Geologic Implications of Basin- and Gigaton-Scale Storage of Greenhouse Gases: Modeling the Powder River Basin for Economic EOR and CO₂ Storage and Leakage

Melick, Jesse J. ¹, Michael H. Gardner¹ (1) Montana State University, Bozeman, MT

The goal of carbon sequestration is to achieve zero-emission by helping balance anthropogenic sources through increased conservation, enhancing natural sinks for carbon cycle gases, and employing geologic storage. Because current EOR practices capture about one per cent of these requirements (in 2000 the US used 34 million tons), basin-scale geologic sequestration of gigatons of CO₂ could help offset this deficit. The immense storage capacity needed to achieve zero emission requirements and the inherent dangers with these concentrations demand solutions that address multiple scale issues. Building geologic models at the scale of basins, characterizing a portfolio of geologic storage sites, and simulating pore to field to basin scale permeability distributions and leakage pathways, can provide insight on this problem.

Modeling the Powder River Basin (PRB), a mature petroleum basin with almost 100 years of hydrocarbon production, places an assortment of reservoirs (e.g., carbonate, shoreface, valley fill, mixed carbonate - aeolian clastics, coal bed) within a basin-scale fluid-flow context. This holistic approach characterizes the principal reservoir types as storage sites, and continuity and connectivity along high permeability pathways as leakage mechanisms, all framed within a basin-wide plumbing system.

Evaluation of the PRB, where extensive data and infrastructure already exist, permits understanding and reconciling critical logistical and economic issues related to combining storage with EOR, which currently are not being assessed together. Moreover, engaging the petroleum industry with built-in economic incentives for EOR will help significant expenses of long-term CO₂ storage to be cost-effectively transferred from the public to the private sector.

AAPG Search and Discovery Article #90055©2006 AAPG Rocky Mountain Section Meeting, Billings, Montana