Abstract: A new method is presented for generating a probability map, a cutoff map, and a confidence limit map in one single operation. In addition, the new method can also generate a cube representing a cubic volume of earth formation by using the same method for generating the aforementioned maps.

Abstract: A seismic signal processing method will analyze a resultant set of seismic data, generated in response to a seismic operation performed on a particular portion of an Earth formation, for the purpose of determining a set of geologic characteristics of the particular portion of the Earth formation. When the seismic signal processing method is performed, a cross correlation technique is utilized. In particular, a first data set, which represents a standard set of ‘comparison traces having known geologic characteristics’ and includes two or more traces having known geologic characteristics but does not constitute a part of an input seismic volume, is cross correlated with a second data set having unknown geologic characteristics. As a result of that cross correlation, an output record, known as a ‘correlation spectral volume’, is generated.

Abstract: A seismic signal processing method will analyze a resultant set of seismic data, generated in response to a seismic operation performed on a particular portion of an Earth formation, for the purpose of determining a set of geologic characteristics of the particular portion of the Earth formation. When the seismic signal processing method is performed, a cross correlation technique is utilized. In particular, a first data set, which represents a standard set of ‘comparison traces having known geologic characteristics’ and includes two or more traces having known geologic characteristics but does not constitute a part of an input seismic volume, is cross correlated with a second data set having unknown geologic characteristics. As a result of that cross correlation, an output record, known as a ‘correlation spectral volume’, is generated.

Abstract: A Semi-Variogram is generated by taking the Fourier Transform of ‘spatial data in the space domain’ thereby producing a frequency domain representation of the spatial data having a DC component (equivalent to a mean of the spatial data), removing the DC component to produce the frequency domain representation of the spatial data with zero mean (FFT), computing the complex conjugate of FFT (FFT*), complex multiplying FFT and FFT* to produce a complex product, taking the inverse Fourier Transform of the complex product to produce a space domain representation of the complex product (IFFT), and subtracting IFFT from the zero lag covariance to generate a Semi-Variogram. This Abstract is given for the sole purpose of allowing a patent searcher to easily determine the content of the disclosure in this specification.

Abstract: A method and apparatus are disclosed for testing a large plurality of displayed data points of recorded spatial data to determine and display trends created by different sets of the data points within the recorded spatial data. An analysis operator interactively uses an onscreen graphic tool called a widget to set trend search parameters after studying the displayed data points, and uses a pop-up menu to set other search and display parameters for the trend search. The onscreen graphic tool permits the user to easily see on-screen, and manually set, search parameters indicating the direction of a search from a user selected starting point, how far each step of a search will be performed for adjacent data points in a fault line, within what angle the search will be performed on either side of the user indicated search direction, and if trend searches being performed are in one or both directions from the user selected starting point in the recorded spatial data.

Abstract: A workstation computer system, and its associated method and program storage device, stores a novel software package known as "Variance Cube". The computer system is responsive to a plurality of seismic signals propagating through a cubic volume of an earth formation for generating a cube, representing said cubic volume of earth, where the cube includes a plurality of seismic data samples and where each seismic data sample has a corresponding "variance value" assigned thereto. The computer system also generates one or more maps, such as a time slice map, representing one or more slices through the cube. Each map displays and is used to determine certain geologic features which exist along the corresponding slice through the cube, each map including a plurality of the variance values representing the geologic features, each such variance value being defined as the degree to which an amplitude of each seismic data sample in the cube at a particular reflection time "t" varies about an average amplitude.

Abstract: An operator sitting at a workstation views, on a display, a multitude of seismic traces having one or more horizons indicated therein by a plurality of sets of events (such as peaks or troughs or zero crossings) on the seismic traces. The operator uses a mouse to draw a line from left to right across a plurality of seismic traces being displayed on the workstation display screen. At this point, the line does not lie on the events (such as the peaks) of the seismic traces. Therefore, the line does not yet represent a horizon in an earth formation. The operator presses a key on the keyboard of the workstation. In response to the pressing of this key, the workstation processor executes a "snapper software" in accordance with the present invention.

Abstract: Formation tops correlation is interpreted between sampled log curves by a weighted combination of covariance, the ratio of standard deviation, and the ratio of summed amplitude. This covariance function is computed and evaluated appropriately for the geologic environment over a sliding analysis window. Correlations are determined for any number of wells and any number of events in each well. Geologic rules are used to establish a parameter for the algorithm operation and for the analysis of the resulting function. The geologic rules include bounding guide horizons, sequence rules, and a covariance cutoff parameter. Bounding horizons are picked from pre-existing seismic or geologic interpretations and from map grids. The rule set includes onlap, truncated, conformable, and unstructured sequence definitions. Additional geologic complexity such as crossover, repeat sections, and inverted sections are accommodated by the rule set.

Abstract: An interpretation workstation based apparatus having an "Auto Fault" software stored therein automatically identifies a plurality of fault cuts in each of a plurality of horizons in a seismic data volume in response to a plurality of predetermined "horizon time structures".

Abstract: A method and associated apparatus for generating time slice maps and/or horizon maps, representative of a time slice or a horizon in an earth formation that is subject to a seismic operation, in response to received seismic data includes the steps of: (a) cross correlating a plurality of seismic traces from the seismic data and a corresponding plurality of quadrature traces associated, respectively, with the plurality of seismic traces to obtain a corresponding plurality of cross correlation functions "Q(.tau.)", (b) obtaining a plurality of particular values from the plurality of cross correlation functions "Q(.tau.)", at least one particular value being obtained from each cross correlation function, and (c) assigning the plurality of particular values to a respective plurality of reflection points on a map, each particular value being assigned to a different one of the reflection points, thereby constructing the time slice map and/or the horizon map.

Abstract: A processing system stores a special software known as the Cubemath software. The Cubemath software allows the processing system to process, analyze, and interpret a second set of seismic data relative to a first set of seismic data obtained from either a repeat seismic operation or a single seismic two processing method operation. A first set of 3D seismic data is collected at a particular location on the surface of the earth at time "t1", and a second set of 3D seismic data is collected at that same particular location on the surface of the earth (at a different time "t2" when the repeat seismic operation is being performed).

Abstract: In one exemplar embodiment, an improved method is provided for compensating received propagated seismic signals for the absorption by the earth of all frequencies of a vibrator source signal. The received seismic data is crosscorrelated with the original source signal and a Fourier amplitude spectral analysis obtained. Then an attenuation function is determined by the attenuation exhibited by the spectrum. The quantified attenuation function is then applied as a compensation function to the original source signal to obtain a "weighted" vibrator sweep signal that is then used in crosscorrelating with the received seismic data to compensate for the frequency dependent attenuation in the earth of received propagated seismic data.