Surface Wave Sensor for Downhole Applications

Abstract

The present disclosure relates to an apparatus and method for estimating a parameter of interest in a downhole fluid using a fluid analysis module. The fluid analysis module may include: a first transducer configured to generate a surface wave in a fluid. The first transducer may include one or more of: a piezoelectric crystal, a electromagnetic transducer, and a surface acoustic wave crystal. The apparatus may use the first transducer or a second transducer to generate a signal indicative of the dissipation of the surface wave in the fluid. The apparatus may include a compensator configured to reduce mechanical pressure on the transducer. The method may include estimating a parameter of interest of the fluid using a signal indicative of the dissipation of the surface wave.

1 . An apparatus for estimating a parameter of interest of a fluid downhole, comprising:
 a first transducer responsive to a dissipation of at least one surface wave in the fluid and configured to generate an electrical signal indicative of the parameter of interest.   
     
     
         2 . The apparatus of  claim 1 , the first transducer being disposed downhole and in communication with the fluid. 
     
     
         3 . The apparatus of  claim 1 , wherein the first transducer is configured to generate the at least one surface wave in the fluid. 
     
     
         4 . The apparatus of  claim 1 , further comprising:
 a second transducer configured to generate the at least one surface wave in the fluid.   
     
     
         5 . The apparatus of  claim 4 , wherein the generation of the electrical signal and the generation of the at least one surface wave take place simultaneously. 
     
     
         6 . The apparatus of  claim 1 , wherein the at least one surface wave includes at least one of: i) a Lamb wave, ii) a Love wave, iii) a Rayleigh wave, iv) a flexural plate wave, and v) a skimming bulk wave. 
     
     
         7 . The apparatus of  claim 1 , wherein the parameter of interest includes at least one of: i) a density of the fluid, ii) a viscosity of the fluid, and iii) a density-viscosity product of the fluid. 
     
     
         8 . The apparatus of  claim 1 , wherein the first transducer includes:
 an element configured to generate an alternating magnetic field when energized; and   a plate disposed between the element and the fluid and configured to generate the at least one surface wave when exposed to the alternating magnetic field.   
     
     
         9 . The apparatus of  claim 8 , wherein the plate is, at least in part, metallic. 
     
     
         10 . The apparatus of  claim 8 , wherein the element includes at least one of: a permanent magnet and an electromagnet coil. 
     
     
         11 . The apparatus of  claim 1 , wherein the first transducer includes:
 a piezoelectric crystal; and   a wedge configured to couple lamb waves to a body in communication with the fluid.   
     
     
         12 . The apparatus of  claim 1 , wherein the first transducer includes a surface acoustic wave crystal. 
     
     
         13 . The apparatus of  claim 12 , further comprising:
 a second transducer in communication with the fluid.   
     
     
         14 . The apparatus of  claim 12 , further comprising:
 a compensator configured to reduce a physical stress from the fluid on the first transducer.   
     
     
         15 . The apparatus of  claim 14 , wherein the compensator includes at least one of: i) a pressurized fluid, ii) a piston, and iii) a mechanical spring. 
     
     
         16 . A method of estimating a parameter of interest in a fluid downhole, comprising:
 estimating the parameter of interest using an electrical signal indicative of a dissipation of at least one surface wave in the fluid, the electrical signal being generated using a first transducer.   
     
     
         17 . The method of  claim 16 , the first transducer being disposed downhole and in communication with the fluid. 
     
     
         18 . The method of  claim 16 , further comprising:
 generating the at least one surface wave in the fluid.   
     
     
         19 . The method of  claim 18 , wherein the at least one surface wave is generated using one of: the first transducer and a second transducer. 
     
     
         20 . The method of  claim 16 , wherein the first transducer includes:
 an element configured to generate an alternating magnetic field when energized; and   a plate disposed between the element and the fluid and configured to generate the at least one surface wave when exposed to the alternating magnetic field.   
     
     
         21 . The method of  claim 16 , wherein the estimation of the parameter of interest includes using at least one of: a sound speed in the fluid and a compressibility of the fluid. 
     
     
         22 . The method of  claim 16 , wherein the first transducer includes a surface acoustic wave crystal; and
 further comprising reducing a physical stress from the fluid on the surface acoustic wave crystal.