Abstract: In order to monitor the subsoil of the earth under a target zone, seismic waves coming from an identified mobile noise source are recorded by means of at least one pair of sensors disposed on either side of the target zone, time periods are selected corresponding to the alignments of the pairs of sensors with the noise source, a seismogram of the target zone is reconstructed by interferometry based on the recorded seismic waves and on the selected time periods and an image of the subsoil of the target zone is generated using the seismogram.

Abstract: The invention relates to a method for monitoring the physical state of a longitudinal element (IO) of a railway-type rail, the method having a step of detecting mechanical waves moving along the longitudinal element (IO), in particular due to the passing of a train, by means of an array of mechanical wave sensors placed along and in contact with the longitudinal element, the array having at least one first pair (A) of sensors each positioned at one end of a first portion (IOa) of the longitudinal element (IO), and a step of processing the signals emitted by the sensors in the array of sensors, the processing step having the determination of at least one first interfered signal determined from signals provided by the sensors in the first pair (A) of sensors over a first predetermined period of time.

Abstract: In order to monitor the subsoil of the earth under a target zone, seismic waves coming from an identified mobile noise source are recorded by means of at least one pair of sensors disposed on either side of the target zone, time periods are selected corresponding to the alignments of the pairs of sensors with the noise source, a seismogram of the target zone is reconstructed by interferometry based on the recorded seismic waves and on the selected time periods and an image of the subsoil of the target zone is generated using the seismogram.

Abstract: The present disclosure includes a method including determining a spatial region for analysis and selecting a segment of time for analysis, analyzing and correcting a plurality of traces from a plurality of receivers using an iterative non-linear inversion algorithm, wherein each iteration of the non-linear algorithm corrects the plurality of traces using at least one set of parameters defining a microseismic event, determining whether a final stack value of the plurality of traces corrected based on the at least one set of parameters of a final iteration of the iterative non-linear inversion algorithm exceeds a predetermined threshold and upon a determination that the final stack value exceeds the predetermined threshold, detecting a microseismic event defined by the at least one set of parameters of final iteration. The present disclosure also includes associated systems and computer-readable media.

Abstract: A moment tensor is determined using an inversion algorithm for each of a plurality of microseismic events passively detected by receivers. Each of the moment tensors includes two nodal planes. A subset of the microseismic events is grouped into a family of microseismic events. If the microseismic events in the family have a common nodal plane, the common plane is a solution fault plane for the family of microseismic events. Information related to the fault plane is used to optimize fracking operation.

Abstract: An embodiment of a method includes receiving seismic data from an array of seismic receivers, selecting a time window, and dividing the time window into a plurality of consecutive time segments, each corresponding to a subset of the seismic data. The method also includes performing a transformation of each subset into a frequency domain subset having a total frequency band, and selecting a narrow frequency band bounded by the lowest frequency of the total band and a threshold frequency. The method further includes, for each of the plurality of frequencies in the narrow frequency band, determining a cross-spectral density matrix (CSDM) of data values in each frequency domain subset, decomposing the CSDM to generate a plurality of eigenvalues, and removing at least the most significant eigenvalue from each frequency domain subset. The method still further includes transforming each frequency domain subset into a time domain to generate de-noised seismic data.

Abstract: The present disclosure includes a method including determining a spatial region for analysis and selecting a segment of time for analysis, analyzing and correcting a plurality of traces from a plurality of receivers using an iterative non-linear inversion algorithm, wherein each iteration of the non-linear algorithm corrects the plurality of traces using at least one set of parameters defining a microseismic event, determining whether a final stack value of the plurality of traces corrected based on the at least one set of parameters of a final iteration of the iterative non-linear inversion algorithm exceeds a predetermined threshold and upon a determination that the final stack value exceeds the predetermined threshold, detecting a microseismic event defined by the at least one set of parameters of final iteration. The present disclosure also includes associated systems and computer-readable media.

Abstract: The present disclosure includes a method comprising detecting arrival times of a P-wave and an S-wave at a plurality of receivers, the P-wave and the S-wave generated by a calibration event. The method also comprises fitting the P-wave arrival times as a first curve on a plot of distance versus time based on a first velocity model with a first type and fitting the S-wave arrival times as a second curve on the plot based on a second velocity model with a second type similar to the first type. The method additionally comprises determining a difference between a first origin time based on the first curve and a second origin time based on the second curve, and upon a determination that the difference between the first origin time and the second origin time is within a convergence criteria, selecting the first velocity model as a calibrated velocity model.

Abstract: An embodiment of a method includes receiving seismic data from an array of seismic receivers, selecting a time window, and dividing the time window into a plurality of consecutive time segments, each corresponding to a subset of the seismic data. The method also includes performing a transformation of each subset into a frequency domain subset having a total frequency band, and selecting a narrow frequency band bounded by the lowest frequency of the total band and a threshold frequency. The method further includes, for each of the plurality of frequencies in the narrow frequency band, determining a cross-spectral density matrix (CSDM) of data values in each frequency domain subset, decomposing the CSDM to generate a plurality of eigenvalues, and removing at least the most significant eigenvalue from each frequency domain subset. The method still further includes transforming each frequency domain subset into a time domain to generate de-noised seismic data.

Abstract: The present disclosure includes a method of passive seismic data processing comprising determining a moment tensor for each of a plurality of microseismic events using an inversion algorithm and raw data detected at a plurality of receivers, each of the moment tensors including two nodal planes and grouping a subset of the plurality of microseismic events into a family of microseismic events. The method also includes determining whether the family of microseismic events include a single plane that is common across each of the nodal planes of the microseismic events for the moment tensors of the family of microseismic events. The method additionally includes selecting a solution fault plane for the family of microseismic events, the solution fault plane being the single plane. The present disclosure may also include associated systems and apparatuses.

Abstract: Methods and systems for designing or configuring a microseismic monitoring network are described. The design is based on a regular and homogeneous repartitioning of seismic sensor locations associated with a focal sphere. The methods and systems determine an optimal sampling of the focal sphere of microseismic events and a takeoff angle associated with each of the optimal sampling points. The sampling points are propagated to the surface based on the associated rays and any of a plurality of ray tracing techniques.