Abstract: To survey a subterranean structure, measured seismic data is processed using an algorithm for deriving a single-mode absorption parameter. A first absorption parameter for a mode-converted seismic wave is computed based on an output of the algorithm. The first absorption parameter represents an absorption effect of the mode-converted seismic wave by the subterranean structure, where the mode-converted seismic wave is reflected from the subterranean structure in response to a source seismic wave of a different mode than the mode-converted seismic wave.

Abstract: Method for processing seismic data. In one implementation, the method includes converting a common midpoint (CMP) gather of seismograms into one or more interferogram common midpoint (ICMP) gathers, generating a semblance spectrum for each ICMP gather, stacking the semblance spectrum from each ICMP gather to generate a combined semblance spectrum and deriving a normal moveout (NMO) velocity profile from the combined semblance spectrum.

Abstract: A method to attenuate unwanted signals in seismic data using seismic interferometry techniques. In one implementation, seismograms may be converted into seismic interferograms. In the seismic interferogram domain, unwanted signals may be attenuated by various techniques, such as muting, filtering and the like. The modified seismic interferograms may then be converted back into seismograms with the unwanted signals having been attenuated.

Abstract: To survey a subterranean structure, measured seismic data is processed using an algorithm for deriving a single-mode absorption parameter. A first absorption parameter for a mode-converted seismic wave is computed based on an output of the algorithm. The first absorption parameter represents an absorption effect of the mode-converted seismic wave by the subterranean structure, where the mode-converted seismic wave is reflected from the subterranean structure in response to a source seismic wave of a different mode than the mode-converted seismic wave.

Abstract: A method and apparatus for filtering data acquired at a plurality of discrete data points is described, using the steps of defining a filter having defined filter values at defined filter points at least partially not coincident with the data points and using the defined filter values at the defined filter points to determine filter values at the data points, thereby correcting the filter to have filter values at filter points coinciding with the data points and filtering the data using the corrected filter.

Abstract: Implementations of various techniques for processing seismic data acquired by three or more over/under streamers. In one implementation, the seismic data may be processed by grouping the seismic data into one or more sets of seismic data based on all possible pairs of the three or more over/under streamers, wherein each set of seismic data comprises seismic data that had been acquired by a pair of the three or more over/under streamers, applying a shift and subtract algorithm to the one or more sets of seismic data, and applying a dephase and sum algorithm to the one or more sets of seismic data.

Abstract: Implementations of various techniques for processing seismic data acquired by three or more over/under streamers. In one implementation, the seismic data may be processed by grouping the seismic data into one or more sets of seismic data based on all possible pairs of the three or more over/under streamers, wherein each set of seismic data comprises seismic data that had been acquired by a pair of the three or more over/under streamers, applying a shift and subtract algorithm to the one or more sets of seismic data, and applying a dephase and sum algorithm to the one or more sets of seismic data.

Abstract: The present invention provides a method and apparatus for analyzing seismic data. The method includes determining a portion of the seismic data recorded substantially before the arrival of a seismic signal and adding a test signal to the portion of the seismic data recorded substantially before the arrival of the seismic signal.

Abstract: A method and apparatus for filtering data acquired at a plurality of discrete data points is described, using the steps of defining a filter having defined filter values at defined filter points at least partially not coincident with the data points and using the defined filter values at the defined filter points to determine filter values at the data points, thereby correcting the filter to have filter values at filter points coinciding with the data points and filtering the data using the corrected filter.

Abstract: The present invention provides a method and apparatus for analyzing seismic data. The method includes determining a portion of the seismic data recorded substantially before the arrival of a seismic signal and adding a test signal to the portion of the seismic data recorded substantially before the arrival of the seismic signal.

Abstract: A method of attenuating noise in three dimensional seismic data using a projection algorithm is disclosed. A frequency—space—space (“f-xy”) projection algorithm is used which is a generalization of the f-x projection algorithm. The predictability of the seismic signals in the f-xy domain constitutes the basis of the algorithm. Specifically it is demonstrated that if the seismic events are planar in the t-xy domain, then in the f-xy domain they consist of predictable signals in the xy-plane for each frequency f. A crucial step of the 2-D spectral factorization is achieved through the helical coordinate transformation. In addition to the disclosed general algorithm for arbitrary coherent noise, a specialized algorithm for random noise is disclosed. It has been found that the disclosed projection algorithm is effective even in extreme cases of poor signal to noise ratio. The algorithm is also signal preserving when the predictability assumptions hold.