--> Influence of Lithology and Diagenesis on Mechanical and Sealing Properties of the Thirteen Finger Limestone and Upper Morrow Shale, Farnsworth Unit, Texas

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Influence of Lithology and Diagenesis on Mechanical and Sealing Properties of the Thirteen Finger Limestone and Upper Morrow Shale, Farnsworth Unit, Texas

Abstract

The Thirteen Finger Limestone and upper Morrow shale make up the caprock units within Farnsworth Unit (FWU), Texas. The site is the location of a commercial-scale CCUS project conducted by the Southwest Regional Partnership on Carbon Sequestration (SWP). Chaparral Energy, LLC, the operator of FWU, is currently injecting anthropogenic CO2 for the purposes of enhanced oil recovery. The goal of the SWP is to characterize, monitor and verify the storage of up to 1 million metric tons of CO2 in the upper Morrow sandstone reservoir. The Morrow sandstone is overlain by a caprock of mudstone, cementstone, and coal. The principal objective of this work is to understand the lithologic and diagenetic controls on the mechanical attributes of the rock. The mechanical properties of these formations, along with an understanding of the diagenetic history of each lithology, will help determine how the caprock will react to stress perturbation resulting from elevated pore pressure due to injection of supercritical CO2 into the underlying reservoir. Thin section petrography and microprobe analysis are two methods being used to investigate how diagenesis affects the caprock. Important diagenetic processes that have affected the rock include pyrite precipitation, carbonate precipitation, and fracture mineralization. A paragenetic sequence will be determined for the caprock and for each lithology. Overall, the goal is to relate the core scale data, such as lithofacies, diagenesis and mechanics to the basin scale data that includes the well logs, geologic and property models and seismic attributes. Funding for this project is provided by the U.S. Department of Energy's (DOE) National Energy Technology Laboratory (NETL) through the Southwest Regional Partnership on Carbon Sequestration (SWP) under Award No. DE-FC26-05NT42591