Geologic CO2 Sequestration: Predicting and Confirming Performance in Oil Reservoirs and Saline Aquifers
Abstract
Reducing anthropogenic CO2 emissions ranks high among the grand scientific challenges of this century. In the near-term, significant reductions can only be achieved through innovative sequestration strategies that prevent atmospheric release of large-scale CO2 waste streams. Among such strategies, injection into confined geologic formations represents arguably the most promising alternative; and among potential geologic storage sites, oil reservoirs and saline aquifers represent the most attractive targets. Oil reservoirs offer a unique "win-win" approach because CO2 flooding is an effective technique of enhanced oil recovery (EOR), while saline aquifers offer immense storage capacity and widespread distribution. Although CO2-flood EOR has been widely used in the Permian Basin and elsewhere since the 1980s, the oil industry has just recently become concerned with the significant fraction of injected CO2 that eludes recycling and is therefore sequestered. This "lost" CO2 now has potential economic value in the growing emissions credit market; hence, the industry's emerging interest in recasting CO2 floods as co-optimized EOR/sequestration projects. The world's first saline aquifer storage project was also catalyzed in part by economics: Norway's newly imposed atmospheric emissions tax, which spurred development of Statoil's unique North Sea Sleipner facility in 1996. Successful implementation of geologic sequestration projects hinges on development of advanced predictive models and a diverse set of remote sensing, in situ sampling, and experimental techniques. The models are needed to design and forecast long-term sequestration performance; the monitoring techniques are required to confirm and refine model predictions and to ensure compliance with environmental regulations. We have developed a unique reactive transport modeling capability for predicting sequestration performance in saline aquifers, and used it to simulate CO2 injection at Sleipner; we are now extending this capability to address CO2-flood EOR/sequestration in oil reservoirs. We have also developed a suite of innovative geophysical and geochemical techniques for monitoring sequestration performance in both settings. These include electromagnetic induction imaging and electrical resistance tomography for tracking migration of immiscible CO2, noble gas isotopes for assessing trace CO2 leakage through the cap rock, and integrated geochemical sampling, analytical, and experimental methods for determining sequestration partitioning among solubility and mineral trapping mechanisms. We have proposed to demonstrate feasibility of the co-optimized EOR/sequestration concept and utility of our modeling and monitoring technologies to design and evaluate its implementation by conducting a demonstration project in the Livermore Oil Field. This small, mature, shallow field, located less than a mile east of Lawrence Livermore National Laboratory, is representative of many potential EOR/sequestration sites in California. In approach, this proposed demonstration is analogous to the Weyburn EOR/CO2 monitoring project, to which it will provide an important complement by virtue of its contrasting depth (immiscible versus Weyburn's miscible CO2 flood) and geologic setting (clay-capped sand versus Weyburn's anhydrite-capped carbonate reservoir).
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2002
- Bibcode:
- 2002AGUSMGC31A..04J
- Keywords:
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- 1010 Chemical evolution