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Geologic Modeling of an Active CO2 EOR and Carbon Storage Project Using 3-D Seismic Models and Extracted Attributes, Farnsworth, TX


The Farnsworth Unit in Ochiltree County, TX, is the site of the Southwest Partnership (SWP) on Carbon Sequestration's large-scale carbon capture, utilization, and storage experiment. A comprehensive 3D geologic model provides the basis for monitoring and modeling CO2 migration or leakage from the upper Morrow sandstone reservoir, which is undergoing tertiary recovery using anthropogenic CO2. The SWP acquired a 45 square mile 3D seismic survey over the entire Farnsworth Unit. Also acquired were vertical seismic profiles, wireline logs, and core data from three new wells. Formation top interpretations are based on integrating 3D seismic and compressional sonic well log data into a velocity model to convert the seismic z-axis into the depth-domain. Converting domains allowed the 3D seismic data to be correlated to other depth-domain datasets, such as new and legacy well log data and core sections. Surfaces generated from seismic interpretation also provided the framework for a geologic model that can be populated with information from seismic attributes and thus allows propagation of reservoir properties into the 3D seismic volume. Seismic attributes describe a measurable characteristic of seismic data that resolves features or quantifies some physical property. While fractures and faults are not always obvious in seismic data, edge enhancing seismic attributes can be employed to highlight those features. Coherency volumes that measure waveform similarity and ant-tracking volumes that track continuous features were generated to illuminate possible fault structures. Three faults were interpreted that were resolvable across different attributes and defined planar features in three dimensions. Seismic attributes are also useful for determining rock properties that can populate a 3D geomodel. Geometric attributes that are sensitive to reflection impedance changes help predict porosity, lithology, and formation thicknesses. Work is ongoing to propagate lithologically sensitive attributes to identify channels that could act as preferential fluid flow paths in the Morrow sandstone.