METHOD AND APPARATUS FOR SEISMICALLY SURVEYING AN EARTH FORMATION IN RELATION TO A BOREHOLE

摘要

The present invention provides a new and unique method, sensor and apparatus for performing a seismic survey of an earth formation (60) in relation to a borehole (40). The method includes arranging at least one strain seismic sensor (112, 112a, 112b, 112c, 114, 114a, 114b, 114c, 116, 117) in borehole structure. The invention includes providing a combined optical strain seismi c sensor having an optical fiber arranged therein into the borehole (40); providing an optical signal through the optical fiber; providing a seismic disturbance in relation to the borehole; receiving a combined optical seismi c sensor and borehole structure signal containing information about the seismi c disturbance in relation to the borehole (40); and providing seismic survey information about the earth formation (60) in relation to the borehole (40) depending on the information contained in the optical seismic sensor and borehole structure signal. The at least one combined optical seismic sensor and borehole structure may include a flexible carrier film having the optica l fiber arranged therein or thereon, a coiled tubing, a production tube (108) or a well casing (104) having the optical fiber wrapped therein or thereabout, or a combination thereof. The optical fiber may have a Fiber Bragg Grating sens or (113, 115) therein for sensing the seismic disturbance. The flexible carrier film may be deposed in or on a packet/bladder (110) arranged between the production tube (108) or the well casing (110) also in the borehole. In operation, the method and apparatus measures the change in the length of the optical fiber as a function of the seismic disturbance.