Mechanical and Fracture Stratigraphy Modeling for Development Optimization in the Vaca Muerta Formation, Neuquen Basin, Argentina

Abstract

The Neuquén Basin sits at the base of the Andes in west-central Argentina, with a western margin that passes just over the border into central Chile. The Neuquén is the most prolific of Argentina's petroliferous basins (Legarreta and Villar, 2011) and the Vaca Muerta is the richest source within the basin, from which up to 50% of Argentina's current produced hydrocarbons are sourced (Urien et al, 1995, Kietzmann et al, 2011). There have been 220 wells drilled in the Vaca Muerta as of May 2014, 90% of which are vertical completions with an average of 4-5 hydraulic fracture stages (Ejofodomi et al, 2014). As Argentina increasingly becomes the focus of foreign unconventional exploration interest, the Vaca Muerta play is of prime importance to Argentina's energy potential, and understanding the heterogeneities inherent to the reservoir will be essential to creating effective development strategies (Suarez-Rivera et al, 2005). Shale plays are heterogeneous in their nature, and in order to properly be characterized analysis must include a large, diverse, and complete data set (Passey et al, 2010). Since permeabilities in unconventional reservoirs are low, some type of stimulation is required to allow for economic production (Warpinski et al, 2009) and the efficacity of such treatments may vary along with the rock properties. In this case, the mechanical behavior of the reservoir as it relates to the ability of natural and induced fractures to sustain hydraulic conductivity pathways may be the primary factor controlling play economics. In order to assess the optimal completions design for such a reservoir, a thorough characterization of the mechanical properties of the formation, the stress state at the reservoir level, and the natural fractures already present at depth, is essential (Gale et al, 2009). This study was designed to examine how to achieve an applicable model of the variable mechanical rock properties within the Vaca Muerta, to examine the variability in these properties as they relate to natural fracture occurrence, and to combine these concepts in the framework of stimulation efficacy, particularly as relates to the development of complex fracture networks. This was accomplished using borehole images, as well as petrophysical analysis, and rock typing using a clustering algorithm. Where available, images of core and CT scan data were used to provide validation to the interpretation of the petrophysical and image logs.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016