Abstract: An initial gather of blended seismic signals induced in a common seismic receiver by a plurality of actual sources grouped in actual source groups is provided. Each actual source group has a linear source geometry that is the same for each actual source group. The plurality of sources in each actual source group is fired according to a pre-selected firing sequence that is the same for each actual source group. Actual shot records are created from the blended signals, and fictive shot records are created of seismic signals for fictive source groups that each have the same source geometry as the actual source groups, by interpolation of the actual shot records. Single source shot records of single source signals are separated by discrete deconvolution of the actual shot records and the fictive shot records. The output includes a seismic gather comprising a plurality of the single source shot records.

Abstract: Systems and methods, including computer-implemented systems and methods, for determining an optimized geometry of seismic sources and receivers in order to generate a desired dense wavefield.

Abstract: The orientation of the symmetry axis of an underground formation including an HTI layer is determined by comparing azimuthal Fourier coefficient of inversion results in distinct source-receiver azimuth ranges with values expected from the HTI assumption. A branch-stacking technique or prior knowledge may be used to select one of the anisotropy axis orientation values.

Abstract: A method can include receiving seismic data acquired by a sensor unit responsive to emission of seismic energy in a frequency sweep of a duration having a duration time; correlating the seismic data and individual portions of the frequency sweep that correspond to individual time windows to generate individual sets of correlated seismic data; for a common event, identifying a corresponding event time in each of the individual sets of correlated seismic data; and determining a clock drift time based at least in part on the event times.

Abstract: High fidelity velocity models are generated for acoustic vertically transverse isotropic media by taking advantage of full-waveform based modeling using VSP data. The present disclosure determines VTI parameters in acoustic media using pseudo-acoustic equations which can eliminate the contribution from shear waves, and thus significantly reduce the time needed to perform inversion. The methods disclosed herein provide workflows for performing full waveform inversion to provide velocity models used to generate seismic images with high quality and resolution.

Abstract: In accordance with presently disclosed embodiments, a system and method for determining a measurement for a pseudo receiver antenna with a different lateral position and a different azimuthal direction than at least two receiver antennas disposed on one or more wellbore tools is provided. The method involves transmitting an electromagnetic signal into a subterranean formation surrounding a borehole, and measuring one or more responses of the subterranean formation to the electromagnetic signal using at least two receiver antennas. The two receiver antennas are oriented in differing azimuthal directions relative to one or more tools to which the receiver are coupled, and arranged in a non-parallel angular orientation with respect to each other. The method then includes determining a response measured by a pseudo receiver antenna with a desired angular orientation and a desired azimuthal direction with respect to the one or more tools.

Abstract: A geologic survey system includes a plurality of acoustic sources spaced at intervals over a target area of a terranean surface. Each of the plurality of acoustic sensors is configured to generate a seismic energy wave. The system also includes a plurality of acoustic sensors positioned in a plurality of boreholes formed in a geologic formation, where the boreholes have a depth sufficient to reach a geologic datum. The system also includes a control system communicably coupled to the plurality of acoustic sensors and configured to perform operations including receiving, from the plurality of acoustic sensors, data associated with reflected acoustic signals generated by the plurality of acoustic sources and received by the plurality of acoustic sensors; determining, based on the received data, a subsurface topology of the geologic formation; and generating a subsurface model of the geologic formation based on the determined subsurface topology.

Abstract: A method can include measuring microseismic activity in a relief wellbore, thereby detecting a microseismic event in an earth formation penetrated by the relief wellbore, and determining a location of an influx into a target wellbore, based on the microseismic event detecting. A microseismic ranging system for use with a subterranean well can include at least one microseismic sensor in a relief wellbore that penetrates an earth formation, with the microseismic sensor detecting a microseismic event in the formation, the microseismic event being caused by an influx into a target wellbore. Another method can include measuring optical scattering in an optical waveguide positioned in a relief wellbore, thereby detecting a microseismic event in an earth formation penetrated by the relief wellbore, and determining a location of an influx into a target wellbore, based on the microseismic event detecting.

