Shear-enhanced compaction analysis of the Vaca Muerta formation

TL;DR

This paper presents laboratory evidence of nonlinear elastic and shear-enhanced compaction behaviors in Vaca Muerta formation samples, challenging previous assumptions of linear-elastic response, and introduces a calibrated elastoplastic model to capture these phenomena.

Contribution

It provides the first comprehensive laboratory analysis showing nonlinear elastic and shear-enhanced compaction in Vaca Muerta samples and develops a calibrated elastoplastic model.

Findings

Samples exhibit stress-dependent elastic behavior.

Shear-enhanced compaction is identified as a main plasticity mechanism.

The calibrated model reproduces observed nonlinear and shear behaviors.

Abstract

Laboratory measurements on Vaca Muerta formation samples show stress-dependent elastic behavior and compaction at representative in-situ conditions. Experimental results show that the analyzed samples exhibit elasto-plastic deformation and shear-enhanced compaction as the main plasticity mechanism. These experimental observations conflict with the anticipated linear-elastic response prior to the brittle failure reported in several works on the geomechanical characterization of the Vaca Muerta formation. Therefore, we present a complete laboratory analysis of samples from the Vaca Muerta formation showing experimental evidence of nonlinear elastic and unrecoverable shear-enhanced compaction. We also calibrate an elastoplastic constitutive model using these experimental observations; the resulting model reproduces the observed phenomena adequately.