Abstract: 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.

Abstract: The disclosure is directed to a method of utilizing an acoustic sensing cable, such as a fiber optic distributed acoustic sensing (DAS) cable, in a borehole to detect microseismic events and to generate three dimensional fracture plane parameters utilizing the detected events. Alternatively, the method can use various categorizations of microseismic data subsets to generate one or more potential fracture planes. Also disclosed is an apparatus utilizing a single acoustic sensing cable capable of detecting microseismic events and subsequently calculating fracture geometry parameters. Additionally disclosed is a system utilizing a processor to analyze collected microseismic data to generate one or more sets of fracture geometry parameters.

Abstract: A fracture mapping system for use in hydraulic fracturing operations utilizing non-directionally sensitive fiber optic cable, based on distributed acoustic sensing, deployed in an observation well to detect microseismic events and to determine microseismic event locations in 3D space during the hydraulic fracturing operation. The system may include a weighted probability density function to improve the resolution of the microseismic event on the fiber optic cable.

Abstract: The way in which a fiber optic cable is wrapped around a casing string in a wellbore can be modeled using information from downhole sensor devices. For example, a system can include a fiber optic cable located along a length of a wellbore. The system can also include sensor devices located near the fiber optic cable at various depths to transmit acoustic signals indicating depths and orientations of segments of the fiber optic cable. The system can build a model describing how the fiber optic cable is positioned around the casing string based on the acoustic signals transmitted from the sensor devices. The system can also determine a target position for a perforating gun to perform a perforation operation through the casing string that avoids damaging the fiber optic cable. The system can output the target position for the perforating gun to an electronic device to facilitate the perforation operation.

Abstract: A method for determining microseismic events. The method may include measuring a seismic travel time of a microseismic event with a fiber optic line disposed in a first wellbore, forming a probability density function for the microseismic event based at least in part on the seismic travel time measurement, modifying the probability density function by applying one or more constraints to form a modified probability density function, identifying one or more most probable source locations from the modified probability density function, and forming a microseismic event cloud from the one or more most probable source locations.

Abstract: 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.

Abstract: A distributed acoustic sensing (DAS) system for determining an acoustic event may include an interferometer and an acoustic event detection processing device. The interferometer may measure DAS data from sensed signals from a sensing fiber deployed in a wellbore. The acoustic event detection processing device may determine an acoustic event in the wellbore from an out-of-band signal using the DAS data by performing operations. The operations can include determining a first acoustic event and a second acoustic event from the DAS data. The operations can include determining a first set of aliased frequencies from the first acoustic event and a second set of aliased frequencies form the second acoustic event. The operations can include determining, using an intersection of the first set of aliased frequencies and the second set of aliased frequencies, a frequency or amplitude of out-of-band signals that are usable to determine the at least one acoustic event.

Abstract: A fiber optic cable positioned along a casing string in a wellbore may be calibrated by exciting a tube wave in the wellbore and detecting, by the fiber optic cable, a reflected tube wave. The reflected tube wave may correspond to a reflection of the tube wave off an obstacle within the wellbore. The obstacle may have a known location such that a reference point along the fiber optic cable may be associated with the known location of the obstacle for calibrating the fiber optic cable. Downhole applications utilizing data collected by the calibrated fiber optic cable, including location data, may weight the data collected based at least in part on an uncertainty value associated with a particular calibrated location along the length of the fiber optic cable.

Abstract: 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.

Abstract: A method for improving a signal-to-noise ratio of distributed acoustic sensing data may comprise transmitting an acoustic wave from an acoustic source into a subterranean formation, recording a first acoustic noise at a first time interval with a distributed acoustic sensing system, recording at least one acoustic wave and a second acoustic noise at a second time interval with the distributed acoustic sensing system, calculating a noise spectrum from the first time interval, calculating the noise spectrum in the second time interval, and removing the noise spectrum from acoustic data measured during the second time interval to identify acoustic data of the subterranean formation. A system may comprise an acoustic source, a distributed acoustic sensing system disposed within a well, and an information handling system.

Abstract: The way in which a fiber optic cable is wrapped around a casing string in a wellbore can be modeled using information from downhole sensor devices. For example, a system can include a fiber optic cable located along a length of a wellbore. The system can also include sensor devices located near the fiber optic cable at various depths to transmit acoustic signals indicating depths and orientations of segments of the fiber optic cable. The system can build a model describing how the fiber optic cable is positioned around the casing string based on the acoustic signals transmitted from the sensor devices. The system can also determine a target position for a perforating gun to perform a perforation operation through the casing string that avoids damaging the fiber optic cable. The system can output the target position for the perforating gun to an electronic device to facilitate the perforation operation.

