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Black Rock, Australia

Joy C.,University of Texas at Austin | Vanorio T.,Stanford Rock Physics Laboratory | Sen M.K.,University of Texas at Austin
SEG Technical Program Expanded Abstracts

The purpose of this study is to understand the effects of injecting carbon dioxide rich brine on the elastic and transport properties of the Lower Tuscaloosa sandstone of Cranfield, Mississippi. We measured compressional and shear wave velocities before and after injecting one sandstone sample with carbon dioxide rich synthetic Tuscaloosa brine at various confining pressures. The bulk and shear moduli decreased from 19 GPa and 12.4 GPa by roughly 9% and 6.5%, respectively, immediately following the first injection of 30 pore volumes of CO2 rich synthetic Tuscaloosa brine. After injecting a total of 160 pore volumes, the rigidity remained constant and the bulk modulus decreased by a total of 13%, which is detectable on the seismic scale. The decrease in elastic properties is likely due to the dissolution of iron-bearing minerals and calcite that have formed at grain contacts as testified by the negligible change in porosity measured after injection. Decreasing the differential pressure acting on the core plug also decreased both P and S-wave velocities by 60 and 20 m/s respectively. Decreasing the differential pressure simulates an increase in pore pressure, which is experienced in the field by injecting CO2 into the reservoir. The chemical reaction has more of an effect on velocities than differential pressure in a range of 20 to 55 MPa. Overall, the P and S-wave velocities are a function of reactant saturation and differential pressure. © 2011 Society of Exploration Geophysicists. Source

Jackson M.D.,University of California at Berkeley | Gudmundsson M.T.,University of Iceland | Bach W.,University of Bremen | Cappelletti P.,University of Naples Federico II | And 19 more authors.
Scientific Drilling

A new International Continental Drilling Program (ICDP) project will drill through the 50-year-old edifice of Surtsey Volcano, the youngest of the Vestmannaeyjar Islands along the south coast of Iceland, to perform interdisciplinary time-lapse investigations of hydrothermal and microbial interactions with basaltic tephra. The volcano, created in 1963-1967 by submarine and subaerial basaltic eruptions, was first drilled in 1979. In October 2014, a workshop funded by the ICDP convened 24 scientists from 10 countries for 3 and a half days on Heimaey Island to develop scientific objectives, site the drill holes, and organize logistical support. Representatives of the Surtsey Research Society and Environment Agency of Iceland also participated. Scientific themes focus on further determinations of the structure and eruptive processes of the type locality of Surtseyan volcanism, descriptions of changes in fluid geochemistry and microbial colonization of the subterrestrial deposits since drilling 35 years ago, and monitoring the evolution of hydrothermal and biological processes within the tephra deposits far into the future through the installation of a Surtsey subsurface observatory. The tephra deposits provide a geologic analog for developing specialty concretes with pyroclastic rock and evaluating their long-term performance under diverse hydrothermal conditions. Abstracts of research projects are posted at http://surtsey. icdp-online.org. © Author(s) 2015. Source

Vanorio T.,Stanford Rock Physics Laboratory | Mavko G.,Stanford Rock Physics Laboratory | Vialle S.,Stanford Rock Physics Laboratory | Spratt K.,Stanford Rock Physics Laboratory
Leading Edge (Tulsa, OK)

Monitoring, verification, and accounting (MVA) of CO2 fate which are the three fundamental needs in geological sequestration are discussed. The primary objective of MVA protocols is to identify and quantify the injected CO2 stream within the injection/storage horizon and any leakage of sequestered gas from the injection horizon, providing public assurance. Changes in the elastic properties of the reservoir induced by the injection of CO2 can be various, affecting the properties of the fluid, those of the rock frame, or both. Seismic reservoir monitoring has traditionally treated the changes in the reservoir rock as a physical-mechanical problem, that is changes in seismic signatures are mostly modeled as functions of saturation and stress variations and/or intrinsic rock properties. To enhance the effectiveness of time-lapse seismic studies, CO2-optimized physical-chemical models involving frame substitution schemes must be developed to account for the type and magnitude of reductions caused by rock-fluid interactions at the grain/pore scale. Source

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