Rock property analysis of core samples from the Yucca Mountain UE25a-1 borehole, Nevada Test Site, Nevada

Abstract

Core samples from the Yucca Mountain UE25a-1 borehole were measured for bulk density, porosity, resistivity, induced polarization, compressional sonic velocity, hydraulic conductivity (water permeability), magnetic susceptibility, and remanent magnetization as part of a large-scale site evaluation program designed to identify suitable locations for the containment of radioactive waste products. The samples are representative of stratigraphic units of the Paintbrush Tuff, the tuffaceous beds of Calico Hills, and the Crater Flat Tuff. Resistivity and bulk density values of water-saturated samples closely approximate those at near in situ levels of water saturation and variations in resistivity, density, and sonic velocity are largely dependent upon porosity. The Tiva Canyon Member of the Paintbrush Tuff has an inversely polarized component of remanent magnetization and the entire Paintbrush has a magnetization appreciably greater than the underlying formations. There is no direct correlation between porosity and permeability; the latter varying widely and often decreasing with time as unconsolidated particles within the pore network are repositioned so as to impede the continued flow of water through the rock.

Report on televiewer log and stress measurements in core hole USW G-2, Nevada Test Site, October-November, 1982

“…The same stratigraphic units from hole UE25a-l (4.6 km SE of USW G-2) show a wide variation in porosity in the interval from the Tiva Canyon Member to the Crater Flat Tuff, with porosity as low as 8% in parts of the Topopah Springs Member and as high as 35% in the tuffaceous beds of Calico Hills (Anderson, 1981). Core specific gravity measurements and borehole gravimetry tied to gamma-gamma well log measurements in holes USW H-l and USW G-l (both about 3 km SSE of USW G-2) give average density values for these volcanic units ranging from 1.90 g/cm3 for the tuffaceous beds of Calico Hills to approximately 2.40 g/cm3 for the older tuffs (Snyder and Carr, 1982).…”

Hydrology of Yucca Mountain and vicinity, Nevada-California — Investigative results through mid-1983

“…Theg saturated matrix conductivity of the welded tuffs is small--less than 10" cm/s, and as low at 10~ cm/s (table 9). The geometric-mean saturated hydraulic conductivity of cores from the Topopah Spring Member from well UE-25a#l (Anderson, 1981) is approximately 9.5 x 10 cm/s. Matric tensions have been estimated at 1 to 2 bars, based on mercury-injection test data from core from USW H-l.…”

“…Moderately and densely welded tuffs are characterized by relatively low porosities (5 to 25 percent) (Anderson, 1981;Lappin and others, 1981), a tendency to fracture easily, and low-matrix conductivi-ties. Water movement generally is along fractures, rather than through the matrix.…”

Bulk, thermal, and mechanical properties of the Topopah Spring Member of the Paintbrush Tuff, Yucca Mountain, Nevada

“…-85- -86-Based on data in Caporuscio et al (1982), Maldonado and Koether (1983, p. 63), and Levy (1986) (Anderson, 1981(Anderson, , 1984, HN, and LANL (Blacic et al, 1982). Data for one sample from USW G-1 were obtained by either SNL, HN, or TT, but records do not indicate which one, so data for this sample are treated as though they had been measured by an entirely different laboratory.…”

“…Data in Table B-1 have been measured by Sandia National Laboratories (SNL) , Terra Tek (TT) , the U.S. Geolo&ical Survey (USGS) (Anderson, 1981;, Holmes and Narver (HN), and Los Alamos National Laboratory (LANL) (B1acic et al, 1982). Data for three samples from USW G-1 were obtained by either SNL, HN, or TT, but records do not indicate which one, so data for these three samples were treated initially as if they were measured by an entirely different laboratory.…”