Abstract: A method for detecting fluid ingress in a wellbore. An acoustic sensor is placed along a wellbore. The acoustic sensor is adapted to sense individual acoustic signals from a plurality of corresponding locations along the wellbore. The individual acoustic signals are analyzed to determine if there exists a common acoustic component in acoustic signals generated from proximate locations in the wellbore. If so, the acoustic signal having the common acoustic component which appears earliest in phase, by virtue of such acoustic signal's corresponding location in the wellbore, determines the location in the wellbore of likely fluid ingress. The acoustic sensor may be a fiber optic cable extending substantially the length of the wellbore, or alternatively a plurality of microphones situated at various locations along the wellbore.

Abstract: The present disclosure is directed at a method and system for determining relative depth of an acoustic event within a wellbore. The method includes obtaining two acoustic signals at two different and known depths in the wellbore, in which each of the acoustic signals includes the acoustic event; dividing each of the acoustic signals into windows; determining cross-correlations of pairs of the windows, in which each of the pairs includes one window from one of the acoustic signals and another window from the other of the acoustic signals that at least partially overlap each other in time; and determining the relative depth of the acoustic event relative to the two known depths from the cross-correlations. The acoustic event may represent, for example, fluid flowing from formation into the wellbore (or vice-versa) or fluid flowing across any casing or tubing located within the wellbore.

Abstract: A method for determining relative location of an acoustic event along a channel such as a wellbore includes obtaining two acoustic signals at are obtained at two different and known depths in the wellbore, dividing the acoustic signals into windows, and determining the relative loudnesses of pairs of the windows. The power of the acoustic signals may be used as a proxy for the loudness of the acoustic event, and this determination can be made in the time or frequency domains. The relative depth of the acoustic event can then be determined relative to the two known depths from the relative loudnesses. The acoustic event may be, for example, casing vent flow, gas migration, a leak along a pipeline, or sounds observed in an observation well from a nearby well in which fracking is being performed.

Abstract: The present disclosure is directed at methods, apparatuses, and techniques for detecting an acoustic event along a channel. Different wavelengths of an optical signal are multiplexed along a fiber optic strand extending along the channel. The strand has groups of transducers located along its length, and all of the transducers in any one of the groups reflect a tuned wavelength when not under strain. The wavelength that the transducers reflect changes in response to strain. Optical signal processing equipment receives reflected optical signals from the groups of transducers, and determines, for each of the groups of transducers, differences between wavelengths of the optical signals reflected by the transducers of that group and the tuned wavelength for that group. The differences correspond to the loudness of the event measured by that group of transducers, which can then be graphically represented to a person for analysis.

Abstract: The method for obtaining a fluid migration profile for a wellbore, including the steps of obtaining a static profile for a logged region of the wellbore, obtaining a dynamic profile for the logged region of the wellbore, digitally filtering the dynamic profile to remove frequency elements represented in the static profile, to provide a fluid migration profile, and storing the fluid migration profile on a computer-readable memory.

Abstract: A method for detecting fluid ingress in a wellbore, and if detected, obtaining an indication of where along said wellbore said fluid ingress is occurring. Acoustic sensing means, adapted to sense individual acoustic signals from a plurality of corresponding locations along said wellbore, are analyzed to determine if there exists a common acoustic component in acoustic signals generated from proximate locations in said wellbore. If so, the acoustic signal having the common acoustic component which appears earliest in phase, by virtue of such acoustic signal's corresponding location in the wellbore, determines the location in the wellbore of likely fluid ingress. In a preferred embodiment the acoustic sensing means comprises a fibre optic cable extending substantially the length of the wellbore, or alternatively a plurality of microphones situated at various locations along the wellbore comprising substantially the length of the wellbore.

Abstract: A method for obtaining a fluid migration profile for a wellbore, comprising the steps of obtaining a static profile for a logged region of the wellbore, obtaining a dynamic profile for the logged region of the wellbore, digitally filtering the dynamic profile to remove frequency elements represented in the static profile, to provide a fluid migration profile, and storing the fluid migration profile on a computer-readable memory.