System and method for locating an area of interest in a conduit

A system for locating an area of interest in a conduit, the system comprising:

• a conduit;
• one or more optical fiber sensors positioned alongside the conduit;
• an optical interrogator configured to:
• transmit one or more light pulses along the one or more optical fiber sensors;
• receive reflections of the one or more light pulses;
• and
• determine from the reflections one or more interference signals;
• and
• one or more processors communicative with the optical interrogator and with a computer- readable medium having stored thereon computer program code configured when executed by one or more processors to cause the one or more processors to perform a method comprising:
• processing the one or more interference signals to obtain multiple acoustic recordings as a function of position along the conduit;
• for each acoustic recording, determining its autocorrelation;
• and
• applying a relationship to the determined autocorrelations to estimate a location of the area of interest, wherein the relationship is between autocorrelations of acoustic signals measured in a modelled conduit and modelled areas of interest in the modelled conduit, wherein it is assumed that acoustic signals propagating along the modelled conduit reflect from at least one point in the modelled conduit,
• wherein determining the autocorrelations comprises determining Rw(τ, dr)=E [wm(t, dr)wm(t−τ, dr)], wherein R is the autocorrelation of the acoustic recording, τ is a time lag of the autocorrelation, dr is a position along the conduit at which the acoustic recording is obtained, E is an expected value operator, t is time, and w is the acoustic recording.