Valgarður: a database of the petrophysical, mineralogical, and chemical properties of Icelandic rocks

Abstract

Abstract. The Valgarður database is a compilation of data describing the physical and geochemical properties of Icelandic rocks. The dataset comprises 1166 samples obtained from fossil and active geothermal systems as well as from relatively fresh volcanic rocks erupted in subaerial or subaqueous environments. The database includes petrophysical properties (connected and total porosity, grain density, permeability, electrical resistivity, acoustic velocities, rock strength, and thermal conductivity) as well as mineralogical and geochemical data obtained by point counting, X-ray fluorescence (XRF), quantitative X-ray diffraction (XRD), and cation exchange capacity (CEC) analyses. The database may be accessed at https://doi.org/10.5281/zenodo.6980231 (Scott et al., 2022a). We present the database and use it to characterize the relationship between lithology, alteration, and petrophysical properties. The motivation behind this database is to (i) aid in the interpretation of geophysical data, including uncertainty estimations; (ii) facilitate the parameterization of numerical reservoir models; and (iii) improve the understanding of the relationship between rock type, hydrothermal alteration, and petrophysical properties.

Advanced Monitoring of H2S Injection through the Coupling of Reactive Transport Models and Geophysical Responses

“…Since the short time frame of H 2 S injection between IP measurements is short (40 days) and basaltic glass dissolution is faster than the dissolution of crystalline minerals in basalt, , we assume that basaltic glass is the primary phase affected most by the reaction of the injection fluid and host rock. Basaltic glass is estimated to be 25% of the matrix volume based on measurements from unaltered hyaloclastites in south and southwest Iceland . The saturation conditions of the dissolving basaltic glass were calculated assuming that the primary phase is a leached layer of amorphous Al-hydroxide and amorphous silica. − Its reactive surface area (RSA), a parameter generally unknown in natural settings and uncertain in reactive transport modeling, − was assumed to be 20 cm 2 /g of basaltic glass, consistent with previous studies. , The RSA varies as a function of the porosity and the amount of basaltic glass dissolved, assuming the dissolution of spherical particles .…”

“…We focus on broad temperature trends over the 25 m borehole intervals and not localized temperature increases, which may indicate fracture-dominated flow paths that facilitate rapid fluid migration outside the near-borehole model domain. Permeabilities were grouped into high (1 × 10 –11 m 2 ) and low (1 × 10 –13 m 2 ) categories based on values reported for basalts in the Hengill area. ,,,, These permeability estimates control the injection water supply to each layer in the RTM, with larger permeabilities facilitating more water flow (SI Text S3).…”

“…Basaltic glass is estimated to be 25% of the matrix volume based on measurements from unaltered hyaloclastites in south and southwest Iceland. 74 The saturation conditions of the dissolving basaltic glass were calculated assuming that the primary phase is a leached layer of amorphous Al-hydroxide and amorphous silica. 75−77 Its reactive surface area (RSA), a parameter generally unknown in natural settings and uncertain in reactive transport modeling, 78−80 was assumed to be 20 cm 2 /g of basaltic glass, consistent with previous studies.…”

“…Permeabilities were grouped into high (1 × 10 −11 m 2 ) and low (1 × 10 −13 m 2 ) categories based on values reported for basalts in the Hengill area. 1,70,74,93,94 These permeability estimates control the injection water supply to each layer in the RTM, with larger permeabilities facilitating more water flow (SI Text S3).…”