Sonic Enhanced Oil Recovery System and Method

Abstract

To increase oil recovery from an oil reservoir, an acoustic transmitter is disposed in a source well and an acoustic receiver is disposed in a producing well. A portion of the oil reservoir is disposed between the source well and the producing well. An acoustic signal is transmitted from the acoustic transmitter at frequencies of 30 Hz and greater. The transmitted acoustic signal is received by the acoustic receiver and a resonant frequency of the portion of the oil reservoir is determined based on attenuation of the transmitted signal. The acoustic signal is transmitted from the acoustic transmitter at the determined resonant frequency to reduce a boundary layer effect between oil in the oil reservoir and a surface of a substrate in the oil reservoir and between the oil and a brine interface in the oil reservoir.

What is claimed is: 
     
         1 . A method of increasing oil recovery from an oil reservoir, the method comprising:
 disposing an acoustic transmitter in a source well;   disposing an acoustic receiver in a producing well, wherein a portion of the oil reservoir is disposed between the source well and the producing well;   transmitting an acoustic signal from the acoustic transmitter at frequencies of 30 Hz and greater;   receiving the transmitted acoustic signal;   determining a resonant frequency of the portion of the oil reservoir based on attenuation of the transmitted signal; and   transmitting the acoustic signal from the acoustic transmitter at the determined resonant frequency to reduce a boundary layer effect between oil in the oil reservoir and a surface of a substrate in the oil reservoir and between the oil and a brine interface in the oil reservoir.   
     
     
         2 . The method according to  claim 1 , further comprising:
 conducting cross well bore tomography between the source well and the producing well to determine the resonant frequency.   
     
     
         3 . The method according to  claim 1 , further comprising:
 determining effective coverage and sweep efficiency of the acoustic signal by modulating the acoustic signal from about 100 Hz above the determined resonant frequency to about 100 Hz below the determined resonant frequency and monitoring an acoustic wavelet generated by the acoustic signal.   
     
     
         4 . The method according to  claim 1 , wherein the acoustic signal is transmitted at a frequency band of about 80 Hz to about 120 Hz wide. 
     
     
         5 . The method according to  claim 1 , further comprising:
 injecting water into the source well.   
     
     
         6 . The method according to  claim 5 , wherein the injected water includes a cationic surfactant. 
     
     
         7 . The method according to  claim 5 , wherein the injected water includes an anionic surfactant. 
     
     
         8 . The method according to  claim 5 , wherein the injected water includes a nonionic surfactant. 
     
     
         9 . The method according to  claim 1 , further comprising:
 re-measuring the resonant frequency of the oil reservoir and modifying the acoustic signal in response to changes in the resonant frequency of the oil reservoir due to saturation and reservoir pressure.   
     
     
         10 . An apparatus for increasing oil recovery from an oil reservoir, the apparatus comprising:
 an acoustic transmitter disposed in a source well, the acoustic transmitter being configured to transmit an acoustic signal at frequencies of 30 Hz and greater;   an acoustic receiver disposed in a producing well, wherein a portion of the oil reservoir is disposed between the source well and the producing well, the acoustic receiver being configured to receive the transmitted acoustic signal; and   means for determining a resonant frequency of the portion of the oil reservoir based on attenuation of the transmitted signal, wherein the acoustic transmitter being configured to transmit the acoustic signal at the determined resonant frequency to reduce a boundary layer effect between oil in the oil reservoir and a surface of a substrate in the oil reservoir and between the oil and a brine interface in the oil reservoir.   
     
     
         11 . The apparatus according to  claim 10 , further comprising:
 means for conducting cross well bore tomography between the source well and the producing well to determine the resonant frequency.   
     
     
         12 . The apparatus according to  claim 10 , further comprising:
 means for determining effective coverage and sweep efficiency of the acoustic signal by modulating the acoustic signal from about 100 Hz above the determined resonant frequency to about 100 Hz below the determined resonant frequency and monitoring an acoustic wavelet generated by the acoustic signal.   
     
     
         13 . The apparatus according to  claim 10 , wherein the acoustic transmitter is configured to transmit the acoustic signal at a frequency band of about 80 Hz to about 120 Hz wide. 
     
     
         14 . The apparatus according to  claim 10 , further comprising:
 means for injecting water into the source well.   
     
     
         15 . The apparatus according to  claim 14 , wherein the injected water includes a cationic surfactant. 
     
     
         16 . The apparatus according to  claim 14 , wherein the injected water includes an anionic surfactant. 
     
     
         17 . The apparatus according to  claim 14 , wherein the injected water includes a nonionic surfactant. 
     
     
         18 . The apparatus according to  claim 10 , further comprising:
 means for re-measuring the resonant frequency of the oil reservoir and modifying the acoustic signal in response to changes in the resonant frequency of the oil reservoir due to saturation and reservoir pressure; and   means for measuring saturation changes in the oil reservoir due to changes in the resonant frequency.