Methods for processing seismic data acquired with non-impulsive moving sources are provided. Some methods remove cross-talk noise from the seismic data using emitted signal data and an underground formation's response estimate, which may be iteratively enhanced. Some methods perform resampling before a spatial or a spatio-temporal inversion. Some methods compensate for source's motion during the inversion, and/or are usable for multiple independently moving sources.

There is a method for correcting seismic wave propagation paths through the earth. The method includes determining a first fixed shooting sequence for a first bandlimited seismic source; determining a second shooting sequence for a second bandlimited seismic source, wherein the second shooting sequence includes second shooting positions that correspond to second energy emissions, and the second energy emissions differ from the first energy emissions in at least one of an emission time, phase and amplitude; receiving raw seismic data recorded with seismic receivers and generated as a result of the first and second energy emissions, wherein the raw seismic data is indicative of seismic wave paths from the first and second bandlimited seismic sources to the seismic receivers; separating the raw seismic data into a first bandlimited set corresponding to the first bandlimited seismic source and a second bandlimited set corresponding to the second bandlimited seismic source; and correcting the seismic wave paths, from the first and second bandlimited seismic sources to the seismic receivers, based on at least one of the first and second bandlimited sets.

A method of seismic acquisition using a dispersed-source array (DSA) comprising two or more sources. The method comprises determining, for each of the two or more sources of the DSA, an individual spectrally-banded waveform. For each of the two or more sources, a primary waveform is formed by repeating the individual spectrally-banded waveform. For each of the two or more sources, a secondary waveform is formed based on the primary waveform. The secondary waveform is spectrally shifted relative to the primary waveform such that secondary waveforms of any two of the two or more sources are spectrally non-overlapping. The blending operator based on the secondary waveform of each of the two or more sources is provided to the DSA. The method also includes performing deblended-data reconstruction of acquired seismic data using one or more properties of the blending operators of the two or more sources.

Methods and systems for separating seismic data acquired using a plurality of substantially simultaneously fired sources are described. The sources use sweep sequences having low cross correlation levels to generate seismic waves, and their source signatures are determined. Using the source signatures, the wave fields associated with each of the sources are extracted from the seismic data by, for example, performing a time domain deconvolution.

A method for de-blending seismic data associated with an interface located in a subsurface of the earth, includes receiving blended seismic data E generated by firing N source arrays according to a pre-determined sequence Seq; selecting N sub-datasets SDn from the blended seismic data E; interpolating each selected sub-dataset SDn to reference positions ref, where the blended seismic data E is expected to be recorded, to generate interpolated data k; de-blending, in a processor, the interpolated data k to generate de-blended data o; and generating an image of the interface of the subsurface based on the de-blended data o.

Imperfect separation at the higher frequencies has been observed and was eventually was tracked down to the poor GFE signal that is normally used in the inversion. The invention thus uses a “derived GFE” for each source, obtained by comparing the shot records and remove the differences, instead of the prior estimated GFE signal put out by the controller, thus accurately maximizing the separation of the data.

A computer-implemented method includes the following. A frequency sweep using sweep parameters is emitted from a vibratory seismic source into geological layers. The sweep parameters include frequencies and modulation parameters for seismic waves. Signals are received from one or more sensors. The signals include seismic data acquisition information, including values identifying energy reflected back from boundaries where rock properties change. A determination is made regarding which of the reflected seismic waves are attenuated. The determination uses an integral transform and a thresholding algorithm for image segmentation. Optimum sweep parameters are determined based on the reflected seismic values that are attenuated and updated to compensate for local geology effects. The emitting, receiving, determining attenuation, determining optimum parameters, and updating are repeated until the received signals are determined to be satisfactory.

Techniques for determining a drill bit location includes identifying a plurality of acoustic energy signals received at a plurality of sets of acoustic receivers from a passive acoustic energy source that is part of a wellbore drilling system; processing the plurality of acoustic energy signals; determining a location of a drill bit of the wellbore drilling system based on the processed plurality of acoustic signals; and updating a geo-steering path of the drill bit based on the determined location of the drill bit.

A method for echo detection may comprise recording one or more reflected waveforms, segmenting the one or more reflected waveforms based at least in part on a firing pulse length, applying a shaped filter to each segment of the one or more reflected waveforms, decoupling the one or more reflected waveforms into a time-frequency energy map, extracting a firing frequency band time domain plot from the decoupled time-frequency map, identifying a maximum amplitude in the extracted firing frequency band of the one or more reflected waveforms as an excitation, and identifying a second maximum amplitude in the extracted firing frequency band of the one or more reflected waveforms as an echo. A system for echo detection may comprise a digital signal processor, a transmitter, a transducer, a receiver, an analog to digital converter configured to digitize the measurement, and an information handling system.

Techniques are disclosed relating to geophysical surveying. In various embodiments, a computer system may access seismic data for a geological formation, where the seismic data is recorded, using one or more sensors, during a seismic survey in which a first vibratory source was driven using a first digital code for at least a first time interval. The first digital code, in some embodiments, may include a first plurality of subsections corresponding to portions of the first time interval. In some embodiments, the computer system may image a first location of the geological formation using a correlation of only a first sub-section of the first plurality of sub-sections with the seismic data. Further, in some embodiments, the computer system may image a second location of the geological formation using a correlation of two or more of the first plurality of sub-sections with the seismic data.