Dynamic Risk Assessment for Geologic CO2 Sequestration

Abstract

At a geologic CO2 sequestration (GCS) site, geologic uncertainty usually leads to large uncertainty in the predictions of properties that influence leakage risk such as CO2 saturations and pressures in potentially leaky wellbores, CO2/brine leakage rates, and risk metrics such as impacts of leakage on drinking water quality in groundwater aquifers (e.g., sizes of the pH and total dissolved solids (TDS) plumes in the aquifer). The uncertainty in these risk-related system properties and risk metrics can substantially affect decisions related to safe operations and management of GCS sites. The objective of this study is to develop a novel approach based on dynamic risk assessment to effectively reduce the uncertainty in the predicted risk-related system properties and risk metrics. The proposed workflow for dynamic risk assessment was demonstrated with a synthetic field case based on the Rock Springs Uplift (RSU) site in southwestern Wyoming, USA. It was observed that the NRAP-Open-IAM risk assessment tool coupled with a conformance evaluation can be used to effectively quantify the uncertainty reduction in the predictions of risk metrics and related system properties in GCS.