Distributed sensor network

Abstract

A system may include a sensor to detect a characteristic of a fluid and output an electrical signal proportional to the characteristic, an acoustic signal generator to output an acoustic signal proportional to the electrical signal, and a signal detection apparatus to generate a signal proportional to the acoustic signal and transmit the signal to a remote location.

What is claimed is: 
     
         1 . A system, comprising:
 a sensor to detect a characteristic of a fluid and output an electrical signal proportional to the characteristic;   an acoustic signal generator to output an acoustic signal proportional to the electrical signal; and   a signal detection apparatus to generate a signal proportional to the acoustic signal and transmit the signal to a remote location.   
     
     
         2 . The system of  claim 1 , wherein the sensor comprises one of a chemical sensor, an optical sensor, a pH sensor, a density sensor, a viscosity sensor, a thermal sensor, and a pressure sensor. 
     
     
         3 . The system of  claim 1 , wherein the acoustic signal generator includes one of a piezoelectric device, a magnetostriction device, an electro-optic device, and an electrostriction device. 
     
     
         4 . The system of  claim 1 , wherein the signal detection apparatus generates an optical signal proportional to the acoustic signal using interferometric phase modulation techniques and transmits the optical signal to the remote location. 
     
     
         5 . The system of  claim 4 , wherein the signal detection apparatus is positioned in an annulus defined between a wellbore and a casing secured within the wellbore. 
     
     
         6 . The system of  claim 4 , wherein the signal detection apparatus is conveyed into a wellbore on slickline or wireline. 
     
     
         7 . The system of  claim 1 , wherein the signal detection apparatus is a non-fiber optic based apparatus that detects the acoustic signal. 
     
     
         8 . The system of  claim 1 , further comprising a frequency generator that receives the electrical signal and generates a control signal proportional to the electrical signal. 
     
     
         9 . The system of  claim 8 , wherein the acoustic signal generator comprises an acoustic transducer to receive the control signal and generate the acoustic signal proportional to the control signal. 
     
     
         10 . The system of  claim 1 , wherein the acoustic signal generator and the signal detection apparatus contact each other. 
     
     
         11 . The system of  claim 1 , wherein the acoustic signal generator and the signal detection apparatus are separated from each other. 
     
     
         12 . The system of  claim 1 , further comprising a processing unit located at the remote location and configured to process the signal from the signal detection apparatus to determine a location of the fluid. 
     
     
         13 . A method, comprising:
 monitoring a fluid in a wellbore with a sensor;   generating an electrical signal proportional to a characteristic of the fluid with the sensor;   generating a control signal proportional to the electrical signal using a frequency generator;   generating an acoustic signal proportional to the control signal using an acoustic transducer;   detecting the acoustic signal and generating a signal based on the acoustic signal using a signal detection apparatus; and   transmitting the signal to a remote location.   
     
     
         14 . The method of  claim 13 , further comprising generating an optical signal proportional to the acoustic signal using the signal detection apparatus, the optical signal being generated by the signal detection apparatus using interferometric phase modulation techniques. 
     
     
         15 . The method of  claim 13 , further comprising generating the acoustic signal when the electrical signal meets or exceeds a predetermined threshold level, the threshold level corresponding to the characteristic of the fluid measured by the sensor. 
     
     
         16 . The method of  claim 13 , further comprising varying a frequency of the control signal proportional to the electrical signal. 
     
     
         17 . The method of  claim 13 , further comprising varying an amplitude of the control signal proportional to the electrical signal. 
     
     
         18 . The method of  claim 13 , further comprising varying a frequency of the acoustic signal proportional to the control signal. 
     
     
         19 . The method of  claim 13 , further comprising varying an amplitude of the acoustic signal proportional to the control signal. 
     
     
         20 . The method of  claim 13 , further comprising:
 generating the acoustic signal having a predetermined base frequency; and   shifting the base frequency proportional to the characteristic of the fluid measured by the sensor.