Abstract: Embodiments of the subject technology provide for predicting seismic impedance. The subject technology generates a corridor stack based on vertical seismic profile (VSP) data of a wellbore in a subterranean formation. The subject technology generates an initial estimate of a velocity model for the subterranean formation below the wellbore. The subject technology generating a density model for the subterranean formation below the wellbore based on information from nearby wells. The subject technology inverts, based on a global inversion algorithm and the initial estimate of the velocity model, the generated corridor stack to determine a set of velocity models. The subject technology generates impedance models in a depth domain based on the generated density model and the set of velocity models. Further, the subject technology stores the generated impedance models.

Abstract: Techniques, systems and apparatus are described for operating a multimode passive detection system (MMPDS). A multimode passive detection system includes charged particle tracking detectors to measure cosmic ray-based charged particle trajectories in a volume of interest. The multimode passive detection system includes fission product detectors to detect cosmic ray-based charged particle induced fission in a fissile material present in the volume of interest.

Abstract: In some embodiments, a time migration diffraction imaging method includes computing a pseudo-depth characterizing a subsurface seismic event by scaling a vertical traveltime using a scaling velocity. A specularity value for a subsurface seismic event is determined according to the pseudo-depth, and a contribution weight for a corresponding seismic trace amplitude is determined according to the specularity value. The specularity value may be determined according to an angle between a traveltime gradient and a normal to a local reflector surface. A diffraction image is generated according to a weighted sum of seismic trace amplitudes. The weighted sum attenuates the contribution of specular events relative to diffraction events.

Abstract: A communications path between a surface control system and downhole equipment includes a network of wirelessly interconnected communication devices that are located along a conduit. When the communications path fails or cannot be established during performance of a downhole operation, a mobile master communication tool that is in communication with the surface system can be deployed within the wireless range of one of the devices to provide an alternative communication path between the surface system and the downhole equipment. In other embodiments, the alternative communication path can be a temporary path to provide for communications before the network is fully deployed.

Abstract: A technique is designed to facilitate obtaining of acoustic data. The technique comprises traversing a tool through a subterranean formation from a first depth to subsequent depths. The tool receives a seismic signal during predetermined time windows. The seismic signal is generated by a seismic source which is activated at varying times relative to the predetermined time windows based on the depth of the tool.

Abstract: Systems and methods for geological medium exploration are provided herein. A method of geological medium exploration may include generating vibrations in a geological medium and recording wave-fields at a surface and in a borehole. Additionally, the method may include obtaining a wave field modification operator and applying the wave-field operator to a full range of seismic data to achieve a spectrally-modified wave field.

Abstract: A method for determining positions and origin times of seismic events occurring in the Earth's subsurface includes accepting as input to the method signals recorded from a plurality of seismic sensors deployed above a subsurface volume of interest. The recorded signals are a representation of seismic amplitude with respect to time. Origin time and location of each of a plurality of subsurface seismic events are determined from the recorded signals. The origin times and locations of each event are inverted to obtain Thomsen's parameters in formations in the volume of interest. Depths of each of the events are determined by individually searching the depth of each event, the inversion with each incorporated new depth including updating the Thomsen parameters and setting as a limit a minimum value of RMS error.

Abstract: A method having obtaining one or more porosity data of a subsurface of the Earth using a data acquisition tool; computing one or more permeability data from the porosity data using a transformation function; computing a first quantile regression function and a second quantile regression function of the one or more permeability data; producing a combined mean regression function of the one or more permeability data by summing the first quantile regression function and the second quantile regression function, wherein the first quantile regression function is multiplied by a first coefficient and the second quantile regression function is multiplied by a second coefficient; and using the combined mean regression function to predict a mean permeability of the subsurface.

