Abstract: A method may include obtaining seismic data for a geological region of interest. The method may further include determining various velocity semblance values for the geological region of interest using a time window and the seismic data. The method may further include determining, automatically by a computer processor, one or more stacking velocities for the geological region of interest using a traced path based on the velocity semblance values and a path tracing algorithm. The path tracing algorithm may recursively determine an accumulated amplitude array based on the velocity semblance values. The path tracing algorithm may further determine the traced path among the velocity semblance values and the accumulated amplitude array, the traced path corresponding to the one or more stacking velocities. The method may further include generating a velocity model of the geological region of interest using the one or more stacking velocities.

Abstract: A method and apparatus of locating subsurface geohazards in a geographical area that includes: receiving a plurality of seismic trace signals in the geographical area based on a shot gather from a seismic shot source; isolating and stacking the plurality of seismic trace signals to generate a windowed trace signal associated with refraction traces from the seismic shot source; transforming the windowed trace signal to a frequency domain; calculating a low frequency to high frequency ratio for the transformed trace signal; outputting the calculated ratio to a two-dimensional array representing the geographical area at a source location and at a mean receiver location; repeating the steps for a plurality of other shot gathers in the geographical area; and multiplying each source location ratio with one or more mean receiver location ratios on the two-dimensional array to generate a final frequency ratio map.

Abstract: Systems and methods for automated first arrival picking are disclosed. The method includes obtaining a seismic dataset composed of a plurality of seismic gathers and determining a pilot for each gather, where the pilot includes a position on an ordinate axis for each seismic trace representing a first arrival. The method continues iteratively until a stopping criterion is met by creating a preconditioned gather using the pilot, determining a differential pilot using global path tracing subject to a constraint and incrementing the pilot using the differential pilot to create a total picked first arrival. Once the stopping criterion has been met, the method further includes determining a final picked first arrival based on the total picked first arrival, determining a seismic velocity model from the final picked first arrival using a tomographic inversion and creating a seismic image using the seismic velocity model and the seismic dataset.

Abstract: A method and apparatus of locating subsurface geohazards in a geographical area that includes: receiving a plurality of seismic trace signals in the geographical area based on a shot gather from a seismic shot source; isolating and stacking the plurality of seismic trace signals to generate a windowed trace signal associated with refraction traces from the seismic shot source; transforming the windowed trace signal to a frequency domain; calculating a low frequency to high frequency ratio for the transformed trace signal; outputting the calculated ratio to a two-dimensional array representing the geographical area at a source location and at a mean receiver location; repeating the steps for a plurality of other shot gathers in the geographical area; and multiplying each source location ratio with one or more mean receiver location ratios on the two-dimensional array to generate a final frequency ratio map.

Abstract: Systems, methods, and apparatuses for generating a subsurface image using diffraction energy information are disclosed. The systems, methods, and apparatuses may include converting a shot gather into one or more plane-wave gather using a Radon transform. The plane-wave gathers may be extrapolated into source-side wavefields and receiver-side wavefields and further generate a pseudo dip-angle gather. The diffraction energy information may be extracted from the pseudo dip-angle gather, and an image containing subsurface features may be generated from the extracted diffraction energy information. The receiver-side wavefields may be decomposed using a recursive Radon transform.

Abstract: A method may include obtaining seismic data for a geological region of interest. The method may further include determining various velocity semblance values for the geological region of interest using a time window and the seismic data. The method may further include determining, automatically by a computer processor, one or more stacking velocities for the geological region of interest using a traced path based on the velocity semblance values and a path tracing algorithm. The path tracing algorithm may recursively determine an accumulated amplitude array based on the velocity semblance values. The path tracing algorithm may further determine the traced path among the velocity semblance values and the accumulated amplitude array, the traced path corresponding to the one or more stacking velocities. The method may further include generating a velocity model of the geological region of interest using the one or more stacking velocities.

Abstract: Methods and systems including computer programs encoded on a computer storage medium, for utilizing equivalent linear velocity for first arrival picking of seismic refraction. In one aspect, a method includes receiving data for the shot gather record, generating a diving wave equation curve for a particular parameter pair of multiple parameter pairs, and integrating the shot gather record data corresponding to the diving wave equation curve over a selected range of offsets of the shot gather to generate an equivalent linear velocity value for the particular parameter pair and the shot gather record data, selecting, from the equivalent linear velocity values for the plurality of parameter pairs, a greatest equivalent linear velocity value of the equivalent linear velocity values, the greatest equivalent linear velocity value corresponding to a first-arrival parameter pair, and determining, using the first-arrival parameter pair, a set of first-arrival onsets for the selected sub-range of offsets.

