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U.S. Department of Energy
Office of Scientific and Technical Information

Geophysical logs and core measurements from forty boreholes at Yucca Mountain, Nevada

Technical Report ·
OSTI ID:138251

A data base of geophysical logs and core measurements acquired in boreholes at Yucca Mountain, Nevada, has been established. We used this data set to generate log plots from 40 boreholes at a scale of 1:1200 for reference and for correlation. Log headers summarize the drilling and logging sequence. We describe the logging tools, the sources of core data, and the editing procedures. We illustrate the adverse effects of casing on the gamma-ray log, of borehole rugosity on the density log, and of borehole diameter and fluid resistivity on the resistivity logs. Welding and alteration of the tuffs are the dominant geological controls on the response of the density, velocity, neutron, and resistivity logs. Density, resistivity, gamma-ray, and, in particular, the magnetic-field logs are useful for correlation of stratigraphy and alteration. A few zones in which the matrix is moderately permeable have produced log responses indication invasion of the rock by drilling fluid. Readings from the density log were confirmed with core measurements. It appears that the epithermal-neutron and dielectric-permittivity logs can be used to estimate water content providing calibration methods are established. 82 refs., 30 figs., 6 tabs.

Research Organization:
Geological Survey, Washington, DC (United States)
Sponsoring Organization:
USDOE, Washington, DC (United States); Geological Survey, Reston, VA (United States)
DOE Contract Number:
AI08-78ET44802
OSTI ID:
138251
Report Number(s):
USGS/MAP/GP--1001
Country of Publication:
United States
Language:
English