US 4,028,660 A · Well logging method and means using an armored multiconductor coaxial cable

Abstract

A logging system employs an armored multiconductor coaxial cable, including an inner conductor, a shield and conductive outer armor and in which the shield, encompassing the inner conductor, comprises a plurality of conductors which includes groups of conductors, each group being separated from another group by an insulator. A distribution circuit has capacitors connected between each shield conductor to improve transmission of a high frequency signal by the inner conductor and the shield conductors while low frequency signals and direct current voltages may be transmitted by the shield conductors and the conductive armor of the cable. A logging tool, including pulse neutron source, gamma ray detector and collar detector, is passed through a borehole traversing an earth formation. Data pulses corresponding in number and amplitude to detected gamma radiation are provided by the gamma ray detector to the inner conductor and to the plurality of conductors of the cable. The signal from the collar detector is applied to a first group of conductors of the plurality of conductors and the armor of the cable. Surface electronics adjacent to the borehole process data pulses received from the cable. A high voltage direct current power is provided to logging tool by way of the inner conductor and the armor of the cable. While second and third direct current voltages are applied to second and third groups of conductors, respectively, of the plurality of conductors and to the armor.

Claims11

Dependent claims

A well logging system comprising a logging tool adapted to be passed through a borehole in an earth formation, said logging tool includes means for sensing conditions in a borehole and providing at least two signals corresponding to the sensed conditions, one signal having a high frequency and at least one other signal having a low frequency;

a transmission system including a shieldless armored multiconductor coaxial cable which comprises an inner conductor, a coaxial first insulator, groups of conductors arranged in a predetermined relationship to said inner conductor and separated from said inner conductor by said first coaxial insulator, means for separating the groups of conductors so as to insulate each conductor group from any other conductor group, a second coaxial insulator, and an outer armor of conductive material separated from said groups of conductors by said second coaxial insulator;
the logging tool also includes means connected to the sensing means and to the transmission system for applying the high frequency signal to the inner conductor and to the groups of conductors of the cable and for applying the low frequency signal to one conductor group and to the outer armor of conductive material;
and surface electronics adjacent to the borehole for processing the signals transmitted by the transmission system to provide outputs corresponding to the sensed condition.

A well logging system comprising a logging tool adapted to be passed through a borehole in an earth formation, said logging tool includes means for sensing conditions in a borehole and providing at least two signals corresponding to the sensed conditions, one signal having high frequency and at least one other signal having a low frequency;

a transmission system including an armored multiconductor coaxial cable which comprises an inner conductor, a coaxial first insulator, groups of conductors arranged in a predetermined relationship to said inner conductor and separated from said inner conductor by said first coaxial insulator, means for separating the groups of conductors so as to insulate each conductor group from any other conductor group, a second coaxial insulator, and an outer armor of conductive material separated from said groups of conductors by said second coaxial insulator;
the logging tool also includes applying means connected to the sensing means and to the transmission system for applying the high frequency signal to the inner conductor and to the groups of conductors of the cable and for applying the low frequency signal to one conductor group and to the outer armor of conductive material, the applying means includes a plurality of capacitors connected with the groups of conductors in a manner so that the groups of conductors have improved coupling between them for high frequency alternating signals and decoupling for low frequency alternating signals and direct current voltages, and another capacitor connects one of the conductors of the plurality of conductors to the outer armor of the cable to improve the coupling of the groups of conductors to ground for high frequency signals, and surface electronics adjacent to the borehole for processing the signals transmitted by the transmission system to provide outputs corresponding to the sensed condition.

A well logging method which comprises the steps of sensing conditions in a borehole in an earth formation, providing a signal having a high frequency and corresponding to a sensed condition, providing at least one other signal having a low frequency and corresponding to a second sensed condition, transmitting the high frequency signal by way of an inner conductor and groups of conductors arranged in a predetermined relationship to the inner conductor of a shieldless armored multiconductor coaxial cable, said inner conductor being separated from said plurality of conductors by a first coaxial insulator;

transmitting the low frequency signal by way of a first conductor group of the groups of conductors and an outer armor of the armored multiconductor coaxial cable, said outer armor being separated from said groups of conductors by a second coaxial insulator, receiving the transmitted signals at the surface of the earth formation, and processing the transmitted signals to provide outputs corresponding to the sensed conditions.

Dependencies are inferred from the claim text.

Well logging method and means using an armored multiconductor coaxial cable

Life of this patent

Well logging method and means using an armored multiconductor coaxial cable

Life of this patent

Abstract

Claims11