Abstract: A well system includes a fiber optic cable positionable downhole along a length of a wellbore. The well system also includes a reflectometer communicatively coupleable to the fiber optic cable. The reflectometer injects optical signals into the fiber optic cable and receives reflected optical signals from the fiber optic cable. Further, the reflectometer identifies strain detected in the reflected optical signals generated from seismic waves of a microseismic event. Additionally, the reflectometer identifies a focal mechanism of the microseismic event and velocities of the seismic waves. The reflectometer also determines a position of the microseismic event using the strain detected in the reflected optical signals, the focal mechanism of the microseismic event, and the velocities of the seismic waves.

Abstract: A well system includes a fiber optic cable positionable downhole along a length of a wellbore and a reflectometer communicatively coupleable to the fiber optic cable. The reflectometer detects and locates a microseismic event using strain detected in reflected optical signals received from the fiber optic cable. Further, the reflectometer computes a set of spectra for waveforms of the microseismic event. Additionally, the reflectometer aggregates each spectrum from the set of spectra that meet an acceptance threshold to generate an aggregate spectrum. Furthermore, the reflectometer applies a fault source model to the aggregate spectrum to determine a magnitude of the microseismic event.

Abstract: A sequence of stimuli produced by an electric frac pump can be generated by a treatment optimization system. Well environment responses to the sequence of stimuli may be measured by sensors and respective sensor data may be received. The sensor data may be used to select a representative system model which can then be used to control the electric frac pump. The representative system model may be used to achieve well stage objectives such as particular cluster efficiencies, complexity factors, or proximity indices.

Abstract: A fracture mapping system for use in hydraulic fracturing operations utilizing non-directionally sensitive fiber optic cable, based on distributed acoustic sensing, deployed in an observation well to detect microseismic events and to determine microseismic event locations in 3D space during the hydraulic fracturing operation. The system may include a weighted probability density function to improve the resolution of the microseismic event on the fiber optic cable.

Abstract: A perforation tool for perforating casing in a borehole. The perforation tool may include a body, charges spaced along an axial length of the body, and a first compartment positioned along the axial length of the body. The compartment may be filled with a diverter material and operable to selectively release the diverter material.

Abstract: A fiber optic cable positioned along a casing string in a wellbore may be calibrated by exciting a tube wave in the wellbore and detecting, by the fiber optic cable, a reflected tube wave. The reflected tube wave may correspond to a reflection of the tube wave off an obstacle within the wellbore. The obstacle may have a known location such that a reference point along the fiber optic cable may be associated with the known location of the obstacle for calibrating the fiber optic cable. Downhole applications utilizing data collected by the calibrated fiber optic cable, including location data, may weight the data collected based at least in part on an uncertainty value associated with a particular calibrated location along the length of the fiber optic cable.

Abstract: A system for downhole wellbore vector strain sensing including a strain sensor positionable between an outer surface of a wellbore casing and a subterranean formation for sensing a plurality of strain tensor elements, the plurality of strain tensor elements comprising multiple components of a strain tensor; a computing device positionable at a surface of a wellbore and communicatively coupled to the strain sensor; and a communication link between the strain sensor and the computing device for communicatively coupling the strain sensor to the computing device to relay strain data, the strain data comprising the plurality of strain tensor elements.

Abstract: A system for downhole wellbore vector strain sensing including a strain sensor positionable between an outer surface of a wellbore casing and a subterranean formation for sensing a plurality of strain tensor elements, the plurality of strain tensor elements comprising multiple components of a strain tensor; a computing device positionable at a surface of a wellbore and communicatively coupled to the strain sensor; and a communication link between the strain sensor and the computing device for communicatively coupling the strain sensor to the computing device to relay strain data, the strain data comprising the plurality of strain tensor elements.

Abstract: A well system includes a fiber optic cable positionable downhole along a length of a wellbore. The well system also includes a reflectometer communicatively coupleable to the fiber optic cable. The reflectometer injects optical signals into the fiber optic cable and receives reflected optical signals from the fiber optic cable. Further, the reflectometer identifies strain detected in the reflected optical signals generated from seismic waves of a microseismic event. Additionally, the reflectometer identifies a focal mechanism of the microseismic event and velocities of the seismic waves. The reflectometer also determines a position of the microseismic event using the strain detected in the reflected optical signals, the focal mechanism of the microseismic event, and the velocities of the seismic waves.