Method and resonant source for generating low-frequency seismic waves. The resonant source includes a frame; a reaction mass configured to oscillate relative to the frame; a resonant suspension system connecting the reaction mass to the frame and including at least a spring; and a spring clamp system connected to the resonant suspension system and configured to modify a resonant frequency of the resonant suspension system. The resonant suspension system is configured to allow the reaction mass to oscillate relative to the frame with a corresponding resonant frequency.

Sensors for imaging boreholes via the detection of electrical and optical properties may be subject to harsh conditions downhole, such as from pressure and temperature. In addition, these sensors may be subject to impact, such as tension, elongation, and compression forces, along the wall of the borehole. The harsh conditions downhole and impacts on the sensor can lead to premature wear and even breaking. The present disclosure generally relates to an apparatus for measuring electrical and optical properties of the borehole and methods for manufacturing the apparatus.

A nodal seismic unit for acquiring seismic information includes an enclosure, a GPS receiver disposed in the enclosure; a motion sensor disposed in the enclosure; a LPWAN radio transceiver disposed in the enclosure; and a control unit disposed in the enclosure. The control unit is configured to transmit an unplanned movement signal to a remote operator using the LPWAN radio transceiver if the control unit receives a signal from the motion sensor indicative of an acceleration greater than a preset level. Additionally, he control unit may be configured to change an operating state of the nodal seismic unit in response to detecting a predetermined pattern of motion using the motion sensor.

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.

A method for receiving an encoded integer includes acquiring a digitized waveform including a first plurality of pulses distributed among a second plurality of time slots, locating each of the pulses in the digitized waveform, computing a confidence value for each of the pulses, selecting a subset of the plurality of pulses, the subset including pulses having low confidence values computed, generating a set of unique waveforms corresponding to various combinations of the subset of pulses selected, computing a cross-correlation between each of the waveforms generated and the digitized waveform acquired, and selecting the waveform having the highest cross-correlation computed.

Methods for selecting a receiver line orientation for a seismic data acquisition array and methods for performing a seismic survey using the selected receiver line orientation are provided herein. A method of selecting a 3D seismic data acquisition array comprising: selecting a survey area, determining the location of a plurality of source lines in the survey area, pre-planning a plurality of receiver line grids with differing orientations, assigning a cell grid to each receiver line grid, generating a fold level for each cell in each receiver line grid, determining a fold variation for each receiver line grid, and selecting a receiver line grid from the plurality of receiver line grids with the lowest fold variation.

Surface wave coda in seismic data recorded with a data acquisition system over an underground formation is estimated using time-reversal experiments. First time-reversal experiments use a first time-reversal mirror including a target source and one or more other sources to obtain estimates of surface waves traveling from other receivers to a target receiver. Second time-reversal experiments obtain a coda estimate for a surface wave traveling from the target source to the target receiver using a second time-reversal mirror including the target receiver and the other receivers.

A long offset land seismic survey spread includes a plurality of sensors within an area thereby defining a sensor receiver patch, a plurality of long offset sensor receivers outside of the receiver patch thereby surrounding the receiver patch and defining a sensor long offset area that is fee from sensor receivers that also defines a distance separating an external border of the sensor receiver patch and the long offset sensor receivers being a minimum offset distance that is a long offset distance.

An internal structure detection system includes: two kinds of sensors with different operating principles for receiving reflected waves of vibration applied to an inspection target in an investigation area; and a processing apparatus that detects an internal structure of the inspection target by using the sensor data received by the two kinds of sensors. The two kinds of sensors are deployed in the investigation area with different densities, in a distributed manner.

A computing system and method for mitigating, in a first seismic survey, cross-talk generated by a second seismic survey. The method includes performing the first seismic survey with a first survey seismic source driven by a first survey pilot sweep, performing the second seismic survey with a second survey seismic source, simultaneously with the first seismic survey, recording with first survey seismic sensors (i) first survey seismic signals that originate from the first survey seismic source and (ii) second survey seismic signals that originate from the second survey seismic source, selecting another first survey pilot sweep, which has less cross-correlation noise with the second survey seismic signals than the first survey pilot sweep, and continuing the first seismic survey with the another first survey pilot sweep.