Detection of seismic signals using fiber optic distributed sensors

摘要

A fiber optic distributed vibration system for detecting seismic signals in an earth formation is provided. The system includes a fiber optic cable deployed in a borehole that extends into the earth formation and which is configured to react along its length to a seismic wave incident on the fiber optic cable from outside the borehole. An optical source launches an optical signal into the fiber optic cable while the seismic wave is incident thereon. A receiver detects coherent Rayleigh noise (CRN) produced in response to the optical signal. A processing circuit processes the detected CRN signal to determine characteristics of the earth formation.

主权项

1. A seismic event detection system, comprising:
a first fiber optic cable disposed in a borehole extending from an earth surface into a formation, the first fiber optic cable configured to react along its length to incident seismic signals originating inside the borehole and propagating through the formation and the borehole; an optical source to launch optical pulses into the first fiber optic cable while the seismic signals are incident on the first fiber optic cable; and a data acquisition system coupled to the first fiber optic cable to detect coherent Rayleigh noise (CRN) generated in response to the optical pulses to determine characteristics of the formation based on the detected CRN.