Methods and apparatus for acoustic assessment from the interior of fluid conduits

Abstract

The invention provides a method and apparatus for assessing a condition of a fluid conduit from its interior. The method comprises providing a measurement apparatus comprising at least one wideband acoustic transducer within the fluid conduit and transmitting a wideband acoustic signal from the measurement apparatus to excite a broadside resonance in at least a portion of the fluid conduit. A wideband acoustic signal is received in the measurement apparatus due to a broadside resonant response of the fluid conduit to obtain a wideband acoustic data set; and the data set is analysed to assess the condition of the fluid conduit.

1 . A method of assessing a condition of a fluid conduit from its interior, the method comprising:
 providing a measurement apparatus comprising at least one wideband acoustic transducer within the fluid conduit;   transmitting a wideband acoustic signal from the measurement apparatus to excite a broadside resonance in at least a portion of the fluid conduit;   receiving a wideband acoustic signal in the measurement apparatus due to a broadside resonant response of the fluid conduit to obtain a wideband acoustic data set; and   analysing the wideband acoustic data set to assess the condition of the fluid conduit.   
     
     
         2 . The method according to  claim 1 , wherein at least one of the transmitted or received wideband acoustic signals is transmitted or received with an axial beamwidth corresponding to a maximum angle of deviation of the longitudinal axis of the measurement apparatus with the longitudinal axis of the fluid conduit. 
     
     
         3 . The method according to  claim 1 , comprising detecting the presence of, measuring the extent of, and/or identifying the composition of deposits, debris and foreign bodies within fluid conduits. 
     
     
         4 . The method according to  claim 1 , wherein the wideband acoustic signal comprises at least one frequency in the range of approximately 150 kHz to approximately 10 MHz, and comprises a distribution of frequencies between 150 kHz and 10 MHz. 
     
     
         5 . The method according to  claim 1 , wherein the wideband acoustic signal comprises a lower frequency of approximately 150 kHz, and an upper frequency of approximately 1 MHz, and comprises a distribution of frequencies between the upper and lower frequencies. 
     
     
         6 . The method according to  claim 1 , comprising transmitting a wideband acoustic signal from the measurement apparatus, through a fluid which couples the measurement apparatus to at least a portion of the fluid conduit. 
     
     
         7 . The method according to  claim 1 , comprising maintaining a distance between the at least one transducer and the fluid conduit to avoid near-field interference effects. 
     
     
         8 . The method according to  claim 1 , comprising translating the measurement apparatus within the fluid conduit. 
     
     
         9 . The method according to  claim 1 , comprising transmitting a plurality of wideband acoustic pulses separated in time. 
     
     
         10 . The method according to  claim 1 , comprising transmitting a plurality of wideband acoustic pulses at a fixed transmission rate. 
     
     
         11 . The method according to  claim 1 , comprising triggering the transmission and/or sampling of subsequent wideband acoustic pulses according to a distance translated by the measurement apparatus in the fluid conduit. 
     
     
         12 . The method according to  claim 1 , comprising transmitting a wideband acoustic pulse with a duration of at least 10 times the acoustic wave period. 
     
     
         13 . The method according to  claim 1 , comprising transmitting a wideband acoustic pulse with a duration of less than 100 μS. 
     
     
         14 . The method according to  claim 1 , comprising transmitting a wideband acoustic signal comprising a frequency chirp. 
     
     
         15 . The method according to  claim 1 , comprising transmitting a wideband acoustic signal comprising a plurality of frequency chirps. 
     
     
         16 . The method according to  claim 1 , comprising transmitting a wideband acoustic signal comprising a plurality of stacked frequency chirps. 
     
     
         17 . The method according to  claim 1 , wherein the transmitted wideband acoustic signal comprises a complex-stacked chirped signal. 
     
     
         18 . The method according to  claim 1 , wherein the wideband acoustic signal comprises a first chirp having a first frequency range, and a second chirp having a second frequency range. 
     
     
         19 . The method according to  claim 18 , wherein the first and second chirps overlap in time. 
     
     
         20 . The method according to  claim 18 , wherein the first and second chirps overlap in time for greater than 50% of the duration of the first chirp. 
     
     
         21 . The method according to  claim 1 , comprising transmitting and/or receiving over a segmented annular wideband receiver array. 
     
     
         22 . The method according to  claim 1 , comprising analysing the wideband acoustic data set, by comparing the data set with a database of wideband acoustic data signatures. 
     
     
         23 . The method according to  claim 1 , comprising comparing the frequency content of the wideband acoustic data set with the frequency content of previously acquired acoustic data. 
     
     
         24 . The method according to  claim 1 , comprising interrogating a database of wideband acoustic data, wherein the acoustic data is data collected from one or more tests performed on a sample fluid conduit of known condition. 
     
     
         25 . The method according to  claim 1 , comprising analysing the wideband acoustic data set to assess one or more acoustic properties or attributes of a physical condition of the fluid conduit. 
     
