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 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.

Various aspects described herein relate to a machine learning based detecting of fracture hits in offset monitoring wells when designing hydraulic fracturing processes for a particular well. In one example, a computer-implemented method includes receiving a set of features for a first well proximate to a second well, the second well undergoing a hydraulic fracturing process for extraction of natural resources from underground formations; inputting the set of features into a trained neural network; and providing, as output of the trained neural network, a probability of a fracture hit at a location associated with the set of features in the first well during a given completion stage of the hydraulic fracturing process in the second well.

A data seismic sensing system and method for obtaining seismic refraction data and tomography data. The system may comprise a subsurface sensor array, wherein the subsurface sensor array is a fiber optic cable disposed near a wellbore, a seismic source, wherein the seismic source is a truck-mounted seismic vibrator comprising a base plate, and a surface sensor array, wherein the surface sensor array is coupled to the seismic source. The method may comprise disposing a surface sensor array on a surface, disposing a subsurface sensor array into a wellbore, activating a seismic source, wherein the seismic source is configured to create a seismic wave, recording a reflected seismic wave with the surface sensor array and the subsurface sensor array, and creating a seismic refraction data and a seismic tomography data from the reflected seismic wave.

Systems and methods include a number of optical pulses are transmitted by transmitting, by a distributed acoustic sensor (DAS), where the optical pulses are transmitted at an input port associated with a multimode fibers (MMF) used by the DAS, and where the fundamental mode of the MMF is excited. A number of backscattered Rayleigh signals are collected by the DAS. The Rayleigh signals are recorded as an output intensity profile. A position along the MMF that is subject to vibrations and corresponding vibration parameters are determined by analyzing the recorded output intensity profile.

An apparatus for detecting a location of an optical fiber having an acoustic sensor disposed subsurface to the earth includes an acoustic emitter configured to emit a first signal having a first frequency and a second signal having a second frequency that is higher than the first frequency, the first and second emitted acoustic signals being azimuthally rotated around the borehole and an optical interrogator configured to interrogate the optical fiber to receive an acoustic measurement that provides a corresponding first received signal and a corresponding second received signal. The apparatus also includes a processor configured to (i) frequency-multiply the first received signal to provide a third signal having a third frequency within a selected range of the second frequency, (ii) estimate a phase difference between the second received signal and the third signal, and (iii) correlate the phase difference to the location of the optical fiber.

A method of detecting an event by: obtaining a first sample data set; determining a frequency domain feature(s) of the first sample data set over a first time period; determining a first threshold for the a frequency domain feature(s) using the first sample data set: determining that the frequency domain feature(s) matches the first threshold; determining the presence of an event during the first time period based on determining that the frequency domain feature(s) matches the first threshold; obtaining a second sample data set; determining a frequency domain feature(s) of the second sample data set over a second time period; determining a second threshold for the frequency domain feature(s) using the second sample data set; determining that the frequency domain feature(s) matches the second threshold; and determining the presence of the event during the second time period based on determining that the frequency domain feature(s) matches the second threshold.

A piezoelectric hydrophone with perforations and an array comprising a plurality of hydrophones comprises a stack of layers that are bonded to one another, the layers comprising at least one piezoelectric layer and a plurality of layers referred to as rigid layers, at least two of which are electrode layers, the rigid layers exhibiting a stiffness perpendicularly to the direction of stacking, which stiffness is higher than the stiffness of the piezoelectric layer perpendicularly to the direction of stacking. At least one piezoelectric layer comprises a central zone comprising a set of perforations that pass through the piezoelectric layer solely along the direction of stacking, each perforation being closed tight by closure elements comprising portions of two of the rigid layers, the two rigid layers extending over the entirety of the surface of the central zone.

A distributed optical fiber sensing signal processing method for safety monitoring of underground pipe network, which belongs to infrastructure safety monitoring field, which is aimed to improve the intelligent ability of detection and identification of the existing distributed optical fiber sound/vibration sensing system under complex application conditions. The present invention utilizes the distributed optical fiber sound/vibration sensing system to pick up the sound or vibration signal of the whole line along the detection cable; and the customized short time feature and long time feature are respectively extracted from the relative quantity of the sound or the vibration signal at each spatial point in the whole monitoring range. The Bayesian identification and classification network at each spatial point is constructed and trained based on the prior knowledge of the collected signal features and their different background noises.

Various embodiments include apparatus and methods implemented to simulate geophone data from distributed acoustic sensing data, such as simulating vertical component geophone waveform data from distributed acoustic sensing data. Embodiments include measuring vertical component of strain at a plurality of vertical positions along an optical fiber disposed along a wellbore at a well site. The measured vertical component of strain can be processed to generate a vertical component of displacement. The vertical component of displacement can be generated to generate a vertical component of velocity from which a waveform simulating a waveform of geophone data can be output. Additional apparatus, systems, and methods are disclosed.

A fiber optic cable assembly includes an elongate housing, a signal fiber placed inside the housing and extending longitudinally, and a plurality of sensing fibers placed inside the housing and extending longitudinally. The plurality of sensing fibers is placed around the signal fiber. Each of the plurality of sensing fibers carries a respective laser signal of a distinct frequency. The signal fiber carries one or more evanescent coupling signals responsive to the laser signals in the plurality of sensing fibers.