Reservoir Characterization of the Permian White Rim Sandstone: Outcrop and Core Assessment for Carbon Capture and Sequestration

Abstract

The increased need and regulatory demand for carbon capture and sequestration (CCS) has launched a wave of CCS reservoir characterization. The Rocky Mountain CarbonSAFE project, funded by the Department of Energy, has selected several eolian formations near the San Rafael Swell, UT as potential reservoirs including the Permian White Rim Sandstone (~140 m thick). Decimeter to meter-scale trough cross-bedded grainflow and wind ripple laminae characterize the majority of the formation. The upper ~4-10 m of the White Rim Sandstone was reworked by a marine transgression and contains abundant marine trace fossils such as Ophiomorpha and Thalassinoides as well as massive, wave rippled, and soft-sediment deformation facies.

Diagenetic cement precipitation and dissolution can correspondingly destroy or create porosity and permeability within the reservoir. This project utilizes petrography, very near-infrared spectroscopy (VNIR), and X-ray florescence (XRF) to determine diagenetic phases and timing relationships. Porosity is measured petrographically and a Tinyperm II device is used to measure permeability.

Petrographic observations from outcrop samples indicate a complex set of cement relationships including: (1) initial quartz overgrowths, followed by (2) rim forming and some pore filling “fine-grained” carbonate cements with (3) later iron oxide precipitation, and finally in some cases (4) late-stage, pore-filling carbonate cements. VNIR shows the presence of calcite, hematite, goethite, and clay mineral diagenetic phases.

Initial investigation of outcrop exposures of the White Rim Sandstone indicated the formation is a potential CCS reservoir with permeability in the 10s to 100s of mD and porosity in the 9% - 16% range. However, in contrast, permeability of White Rim Sandstone core samples (~34 - 48 km from the outcrop sites and at depths of 1550 - 2230 m) show insufficient reservoir properties for CO₂ injection and storage with permeability consistently below 0.1 mD. The contrast between outcrop and core samples is due to diagenetic and cementation differences.

Overall, the stark contrast in White Rim Sandstone core samples and outcrop samples indicates a significant diagenetic difference at depth, which significantly reduces the reservoir quality of the formation. Therefore, the White Rim Sandstone will likely make a poor CCS reservoir compared to other available eolian reservoirs higher in the section such as the Navajo and/or Wingate Sandstone.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018