     
         26 . The method according to  claim 1 , comprising modelling a fluid conduit response, and
 selecting one or more characteristics of a transmitted or received wideband acoustic signal based on the modelled fluid conduit response.   
     
     
         27 . The method according to  claim 1 , comprising:
 designing a wideband acoustic signal having one or more acoustic characteristics and simulating a wideband acoustic signal response based on a fluid conduit model to obtain a first simulated wideband acoustic data set.   
     
     
         28 . The method according to  claim 27 , comprising perturbing at least one acoustic characteristic of the wideband acoustic signal, and
 simulating a second wideband acoustic signal response based on a fluid conduit model to obtain a second simulated wideband acoustic data set.   
     
     
         29 . The method according to  claim 28 , comprising analysing the second simulated wideband acoustic data set. 
     
     
         30 . The method according to  claim 29 , comprising optimising the wideband acoustic signal by repeating the steps of perturbing at least one acoustic characteristic of the wideband acoustic signal;
 simulating a wideband acoustic signal response based on the wideband acoustic signal with the perturbed characteristic; and   analysing a resulting simulated wideband acoustic data set.   
     
     
         31 . The method according to  claim 1 , comprising the step of designing a wideband acoustic signal having one or more acoustic characteristics and
 measuring a wideband acoustic signal response from a sample fluid conduit to obtain a first training wideband acoustic data set.   
     
     
         32 . The method according to  claim 31 , comprising analysing the training wideband acoustic data set. 
     
     
         33 . The method according to  claim 31 , comprising perturbing at least one acoustic characteristic of the wideband acoustic signal, and measuring a second wideband acoustic signal response from the sample fluid conduit model to obtain a second training wideband acoustic data set. 
     
     
         34 . The method according to  claim 33 , comprising analysing the second training wideband acoustic data set. 
     
     
         35 . The method according to  claim 34 , comprising optimising the wideband acoustic signal by repeating the steps of perturbing at least one acoustic characteristic of the wideband acoustic signal;
 measuring a wideband acoustic signal response based on the wideband acoustic signal with the perturbed characteristic; and   analysing a resulting training wideband acoustic data set.   
     
     
         36 . The method according to  claim 1 , comprising using empirical measurements to design a wideband acoustic signal. 
     
     
         37 . The method according to  claim 1 , comprising perturbing an acoustic characteristic of the wideband acoustic signal to excite a broadside or bulk resonance in a simulated wideband acoustic data set or measured training wideband acoustic dataset. 
     
     
         38 . The method according to  claim 1 , comprising generating a library or database of wideband acoustic data sets and/or signal responses corresponding to range of fluid conduit characteristics and/or conditions. 
     
     
         39 . A measurement apparatus for assessing a condition of a fluid conduit from its interior, the measurement apparatus comprising:
 a body and at least one wideband acoustic transducer disposed on the body;   wherein the body is configured to be disposed within a fluid conduit to be assessed;   and wherein the apparatus is operable to:   transmit a wideband acoustic signal from the at least one wideband acoustic transducer into a fluid volume in the fluid conduit to excite a broadside resonance in at least a portion of the fluid conduit; and   receive a wideband acoustic signal due to a broadside resonant response of the fluid conduit at the at least one wideband acoustic transducer to obtain a wideband acoustic data set.   
     
     
         40 . The apparatus according to  claim 39 , wherein the transducers comprise backward or rearward facing transducers, which are arranged to insonify the fluid conduit and/or receive a signal from a region of the fluid conduit behind the apparatus in the direction of travel. 
     
     
         41 . The apparatus according to  claim 39 , wherein the transducers comprise forward facing transducers, which are arranged to insonify the fluid conduit and/or receive a signal from a region of the fluid conduit ahead of the apparatus in the direction of travel. 
     
     
         42 . The apparatus according to any of  claim 39 , wherein the transducers comprise rear mounted transducers, which are arranged to transmit a wideband acoustic signal generally in a tangential or radially perpendicular direction. 
     
     
         43 . The apparatus according to any of  claim 39 , wherein the transducers comprise mid-mounted transducers, which are arranged to transmit a wideband acoustic signal generally in between the forward and rearward discs, seals or cups of the apparatus. 
     
     
         44 . The apparatus according to any of  claim 39 , wherein the apparatus comprises a plurality of pairs of transmitting/receiving wideband acoustic transducers. 
     
     
         45 . The apparatus according to any of  claim 39 , wherein the wideband acoustic transducer has a Q-factor of less than 5.0. 
     
     
         46 . The apparatus according to any of  claim 39 , wherein the efficiency of the wideband acoustic transducer is greater than 50%. 
     
     
         47 . The apparatus according to any of  claim 39 , wherein the apparatus comprises one or more segmented arrays of transducers. 
     
     
         48 . The apparatus according to any of  claim 39 , wherein the apparatus comprises a pipeline pig.