Abstract: A technique includes estimating propagation parameters that are associated with a towed seismic survey based at least in part on seismic signal measurements and noise measurements.

Abstract: A method for updating a velocity model of a subsurface of the earth is described herein. A tomographic update to the velocity model of the subsurface may be performed to generate a tomographic velocity model update. A geomechanical velocity model update of the subsurface may be calculated. The geomechanical velocity model update may be combined with the tomographic velocity model update.

Abstract: Techniques for estimating velocity ahead of a drill bit include generating seismic waves at a surface from at least two different source positions in the vicinity of a borehole, receiving seismic waves reflected from a reflector ahead of the drill bit at one or more locations in the borehole, determining travel times of the seismic waves received at the one or more locations in the borehole, and inverting the travel times to determine a velocity of a formation ahead of the drill bit. One embodiment includes transforming the velocity into pore pressure of the formation.

Abstract: A zero-offset VSP survey is carried out with spaced apart receivers located in a vertical wellbore. Spectra of the signals at the receivers following wavefield separation are estimated. An absorption coefficient is estimated using differences in spectra between all pairs of receivers.

Abstract: A system, method and computer-readable medium for acquiring seismic data, which includes activating a seismic source at a surface location; defining a seismic trace of a seismic wave received at a downhole location on a bottomhole assembly in a borehole in response to the activation of the seismic source; compressing the seismic trace; and recording the compressed seismic trace to a storage medium.

Abstract: Methods and apparatuses are disclosed for generating three dimensional (3D) vertical seismic profiles (VSPs) in a more time efficient manner. The methods and apparatuses enable faster and more efficient VSP surveys than previous techniques. Real-time updating of the velocity model and real-time reflection point density calculations are carried out, which are used to determine the location of the next seismic source firing. In the event the data of a particular bin has an insufficient fold, common image points (CIPs) or reflection point density, additional source firings may be carried out prior to moving the source. Further, in the event the data of a particular bin is excessive in terms of the fold, CIPs or reflection point density before the planned source firings for the bin are completed, remaining source firings for that bin may be skipped to save time and improve the efficiency of the data collection.

Abstract: Acoustic signals resulting from microseismic events in the subsurface are received in a first array of detectors deployed in a borehole and in a second array of detectors at or near the surface of the earth. The signals are converted to give the locations of the microseismic events.

Abstract: A borehole seismic acquisition system is described with a plurality of sensors arranged so as to identify within the data measured by the pressure sensors P- and S-wave related signals converted at the boundary of the borehole into pressure waves, the sensors being best arranged in groups or clusters sensitive to pressure gradients in one or more directions.

Abstract: A technique includes receiving first seismic data acquired by one or more receivers in response to energy produced by one or more seismic sources interacting with a subsurface feature. The first seismic data is indicative of measured reflection coefficients for image points for the subsurface feature, the measured reflection coefficients are associated with incidence angles, and a range of the incidence angles varies with respect to an image point position. The technique includes processing the first seismic data in a machine to generate second data indicative of a normal incidence reflection coefficient for at least one of the image points not associated with a normal angle of incidence.

Abstract: Direct arrivals from walkaway vertical seismic profiling or VSP survey data are used to derive Green's functions representing the seismic wave amplitude and travel time information required to extrapolate the vertical seismic profiling survey data from individual wellbore receivers to the individual source locations. The derived Green's functions are employed in a convolution process with upcoming primary wavefields from the VSP survey data for other surface locations. The derived Green's functions are also used in a correlation process with downgoing wavefields from the VSP survey data to extend lateral coverage of the VSP image. The sets of VSP-CMP gathers so formed are then processed to obtain information about the subsurface formations.

