A system for processing DAS VSP surveys in real-time is provided. The system includes a DAS data collection system coupled to at least one optical fiber at least partially positioned within a wellbore and configured to repeatedly activate a seismic source of energy. The system further includes an information processing system connected to the DAS data collection system. A seismic dataset is received from the DAS data collection system. The seismic dataset includes a plurality of seismic data records. Two or more of the plurality of seismic data records are combined into a stack. A quality metric indicative of a desired signal-to-noise ratio or incoherence of the stack is determined for each processed seismic dataset collected from a repeated source. Instructions are sent to the DAS data collection system to stop activating the seismic source, in response to determining that the quality metric has reached a predefined threshold.

A system includes a first instrumented bridge plug positionable in a downhole wellbore environment. The first instrumented bridge plug includes an acoustic source for transmitting an acoustic signal. The system also includes a second instrumented bridge plug positionable in the downhole wellbore environment. The second instrumented bridge plug includes an acoustic sensor for receiving a reflected acoustic signal originating from the acoustic signal. The reflected acoustic signal being usable to interpret wellbore formation characteristics of the downhole wellbore environment.

Monitoring and diagnosing completion during hydraulic fracturing operations provides insights into the fracture geometry, inter-well frac hits and connectivity. Conventional monitoring methods (microseismic, borehole gauges, tracers, etc.) can provide a range of information about the stimulated rock volume but may often be limited in detail or clouded by uncertainty. Utilization of DAS as a fracture monitoring tool is growing, however most of the applications have been limited to acoustic frequency bands of the DAS recorded signal. In this paper, we demonstrate some examples of using the low-frequency band of Distributed Acoustic Sensing (DAS) signal to constrain hydraulic fracture geometry. DAS data were acquired in both offset horizontal and vertical monitor wells. In horizontal wells, DAS data records formation strain perturbation due to fracture propagation. Events like fracture opening and closing, stress shadow creation and relaxation, ball seat and plug isolation can be clearly identified. In vertical wells, DAS response agrees well with co-located pressure and temperature gauges, and illuminates the vertical extent of hydraulic fractures. DAS data in the low-frequency band is a powerful attribute to monitor small strain and temperature perturbation in or near the monitor wells. With different fibered monitor well design, the far-field fracture length, height, width, and density can be accurately measured using cross-well DAS observations.

In some implementations, a system may receive a cable map for a deployed cable. The system may receive vibration data indicating a vibration associated with a first section of the cable. The system may determine a characteristic associated with the first section of the cable based on the vibration. The system may determine a location associated with the characteristic based on the cable map. The system may determine that the first section of the cable is associated with the location based on the location being associated with the characteristic. The system may associate the location and a length of a second section of the cable extending from an initial location to the location. The system may receive an input identifying the length of the second section of the cable and may output the location based on associating the location and the length of the second section of the cable.

An apparatus comprises a distributed acoustic sensing (DAS) optical fiber, a DAS interrogator coupled to the DAS optical fiber, and a connector. The connector couples the DAS interrogator, a first digitizer, and a second digitizer, wherein the first digitizer is to generate a first digitized DAS signal based on an analog DAS signal from the DAS interrogator, and the second digitizer is to generate a second digitized DAS signal based on the analog DAS signal. The apparatus also comprises one or more processors and a machine-readable medium having program code executable to cause the apparatus to simultaneously generate a first set of values that correlate with a first physical property based on the first digitized DAS signal and generating a second set of values that correlate with a second physical property based on the second digitized DAS signal.

An active fiber stretcher assembly can be used for data acquisition systems. A time-break signal can be detected that coincides with a seismic event emitted from a seismic controller. A predetermined waveform can be generated in response to detecting the time-break signal. The predetermined waveform may be encoded onto a fiber optic cable using a fiber stretcher. A data acquisition system connected to the fiber optic cable may detect the predetermined waveform on the fiber optic cable and initiate acquisition operations including: receiving, during the seismic event, light signals returning from a portion of the fiber optic cable in a subterranean environment; determining one or more characteristics of the subterranean environment from the light signals; and storing the one or more characteristics.

A long range optical fiber sensor such as a distributed acoustic sensor has a sensing fiber located remotely from the interrogator, with a length of transport fiber path connecting the two. Because no sensing is performed on the transport fiber then the pulse repetition rate from the interrogator can be high enough such that the pulse repetition rate and pulse power are optimised according to the sensing fiber length and hence sensing frequency response and sensitivity are also optimised according to the sensing fiber length.

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.

The present invention provides an intelligent geophysical data acquisition system and acquisition method for shale oil and gas optical fiber. A pipe string is arranged in a metal casing, and an external armored optical cable is fixed outside the metal casing; an, internal armored optical cable is fixed outside the pipe string; the external armored optical cable comprises a downhole acoustic sensing optical cable, two multi-mode optical fibers, a strain optical cable and a pressure sensor array, and further comprises horizontal ground acoustic sensing optical cables arranged in the shallow part of the ground according to an orthogonal grid, and artificial seismic source excitation points arranged on the ground according to the orthogonal grid.

A frequency response estimation method to compensate for channel differences in distributed acoustic sensing systems include two compensation algorithms, online and offline, and these two compensation algorithms are presented to generate standardized mel-frequency features, as an input to neural networks. By this scheme, the variance of mel-frequency feature space is decreased and normalized among different channels, which enables to use less training data and smaller architectures for classification and anomalous event detection tasks.