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Characterization of the High Island 24L Oil and Gas Field for Modeling and Estimating CO2 Storage Capacity


Carbon capture and storage (CCS) is an essential process that ultimately can be the solution in reducing CO2 emissions by injecting captured gas from large point sources into geologic formations. In the state waters off the Texas coast, there is great potential for a CO2 storage project. This research characterizes an oil and gas field, High Island 24L, that has produced over 467 bcf of gas and 4 million bbl of oil. A simplistic approach in understanding CO2 can most likely occupy the space (and much more) that before had hydrocarbon in the geologic formation is the primary motivation for this study. The stratigraphy of the inner continental shelf in the Gulf of Mexico is important for recognizing which reservoirs are best suited for the injection of CO2. Lower Miocene sands in the Fleming Group beneath the regional transgressive Amphistegina B shale show great geologic properties and are characterized with 3-D seismic and well logs. Key surfaces between MFS-9 to MFS-10 demonstrate how marine regression and transgression impact the stacking pattern of the thick sands, influencing the overall potential for CO2 storage. This interval does not capture the most producing reservoir (HC sand) of the field, therefore illustrating how different methodologies for saline formations and depleted reservoirs affect capacity estimates. In estimating the capacity of this field and interpreting the effects of various geologic parameters, three model scenarios were constructed: homogeneous, statistically heterogeneous, and seismic-based heterogeneous. Incorporating previous work that has been implemented on a more regional scale, the results show that capacity estimation decreases with more refinement of the data. This is significant because a trend can be defined and more questions can start to be asked about the geology when trying to reach a target capacity for a project.