The disclosure relates to a system, downhole device and method for monitoring a wellbore, in particular in a lateral section, during stimulation, with an equipment enabling retrieval in many conditions. The method includes monitoring the wellbore with a distributed fiber optic sensor to determine one or more characteristics of the stimulation operation using detected backscattered optical signals on the distributed fiber optic sensor. The cable is retrieved by exerting a traction force. The disclosure also relates to a downhole device for receiving a cable and retainers to maintain the cable and having a weakpoint configured to break when subjected to a force along the longitudinal axis greater than a predetermined threshold. The system comprises the cable having the distributed fiber optic sensor, the downhole device and a surface monitoring system for determining the characteristic of the stimulation operation using detected backscattered optical signals on the distributed fiber optic sensor.

A position detection device includes a transmitter that transmits an optical pulse into an optical transmission line laid along the movement path of a moving body; a detector that detects back-scattered light in the optical transmission line; a data processor that calculates the intensity of the back-scattered light and the generation position of the back-scattered light; a storage in which the processing results of the data processor are saved; a search range derivation circuit that derives a search range for the position of the moving body; a maximum value extraction circuit that extracts the generation position at which the variation of intensity within the search range is at a maximum, and causes the extracted generation position to be saved in the storage; and an output circuit that outputs the extraction result.

The subject matter of this specification can be embodied in, among other things, a method for remotely sensing vibration includes transmitting a collection of optical pulses through an optical fiber at a predetermined frequency, detecting a collection of backscattered Rayleigh traces from the optical fiber based on a vibration of the optical fiber at a vibration frequency at a location along the optical fiber, determining a normalized differential trace based on the collection of Rayleigh traces, determining, based on the normalized differential trace, the location in the optical fiber of the vibration, and determining, based on the raw Rayleigh traces, the vibration frequency.

A method and arrangement of fibre optic distributed sensing for detection of an event at an event location within a blind region including using at least one optical fibre arranged at least partly along an object to be monitored and at least one light pattern interrogator coupled with the optical fibre; injecting light patterns at subsequent times; detecting backscatter light from the light patterns; and analyzing the backscatter light to determine the event location so that a detection range of the fiber optic distribution range of the fiber-optic distributed sensing system is extended into a blind region conventionally not accessible for detecting acoustic disturbances or acoustic events.

A method providing an increased signal-to-noise (SNR) characteristic for coherent distributed acoustic sensing (DAS) systems, the method employing fiber coils (microphones) made from sections of an optical sensing fiber that collect acoustic signals and uses multiple differential pairs of the microphones for signal averaging to improve the SNR. An analysis determines complex products (beating products) for a pair of locations that are part of a fiber microphone along the length of the optical sensing fiber that are used to determine a phase change in-between locations along the length of the optical sensing fiber.

Systems and methods for operating a distributed fiber optic sensing (DFOS)/distributed acoustic sensing (DAS) system include a length of optical sensing fiber suspended aerially by a plurality of utility poles and in optical communication with a DFOS interrogator/analyzer. The method includes operating the DFOS/DAS system while manually exciting more than one of the poles to obtain frequency response(s) of the excited poles; contrastively training a convolutional neural network (CNN) with the frequency responses obtained; classifying the utility poles using the contrastively trained CNN; and generating a profile map of the excited poles indicative of the classified utility poles.

Disclosed herein are embodiments of apparatuses, systems and methods configured to monitor vibrations and other signals in a pipeline to detect activities associated with theft of a substance flowing through the pipeline. To this end, such activities are determined by correlating pipeline sensor signals to anomalistic reference signals characterizing activity(ies) known to be associated with theft of a substance flowing through a pipeline—e.g., formation of a hole within a tubular member of the pipeline, a liquid being pumped into the pipeline through a wall of a tubular member thereof, a metallic article (e.g., drill) coming into contact with a tubular member of the pipeline, and the like. Advantageously, fiber optic sensors are utilized for such monitoring of vibrations and other operating conditions in elongated tubular members making up the pipeline thereby enabling activities associated with theft of a substance from the pipeline to be effectively and inexpensively detected over extended lengths of pipelines.

A method for automatic diagnosis of a mechanical system of a group of mechanical systems sharing mechanical characteristics includes obtaining data relating to a vibration. The vibration-related data is acquired by a portable communications device configured to communicate with a remote processor. The processor automatically diagnoses the mechanical system by applying a relationship to the obtained vibration-related data. The relationship is based on sets of vibration-related data previously obtained from the mechanical systems. Each set of vibration-related data relates to vibrations of a mechanical system. The relationship is further based on sets of operation data previously obtained for mechanical systems of the group. Each set of operation data indicates a previous state of operation of a mechanical system. Each of the previous states of operation is associated with at least one of the previously obtained sets of vibration-related data.

A method is provided including the steps: —first excitation of the object via a multifrequency signal; —detecting a first response signal of the object at one or multiple measuring points at the object; —transforming the first response signal from a time range into a frequency-dependent range; —selecting one or multiple frequencies, based on the frequency-dependent range; —second excitation of the object based on the selected frequencies; —detecting a second response signal of the object at one or multiple measuring points of the object; —ascertaining a mechanical parameter based on the second response signal.

A method is provided including the steps: —first excitation of the object via a multifrequency signal; —detecting a first response signal of the object at one or multiple measuring points at the object; —transforming the first response signal from a time range into a frequency-dependent range; —selecting one or multiple frequencies, based on the frequency-dependent range; —second excitation of the object based on the selected frequencies; —detecting a second response signal of the object at one or multiple measuring points of the object; —ascertaining a mechanical parameter based on the second response signal.