Tracking objects in conduits
First Claim
1. A method of tracking movement of an object in a conduit comprising:
- taking data corresponding to signal returns from interrogation of a length of an optic fibre positioned along the path of said conduit to provide distributed acoustic sensing; and
processing the returns from each of a plurality of discrete longitudinal sensing portions to detect an acoustic signature associated with movement of said object in said conduit and determine the origin of said acoustic signature;
wherein the processing of the returns involves determining the presence of a pressure wave propagating through the conduit caused by travel of the object in the conduit, by determining the presence of a first acoustic disturbance travelling in a first direction past a plurality of successive longitudinal sensing portions.
2 Assignments
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Accused Products
Abstract
Methods and apparatus for tracking objects in conduits, especially for tracking the movement of a pig in a pipeline, are disclosed. Distributed acoustic sensing is used to obtain signal returns from a plurality of discrete longitudinal sensing portions of a fibre optic cable which is laid along the length of the conduit. The method involves detecting an acoustic signature corresponding to the object moving in the conduit. The acoustic signature may comprise a series of pressure pulses caused by the object traversing joints etc. in the conduit. Preferably the method involves detecting pressure waves caused by the object as it moves through the conduit. Detecting the characteristic pressure wave signal provides discrimination of the object from other acoustic disturbances. In pipeline applications a pig can be tracked in real time, if the pig stops moving an alert can be generated and the location of the pig will be known.
38 Citations
18 Claims
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1. A method of tracking movement of an object in a conduit comprising:
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taking data corresponding to signal returns from interrogation of a length of an optic fibre positioned along the path of said conduit to provide distributed acoustic sensing; and processing the returns from each of a plurality of discrete longitudinal sensing portions to detect an acoustic signature associated with movement of said object in said conduit and determine the origin of said acoustic signature; wherein the processing of the returns involves determining the presence of a pressure wave propagating through the conduit caused by travel of the object in the conduit, by determining the presence of a first acoustic disturbance travelling in a first direction past a plurality of successive longitudinal sensing portions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of tracking movement of an object in a conduit comprising:
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taking data corresponding to signal returns from interrogation of an optic fibre positioned along the path of said conduit to provide distributed acoustic sensing; and processing the returns from each of a plurality of discrete longitudinal sensing portions to detect an acoustic signature associated with movement of said object in said conduit and determine the origin of said acoustic signature, wherein the step of processing the returns comprises the steps of, for each of a plurality of test positions along the conduit; forming a first subset of data corresponding to a plurality of frames of data from discrete sensing portions corresponding to portions of the conduit on one side of the test position ; forming a second subset of data corresponding to a plurality of frames of data from discrete sensing portions corresponding to portions of the conduit on the opposite side of the test position; and processing the first and second subsets to determine the presence of an acoustic disturbance in the first and second subsets propagating away from the test position. - View Dependent Claims (11, 12, 13, 14)
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15. Apparatus for tracking a pig in a pipeline comprising:
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an optic fibre interrogator adapted to interrogate an optic fibre and provide distributed acoustic sensing; and a processor adapted to receive sensed data from said interrogator and determine the presence of an acoustic signature associated with movement of said pig in said pipeline and to determine the location of said pig wherein said processor is configured to determine the presence of a pressure wave propagating through the conduit by determining the presence of a first acoustic disturbance travelling in a first direction past a plurality of successive longitudinal sensing portions. - View Dependent Claims (16, 17, 18)
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Specification