A vibration sensor includes: a supporting structure provided with a cavity; a proof mass accommodated in the cavity; a plurality of elastic bodies, each connecting the proof mass to the supporting structure along a corresponding connection axis; an optical fibre portion arranged in contact with each elastic body and wound around the corresponding connection axis. The proof mass has an elongated shape according to a main reference direction (Z), and the plurality of elastic bodies comprises two or more first elastic bodies which are spaced along the main reference direction (Z) and are arranged so that they are all caused to be simultaneously compressed along their corresponding connection axes following a displacement of the proof mass in a first reference direction (X) perpendicular to the main reference direction (Z), and simultaneously stretched along their corresponding connection axes following a displacement of the proof mass in a direction opposite the first reference direction.

A downhole seismic array is disclosed. The array comprises a load-bearing cable for carrying a series of seismic sensor units arranged along its length. Each seismic sensor unit is attached to the load-bearing cable via a vibration-absorbing material and has a magnet to attach the seismic sensor unit to the well casing.

A downhole seismic array is disclosed. The array comprises a load-bearing cable for carrying a series of seismic sensor units arranged along its length. Each seismic sensor unit is attached to the load-bearing cable via a vibration-absorbing material and has a magnet to attach the seismic sensor unit to the well casing.

This disclosure presents systems to enable downhole bi-directional communications using a long length of fiber optic cable located within or partially within the internal diameter of a set of lower pipe segments and communicatively coupled to one or more upper pipe segments that utilize pipe cable attached to the outside diameter of each of the upper pipe segments. The long length of fiber optic cable and the one or more pipe cables from the upper pipe segments allow for communication coupling between downhole tools and surface equipment and surface computing systems. In some aspects, the pipe cable attached to the upper pipe segments can be protected from wear using clamps, collars, cages, and other protectors. In some aspects, an optical signal generator and modulator, e.g., a light source, can be located downhole proximate the downhole tools, uphole proximate one of the upper pipe segments, or proximate the surface equipment.

This disclosure presents systems to enable downhole bi-directional communications using a long length of fiber optic cable located within or partially within the internal diameter of a set of lower pipe segments and communicatively coupled to one or more upper pipe segments that utilize pipe cable attached to the outside diameter of each of the upper pipe segments. The long length of fiber optic cable and the one or more pipe cables from the upper pipe segments allow for communication coupling between downhole tools and surface equipment and surface computing systems. In some aspects, the pipe cable attached to the upper pipe segments can be protected from wear using clamps, collars, cages, and other protectors. In some aspects, an optical signal generator and modulator, e.g., a light source, can be located downhole proximate the downhole tools, uphole proximate one of the upper pipe segments, or proximate the surface equipment.

Disclosed is a system and method for improving the performance of downhole Distributed Acoustic Sensing (DAS) systems by simultaneous use of co-propagating and counter-propagating Distributed Raman Amplification (DRA). It uses a surface DRA system with a surface DAS system to combine their laser sources where the distal end of the downhole sensing fiber use uses a Wavelength Division Multiplexer (WDM) to optically split the DRA and DAS signals onto two optical fibers. The DAS fiber/signal is terminated with a low reflectance termination to minimize a potential back reflection whereas the DRA fiber is terminated with a high reflectance termination causing all the light to reflect back up the sensing fiber. This arrangement allows for simultaneous co and counter-propagating DRA of the DAS signals, both the transmitted pulse and the back scattered light, thus creating the maximum amount of gain possible.

Disclosed is a system and method for improving the performance of downhole Distributed Acoustic Sensing (DAS) systems by simultaneous use of co-propagating and counter-propagating Distributed Raman Amplification (DRA). It uses a surface DRA system with a surface DAS system to combine their laser sources where the distal end of the downhole sensing fiber use uses a Wavelength Division Multiplexer (WDM) to optically split the DRA and DAS signals onto two optical fibers. The DAS fiber/signal is terminated with a low reflectance termination to minimize a potential back reflection whereas the DRA fiber is terminated with a high reflectance termination causing all the light to reflect back up the sensing fiber. This arrangement allows for simultaneous co and counter-propagating DRA of the DAS signals, both the transmitted pulse and the back scattered light, thus creating the maximum amount of gain possible.

An acoustic while drilling receiving transducer array adopts a full-digital structure and a non-oil-filled rubber encapsulation arrangement mode, and the full-digital device of the acoustic while drilling receiving transducer array includes first modules, configured to carry out acoustic-to-electric conversion on weakly received acoustic signals of strata; second modules, configured to carry out amplification, filtering, gain control and digital-to-analog conversion on the weakly received acoustic signals; and a third module, configured to control interfaces of the device and convert external input and output signals.

An acoustic while drilling receiving transducer array adopts a full-digital structure and a non-oil-filled rubber encapsulation arrangement mode, and the full-digital device of the acoustic while drilling receiving transducer array includes first modules, configured to carry out acoustic-to-electric conversion on weakly received acoustic signals of strata; second modules, configured to carry out amplification, filtering, gain control and digital-to-analog conversion on the weakly received acoustic signals; and a third module, configured to control interfaces of the device and convert external input and output signals.

Apparatus, methods, and systems for determining body wave slowness values for a target formation zone. A method includes selecting a target axial resolution based on the size of a receiver array, obtaining a plurality of waveform data sets corresponding to a target formation zone and each acquired at a different shot position, reconstructing the plurality of waveform data sets to generate a plurality of subarray data sets corresponding to the target formation zone, determining a slowness value for each subarray data set and determining a slowness versus offset value for each subarray data set. The method may also include generating a borehole model having at least one alteration formation zone and a virgin formation zone and generating a slowness versus offset model based at least in part on the borehole model. The method may also include determining a radial depth of the alteration formation zone.