Geochemical Modeling of CO2-Based Huff 'n' Puff Oil Recovery at the Northwest Mcgregor Oil Field
The Plains CO2 Reduction Partnership, one of the seven U.S. Department of Energy National Energy Technology Laboratory Regional Partnerships, has conducted a project in the Northwest McGregor oil field in North Dakota to determine the effects CO2 will have on the productivity of the reservoir, wellbore integrity, and the carbonate formation into which CO2 was injected. The method used in this project is called huff 'n' puff, whereby 400 tons of supercritical CO2 was injected into a well over a 2-day period and allowed to "soak" for a 2-week period. The well was subsequently put back into production for incremental oil recovery.The purpose of this paper is to outline the approach and current observations for the numerical modeling of potential geochemical reactions in an effort to evaluate the short-term risks for operations (e.g., porosity and permeability decrease) and long-term implications for CO2 storage via mineralization. Mineralogy of the reservoir was determined using well logs, traditional core sample analysis, x-ray diffraction, and QEMSCAN® techniques. A pressurized bottom-hole fluid sample was also collected, and its composition was determined and used as input parameters for the model.Modeling was performed using PHREEQC and Geochemist's Workbench software in order to determine the most favorable geochemical interactions and evaluate in situ fluid properties. The Computer Modelling Group Ltd. GEM simulator was utilized for the creation of a 3-D model for reactive transport evaluation. It was determined that the already acidic and highly saline environment of the Northwest McGregor oil field should not experience significant changes in mineralogy, especially in the near term. Insignificant increase in porosity was predicted as a result of carbonate rock dissolution, and precipitation of iron-bearing minerals (e.g., hematite) was modeled.View/Download Document
Event/Meeting Information
2011 SPE International Symposium on Oilfield Chemistry
4/11/2011
The Woodlands, TX