Abstract: A walkaway VSP survey is carried out using a receiver array. First arrivals to a plurality of receivers are picked and used to estimate a normal-moveout (NMO) velocity. Using the NMO velocity and vertical velocities estimated from the VSP data, two anisotropy parameters are estimated for each of the layers. The anisotropy parameters may then be used to process surface seismic data to give a stacked image in true depth and for the interpretation purposes. For multi-azimuthal walkaway or 3D VSP data, we determine two VTI parameters ? and ? for multi-azimuth vertical planes. Then we determine five anisotropic interval parameters that describe P-wave kinematics for orthorhombic layers. These orthorhombic parameters may then be used to process surface seismic data to give a stacked image in true depth and for the interpretation purposes.

Abstract: Devices, systems and methods for land seismic. The devices include an above-ground storage tank in which an acoustic energy source is immersed in liquid. The above-ground storage tank may be portable, reusable, self-supporting and may lay flat when empty of liquid and rise on its own when being filled with liquid. The systems include the seismic source-storage tank device, one or more sensors for recording signals that are generated when the source is activated, and a processor for analyzing the recorded signals for geophysical information. The methods involve methods of inducing seismic waves using the seismic source-storage tank devices, and methods of conducting seismic surveys using the seismic source-storage tank devices.

Abstract: Methods and apparatus for reducing the impact of guided (or “tube”) waves in permanently installed seismic systems. By utilizing passive acoustic absorbers, the impact of tube waves may be reduced, leading to improved performance of permanently installed seismic systems that are installed onto production tubing when the well is completed.

Abstract: Methods for in-situ reservoir investigation by borehole seismic methods are provided using receiver(s) and a downhole source. The downhole source may be a microseismic event, and may be located relative to the receiver(s) in any configuration. The downhole source may also be a controlled source that is positioned in a reverse vertical seismic profile (RVSP) geometry with respect to the receiver(s). The methods may involve locating the receiver(s) in a first well (which may have any orientation, including vertical or horizontal), and locating the source in a monitoring well (which may have any orientation, including vertical or horizontal), such that the source in the monitoring well is positioned at a greater depth in the formation than the receivers in the first well.

Abstract: Disclosed is a method for estimating downhole lateral vibrations a drill tubular disposed in a borehole penetrating the earth or a component coupled to the drill tubular. The method includes rotating the drill tubular to drill the first borehole and performing a plurality of measurements in a time window of one or more parameters of the drill tubular at or above a surface of the earth during the rotating using a sensor. The method further includes estimating the downhole lateral vibrations using a processor that receives the plurality of measurements.

Abstract: A system and method obtain a Vertical Seismic Profile (VSP). The system includes a seismic source disposed in a first borehole at a first depth greater than an identified depth of a interface, the seismic source configured to emit seismic waves. The system also includes one or more receptors disposed in a second borehole that includes a target region of interest, the one or more receptors configured to receive direct and reflected components of the seismic waves.

Abstract: According to a preferred aspect of the instant invention, there is provided herein a system and method for imaging complex subsurface geologic structures such as salt dome flanks using VSP data. In the preferred arrangement, a receiver wave field will be downward continued through a salt flood model and a source wave field will be upward continued through a sediment flood model until they “meet” at the subsurface locations of the VSP receivers. The source and receiver wave fields will be cross correlated as an imaging condition at each depth interval.

Abstract: A system for monitoring seismicity during fluid injection at or near a hydrocarbon reservoir comprising: a first set of seismic sensors for deployment at a site for collecting seismic data; a second set of seismic sensors for sub-surface deployment at the site at a depth lower than the first set of seismic sensors for collecting seismic data, the first set of seismic sensors having a lower frequency response than that of the second set of seismic sensors; and a data collection system in communication with the first and second set of sensors.

Abstract: A method for seismic inversion of vertical seismic profile (VSP) data in an oilfield. The method includes obtaining an initial velocity model of a subterranean formation including acoustic velocities of wave propagation in proximity to the wellbore, determining an acquisition geometry for obtaining the VSP data including receiver locations within the wellbore and a source location, performing a seismic survey to obtain the VSP data based on the acquisition geometry, analyzing arrival signals of the VSP data to generate transit time data for wave propagation from the source location to the receiver locations, modifying the initial velocity model to generate an updated velocity model by performing a tomographic inversion of the transit time data, generating an elastic model of the subterranean formation by performing the seismic inversion of the VSP data using the updated velocity model, and adjusting the operations of the oilfield based on the elastic model.

