Downhole acoustic wave sensing with optical fiber
A technique facilitates geophysical exploration by employing a tool wrapped with an optical fiber. Additionally, an orientation sensor is coupled to the tool and is operable to provide data regarding orientation of the tool. A processing system, which may include an optical interrogation system, cooperates with the optical fiber and with the orientation sensor to obtain acoustic data. For example, the processing system collects tool orientation data and also strain data obtained from a location along the wrapped optical fiber. The strain data results from excitation of an acoustic signal from a suitable acoustic source.
1. A system for geophysical exploration, comprising:
a well tool wrapped with an optical fiber;
an orientation sensor coupled to the well tool to generate data on orientation of the well tool; and
an optical interrogation system coupled to the optical fiber, the optical interrogation system to scan at least one location along the optical fiber wrapped around the well tool to obtain strain data of the at least one location, the scanning of the at least one location along the optical fiber to be based on the data from the orientation sensor.
2. The system as recited in claim 1 , wherein the well tool is wrapped helically with a single optical fiber.
3. The system as recited in claim 1 , wherein the well tool is wrapped with a plurality of optical fibers.
4. The system as recited in claim 1 , wherein the optical interrogation system is mounted to the well tool.
5. The system as recited in claim 1 , wherein the optical interrogation system is positioned at a surface location.
6. The system as recited in claim 1 , wherein the optical interrogation system is positioned at a downhole location.
7. The system as recited in claim 1 , wherein the orientation sensor is mounted to the tool.
8. The system as recited in claim 1 , wherein the tool is a first tool and the orientation sensor is carried by a second tool separately located from the first tool.
9. A method, comprising:
accessing orientation data indicative of an orientation of a tool positioned in a subterranean location, the tool wrapped with an optical fiber;
determining a location along a portion of the optical fiber to scan the optical fiber based on the orientation data;
scanning the location to obtain strain data from the location, the strain data to be generated in response to an acoustic signal excited into a formation surrounding the subterranean location; and
processing the strain data and the orientation data to obtain oriented acoustic data.
10. The method as recited in claim 9 , wherein the subterranean location is in a wellbore.
11. The method as recited in claim 9 , further including initiating an orientation sensor coupled with the tool to generate the orientation data.
12. The method as recited in claim 9 , wherein generating the strain data includes scanning the location.
13. The method as recited in claim 9 , further comprising outputting data regarding characteristics of the formation.