Monitoring Geological CO2 Storage: Quantitative CO2 Prediction with Uncertainty from Physical Modeling and Multiple Time-Lapse Data Types

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The project's main goal is to develop new and improved methods for quantitative prediction of the distributions of CO2 in subsurface storage sites. We will build statistically consistent models that take into account uncertainty at all levels, and use geo physical modeling and multiple time-lapse data sources. The main goal will be achieved by combining the partners' joint expertise on stochastic modeling and uncertainty handling, and theoretical as well as experimental geophysical research. Monitoring CO 2 volumes is a challenge. Main geophysical challenges include establishing proper rock physics relations between seismic velocity and saturation; interaction between injected CO2 and original fluid-rock; and chemical changes to the host rock. From a stati stical point of view it is a challenge to consistenly combine all elements of the rock physical models and appropriate data forward models into an overall scheme for 4D data inversion. We will develop appropriate rock physics relations to explain the sei smic effects of injection of CO2 in subsurface rocks of various reservoir qualities; develop a library of realistic rock physics models suitable for CO2 ; develop consistent stochastic models that jointly take into account various time-lapse data types, a nd find spatially and temporally correlated seismic parameters constrained by data; develop statistical inverse rock physics models; develop a software prototype for 4D joint inversion of multiple data sources; test the new methods on various synthetic sc enarios; and carry out a case study with real data from Statoil's CO2 storage project at Sleipner. Carbon Capture and Storage is currently a major concern for the Norwegian energy and petroleum industry. With CO2 storage quickly gaining international foc us, trustworthy uncertainty estimates based on physical modeling and stringent mathematical reasoning will be increasingly important. The competitive edge of the Norwegian industry is facilitated by this project.