Regional Reservoir Characterization and CO₂ Storage Resource Assessment in a Geologically Complex, Deep Saline Reservoir, Middle Ordovician St. Peter Sandstone, Michigan Basin, USA

Abstract

The Middle Ordovician St. Peter Sandstone is widespread in the Midwest, USA. The formation is an important aquifer, gas storage reservoir, and source of proppant sand with typically friable and super-mature mineralogy/texture in shallowly buried occurrences. In the Michigan basin, the formation ranges in thickness from a stratigraphic pinchout to more than 335m in thickness and occurs at depths of burial of greater than 800m to in excess of 3.35 km throughout much of the Lower Peninsula of Michigan. The St. Peter has been the subject of hydrocarbon exploration/production activity in the basin since the early 1980's. As a result, substantial modern subsurface geological data is available including conventional core and core analysis data from nearly 100 wells and modern, down-hole logs from complete formation penetrations in over 250 wells. CO₂ storage resource estimates (SRE) were developed as part of US DOE-NETL sponsored (ARRA) project led by the Illinois State Geological Survey (ISGS) focusing on the regional site characterization of high-potential geologic storage formations in the Michigan and Illinois basins. The St. Peter is an important, deep saline CO₂ storage target in Michigan with SRE of between 3.0 to 50.1 GT of CO₂ based on various SRE methodologies and a range of confidence intervals. We present the results of high resolution reservoir characterization studies using an extensive subsurface data set to determine a more reliable SRE, compared to more simplistic approaches, in a geologically complex, deep saline reservoir. Sedimentary facies, petrographic and petrologic analysis, including special core analysis studies were used to characterize and quantify reservoir petrophysical properties in the formation throughout the basin. Regional stratigraphic thickness, sedimentary facies trends, and depth of burial-related diagenesis are the first order controls on reservoir quality and the spatial distribution of geological carbon storage capacity. Sedimentary facies variations typically template complex diagenetic modification of primary textures, mineralogy and reservoir quality and these factors have a substantial influence on regional variation in storage resource potential. Application of high resolution reservoir characterization methodology justifies significantly reduced uncertainty in net-to-gross reservoir area, porosity and effective to total porosity estimates and increased storage efficiency factors (SEF) used in SRE calculations.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016