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A New Sonic Velocity-logging Technique and Results in Near-surface Sediments of Northeastern New Mexico.

Authors
Snodgrass-JJ
Source
MISSING :24 pages
Link
NIOSHTIC No.
10002326
Abstract
A new technique was used to obtain detailed sonic logging data in drill holes above the water table at a coal mine site in northeastern New Mexico. The equipment was developed under contract to the Bureau of Mines and the U.S. Department of Energy to indirectly evaluate the in situ structural properties of coal and overburden. The system comprises a hydraulically operated, wall- clamping downhole probe compatible with standard four-conductor logging cable, and a surface control module. Resolution of layering is 0.6 Meter (2.0 Ft), and a redundancy of data from separate receivers provides accurate timing measurements. Preliminary results in the settled overburden of an excavated longwall panel indicated a low average velocity zone, extending approximately 18 meters (60 ft) into the immediate roof of the coal seam. Subsequent measurements improved the field and recording procedures to produce high-quality waveforms from which both p and s arrivals may be visually interpreted. Over a representative section of interbedded sandstone, siltstone, shale, and coal, vr and vs varied considerably even with lithologic units. Compressional wave velocity in the coal seam, vr = 1,740 m/sec (5,700 ft/sec), was in the range of variability of published data.
Publication Date
19820101
Document Type
IH;
Fiscal Year
1982
NTIS Accession No.
NTIS Price
Identifying No.
TPR 117
NIOSH Division
DRC;
Source Name
MISSING
State
NM;
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