Devices and methods for generating radially propogating ultrasonic waves and their use

Abstract

An acoustic waveguide includes a body defining a resonance chamber. The body has a tubular section defining a cylindrical central portion of the chamber along a longitudinal axis. First and second end sections extend from opposite ends of the tubular section. Each end section includes an end wall tapering away from the tubular section and towards the longitudinal axis, thus defining a conoidal end portion of the chamber.

What is claimed is: 
     
         1 . An acoustic waveguide comprising:
 a body defining a resonance chamber, the body comprising
 a tubular section defining a cylindrical central portion of the chamber along a longitudinal axis; and 
 first and second end sections extending from opposite ends of the tubular section, each one of the end sections comprising an end wall tapering away from the tubular section and towards the longitudinal axis thus defining a conoidal end portion of the chamber. 
   
     
     
         2 . The waveguide of  claim 1 , wherein the end wall and the longitudinal axis are at an angle of about 45 to about 70 degrees. 
     
     
         3 . The waveguide of  claim 2 , wherein the angle is about 50 to about 55 degrees. 
     
     
         4 . The waveguide of any one of  claims 1  to  3 , wherein the resonance chamber contains a rarefied gas. 
     
     
         5 . The waveguide of any one of  claims 1  to  4 , wherein the resonance chamber is sized and shaped to exhibit a resonant frequency in the range of 10 to 50 kHz. 
     
     
         6 . The waveguide of any one of  claims 1  to  5 , configured and sized to optimize radial dispersion of sonic energy through the waveguide. 
     
     
         7 . A sonic device comprising the waveguide of any one of  claims 1  to  6 , and an acoustic transducer coupled to at least one of the end sections of the waveguide. 
     
     
         8 . The sonic device of  claim 7 , wherein the transducer is a magnetostrictive or piezoelectric transducer. 
     
     
         9 . The sonic device of  claim 8 , further comprising a housing, wherein the transducer is mounted in the housing and is immersed in a cooling fluid. 
     
     
         10 . The sonic device of  claim 9 , further comprising a pressure compensator in the housing. 
     
     
         11 . The sonic device of any one of  claims 7  to  10 , wherein the transducer has a working frequency, and the waveguide is configured such that a resonant frequency of the sonic device matches the working frequency. 
     
     
         12 . The sonic device of  claim 11 , wherein the resonant frequency of the sonic device is a resonant frequency of longitudinal oscillation. 
     
     
         13 . The sonic device of  claim 11  or  claim 12 , wherein the resonant frequency of the sonic device differs from the working frequency of the transducer by less than 10% of the working frequency. 
     
     
         14 . The sonic device of any one of  claims 7  to  13 , wherein the transducer comprises a magnetostrictive transducer. 
     
     
         15 . The sonic device of  claim 14 , wherein the magnetostrictive transducer has first and second elongated openings, aligned and spaced apart in a longitudinal direction, and wherein a coil passes through each one of the first and second openings. 
     
     
         16 . The sonic device of any one of  claims 7  to  15 , wherein each one of the end sections of the waveguide is coupled to an acoustic transducer. 
     
     
         17 . A method comprising generating a radially propagating acoustic wave with the sonic device of any one of  claims 7  to  16  positioned in a well penetrating a hydrocarbon reservoir. 
     
     
         18 . The method of  claim 17 , further comprising injecting a chemical agent into the well. 
     
     
         19 . The method of  claim 17  or  claim 18 , wherein the sonic device is connected to an injector for injecting the chemical agent, and the sonic device and injector are moved to and fro in the well in synchronization. 
     
     
         20 . The method of  claim 19 , wherein the sonic device and injector are connected to a cable hose, the cable hose comprising a fluid conduit for supplying the chemical agent to the injector and a conducting wire for transmitting power to the sonic device. 
     
     
         21 . The method of  claim 20 , wherein the cable hose further comprises a signal wire for transmitting a signal therethrough. 
     
     
         22 . The method of any one of  claims 17  to  21 , wherein the well is a horizontal well. 
     
     
         23 . A downhole tool assembly comprising:
 the sonic device of any one of  claims 7  to  16 ;   an injector for injecting a chemical agent into a perforated wellbore portion of a well penetrating a hydrocarbon reservoir; and   a movable cable hose connected to the injector and the sonic device for moving the injector and the sonic device to and fro in synchronization, the cable hose comprising a conducting wire for supplying power to the sonic device and having a conduit for supplying the chemical agent to the injector.   
     
     
         24 . The tool assembly of  claim 23 , wherein the cable hose further comprises a signal wire for transmitting a signal therethrough.