Hydrocarbon migration and iron-oxide concretion formation in the Permian White Rim Sandstone: Implications for reservoir characterization of carbon capture and sequestration
Marko Gorenc, Marjorie Chan, and Brian McPherson
The tar-bearing Permian White Rim Sandstone of the Elaterite Basin of Southeastern UT is a valuable unit for understanding reservoir properties and diagenesis in eolian sandstones. The well-exposed White Rim Sandstone lithofacies in the study area include horizontal-bedded sandstones (sand sheet), cross bedded sandstones (eolian dune), and mottled to rippled sandstones (marine reworked veneer). Abundant iron oxide concretions are physical diagenetic markers that record fluid flow regimes through porous media. The purpose of this study is to examine anisotropy and heterogeneity through quantification of outcrop permeability data and characterization of the iron oxide concretions. Outcrop permeability measurements were taken with a handheld permeameter in multiple directions parallel and perpendicular to stratification. These measurements are compared with traditional core plug porosity and permeability data. Preliminary data indicate that within the crossbedded sandstone, grainflow laminae have higher permeability than windripple laminae. The sandsheet deposits have the highest permeability due to the coarse-grain sand composition. The greatest variability of permeability exists in the mottled to rippled sandstones deposited as the marine veneer. Iron oxide concretions indicate reducing conditions to mobilize iron, and oxidizing conditions to re-precipitate iron-oxide minerals upon fluid mixing. Hydrocarbons were the likely reducing fluids to mobilize the iron and bleach the sandstone to its characteristic white color. Both iron concretions and hydrocarbons are most prominent in the Elaterite Basin paleo-topographic high. The iron cycling and heterogeneity of the White Rim system has applications to predicting fluid flow behavior and the potential challenges to successfully sequestering carbon dioxide.
AAPG Search and Discovery Article #90156©2012 AAPG Rocky Mountain Section Meeting, Grand Junction, Colorado, 9-12 September 2012