Using Carbonate Mudrock Pore Architecture to provide insight and predictability to porosity and permeability trends in the Mid-Continent Mississippian Limestone

Abstract

The Mid-Continent Mississippian Limestone is a complex unconventional carbonate reservoir. Horizontal drilling activity has illustrated how crucial it is to understand the petrophysical characteristics to target producing intervals. Recent research has only started to understand the complexity of the pore architecture observed in carbonate mudrocks and the applicability to predicting key petrophysical properties. This study shows examples of how fundamental relationships between porosity, pore architecture, and acoustic response differ in carbonate mudrocks with micro- to picoporosity (<62Âμm diam.) compared to conventional carbonates with primarily macroporosity (256-4mm diam.). Quantitative data show limited positive correlations between porosity and permeability, but negative to no correlation between pore shape and associated properties. There is also a significant shift in the acoustic response relative to values calculated from empirically-derived equations for porosity in carbonates. Visual observations show how post-depositional cementation can increase the complexity of the pore network. When correlated to facies, pore geometry explains deviations to generic relationships between petrophysical parameters. Relationships between pore architecture, porosity, permeability, acoustic response, facies and the sequence stratigraphic framework, when used as an integrated data set, can enhance the predictability of key petrophysical properties within this reservoir system.

AAPG Datapages/Search and Discovery Article #90221 © 2015 Mid-Continent Section, Tulsa, Oklahoma, October 4-6, 2015