Depth Relationships in Porosity and Permeability in the Mount Simon Sandstone of the Midwest Region: Applications for Carbon Sequestration

Cristian R. Medina¹, David A. Barnes², and John A. Rupp^1
1Indiana Geological Survey, Bloomington, IN
²Western Michigan University, Kalamazoo, MI

A comparison of porosity and permeability values (conventional core analyses data) from the Upper Cambrian Mount Simon Sandstone indicate a predictable relationship with depth owing to diagenetic changes in the pore structure. This predictive relationship is useful for evaluating and quantifying the geological carbon sequestration capacity in Indiana and Michigan. Image analyses of thin sections and porosity logs from wells in the study area provide additional sources of petrophysical data. The regional trend of decreasing porosity with depth is described by the equation: φ (d) = 12,789,166 * d^-2.1978, where φ equals porosity and d is depth in feet. This equation indicates that porosity typically falls below 5 percent below 7,000 ft. The correlation between burial depth and porosity is useful for prediction of the petrophysical character of the Mount Simon in more deeply buried and largely undrilled portions of the basins. Understanding the relationship between porosity, permeability, and depth also provides information that can be used in numerical models that simulate supercritical carbon dioxide flow within the Mount Simon. The fundamental relationship of decreasing porosity and permeability with depth generally holds true on a basinwide scale, but localized stratigraphic and areal variations in sedimentary facies also affect reservoir quality of the unit such that, in some areas, a reversal in the porosity/depth relationship is observed. Careful documentation of the mineralogical and sedimentological characteristics of the reservoir are critical to successfully predict the petrophysical attributes of deep saline aquifer systems and how they will perform at a given locality. This work is part of the regional carbon sequestration assessment being conducted by the MRCSP.

Presented AAPG Eastern Section Meeting, Pittsburgh, Pennsylvania 2008 © AAPG Eastern Section