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Hydrogeobiochemical Impacts of Enhanced Oil Recovery Processes: Assessing CO2 Storage in Depleted Petroleum Reservoirs

Jenna Shelton
Hydrologic Science and Engineering, Colorado School of Mines, Golden, CO, USA
[email protected]


Geologic carbon sequestration is a promising technology to reduce greenhouse gas emissions to the atmosphere. Unfortunately, its high cost combined with little to no economic incentives creates a large drawback to implementation. Injecting anthropogenic CO2 into depleted petroleum reservoirs as an enhanced oil recovery (EOR) technique would provide an economic product (e.g., residual crude oil) along with potentially sequestering CO2. However, little research has been done to determine if the CO2 injected and retained in EOR reservoirs is stored in a secure manner. This research looks to track, from source to sink, CO2 gas used for EOR, looking specifically at CO2 storage mechanisms, transformations of the CO2 gas as it travels from source to sink (e.g., target reservoir), and CO2-EOR impacts to crude oil and formation water chemistry.

Samples of injected CO2 coupled with produced water, oil, and gas will be collected from three EOR units in the North Ward Estes Field of western Texas. Geochemical modeling will be utilized to predict the expected geochemical changes to each reservoir with the introduction of CO2. Since specific storage mechanisms of CO2 impart a distinct isotopic signature on the carbon pools present, tracking the injected CO2 will be possible. In addition to isotopic changes, changes in cation, anion and trace metal concentrations occur with different CO2 storage mechanisms. If permanent storage mechanisms can be verified for EOR formations, this could become a popular target site for geologic CO2 sequestration, producing both usable energy and a reduction of CO2 emissions to the atmosphere.

AAPG Search and Discovery Article #90199 © 2014 AAPG Foundation 2014 Grants-in-Aid Projects