A system, in some embodiments, comprises: a fiber optic cable; first and second sensors to control a length of said cable; and first and second receiver coils that control the first and second sensors, respectively, wherein the first and second sensors maintain said length when the first and second receiver coils receive only a direct signal from a transmitter, wherein the first and second sensors modify said length when the first and second receiver coils receive a scattered signal from a formation.

A wellbore system includes a logging unit having a retrievable logging cable coupled to a downhole tool within a wellbore and a depth correlation unit in the downhole tool that provides current depth data for the wellbore through the retrievable logging cable for recording of a current depth by the logging unit. The wellbore system also includes a distributed acoustic sensing unit that includes a seismic processing unit and a seismic profiling unit connected to a separate optical cable of the retrievable logging cable having distributed acoustic sensing channels, wherein an assignment of the distributed acoustic sensing channels along the separate optical cable is determined by an offset distance between the current depth of a formation reference region within the wellbore and a previous reference depth of the formation reference region within the wellbore. A distributed acoustic sensing method is also included.

A wellbore system includes a logging unit having a retrievable logging cable coupled to a downhole tool within a wellbore and a depth correlation unit in the downhole tool that provides current depth data for the wellbore through the retrievable logging cable for recording of a current depth by the logging unit. The wellbore system also includes a distributed acoustic sensing unit that includes a seismic processing unit and a seismic profiling unit connected to a separate optical cable of the retrievable logging cable having distributed acoustic sensing channels, wherein an assignment of the distributed acoustic sensing channels along the separate optical cable is determined by an offset distance between the current depth of a formation reference region within the wellbore and a previous reference depth of the formation reference region within the wellbore. A distributed acoustic sensing method is also included.

A system includes a drillstring with an electromagnetic (EM) transmitter in a first borehole. The system also includes at least one fiber optic sensor deployed in a second borehole. The system also includes a processor configured to demodulate a data stream emitted by the EM transmitter based on EM field measurements collected by the at least one fiber optic sensor.

A system includes a drillstring with an electromagnetic (EM) transmitter in a first borehole. The system also includes at least one fiber optic sensor deployed in a second borehole. The system also includes a processor configured to demodulate a data stream emitted by the EM transmitter based on EM field measurements collected by the at least one fiber optic sensor.

A building rests on the soil. Vertical elongation detectors are placed at the base of pillars above bearing points of the building on the soil, in particular at the corners of the building. Variations in the measurements of vertical elongation of the pillars indicate a variation in the ability of the soil to support the building. In particular, the partial or total unloading of a pillar gives rise to suspicion of a compaction of the soil under the pillar.

The present method is usable for very early detection of risk situations that might eventually compromise the safety of a structure.

A building rests on the soil. Vertical elongation detectors are placed at the base of pillars above bearing points of the building on the soil, in particular at the corners of the building. Variations in the measurements of vertical elongation of the pillars indicate a variation in the ability of the soil to support the building. In particular, the partial or total unloading of a pillar gives rise to suspicion of a compaction of the soil under the pillar.

The present method is usable for very early detection of risk situations that might eventually compromise the safety of a structure.

Method for source localization for cable cut prevention using distributed fiber optic sensing (DFOS)/distributed acoustic sensing (DAS) is described that is robust/immune to underground propagation speed uncertainty. The method estimates the location of a vibration source while considering any uncertainty of vibration propagation speed and formulates the localization as an optimization problem, and both location of the sources and the propagation speed are treated as unknown. This advantageously enables our method to adapt to variances of the velocity and produce a better generalized performance with respect to environmental changes experienced in the field. Our method operates using a DFOS system and AI techniques as an integrated solution for vibration source localization along an entire optical sensor fiber cable route and process real-time DFOS data and extract features that are related to a location of a source of vibrations that may threaten optical fiber facilities.

Method for source localization for cable cut prevention using distributed fiber optic sensing (DFOS)/distributed acoustic sensing (DAS) is described that is robust/immune to underground propagation speed uncertainty. The method estimates the location of a vibration source while considering any uncertainty of vibration propagation speed and formulates the localization as an optimization problem, and both location of the sources and the propagation speed are treated as unknown. This advantageously enables our method to adapt to variances of the velocity and produce a better generalized performance with respect to environmental changes experienced in the field. Our method operates using a DFOS system and AI techniques as an integrated solution for vibration source localization along an entire optical sensor fiber cable route and process real-time DFOS data and extract features that are related to a location of a source of vibrations that may threaten optical fiber facilities.

Provided are a spatial sensing device, and the like, that are suitable for spatial sensing. This spatial sensing device (3) comprises a sensing data acquisition means (11) for acquiring sensing data through optical fiber sensing using a plurality of optical fiber cables (1) laid in different directions and an object detection means (12) for using the sensing data to detect the position of an object in a space of interest.