Shell Argentina has been exploring the Vaca Muerta Play in Neuquén Basin, Argentina since 2012. During this time, two landing targets were identified in the Lower and Upper Vaca Muerta, respectively. Initially, drilling focused on the Lower target, a reservoir that is well understood and predictable within Shell's acreage. Now, Shell's technical team is broadening its focus to further de-risk the more heterogenous and challenging Upper Vaca Muerta with the objective to optimize a two-layer development.
The existing Sierras Blancas multi-well pad (SB-1004, 1005 & 1006) forms the foundational data set for current subsurface understanding, with one horizontal well landed on each target and one slant well crossing both targets.
To further de-risk the play, Shell refined the stratigraphic interpretation of the upper target, finetuning paleoenvironmental interpretation and its link to sweet spots, containment, heterogeneity and pay thickness. The resulting subsurface maps are good indicators of the most likely areas for a two-layer development.
Next, we will execute an instrumented multi-well pad, designed to assess production interference between both targets. This pad will be equipped with fiber optics, chemical tracers, microseismic and geochemical fingerprinting of produced oils.
Within Shell's acreage, the Lower VM target is comprised of toe of slope to basin floor deposits resulting from the initial transgression and early progradation phases. This reservoir is wide spread, homogeneous and its containment is well defined between Catriel Member, at the base, and a regressive sequence, to the top.
The Upper VM target is a more complicated, distal slope depositional setting. This proximity to the shelf increases the impact of relative sea level changes and results in more heterogeneity, and variability in rock properties. Also, fracture containment is an issue, as the hard limestone of the Quintuco Fm. is a strong barrier to upward growth where it overlies the reservoir, but, where a transition zone with poor marls overlies it, the fractures are not well contained.
The ideal unconventional development plan is one where all the target reservoirs are drilled and completed in one pass; thus, lowering the drilling and completion risks and maximizing pad efficiency. By judicious and timely multidisciplinary data gathering, the aim is to optimize the development plan as early as possible.
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