Reservoir Quality Assessment and Petrofacies of the Lower Cretaceous Siliciclastic, Carbonate and Hybrid Arenites From the Jequitinhonha Basin, Eastern Brazil

Abstract

A study of the rift to early drift phase, fluvial, deltaic and shallow-marine Lower Cretaceous (Upper Aptian to Lower Albian) siliciclastic sandstones, hybrid arenites and calcarenites from the Jequitinhonha Basin, eastern Brazilian margin, has shown that the distribution of diagenetic alterations and of related reservoir quality evolution can be constrained within a sequence stratigraphic framework. Description of cores, wireline logs, thin sections and petrophysical (porosity and permeability) analyses were integrated in order to investigate the controls on patterns of diagenesis in these rocks, and hence of reservoir quality distribution. The results of this study will be relevant to the exploration of rift and early drift successions in Atlantic-type passive margin settings. The study suggests that depositional facies and detrital composition impact the diagenetic evolution and the characterization and prediction of reservoir quality.Reservoir quality assessment was based on the concept of reservoir petrofacies, which is defined in terms of the main attributes affecting reservoir quality including depositional structures, textures, primary composition, diagenetic processes and products, and pore types. This paper demonstrates the practical use of the reservoir petrofacies concept in the evaluation of the controls on porosity and permeability, as well as on seismic and log signatures.

Diagenesis of Tight‐gas Sandstones in the Lower Cretaceous Denglouku Formation, Songliao Basin, Ne China: Implications for Reservoir Quality

“…Higher values of macropores together with larger pore-throat apertures and less tortuosity result in improved connectivity and storage space for petroleum (e.g. Tobin et al, 2010;Jardim et al, 2011). On the other hand, micropores containing high residual water saturations tend to be poorly connected (e.g.…”

“…Implications for reservoir quality Methods of sandstone reservoir quality prediction have primarily been developed in conventional reservoir sandstones (e.g. Moraes and Surdam, 1993;Gier et al, 2008;Morad et al, 2010;Jardim et al, 2011). Nevertheless, they can also be applied to tight-gas sandstones to predict sweet spots (Tobin et al, 2010;Ozkan et al, 2011).…”

Carbonate reservoir characterization with integrated rock, special well logs, and machine learning methods

“…Petrofacies is a method that attempts to overcome these limitations by identifying the main properties that impact reservoir quality (Kopaska-Merkel & Friedman, 1989;Bhattacharya et al, 2005;Jardim et al, 2011), and mapping them into recognizable units at the well log scale. This framework usually integrates inputs from different tools and scales, such as core, thin sections, well logs, routine petrophysical core analysis (RPCA), Micro-CT, among other analytical tools.…”

“…RPCA, mercury injection capillary pressure, electron microscopy, scanning electrical microscope, X-ray diffraction) (Koteska-Merkel & Friedman, 1989;Jardim et al, 2011;Herlinger Jr., 2017).…”