A Hierarchical Approach for Evaluating Carbon Storage Resource Estimates in Deep Saline Formations

Abstract

For over a decade governments and researchers around the world have been working to estimate the magnitude and distribution of resources available for storage of carbon dioxide in deep saline formations (DSF). Although Carbon Capture, Utilization and Storage (CCUS) technology considers storage in conventional oil and gas reservoirs and unconventional reservoirs as important options with potential revenue streams, DSF are considered essential for storing the significant volumes of CO₂ necessary to achieve effective greenhouse gas mitigation. Results to date from prospective resource assessments tend toward a consensus that sufficient storage is available in DSF for decades to century's worth of CO₂ emissions in many parts of the world. Despite this promising outlook, results from these assessments are also highly uncertain and, as such, it is not clear how useful such assessments are for assisting stakeholders in making decisions towards implementation of CCUS. In this paper, a hierarchical approach is presented as a means for achieving a broader assessment of the uncertainty associated with prospective storage resource estimates (SRE) in DSF. The approach uses multiple methods for estimating storage resources of a single formation, beginning with volumetric calculations underpinned by deterministic-based models of the reservoir, and progressing through probabilistic analyses and dynamic storage assessments using reservoir simulation where data are available for more advanced characterization. Through the analysis of multiple geologic formations in basins in the USA and China, the hierarchical approach is shown to provide both quantitative and qualitative results that enables a more comprehensive assessment of uncertainty beyond what is reported in current assessments. Under the premise that more advanced characterization should lead to reduced uncertainty in SRE, the hierarchical approach is also shown to be useful in revealing limitations of the conventional methodologies. Integrating results into a system-level model for optimized CO₂ source-sink matching demonstrates how pipeline routing, well construction, and overall CCUS costs are impacted by the varying level of characterization used in the underlying SRE. Results from this study suggest that future efforts focused on identifying regions with favorable reservoir properties might provide a more useful product for facilitating CCUS decision making than the current regional-scale SRE approach.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015