Abstract: An acquisition system is configured to acquire seismic data representing a subsurface formation during a fracking process. The system includes at least one acoustic sensor that is configured to obtain vibration data representing vibrations relating to three orthogonal directions relative to the at least one acoustic sensor. The system is configured to receive the vibration data from the at least one acoustic sensor, identify one or more resonance frequencies represented in the vibration data, determine, based on the identified one or more resonance frequencies, a stage of a fracking process being performed, identify, based on the stage of the fracking process that is identified, a feature of one or more fractures in a borehole that is configured for the fracking process, and generate a seismic image of the subsurface formation based on the feature of the one or more fractures.

Abstract: Methods and seismic shot generation and data collection systems configured to determine a monotonically increased velocity v*(z) from a monotonically increased velocity model by requiring the monotonically increased velocity v*(z) to be nearest to a refraction velocity v(z) determined for an estimated depth z and to be characterized by a positive slope such that the refraction velocity v(z) increases with depth, and to generate a subsurface image based on the estimated depth z and the determined monotonically increased velocity v*(z).

Abstract: Techniques are described for generating seismic images based on pressure-shear (PS) wave information. Sensor data is generated by through seismic probing of an underground environment. The sensor data can include pressure (P) wave data. The sensor data is analyzed to determine PS wave data present in the sensor data. A CFP gathers spectrum is generated using the P wave velocity. An optimal curve through the CFP gathers spectrum is determined, and PS image(s) of the underground environment are generated by scanning along the optimal curve. The PS image(s) can be provided for presentation through interface(s). The generated PS wave images are correlated with P wave images, and can be plotted on the same coordinate system as P wave images.

Abstract: Methods and seismic shot generation and data collection systems configured to determine a monotonically increased velocity v*(z) from a monotonically increased velocity model by requiring the monotonically increased velocity v*(z) to be nearest to a refraction velocity v(z) determined for an estimated depth z and to be characterized by a positive slope such that the refraction velocity v(z) increases with depth, and to generate a subsurface image based on the estimated depth z and the determined monotonically increased velocity v*(z).

Abstract: An acquisition system is configured to acquire seismic data representing a subsurface formation during a fracking process. The system includes at least one acoustic sensor that is configured to obtain vibration data representing vibrations relating to three orthogonal directions relative to the at least one acoustic sensor. The system is configured to receive the vibration data from the at least one acoustic sensor, identify one or more resonance frequencies represented in the vibration data, determine, based on the identified one or more resonance frequencies, a stage of a fracking process being performed, identify, based on the stage of the fracking process that is identified, a feature of one or more fractures in a borehole that is configured for the fracking process, and generate a seismic image of the subsurface formation based on the feature of the one or more fractures.

Abstract: The present disclosure describes methods and systems, including computer-implemented methods, computer program products, and computer systems, for generating a velocity model and a density model for a subsurface region of a hydrocarbon reservoir. One method includes: receiving, by a data processing apparatus, a set of seismic data of the hydrocarbon reservoir; setting, by the data processing apparatus, an initial velocity model and an initial density model; generating, by the data processing apparatus, wavefields of the hydrocarbon reservoir based on the set of seismic data; selecting, by the data processing apparatus, a spatial direction; generating, by the data processing apparatus, a velocity gradient and a reflectivity gradient of the selected spatial direction based on the wavefields; and updating, by the data processing apparatus, the velocity model and the density model using the velocity gradient and the reflectivity gradient of the selected spatial direction.

Abstract: A system for seismic imaging of a subterranean geological formation uses a two-way imaging condition. A seismic signal is emitted into a subterranean formation and recorded at receiver(s). Source and receiver wavefields are decomposed into respective right-down/left-up and left-down/right-up propagating waves. The right-down/left-up and left-down/right-up direction can be defined along the direction emitted from the source or receiver to corresponding direction in two dimensional (2D) case. An imaging condition for generating both a positive-dip structure image and a negative-dip structure image is the inner product of the wavefields. Applying the sample-by-sample multiplication imaging condition to the opposite dip images, the diffraction energy is retained while the reflection energy is significantly attenuated. The diffraction image can be used to detect faults and fractures in subsurface regions.

