Abstract: An example method includes at least partially positioning within a wellbore an optical fiber of a distributed acoustic sensing (DAS) data collection system. Seismic data from the DAS data collection system may be received. The seismic data may include seismic traces associated with a plurality of depths in the wellbore. A quality factor may be determined for each seismic trace. One or more seismic traces may be removed from the seismic data based, at least in part, on the determined quality factors.

Abstract: A system includes a light source, optical fiber coupled to the light source, one or more interferometers coupled to the optical fiber, wherein each interferometer of the one or more interferometers comprising a gauge length, a photodetector assembly coupled to the optical fiber, and an information handling system. The photodetector assembly is configured to detect backscattered light from the optical fiber and generate signals based on the detected backscattered light. The an information handling system is configured to receive the signals from the photodetector assembly, apply a de-convolution operation to the signals based on the gauge lengths of the one or more interferometers, and store the de-convolved signals.

Abstract: An example system for noise removal in distributed acoustic sensing data may include a distributed acoustic sensing (DAS) data collection system and an information handling system coupled thereto. The information handling system may receive seismic information from the DAS data collection system. The seismic information may include seismic traces associated with a plurality of depths in the wellbore. The information handling system may also generate a noise pilot trace by stacking one or more of the seismic traces, and subtract the noise pilot trace from the seismic information received from the DAS data collection system.

Abstract: Systems, methods, and software for determining properties of a medium surrounding an exterior portion of a well casing are described. In some aspects, the properties of the medium are determined based on measurements of detected acoustic energy and distances between one or more acoustic transmitters and two or more acoustic receivers. The measurements are obtained based on operating the transmitters and the receivers within a wellbore that includes the well casing.

Abstract: In accordance with embodiments of the present disclosure, systems and methods for downsampling DAS data in a way that enables accurate interpretation of acoustic events occurring in the data are provided. Such methods may be particularly useful when interpreting large sets of data, such as DAS VSP data collected during hydrocarbon recovery operations. The methods generally involve identifying data channels affected by noise from a DAS data set, and then interpolating from the surrounding data. This may improve the quality of the resulting downsampled data, with respect to the signal to noise ratio, compared to what would have occurred by merely decimating unwanted data channels. In addition, a priori information about channel fading, the desired downsampling rate, and the slowest expected elastic waves may be used to filter the DAS data. This may achieve a higher signal-to-noise ratio in the downsampled data.

Abstract: A system includes a light source, optical fiber coupled to the light source, one or more interferometers coupled to the optical fiber, wherein each interferometer of the one or more interferometers comprising a gauge length, a photodetector assembly coupled to the optical fiber, and an information handling system. The photodetector assembly is configured to detect backscattered light from the optical fiber and generate signals based on the detected backscattered light. The an information handling system is configured to receive the signals from the photodetector assembly, apply a de-convolution operation to the signals based on the gauge lengths of the one or more interferometers, and store the de-convolved signals.

Abstract: Systems, methods, and software for determining properties of a medium surrounding an exterior portion of a well casing are described. In some aspects, the properties of the medium are determined based on measurements of detected acoustic energy and distances between one or more acoustic transmitters and two or more acoustic receivers. The measurements are obtained based on operating the transmitters and the receivers within a wellbore that includes the well casing.

Abstract: Geophysical prospecting may be achieved using borehole seismic data and processing velocity seismic profiles using downward continuation to simulate the seismic source being at the depth of the borehole receivers. Such methods may involve collecting seismic data for a subterranean formation with at least one borehole receiver; grouping the seismic data into a one common receiver gather corresponding to each borehole receiver; performing a downward continuation on at least one of the common receiver gathers to produce corresponding downward continued common receiver gathers; performing a normal moveout analysis on at least one of the downward continued common receiver gathers to produce corresponding semblance velocity spectra; and analyzing at least one of the semblance velocity spectra for a zone of interest in the subterranean formation.

Abstract: The present disclosure provides embodiments seismic energy sources configured to generate enhanced shear wave energy in order to more accurately determine the distribution and orientation of fractures in subterranean formations. At least one seismic energy source includes an elongate rod having a first end and a second end, a detonator coupled to the first end, and a bull plug coupled to the second end. An explosive is helically-wrapped about the elongate rod continuously from the first end to the second end and configured to detonate such that a time-delayed detonation is achieved which induces increased shear wave energy in the surrounding formations.

Abstract: Tools and methods for monitoring a subterranean formation is provided. Methods for monitoring include: creating a time-lapse azimuth stack between an azimuth stack on a first seismic survey and an azimuth stack on a second seismic survey; identifying a lowest root mean square energy and a highest root mean square energy for each time-lapse azimuth stack; and recording an azimuth with largest overall root mean square energy.

Abstract: The present disclosure provides embodiments seismic energy sources configured to generate enhanced shear wave energy in order to more accurately determine the distribution and orientation of fractures in subterranean formations. At least one seismic energy source includes an elongate rod having a first end and a second end, a detonator coupled to the first end, and a bull plug coupled to the second end. An explosive is helically-wrapped about the elongate rod continuously from the first end to the second end and configured to detonate such that a time-delayed detonation is achieved which induces increased shear wave energy in the surrounding formations.