CO2 Seal Bypass – A Multidisciplinary Approach to CO2 Migration and Storage

Abstract

A multi-disciplinary project that targets a naturally occurring CO2 plume and its interaction with the overlying sedimentary succession is summarized. The Navajo Sandstone – Page Sandstone – Carmel Formation – Entrada Sandstone – Curtis Formation – Summerville Formation is a largely sandstone-dominated succession which is naturally fed by mantle-derived CO2 in central Utah. The succession has received an influx of CO2-charged groundwater from below at times prior to its present-day state of erosion into cliff-forming strata that allow close inspection and sampling. Visually striking red rocks stained by Fe3+ are bleached by reducing CO2-charged groundwater, creating pale yellow plumes, and striations through strata, and represent readily identifiable reservoirs and migration conduits for fluids, respectively. Typical field expressions are sandstone-dominated reservoir rocks that once hosted CO2, whereas fracture corridors in low-permeability rocks such as marls and mudstones represent the main migration pathways (exceptions exist for both types). The study area displays a high-resolution record of entrapment, seal integrity and fluid flow in a multi-storied, CO2-filled paleo-reservoir. As such, it provides a valuable analogue for understanding and forecasting geologically controlled effects and mechanisms likely encountered during future CO2-capture and - storage efforts.