초록 ▼

Induction logging sonde including transmitter and receiver solenoid coils mounted on a support and axially separated from each other. The support is made of conductive material and comprises at least one first longitudinal portion for mounting the coils and second longitudinal portions on each side

Induction logging sonde including transmitter and receiver solenoid coils mounted on a support and axially separated from each other. The support is made of conductive material and comprises at least one first longitudinal portion for mounting the coils and second longitudinal portions on each side of the first portion. At least the first portion has a substantially continuous and axisymmetric outer surface so as to favor the flow of eddy currents around the surface, whereby the electric field on that surface is substantially cancelled.

대표청구항 ▼

Induction logging sonde adapted for displacement in a fluidfilled borehole for investigating the formations traversed by the borehole, comprising: at least one transmitting solenoid coil transmitting at a frequency between about 10-400 KHz for generating an electromagnetic field substantially free f

Induction logging sonde adapted for displacement in a fluidfilled borehole for investigating the formations traversed by the borehole, comprising: at least one transmitting solenoid coil transmitting at a frequency between about 10-400 KHz for generating an electromagnetic field substantially free from dielectric effects, which field induces currents in the formation, at least one receiving solenoid coil axially spaced from the transmitting coil for producing in response to the field induced by these currents a signal indicative of the conductivity of the formation, an elongate support having at least one first longitudinal portion mounting said coils in coaxial and spaced relationship thereto and second longitudinal portions on both sides of said first portion, said support being made of electrically conductive metal, at least said first portion having a substantially continuous outer surface to favor the flow of eddy currents resulting from said electromagnetic field circularly around said surface, the second portions being exposed to the pressure of the borehole fluid.