Grain Association, Petrography, and Lithofacies

GONZALEZ TOMASSINI, F.; KIETZMANN, D.A.; SMITH, T.

AAPG MEMOIR

The American Association of Petroleum Geologists

Lugar: Tulsa; Año: 2020 vol. 121 p. 267 - 296

0271-8529

This chapter analyzes the different microfacies from standard microscopy textural studies, scanning electron microscopy, and X-ray diffraction technics, but also presented in a paleoenvironmental and a sequence stratigraphic context, that will allow to be used them within a predictive model. Microfacies analysis in the Vaca Muerta Formation reveals a wide range of sedimentary and diagenetic processes that are essential for the understanding of this heterogeneous non-conventional shale system. More than thirty microfacies can be distinguished from textures, particles composition, and matrix type. Here we describe 17 of the more representative microfacies in the Vaca Muerta Formation. Their lateral and vertical distribution is controlled by intrinsic processes to the sedimentary environment, as well as their position in the different sedimentary system tracts, but also by its paleogeographical position along the basin. The diagenetic analysis of carbonate microfacies shows a complex relationship of primary and secondary components. Likewise, clay mineral fraction and its associated mineral paragenesis reveal important variations along the basin, which control not only mineral associations, but also changes in volume in matrix and pores.