(685b) Understanding the Factors That Affect CO2 Transport, Storage, and Enhanced Oil Recovery Potential in Unconventional Reservoirs
Past and ongoing work at the Energy & Environmental Research Center (EERC), funded by the U.S. Department of Energy National Energy Technology Laboratory in conjunction with partners from the oil and gas industry, has been focused on better understanding the factors that affect CO2 transport as it relates to both enhanced oil recovery (EOR) and CO2 storage in unconventional oil reservoirs and organic-rich shales. Much of this work has been performed in several of the EERCâ??s laboratories using rock samples from the Bakken petroleum system, the results of which can be applied to unconventional formations across the United States. The analytical work conducted to date has focused on supercritical CO2 extraction experiments, CO2 sorption experiments, and extensive physical and geochemical characterization using rock samples from several Bakken wells to better understand the factors that can affect CO2 migration, oil extraction, sorption, and storage. Sample characterization has been accomplished using a variety of analytical techniques including whole-core and microcomputerized tomography imaging, conventional scanning electron microscopy (SEM) coupled with energy-dispersive x-ray spectroscopy, field emission SEM, focused ion beam SEM, x-ray fluorescence, x-ray diffraction, optical microscopy, Rock-Eval pyrolysis, vitrinite reflectance, mercury injection capillary pressure testing, and geomechanical testing. Initial characterization work focused on better understanding the occurrence and characteristics of fracture and pore networks and has expanded to the use of advanced analytical and image analysis techniques to quantify fracture and pore occurrence and mineralogical content at various resolutions. Work is ongoing to better understand and quantify the occurrence and accessibility of pores, fractures, clay minerals, and kerogen and the potential implications that those features have on CO2 transport for EOR and on CO2 sorption for storage. The sample characterization efforts are being used to better understand the results of supercritical CO2 extraction experiments and ongoing CO2 sorption experiments using Bakken samples that have undergone extensive characterization. These results are being integrated into modeling research activities to determine the fundamental mechanisms controlling fluid transport and CO2 storage in the Bakken, resulting in the development of improved model simulations. The results of the EERCâ??s laboratory-based work and its implications for CO2 EOR and storage, as well as future research needs, will be discussed.
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