TM 5-818-1 / AFM 88-3, Chap. 7
Table 4-5. Borehole Surveying Devices
a
Device
Measurement Obtained
Primary Use
Electric logging
Spontaneous potential
Natural voltages between
Differentiating be-
(SP)
fluids in materials of
tween sands and
dissimilar lithology
clays
Single-point
Resistance of rock adja-
With SP log provides
resistivity
cent to hole
good indication of
subsurface strati-
fication and soil
type
Multiple-point
Resistivity of
Determination of mud
resistivity
formations
infiltration and
effective porosity
Radiation logging
Gamma
Natural gamma radiation
Identification of
of materials
clay seams, loca-
tion of radioactive
tracers, and with
SP and resistivity
logs provides in-
formation on rela-
tive porosity
Hydrogen atom
Determination of
concentration
moisture content
and porosity below
zone of saturation
porosity
Gamma-gamma
Gamma radiation
Correlates with bulk
absorption
density and useful
to determine poros-
ity if grain spe-
cific gravity is
known
Sonic logging
Travel time of primary
With caliper and den-
velocity
and shear wave
sity logs determine
velocities
dynamic elastic and
shear moduli of in
situ rock
(Continued)
a
All devices currently available at WES. May be furnished as a service to Districts and Divisions on request.(Sheet 1 of 3)
4-13
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