horizontal trends are related to the shaded unit. Vertical trends related to left end of the prograding clinoform. Right: current play concept consisting in landing the horizontal wells in the proximal bottomsets (I) and lower foresets (II), sectors with the best reservoir characteristics. Further play concepts to be proved include: thin carrier beds within high-TOC intervals in the lower foresets (III), tight reservoirs interbedded with transgressive high-TOC intervals in the middle foresets (IV), and stacking of specific foresets with good reservoir characteristics (V).

[[file:M125-VacaMuerta-Figure16.jpeg|center|framed|{{figure number|16}}Left: conceptual sketch generalizing trends of independent proxies in the bottomsets and foresets of the Vaca Muerta–Quintuco system. Horizontal trends are related to the shaded unit. Vertical trends related to left end of the prograding clinoform. Right: current play concept consisting in landing the horizontal wells in the proximal bottomsets (I) and lower foresets (II), sectors with the best reservoir characteristics. Further play concepts to be proved include: thin carrier beds within high-TOC intervals in the lower foresets (III), tight reservoirs interbedded with transgressive high-TOC intervals in the middle foresets (IV), and stacking of specific foresets with good reservoir characteristics (V).]]

In the future, a further play concept may be tested in the foresets, where the number of landing wells has increased since 2019. As evidenced by subtle variations in seismic stacking patterns, the clinoforms did not prograde uniformly, and advanced (as a delta) with discrete steps, recording foresets with variable direction, extent, geometry, lithofacies, and degree of aggradational component. Within this variability, units with appropriate reservoir characteristics and thickness do exist in specific foresets, and represent promising prospects. This new play concept in the foresets consist of a stacking of thin foresets with good reservoir characteristics interbedded with thicker foresets with bad reservoir characteristics, creating a hybrid unconventional play, similar to the Niobrara play in the DJ Basin, the Bazhenov play in Russia, and the Wolfberry and Bone Spring plays in the Permian Basin (([[:file:M125-VacaMuerta-Figure16.jpeg|Figure 16B]], window III and V). Another option consists of transgressive units with good reservoir characteristics, typically deposited in the bottomsets, and cyclically deposited in the foresets. The interbedding of (1) muddy, high-TOC, transgressive units, climbing the clinoform from the bottomsets during sea level rise, and (2) coarse and lean foresets enhances the idea of a hybrid play where source rocks and tight reservoirs are interbedded (([[:file:M125-VacaMuerta-Figure16.jpeg|Figure 16B]], window IV). Furthermore, in the future, exploration may move beyond the Embayment area into the structural highs, in the fold-and-thrust belt, in sectors affected by igneous intrusions, and in areas where the Vaca Muerta is deeply buried.

In the future, a further play concept may be tested in the foresets, where the number of landing wells has increased since 2019. As evidenced by subtle variations in seismic stacking patterns, the clinoforms did not prograde uniformly, and advanced (as a delta) with discrete steps, recording foresets with variable direction, extent, geometry, lithofacies, and degree of aggradational component. Within this variability, units with appropriate reservoir characteristics and thickness do exist in specific foresets, and represent promising prospects. This new play concept in the foresets consist of a stacking of thin foresets with good reservoir characteristics interbedded with thicker foresets with bad reservoir characteristics, creating a hybrid unconventional play, similar to the Niobrara play in the DJ Basin, the Bazhenov play in Russia, and the Wolfberry and Bone Spring plays in the Permian Basin (([[:file:M125-VacaMuerta-Figure16.jpeg|Figure 16B]], window III and V). Another option consists of transgressive units with good reservoir characteristics, typically deposited in the bottomsets, and cyclically deposited in the foresets. The interbedding of (1) muddy, high-TOC, transgressive units, climbing the clinoform from the bottomsets during sea level rise, and (2) coarse and lean foresets enhances the idea of a hybrid play where source rocks and tight reservoirs are interbedded (([[:file:M125-VacaMuerta-Figure16.jpeg|Figure 16B]], window IV). Furthermore, in the future, exploration may move beyond the Embayment area into the structural highs, in the fold-and-thrust belt, in sectors affected by igneous intrusions, and in areas where the Vaca Muerta is deeply buried.