Systems and methods of performing a seismic survey are provided. The system includes a seismic data acquisition unit having a transmitter window disposed in a first aperture of a lid, and having a receiver window disposed in a second aperture of the lid. A first gasket is positioned between the transmitter window and the first aperture to provide a clearance greater than a threshold to allow the transmitter window to deform. A second gasket is positioned between the receiver window and the second aperture to provide a clearance greater than the threshold to allow the receiver window to deform. At least one of the transmitter window and the receiver window of the seismic data acquisition unit are configured to pass at least one of optical and electromagnetic communications to or from an extraction vehicle via at least one of a transmitter window and a receiver window of the extraction vehicle.

Embodiments included herein are directed towards a seismic spread system that may use a MEMS oscillator as a timing reference. The system may include a plurality of nodal seismic sensor units. The system may also include a plurality of MEMS oscillator clock devices, wherein each of the plurality of MEMS oscillator clock devices is associated with a respective one of the plurality of nodal seismic sensor units, the plurality of MEMS oscillator clock devices being configured to input time synchronization to the seismic system. Each MEMS oscillator clock device may include a MEMS resonator in communication with an integrated circuit.

The method for estimating the drift over time of a physical operating parameter of a clock for dating seismic data samples associated with a seismic data collection node involves measuring (10) at least one quantity associated with the clock, at predetermined instants or during predetermined time periods, and applying (12), to this quantity, a predetermined non-linear law of variation of this quantity that depends on the values collected during the measurement step (10), so as to obtain an estimation of the drift over time of the physical operating parameter.

According to one embodiment, there is provided a method of correcting recorded seismic data where each receiver clock is potentially inaccurate. Since the seismic wave field is not random, and contains coherent events that are recorded by all receivers in a local area, it is possible to estimate the differences in the time reference by comparing the recordings of different receivers in a local area. With no external time reference, time signal, or pilot trace, an entire seismic data itself can be used to determine how each receiver's clock is drifting from true time.

A method and apparatus may include activating, by a network node, power of a global-positioning-system receiver or power of an active antenna of the global-positioning-system receiver. The apparatus uses the global-positioning-system receiver to perform synchronization of the apparatus. The method may include receiving at least one measurement, wherein the at least one measurement includes real-time, predictive, or historic data. The method may also include determining a holdover duration based on the at least one measurement. The holdover duration corresponds to a length of time where the power of the global-positioning-system receiver or the power of the active antenna is to be turned off. The method may also include deactivating the power of the global-positioning-system receiver or the power of the active antenna for the holdover duration.

A master data acquisitions system is provided. A trigger emits a sync signal to be sensed by each of a plurality of data acquisition systems. A controller is communicatively coupled with each of the plurality of data acquisition systems. The controller receives data from each of the data acquisition systems. The data for each of the plurality of data acquisition systems include the sensed sync signal. The controller synchronizes the data from each of the plurality of data acquisition systems by aligning the sensed sync signal for each of the plurality of data acquisition systems.

A method includes receiving data indicative of outputs of first and second seismic sensors. The outputs include components corresponding to the detection by the first and second seismic sensors of first and second seismic signals. In addition, the method includes identifying, relative to a first clock in the first seismic sensor, a first time associated with a time of arrival of the first seismic signal at the first seismic sensor, and a second time associated with a time of arrival of the second seismic signal at the first seismic sensor. Further, the method includes identifying, relative to a second clock in the second seismic sensor, a third time associated with a time of arrival of the first seismic signal at the second seismic sensor, and a fourth time associated with a time of arrival of the second seismic signal at the second seismic sensor. Still further, the method includes determining an offset of the first clock relative to the second clock using the first, second, third and fourth times.

A method of correcting clock drift in at least one slave clock in a seismic node. The method comprises obtaining a number of clock drift measurements of the at least one slave clock in the at least one seismic node. A clock drift correction function as a function of time is calculated by curve fitting the number of clock drift measurements to a 2nd order polynomial. A time of reference of the recorded seismic sensor data is corrected by the 2nd order polynomial clock drift correction function.

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.

A seismic system that includes a seismic source configured to generate a first seismic signal and a second seismic signal in a formation adjacent the seismic source. A first downhole sensing device disposed in a first borehole configured to detect the first seismic signal and the second seismic signal in the formation; and a first surface acquisition system is in communication with the first downhole sensing device. The first surface acquisition system is configured to: determine a first reference transit time based at least in part on detection of the first seismic signal by the first downhole sensing device; a first subsequent transit time based at least in part on detection of the second seismic signal by the first downhole sensing device; and whether a synchronization variation is expected to be present based at least in part on the first reference transit time and the first subsequent transit time.