Systems and methods for distributed interferometric acoustic monitoring
AssigneeSchlumberger Technology Corporation
InventorsArthur H. Hartog, J. Ernest Brown, John Mervyn Cook, Jonathan Elphick, Paul S. Hammond, Ashley Bernard Johnson
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Abstract
Acoustic monitoring of a conduit, a wellbore or a reservoir associated with hydrocarbon production or transportation and/or carbon dioxide sequestration is carried out using a fibre optic cable extending along or appurtenant to it as a distributed interferometer. Coherent Raleigh noise generated by the transmission of the coherent beam of radiation through the fiber optic is detected and processed to identify an acoustic occurrence.
Claims21
A method for monitoring a wellbore, a reservoir or a pipeline for occurrences which generate acoustic perturbations therein, comprising:
- transmitting a monitoring signal through a fiber optic cable, wherein the monitoring signal comprises a pulse of a coherent beam of electromagnetic radiation and a coherence time of the coherent beam of electromagnetic radiation is equal to or longer than a duration of the pulse, and wherein the fiber optic cable is disposed along or is disposed appurtenant to at least a section of the wellbore, the reservoir or the pipeline;
- detecting coherent Rayleigh noise generated by the transmission of the coherent beam of radiation through the fiber optic;
- and
- processing the detected coherent Rayleigh noise to identify a said acoustic occurrence in the section of the wellbore, the reservoir or the pipeline.
A system for monitoring a wellbore or a pipeline for events which generate acoustic perturbations therein, comprising:
- a fiber optic coupled with or disposed adjacent to a section of the wellbore or the pipeline;
- a source of coherent electromagnetic radiation coupled with the fiber optic and configured to inject a pulse of the coherent electromagnetic radiation into the fiber optic, wherein the source of coherent electromagnetic radiation is configured to produce a coherent electromagnetic beam with a coherence time that is equal to or greater than a duration of the pulse;
- a detector coupled with the fiber optic and configured to detect coherent Rayleigh noise generated in the fiber optic by the pulse of coherent electromagnetic radiation;
- and
- a processor coupled with the detector and configured to process an output from the detector corresponding to detected coherent Rayleigh noise to identify said acoustic events in the wellbore or pipeline.
A method for monitoring a wellbore, a reservoir or a pipeline for occurrences which generate acoustic perturbations therein, comprising:
- providing a fiber optic cable is disposed along or disposed appurtenant to at least a section of the wellbore, the reservoir or the pipeline;
- transmitting a pair of mutually coherent beams of electromagnetic radiation through the fiber-optic cable, wherein a first frequency of a first beam of the pair of mutually coherent beams is not equal to a second frequency of a second beam of the pair of mutually coherent beams;
- detecting coherent Rayleigh noise generated by the transmission of the pair of mutually coherent beams through the fiber optic cable;
- and
- processing the detected coherent Rayleigh noise to identify a said acoustic occurrence in the section of the wellbore, the reservoir or the pipeline.
A method for monitoring a wellbore or pipeline for occurrences which generate acoustic perturbations therein comprising:
- providing a fiber optic cable disposed along or disposed appurtenant to at least a section of the wellbore or pipeline;
- repeatedly transmitting a coherent beam of electromagnetic radiation along the fiber optic cable in a series of pulses, wherein a coherence time of the coherent beam of electromagnetic radiation is equal to or longer than a duration of each of the pulses;
- detecting coherent Rayleigh noise backscattered from scattering sites distributed along the fiber optic cable;
- and
- processing the detected coherent Rayleigh noise to identify changes in the relative location of said scattering sites and thereby identify a said acoustic occurrence in the section of the wellbore or the pipeline.
Dependencies are inferred from the claim text.