T38 CO2 Sequestration in Deep Saline Aquifers: Leakage Pathways, Risk Assessment, and Impact on Overlying Aquifers (Posters)

Sunday, 31 October 2010
8:00 AM - 6:00 PM
Hall D

NUMERICAL SIMULATIONS OF POTENTIAL LEAKAGE OF CO2 FROM SEQUESTRATION RESERVOIRS

Paper number: T38-2
Program: Technical Sessions
Time: 8:00 AM – 6:00 PM

Authors

Abstract

Permanent capture and storage of anthropogenic CO2 in depleted oil fields and saline aquifers has long been proposed as a viable method of forestalling global warming. Much work has been done to assess porosity and permeability changes as a direct result of CO2 injection into the aquifer. Leakage through the caprock, intermediate zone (IZ), and into drinking water aquifers is not well characterized and can be evaluated by numerical modeling. The multiphase reactive transport finite difference 3-D reservoir simulator PFLOTRAN, developed at Los Alamos National National Lab, was used to simulate potential leakage of CO2 from a sequestration site. The initial simulation was modeled after the Weyburn oil field (Saskachewan, Canada). Weyburn is a small (1.4 billion barrel) field, composed mostly of Missisippian-age (340 Ma) carbonates. With a long production since 1955, declining production rates as of 2006 are now being enhanced by large-scale (several million metric tons per year) CO2 injection. This field is well characterized and considered to be a good candidate for long-term storage.

The first sets of models were designed to simulate the dolomitic marly reservoir of the Weyburn field. As an initial validation test, aqueous CO2 injection into the reservoir was simulated in one-dimension with horizontal layers and included both reactive transport and multiphase flow scenarios. The physical (e.g. porosity, temperature) and chemical (e.g. matrix composition, dissolution rates constants) characteristics in these simulations were chosen to be as realistic as possible, drawing upon parameters published by Cantucci et al. (2009). Initially CO2 injection was simulated along a 500-meter 1D flow path for a period of four calendar years. To simulate leakage from the reservoir, a caprock was added to the model and transport of supercritical and dissolved CO2 was tracked along an upward flow path. Results from simulations with varying porosity and permeability of the reservoir and caprock domains and CO2 injection rates will be presented.

Cantucci, B., Montegrossi, G., Vaselli, O., Tassi, F., Quattrocchi, F., Perkins, E.H.,: Geochemical Modeling of CO2 storage in deep reserviors: The Weyburn Project (Canada) case study. Chem. Geology. 265, 181-197 (2009)