초록 ▼

A system for vertical seismic profiling of an earth borehole includes an optical fiber having a plurality of Bragg grating sensors formed therein, each one of the Bragg grating sensors being tuned to reflect a respective bandwidth of light, each bandwidth having a different respective central wavele

A system for vertical seismic profiling of an earth borehole includes an optical fiber having a plurality of Bragg grating sensors formed therein, each one of the Bragg grating sensors being tuned to reflect a respective bandwidth of light, each bandwidth having a different respective central wavelength. Each of the Bragg grating sensors are responsive to an input light signal, a static strain, a dynamic strain and a temperature strain for each providing a respective light signal indicative of static and dynamic forces and temperature at a respective sensor location. The physical spacing and wavelength spacing of the Bragg grating sensors are known such that each of the sensing light signals are easily correlated to a specific depth. The Bragg grating sensors are tuned such that when a sensor is subjected to a maximum static strain, maximum dynamic strain, and a maximum temperature strain, the maximum wavelength shift of a respective sensing light signal does not cause the frequency of the sensing light signal to enter the bandwidth of another one of the plurality of Bragg grating sensors.

대표청구항 ▼

[ I claim:] [1.] A vertical seismic profiling system for performing a vertical seismic profile of an earth formation (12, 14, 16) in relation to a borehole (10), comprising:seismic disturbance force means (42, 45) being arranged at a selected distance from the borehole (10) for providing a seismic d

[ I claim:] [1.] A vertical seismic profiling system for performing a vertical seismic profile of an earth formation (12, 14, 16) in relation to a borehole (10), comprising:seismic disturbance force means (42, 45) being arranged at a selected distance from the borehole (10) for providing a seismic disturbance force (52, 54) to be sensed to perform the vertical seismic profile of the earth formation (12, 14, 16) in relation to the borehole (10);vertical seismic profiling optical signal processing equipment (35, 135), for providing an optical signal, and-being responsive to a fiber Bragg Grating optical seismic sensor signal, for further providing vertical seismic profile information about the earth formation (12, 14, 16) in relation to the borehole (10) depending on the information contained in the fiber Bragg Grating optical seismic sensor signal; andan optical fiber having fiber Bragg Grating optical seismic sensors (20, 22, 23, 24, 25, 28) spaced at a desired interval therein, arranged in the borehole (10), and distributed along a selected length of the borehole (10), responsive to the optical signal, and further responsive to the seismic disturbance force (52, 54) in relation to the borehole (10), for transforming the seismic disturbance force (52, 54) into the fiber Bragg Grating optical seismic sensor signal using a direct mechanical-to-optical energy conversion and without using an electrical energy conversion, and for providing the fiber Bragg Grating optical seismic sensor signal containing information about the seismic disturbance force (52, 54) in relation to the borehole (10) to the optical signal processing equipment (35, 135).