Flushed Zone Resistivity (Rxo)
Formation Water Resistivity (Rw)
True Resistivity of the Uninvaded Formation (Rt)
Mud Filtrate Resistivity (Rmf)
Resistivity of a formation is inversely proportional to voltage, and directly proportional to current.
A magnetic field intersecting a coil of wire will induce an alternating voltage in that coil.
Current in a coil of wire creates an electromotive force.
Proportional
Inversely Proportional
Resistivity of a formation is inversely proportional to voltage, and directly proportional to current.
A magnetic field intersecting a coil of wire will induce an alternating voltage in that coil.
Current in a coil of wire creates an electromotive force.
R-Signal
X-Signal
Mutual Signal
Subtraction of sonde error from the measurement
The use of multiple transmitter and/or receiver coils.
Measurement of the X-signal in very low resistivity formations
Correction for skin effect in very low resistivity formations
Underestimated
Overestimated
Low resistivity formations
High resistivity formations
Determination of water saturation
Estimation of diameter of invasion
Measure of formation porosity
Qualitative estimation of permeability
Measure resistivity of drilling fluid
24 inches
30 inches
39 inches
60 inches
91 inches
24 inches
30 inches
39 inches
60 inches
91 inches
Invaded mud filtrate
Permeability
Formation water resistivity
Borehole resistivity
Shoulder bed resistivity
Air drilled holes
Oil based mud
Fresh water based mud
Saltwater based mud
Large
Small
True
False
Sonde error
Mutual signal
Skin effect
R-Signal
X-Signal
Mutual Signal
Taylor Signal
Inversely
Directly
Linearly
Perpendicularly
180-degree
270-degree
90-degree
120-degree
X-Signal
R-Signal
Mutual Signal
Taylor Signal
X-Signal
R-Signal
Mutual Signal
Taylor Signal
17-inches
24-inches
30-inches
39-inches
60-inches
91-inches
17-inches
24-inches
30-inches
39-inches
60-inches
91-inches
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