Nuclear magnetic resonance system with feedback induction coils
AssigneeSchlumberger Technology Corporation
InventorsYi-Qiao Song, Michael Wilt, Pabitra Sen
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Abstract
A nuclear magnetic resonance (NMR) system that uses a feedback induction coil to detect NMR signals generated within a substance is described herein. In one embodiment, the NMR system uses the Earth's magnetic field in conjunction with a transmitter coil that applies NMR sequences to a formation. The NMR sequences generate a weak NMR signal within the formation due to the weakness of the Earth's magnetic field. This weak NMR signal is detected using the feedback induction coil.
Claims20
A nuclear magnetic resonance (NMR) system, the system comprising:
- an NMR transmitter that applies an NMR pulse sequence having a series of radio-frequency pulses to a substance;
- and
- an NMR receiver having a plurality of feedback induction coils configured to detect NMR signals generated within the substance in response to the NMR pulse sequence, wherein each of said plurality of feedback induction coils comprises a primary coil, a feedback coil, and feedback electronics (i) coupled to the primary coil and the feedback coil and (ii) configured to detect the NMR signals generated within the substance by applying a current to the feedback coil such that the current cancels a magnetic field through the primary coil produced by the NMR signals.
A method for analyzing a substance using nuclear magnetic resonance (NMR), the method comprising:
- applying an NMR pulse sequence to the substance wherein the NMR pulse sequence is comprised of a series of radio-frequency pulses;
- and
- detecting NMR signals generated by the NMR pulse sequence using an NMR receiver having a plurality of feedback induction coils, each of the plurality of feedback induction coils comprising a primary coil and a feedback coil, wherein the detecting comprises applying respective currents to each of the feedback coils such that the respective currents cancel magnetic fields through the respective primary coils produced by NMR signals generated by the substance in response to the NMR pulse sequence.
A wellbore tool comprising:
- an NMR transmitter that applies an NMR pulse sequence having a series of radio-frequency pulses to a substance;
- and
- an NMR receiver having a plurality of feedback induction coils configured to detect NMR signals generated within the substance in response to the NMR pulse sequence, wherein each of said plurality of feedback induction coils comprises a primary coil, a feedback coil, and feedback electronics (i) coupled to the primary coil and the feedback coil and (ii) configured to detect the NMR signals generated within the substance by applying a current to the feedback coil such that the current cancels a magnetic field through the primary coil produced by the NMR signals.
Dependencies are inferred from the claim text.