Investigations of Carbon Sequestration Mechanisms in Partially Depleted Oil Reservoirs

Authors: 
Kutsienyo, E. J. - Presenter, New Mexico Institute of Mining and Technology
Ampomah, W., New Mexico Institute of Mining and Technology
Sun, Q., New Mexico Institute of Mining and Technology
Balch, R., New Mexico Institute of Mining and Technology
Cather, M., New Mexico Institute of Mining and Technology
The objective of this work is to evaluate various CO2 trapping mechanisms and long-term carbon storage potential involved in CO2 enhanced oil recovery (EOR) projects in a partial depleted sandstone oil reservoir. More importantly, we seek to confirm changes in petrophysical properties induced by CO2 injection that have been observed from laboratory measurement. A field-scale numerical simulation model is established utilizing extensive field data to study the Upper Pennsylvanian Morrow B sandstone. The validity of the reservoir model is confirmed via a rigorous history matching study using field injection and production data. The history-matched model is employed to assess the multiple trapping mechanisms including residual trapping, structural-stratigraphic trapping, solubility trapping and mineral trapping. Numerical experiments are conducted considering the intra-aqueous and mineral dissolution/precipitation reactions, which may promote pore structure alterations. Moreover, we take advantage of Henry’s law to calculate the CO2 dissolution as function of pressure, temperature and salinity. The reservoir is monitored for 1000 years after all the injectors and producers are shut-in to investigate the long-term storage of CO2 injection in the field. Such a robust reservoir model is compentent to evaluate long-term CO2 sequestration potential and study the impact of the CO2 injection on petrophysical properties of the Morrow-B formation, such as pore fluid composition, mineralogy, porosity and permeability. The results from this work provide significant insights in terms of the optimum storage of CO2 in aqueous-gaseous-mineral phases, effect of salinity on storage, and the amounts of dissolution/precipitation of the principal accessory minerals evolving throughout the project. Information gained from this study offers valuable insight regarding physiochemical storage induced by the CO2 injection activities and may serve as a benchmark case for future CO2 -EOR projects when reactive transportations are considered.