Abstract: A method and a retrievable vertical geophone cable for collecting seismic data underground. The retrievable vertical geophone cable includes an envelope having a first end at which a connector mechanism is provided to close the envelope; plural geophones distributed inside the envelope at predetermined positions; and a first expansion mechanism attached to a geophone of the plural geophones and configured to expand the envelope when actuated with a first fluid under pressure.

Abstract: Method and retrievable vertical hydrophone cable for collecting seismic data underground. The retrievable vertical hydrophone cable includes an envelope having a first end at which a connector mechanism is provided to close the envelope; plural hydrophones distributed inside the envelope at predetermined positions; and a fluid provided inside the envelope and around the plural hydrophones. The envelope increases its volume when the fluid is pressurized through the connector mechanism.

Abstract: A method of imaging a target area of the subsoil from “walkaway” data having application to development of oil reservoirs or monitoring of geologic storage sites is disclosed. After acquisition of seismic data of walkaway type and estimation of the rate of propagation of the seismic waves in the subsoil, p illumination angles are selected. The seismic measurements are then converted to data Dp by illumination angle. The distribution of acoustic impedances best explaining data Dp is determined within the target by using a non-linear inversion which minimizes a difference between the data Dp obtained from measurements and data by illumination angle resulting from an estimation. This estimation is performed by solving a wave propagation equation from the velocity field, an acoustic impedance distribution and a pressure distribution at the level of the top of the target for each illumination angle.

Abstract: A method of calculating a seismic noise image for a formation comprises the steps of: a) obtaining data representing a multicomponent seismic signal from at least one receiver, in response to transmitting seismic waves into the formation; b) obtaining a velocity model of the earth formation; c) determining a plurality of wave field components; d) obtaining a set of second components; e) obtaining, for each subsurface point, at least two products, each product comprising the product of a selected wave field component and a different second component; and f) and generating a noise image by calculating at least one difference between different products for at least one image point.

Abstract: A method of processing data obtained from seismic prospecting of an earth formation, comprises obtaining data representing a multicomponent seismic signal from a multicomponent seismic receiver at a receiver location in an earth formation, in response to transmitting seismic waves into the earth formation; performing a wave-equation migration of the multicomponent seismic signal to obtain a seismic image of the earth formation, wherein the polarization of the seismic wave at the receiver location is taken into account and wherein a seismic image value at a point in the earth formation is calculated from a sum of products of a source field component for a particular dimension and a complex conjugated back propagated wave field component for the same dimension, summed over a plurality of dimensions.

Abstract: A walkaway VSP survey is carried out with receivers located in a borehole under a salt overhang. Redatuming of the multicomponent data to virtual sources in the borehole followed by vector Kirchhoff migration using a simple velocity model provides an accurate image of the salt face.

Abstract: In some aspects of the disclosure, a method for creating three-dimensional images of non-linear properties and the compressional to shear velocity ratio in a region remote from a borehole using a conveyed logging tool is disclosed.

Abstract: An apparatus and a method for processing of three components, 3-Dimensions seismic (3-C, 3-D) data acquired by down-hole receivers and surface seismic sources. Automatic velocity analysis is used to identify the velocities of dominant events in a VSP panel. Different wave-types (downgoing P, downgoing PS, upcoming PS and upcoming PP) are identified and sequentially removed.

Abstract: Methods and related systems are described for processing surface seismic data. Surface seismic data representing seismic signals detected at a plurality of surface locations is wavefield deconvolved using a combination of direct wave travel times estimated from borehole seismic data, and wavefield energy estimated from the surface seismic data.

