A method includes obtaining at least one digital waveform corresponding to acoustic signals collected by a logging tool deployed in a downhole environment. The method also includes performing windowed frequency spectra analysis (WFSA) on the at least one digital waveform to obtain frequency semblance information at different time-slices. The method also includes deriving a slowness log as a function of position using the frequency semblance information.

Methods for identifying rock properties in real-time during drilling, are provided. An example of an embodiment of such a method includes positioning one or more acoustic sensors to detect drill sounds emanating from the drill bit and the rock encountered during drilling operations, connecting the sensors to select components of a drilling rig to maximally pick up the drill sounds of the drill bit engaging rock during drilling operations. The method also includes providing and deploying an inductive telemetry, wireless telemetry, or wired transmitting system. The method also includes providing and configuring a computer to analyze the raw acoustic signals received from the acoustic sensors through the respective transmitting system.

Disclosed are methods, systems, and computer-readable medium to perform operations including: spectrally decomposing seismic data associated with a target subsurface area into a plurality of iso-frequency volumes; selecting a low-frequency volume and a high-frequency volume from the plurality of iso-frequency volumes; dividing the low-frequency volume by the high-frequency volume to generate a frequency ratio volume for the target subsurface area; establishing a time-depth relationship in the target subsurface area; extracting, based on the time-depth relationship and the frequency ratio volume, an iso-frequency ratio log in the target subsurface area; and using the iso-frequency ratio log to identify a subsurface gas reservoir in the target subsurface area.

A method and apparatus of locating subsurface geohazards in a geographical area that includes: receiving a plurality of seismic trace signals in the geographical area based on a shot gather from a seismic shot source; isolating and stacking the plurality of seismic trace signals to generate a windowed trace signal associated with refraction traces from the seismic shot source; transforming the windowed trace signal to a frequency domain; calculating a low frequency to high frequency ratio for the transformed trace signal; outputting the calculated ratio to a two-dimensional array representing the geographical area at a source location and at a mean receiver location; repeating the steps for a plurality of other shot gathers in the geographical area; and multiplying each source location ratio with one or more mean receiver location ratios on the two-dimensional array to generate a final frequency ratio map.

Embodiments provide for a method that utilizes the azimuthally spaced receivers of a sonic logging tool. Signals from monopole and dipole sources are reflected from the geologic interfaces and recorded by arrays of receivers of the same tool. For the incident P-waves from the monopole source, phase arrival times for the azimuthal receivers are compensated for stacking using properties of wave propagation in the borehole, and for the incident SH-waves from the dipole source, signs of waveforms for the receivers are changed for specified azimuths.

A method, apparatus, and program product analyze time-series data such as seismic data collected from a subsurface formation by splitting a time-series data set such as an individual seismic trace into a plurality of spectral components, each having an associated frequency, determining an instantaneous frequency for each spectral component, determining a frequency difference for each spectral component based at least in part on the associated and instantaneous frequencies therefor, and determining a tuning parameter based at least in part on the determined frequency difference of each spectral component. Doing so enables, for example, thin-bed structures in the subsurface formation to be identified, and in some instances, thicknesses of such structures to be determined.

The disclosed method includes receiving resulting signals emanating from a subterranean formation, wherein the resulting signals are caused by signals emitted from seismic sources. The method further includes dividing the resulting signals into a plurality of sub-samples. The method includes determining a frequency content of one or more of the sub-samples and assigning a weight to or more components of the frequency content of the sub-sample to produce a weighted frequency content of the sub-sample, wherein the assigned weight is based, at least in part, on an estimate of the amount of noise present in the frequency content of the sub-sample. The method further includes combining the weighted frequency contents of the sub-samples to produce a weighted sample. The method further includes determining one or more properties of the subsurface formation based, at least in part, on the weighted sample.

A method can include receiving seismic data that has an associated bandwidth; for a number of frequency bands, for a number of frequency bands, iteratively filtering and adjusting the seismic data by applying band-pass filters to extract information associated with each of the frequency bands where the adjusting the seismic data includes, after each iteration, subtracting extracted information from the seismic data prior to a subsequent iteration; balancing the extracted information to generate spectrally balanced seismic data; and outputting the spectrally balanced seismic data.

A method of detecting subsurface conditions conducive to fluid transfer can include obtaining microseismic resonance signals from multiple surface locations over a subsurface region of interest using a resonance sensor, wherein for at least a plurality of the multiple surface locations, multiple microseismic resonance signals are obtained at different times to generate signal stacks. In some examples, the method can also include amplifying the microseismic resonance signals, filtering out the high frequencies at least above about 7,500 Hz leaving low frequencies at least as low as about 4 Hz for evaluation, and using these low frequencies to identify subsurface fracture zones where subsurface fluid may be present. In some examples, subsurface fluids can be detected and/or mapped using gamma radiation count and/or magnetometric density data collected using appropriate equipment.

Seismic data processing methods and computing systems are presented. In one embodiment, a method is disclosed that includes simulating a set of simulated seismic data from a set of acquired seismic data; separating the simulated seismic data into a plurality of data sets, wherein one set of data is matched in the acquired seismic data and one set of data is unmatched in the acquired seismic data; conforming the simulated seismic data and the acquired seismic data to one another using separated, simulated seismic data unmatched by a counterpart in the acquired seismic data from the acquired seismic data; and performing an inversion between the acquired seismic data and the separated, simulated seismic data after they are conformed to one another.