Comparison of CO2 and Acid Gas Interactions with Reservoir Fluid and Rocks at Williston Basin Conditions
A series of laboratory experiments, field observations, and numerical modeling of geochemical reactions have been conducted to determine the chemical kinetics of potential mineral dissolution and/or precipitation caused by the injection of carbon dioxide (CO2) and/or sour gas. Kinetic experiments were conducted using core samples representative of potential Williston Basin storage formations and pure mineral samples (e.g., calcite, dolomite, siderite, etc.) obtained from vendors. Two sample sets consisting of 16 samples each, under the same experimental conditions, were "soaked" for a period of 4 weeks at 2500 psi (172 bar) and 176°F (80°C) in synthetically generated brine conditions. Over that time period, one set was exposed to pure CO2 and the other to a mixture of CO2 (88 mol%) and hydrogen sulfide (H2S)(12 mol%). Samples were analyzed using x-ray diffraction (XRD) and QEMSCAN® techniques. The initial XRD mineralogical analysis of selected samples indicates the presence of anhydrite, calcite, dolomite, forsterite, halite, illite, magnetite, and quartz. XRD analysis of obtained reaction products indicated that 1) there is no strong evidence for higher degradation of samples exposed to a mixture of CO2 and H2S if compared to the pure CO2 stream; however, 2) if H2S is present in the stream, it seems to be more dominant in the reactions; and 3) reactivity of the sample is strongly driven by its mineralogy. Results of the laboratory experiments were compared with the numerical modeling performed using the Geochemist's Workbench® simulator and PHREEQC. This work was performed by the Energy & Environmental Research Center through the Plains CO2 Reduction Partnership, one of the U.S. Department of Energy's National Energy Technology Laboratory Regional Carbon Sequestration Partnerships. ;;;View/Download Document
Event/Meeting Information
Second International Acid Gas Injection Symposium
9/28/2010
Calgary, AB