Abstract: A technique includes determining a magnitude and frequency distribution of seismic events attributable to hydraulic fracturing in a given stage of a well. The technique includes based on the determined magnitude and frequency distribution, predicting at least one additional magnitude and frequency distribution of seismic events attributable to hydraulic fracturing in at least one additional stage of the well. The technique includes determining at least one seismic property of a system of hydraulic fractures based at least in part on the determined additional magnitude and frequency distributions.

Abstract: A method is disclosed for more accurately determining the relative bearing angle of a directional receiver in a borehole using an existing three-dimensional (3D) geological model, one or more seismic sources and a three component (3C) directional receiver. A disclosed method includes: receiving direct compressional arrivals generated by multiple source events at the directional receiver disposed in the borehole; rotating the seismic data into the true earth frame using an estimated relative bearing angle; measuring a polarization vector of the rotated seismic data; estimating an incident ray vector of the direct compressional arrivals at the directional receiver using ray-tracing through the 3D model; calculating the weighted sum of an angular difference between the polarization vector and the incident ray vector; and adjusting the estimated relative bearing angle until the angular difference between the polarization and incident ray vectors is minimized.

Abstract: A logging system for measuring anisotrophic properties of the materials penetrated by a borehole. A downhole or “logging tool” element of the system comprises a source section that comprises either a unipole or a dipole acoustic source. The receiver section comprises a plurality of receiver stations disposed at different axial spacings from the acoustic source. Each receiver station comprises one or more acoustic receivers. The system requires that the source and receiver sections rotate synchronously as the logging tool is conveyed along the borehole. Receiver responses are measured in a plurality of azimuthal angle segments and processed as a function of rotation angle of the tool. The logging system can be embodied as a logging-while-drilling system, a measurement-while-drilling system, and a wireline system that synchronously rotates source and receiver sections. All embodiments require that the acoustic source operate at a relatively high frequency.

Abstract: A method for monitoring a multi-layered system below a surface comprising a slow layer and a fast layer; the method comprising: transmitting one or more seismic waves from one or more seismic sources through the multi-layered system; receiving signals emanating from the multi-layered system in response to the one or more seismic waves with one or more receivers located a distance from the one or more seismic sources; identifying one or more critically refracted compressional (CRC) waves amongst the signals; and inferring information about a change in the slow layer based on the one or more CRC waves; wherein the CRC wave is a refracted wave which has traveled along an interface between the fast layer and an adjacent layer.

Abstract: A method for seismic inversion of vertical seismic profile (VSP) data in an oilfield. The method includes obtaining an initial velocity model of a subterranean formation including acoustic velocities of wave propagation in proximity to the wellbore, determining an acquisition geometry for obtaining the VSP data including receiver locations within the wellbore and a source location, performing a seismic survey to obtain the VSP data based on the acquisition geometry, analyzing arrival signals of the VSP data to generate transit time data for wave propagation from the source location to the receiver locations, modifying the initial velocity model to generate an updated velocity model by performing a tomographic inversion of the transit time data, generating an elastic model of the subterranean formation by performing the seismic inversion of the VSP data using the updated velocity model, and adjusting the operations of the oilfield based on the elastic model.

Abstract: Methods and related systems are described making seismic measurements. Seismic energy is transmitted into the earth using a surface seismic source. The seismic energy is received with one or more downhole receivers located in a borehole. In response to the received seismic energy from the surface seismic source, seismic energy is transmitted into the earth using a downhole seismic source. The seismic energy from the downhole seismic source is then received with one or more surface receivers located on the surface of the earth. A delay interval is measured downhole between the first arrival of the seismic energy from the surface seismic source and the transmission from the downhole seismic source. A surface interval is measured between the transmitting of seismic energy from the surface seismic source and first arrival of the seismic energy from the downhole seismic source using the one or more surface receivers. Travel time can be calculated by subtracting the delay interval from the surface interval.