Abstract: A method of generating diffraction images based on wave equations includes generating a source wavefield and a receiver wavefield. Based on the source wavefield, a first source wavefield propagating in a first direction and a second source wavefield propagating in a second direction are generated. Based on the receiver wavefield, a first receiver wavefield propagating in the first direction and a second receiver wavefield propagating in the second direction are generated. A first seismic image is generated based on the first source wavefield and the first receiver wavefield. A second seismic image is generated based on the second source wavefield and the second receiver wavefield. A final seismic image is generated based on the first seismic image and the second seismic image.

Abstract: A method includes generating a seismic shot by a seismic source, the seismic shot directed at a geological subsurface, and receiving, by one or more receivers, a plurality of reflected seismic traces from the seismic shot. The method further includes generating a correlogram of each reflected seismic trace to generate a plurality of correlograms, isolating a coda wave train of each correlogram of the plurality of correlograms, and computing an energy ratio between an energy of the coda wave train of each correlogram and a total energy of a corresponding correlogram of the plurality of correlograms to generate a plurality of energy ratios. The method further includes determining an average of the plurality of energy ratios to generate an average energy ratio of the seismic shot and determining a likelihood of striking a subsurface geohazard when drilling into the geological subsurface based on the average energy ratio.

Abstract: A method for building a three dimensional (3D) model of a subsurface formation includes selecting, from a set of seismic shots, a plurality of first arrival signals representing the seismic shots. The method includes applying a quality control function to the plurality of first arrival signals to obtain a set of remaining first arrival signals. For each remaining first arrival signals, the method includes applying a velocity inversion function to obtain a depth velocity value at a common-midpoint (CMP) location in a shot gather including the seismic shot associated with that remaining first arrival signal, the CMP location representing a lateral variation of the shot gather including that seismic shot. The method includes, based on the depth velocity value for the seismic shot associated with each remaining first arrival signal, generating a velocity model representing the 3D model of the subsurface formation.

Abstract: A method for building a three dimensional (3D) model of a subsurface formation includes selecting, from a set of seismic shots, a plurality of first arrival signals representing the seismic shots. The method includes applying a quality control function to the plurality of first arrival signals to obtain a set of remaining first arrival signals. For each remaining first arrival signals, the method includes applying a velocity inversion function to obtain a depth velocity value at a common-midpoint (CMP) location in a shot gather including the seismic shot associated with that remaining first arrival signal, the CMP location representing a lateral variation of the shot gather including that seismic shot. The method includes, based on the depth velocity value for the seismic shot associated with each remaining first arrival signal, generating a velocity model representing the 3D model of the subsurface formation.

Abstract: Systems and methods include a computer-implemented method for presenting interpretation results of synchronized seismic data and fracture treatment times. A standard format seismic dataset of sensor readings obtained from a three-component sensor is generated. Coordinates and recording times corresponding to the sensor readings are added to the standard format seismic dataset. Synchronized seismic data is generated from the standard format seismic dataset by synchronizing seismic recording times with fracture treatment times. Quality-controlled synchronized seismic data is generated by removing dead traces and abnormal data samples from the synchronized seismic data. A time-frequency analysis is performed on the quality-controlled synchronized seismic data, including performing short-time Fourier transforms to analyze variations of Fourier spectra over time. Based on the time-frequency analysis, resonance frequencies are extracted from each frequency spectrum at different time samples.

Abstract: Systems and methods include a computer-implemented method for presenting interpretation results of synchronized seismic data and fracture treatment times. A standard format seismic dataset of sensor readings obtained from a three-component sensor is generated. Coordinates and recording times corresponding to the sensor readings are added to the standard format seismic dataset. Synchronized seismic data is generated from the standard format seismic dataset by synchronizing seismic recording times with fracture treatment times. Quality-controlled synchronized seismic data is generated by removing dead traces and abnormal data samples from the synchronized seismic data. A time-frequency analysis is performed on the quality-controlled synchronized seismic data, including performing short-time Fourier transforms to analyze variations of Fourier spectra over time. Based on the time-frequency analysis, resonance frequencies are extracted from each frequency spectrum at different time samples.