Downhole induction resistivity tool
View Patent ↗A downhole induction resistivity assembly that comprises a downhole tool string component. The tool string component comprises an induction transmitter. The transmitter is adapted to induce an induction field in the surrounding formation. A first induction receiver is spaced apart from the transmitter and is adapted to measure the induction field. A magnetic field generating mechanism is disposed adjacent on either or both sides of the transmitter and adapted to guide the transmitter's signal into the formation. A second induction receiver is disposed in close proximity to the magnetic field generating mechanism and is adapted to measure the magnetic field generated by the mechanism.
1. A downhole induction resistivity assembly, comprising:
a component configured to be conveyed into a wellbore, said component including:
at least one transmitter, adapted to generate an induction signal and transmit said induction signal into a formation adjacent said wellbore;
at least one receiver being spaced apart from said transmitter, said receiver adapted to receive a formation signal representative of said formation;
a magnetic field generating mechanism adapted to generate a magnetic field, said magnetic field adapted to influence said induction signal: and,
a magnetically conductive, electrically insulating material disposed adjacent a surface of said component and said at least one transmitter.
2. The assembly of claim 1 , further comprising a reference receiver adapted to measure a magnetic field signal representative of said magnetic field.
3. The assembly of claim 2 , wherein said at least one transmitter generates said induction signal having at least one of a phase, a frequency, and an amplitude different than at least one of a phase, a frequency, and an amplitude of said magnetic field generated by said magnetic field generating mechanism.
4. The assembly of claim 2 , further comprising a control loop adapted to receive said magnetic field signal from said reference receiver, said control loop adapted to execute a command to said magnetic field generating mechanism, to adjust said magnetic field.
5. The assembly of claim 4 , wherein said command to said magnetic field generating mechanism adjusts at least one of a phases, an amplitudes, a frequency, a strength, and combinations thereof of said magnetic field.
6. The assembly of claim 1 , wherein said magnetic field generating mechanism comprises a Halbach array.
7. The assembly of claim 1 , wherein said magnetic field is directed away from said assembly.
8. The assembly of claim 1 , wherein said magnetic field generating mechanism comprises a substantially U-shaped magnetic core.
9. The assembly of claim 1 , wherein said transmitter comprises at least one coil disposed circumferentially about said component.
10. The assembly of claim 1 , wherein said at least one transmitter further comprises a plurality of transmitter units adapted to be independently energized.
11. The assembly of claim 10 , further comprising a multiplexer adapted to receive data input from at least one of said transmitter, said receiver, and said reference receiver.
12. The assembly of claim 1 , further comprises a plurality of receivers in which a first receiver includes a core substantially perpendicular to another core of a second receiver.
13. The assembly of claim 1 , wherein said at least one receiver includes a magnetic material having a different magnetic property than another magnetic material of said at least one transmitter.
14. A logging tool, comprising:
a component configured to be conveyed into a wellbore, said component including:
at least one transmitter, adapted to generate an induction signal and transmit said induction signal into a formation adjacent said wellbore;
at least one receiver being spaced apart from said transmitter, said receiver adapted to receive a formation signal representative of said formation;
a magnetic field generating mechanism adapted to generate a magnetic field, said magnetic field adapted to influence said induction signal; and,
a reference receiver adapted to measure a magnetic field signal representative of said magnetic field.
15. The logging tool of claim 14 , further comprising a magnetically conductive, electrically insulating material disposed adjacent a surface of said component and said transmitter.
16. The logging tool of claim 15 , further comprising a control loop adapted to receive said magnetic field signal from said reference receiver, said control loop adapted to execute a command to said magnetic field generating mechanism to adjust said magnetic field.
17. The logging tool of claim 14 , wherein said at least one transmitter generates said induction signal having at least one of a phase, a frequency, and an amplitude different than at least one of a phase, a frequency, and an amplitude of said magnetic field generated by said magnetic field generating mechanism.
18. A logging tool, comprising:
a component configured to be conveyed into a wellbore, said component including:
at least one transmitter, adapted to generate an induction signal and transmit said induction signal into a formation adjacent said wellbore;
at least one receiver being spaced apart from said transmitter, said receiver adapted to receive a formation signal representative of said formation;
a magnetic field generating mechanism adapted to generate a magnetic field, said magnetic field adapted to influence said induction signal; and,
wherein said at least one transmitter generates said induction signal having at least one of a phase, a frequency, and an amplitude different than at least one of a phase, a frequency, and an amplitude of said magnetic field generated by said magnetic field generating mechanism.
19. The logging tool of claim 18 , further comprising a magnetically conductive, electrically insulating material disposed adjacent a surface of said component and said transmitter.
20. The logging tool of claim 18 , further comprising a reference receiver adapted to measure a magnetic field signal representative of said magnetic field.
21. The logging tool of claim 20 , further comprising a control loop adapted to receive said magnetic field signal from said reference receiver, said control loop adapted to execute a command to said magnetic field generating mechanism to adjust said magnetic field.
22. The logging tool of claim 18 , wherein said at least one transmitter generates said induction signal having at least one of a phase, a frequency, and an amplitude different than at least one of a phase, a frequency, and an amplitude of said magnetic field generated by said magnetic field generating mechanism.