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Tool
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Physical Measurement
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Use
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Comments
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Logging Conditions
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Temperature (BHT)
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Temperature
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Borehole temperature
for resistivity calculations .
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Corrected with Horner
plot
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Pressure (PRESS)
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Fluid Pressure
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Fluid pressure for formation volume factor
calculations .
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Incorporated in RFT
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Borehole diameter
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Borehole diameter
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Data quality, in situ
stress tensor, lithology and permeability indicator.
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Available in 2.4. or
multi-arm versions
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Lithology
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Gamma Ray (GR)
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Natural radioactivity of the formation.
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Shale indicator and depth matching
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Can read through casing.
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Spontaneous Potential
(SP)
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Sand/Shale interface
potential .
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Permeable beds
Resistivity of
formation water
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Does not work in
conductive muds, or offshore.
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Porosity
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Sonic (BHC, LSS )
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Velocity of an elastic wave in the formation.
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Effective (connected ) porosity .
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Compaction gas and vugs, calibration of seismic
data.
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Density (FDC , LDT )
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Bulk density of the
formation.
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Total porosity .
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Used to calculate synthetic
seismograms .
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Neutron (SNP, CNL )
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Hydrogen concentration in the formation.
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Total porosity (shale increases measured porosity ,
gas reduces measured porosity )
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Can read through casing
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Resistivity
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Simple electric log
(SN, LN ,Lat )
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Resistivity of
flushed , shallow and deep zones respectively .
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Used in water
saturation calculations.
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Now obsolete, not
focused, can’t be used in oil based muds, prone to invasion.
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Induction
Logs (IES , ISF, DIL, DISF, ILm, ILd )
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Conductivity
of the formation.
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Conductivity and resistivity in oil based muds, and
hence calculation of water saturation.
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Focused devices. Use in oil based and fresh water
muds. Range of depths of investigation. (Vertical resolution 5-10 ft.)
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Laterolog (LL3, LL7,
DLL, LLs, LLd)
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Resistivity of the
formation.
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Resistivity in water
based muds, and hence calculation of water saturation
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Focused devices. Use
in salt water based muds. Range of depths of investigation. (Vertical
resolution 2-4 ft.)
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Microlog (ML)
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Resistivity of mudcake and flushed zone .
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Indicator of permeability. Detector of thin beds.
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(vertical resolution about 1 ft.)
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Micro-laterolog (MLL)
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Resistivity of
flushed zone.
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Measures RXO
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Not good with thick
mudcakes.
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Proximity Log (PL)
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Resistivity of flushed zone .
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Measures RXO
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Not good if invasion is small.
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Micro-spherically
focused log (MSFL)
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Resistivity of
flushed zone .
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Measures RXO
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Part of DLL-RXO tool.
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