System and Method for Sensing Seismic Acoustic Signals

Abstract

A method for forming a sensing system responsive to a wavefield of acoustic or seismic signals. One embodiment includes providing a foil layer having first and second opposing surfaces and piezoelectric properties. The foil layer, configured as a sheet, is positioned about a frame surface which provides the foil layer a stable shape while permitting the sheet configuration of the foil layer to be responsive to a wavefield of seismic or acoustic energy. Coupling between the foil layer and the frame is so limited as to render direct coupling of the foil layer with signals of the wavefield the predominant means for stimulating the sensor element with seismic energy.

The claimed invention is: 
     
         1 . A sensing system responsive to a wavefield of acoustic or seismic signals, comprising:
 a piezoelectric foil layer having first and second opposing surfaces and piezoelectric properties, the layer configured as a piezoelectric sheet; and   a frame having a surface along or about which the piezoelectric sheet is positioned in a manner which provides the foil layer a stable shape while permitting the piezoelectric sheet to be responsive to a wavefield of seismic or acoustic energy, wherein coupling between the piezoelectric sheet and the frame is so limited as to render direct coupling of the piezoelectric sheet with signals of the wavefield the predominant means for stimulating the sensor element with seismic energy.   
     
     
         2 . The sensing system of  claim 1  wherein the frame surface is of a tubular shape and the piezoelectric sheet is positioned along or about the frame. 
     
     
         3 . The sensing system of  claim 1  further including an intermediate layer positioned between the frame surface and the piezoelectric sheet to so limit mechanical coupling between the sheet and the frame as to render the direct coupling of the sheet with the wavefield the predominant means for stimulating the sensor element with seismic energy. 
     
     
         4 . The sensing system of  claim 1  wherein the intermediate layer is characterized by a lower Young's modulus than that of the frame which is relatively rigid while the layer is more easily deformable. 
     
     
         5 . The sensing system of  claim 1  wherein the intermediate layer comprises a closed-cell foam material. 
     
     
         6 . The sensing system of  claim 1  wherein the intermediate layer comprises a silicone foam material. 
     
     
         7 . The sensing system of  claim 1  wherein the intermediate layer is characterized by a higher level of compressibility than a portion of the frame along which the intermediate layer is positioned. 
     
     
         8 . The sensing system of  claim 1  wherein, with the sensing element positioned about the intermediate layer, post manufacture tensioning of the foil layer about the intermediate layer increases sensitivity of response of the foil layer to a signal in the wavefield while the intermediate layer so limits mechanical coupling between the foil layer and the frame as to render the direct coupling of the sheet with the wavefield the predominant means for stimulating the sensor element with seismic energy. 
     
     
         9 . A method of forming a sensing system responsive to a wavefield of acoustic or seismic signals, comprising:
 providing a foil layer having first and second opposing surfaces and piezoelectric properties, the layer configured as a sheet; and   positioning the foil layer along or about a frame having a surface which provides the foil layer a stable shape while permitting the sheet configuration of the foil layer to be responsive to a wavefield of seismic or acoustic energy, wherein coupling between the foil layer and the frame is so limited as to render direct coupling of the foil layer with signals of the wavefield the predominant means for stimulating the sensor element with seismic energy.   
     
     
         10 . The method of  claim 9  including forming the frame surface with a tubular shape and positioning the foil layer along or about the frame. 
     
     
         11 . The method of  claim 9  further including positioning an intermediate layer between the frame surface and the foil layer to so limit mechanical coupling between the sheet and the frame as to render the direct coupling of the sheet with the wavefield the predominant means for stimulating the sensor element with seismic energy. 
     
     
         12 . The method of  claim 9  wherein the intermediate layer is selected to have a lower Young's modulus than that of the frame. 
     
     
         13 . The method of  claim 9  where the step of positioning the foil layer includes tensioning of the foil layer about the intermediate layer to further increase sensitivity of response of the foil layer to a signal in the wavefield while the intermediate layer so limits mechanical coupling between the foil layer and the frame as to render the direct coupling of the sheet with the wavefield the predominant means for stimulating the sensor element with seismic energy.