Abstract: Method and computer program for accepting controlled-source electromagnetic (“CSEM”) source and receiver data (40) as time series, transforming these data into the time-frequency domain, and reducing these data and survey metadata to a form suitable for interpretation or inversion. The invention includes: a number of processing tools or programs (30), each designed to take a specific action on CSEM data or metadata, combine data types in some way, and/or provide a visual representation of data; a Graphical User Interface (32) to specify the action of specific tools (34) on specific data, supply parameters to tools, and monitor progress of the processing project; and a specified common internal data format, so that processing tools may be applied in various orders (36) during different processing flows and processed CSEM data can be passed on to interpretation or inversion systems.

Abstract: Method for separating responses of multiple transmitters m a controlled source electromagnetic survey by using mutually orthogonal transmitter waveforms and transforming the combined response to the frequency domain (144) The mutual orthogonality can be based disjoint frequency spectra or on phase encoding of a common waveform element (FIG.

Abstract: Method for compensating for phase errors in electromagnetic data by exploiting the frequency scaling properties of electromagnetic fields. The data are obtained at various source-receiver offsets. Then, temporal frequency components of the data at each offset R are determined. Next, the phase spectrum (phase vs. offset) for each of the frequency components is determined. Then, the phase spectra for the different frequencies f are displayed vs. scaled offset R??, where ?=2?f. Finally, the phase spectra are then adjusted such that the differences in phases for the different frequencies are reduced. The adjustment process can be repeated until phase differences are reduced to an acceptable level.

Abstract: The method for suppressing noise in the controlled seismic source electromagnetic survey data based on the frequency content of the noise (51) contained in the data. The invention recognizes that some data variations across bins cannot be attributed to resistivity variations within the earth. This variation across the bins constitutes a model of noise in such surveys, and the invention mitigates noise that obeys this model.

Abstract: A frequency domain method of processing geophysical data on a computer having massively parallel processors. The method involves assigning data slice partitions to each processor, precomputing a velocity model corresponding to the geophysical data, and migrating the data on each slice within each processor using a one-pass, split wave equation finite difference technique for depth migration and either phase shift or recursive techniques for time migration. A sequence of transforms and transpositions between processors assigned partitions on each frequency slice transforms into the frequency-wavenumber domain and allows the migration calculations to be directly performed by each processor to be independent of each other processor. The transforms and transposes also allow for depth migration error correction and filtering in the frequency-wavenumber domain.

Abstract: A method of determining traveltime fields for use in processing geophysical data. The method is implemented on a computer having massively parallel processors. The input to the method is a three-dimensional velocity model of a volume of the subsurface of the earth. The method assigns the traveltime calculations to groups of processors, which calculate traveltimes for individual shots. A preliminary simulation of the traveltime calculation process is performed to determine the number of processors required in each group. The groups of processors perform the traveltime calculations independent of the other groups. Calculations are performed in spherical coordinates, with traveltimes interpolated to a rectangular grid for storage and subsequent use. The final traveltimes are compressed in a differential format to reduce data storage and transfer requirements.

Abstract: A method of processing seismic data on parallel processors, preferably on a massively parallel processor. The input ot the process is seismic data from one or more of a number of seismic lines. The end product of the invention is a DMO corrected, zero-offset seismic image of the subsurface. By repeating the method on different input offsets, the variation in reflection strength of a reflector as a function of the angle of incidence can be examined. The method includes a two stage parallelization. First, a parallelization over the incoming traces generates a suite of DMO-corrected partial images for each point on each incoming trace. Secondly, a parallelization over output locations accumulates and combines the partial images, and produces output traces.

Abstract: A method of processing geophysical data on a parallel processor. The method involves decomposition of an analysis cube into depth slices, a second decomposition of a data acquisition cube into traveltime slices, and determination of a variably dimensioned analysis aperture. Precomputed traveltimes are stored in packed format to minimize storage volume and data bandwidths. The method relies on staged access of traveltime fields from high speed mass storage to disk storage and via input/output processors to analysis processor memory. The input/output processors monitor analysis processor memory to optimize the direct scatter download of traveltime fields to the analysis processors. The seismic trace data download is also staged, preferably from tape storage to disk storage to processor memory. A control processor preprocesses the trace data while downloading the trace data from disk storage to processor memory.

Abstract: A method of processing geophysical data on a parallel processor. The method involves decomposition of an analysis cube into depth slices, a second decomposition of a data acquisition cube into traveltime slices, and determination of a variably dimensioned analysis aperture. Precomputed traveltimes are stored in packed format to minimize storage volume and data bandwidths. A processing simulation is performed to optimize the stored sequence of the seismic trace data and to minimize traveltime field input/output demands. The method preferably assigns input/output, analysis, or control tasks to each processor, with depth and traveltime slices assigned to each analysis processor. The method relies on staged access of traveltime fields from high speed mass storage to disk storage and via the input/output processors to analysis processor memory. Seismic trace data are also staged, preferably from tape storage to disk storage to processor memory, and preferably are broadcast under the control of a host computer.

Abstract: A data collection and transmission system for gathering high count vertical seismic data is disclosed using a sequence of vertically aligned seismic receivers, the analog outputs from which are sequentially analog sampled and time multiplexed onto a common pair of data conductors in the support and transmission cable. The data is time demultiplexed at the surface and appears substantially as digital data because of the relatively short sampling times. Such data is converted into analog data with conventional digital-to-analog converter means.A clock signal activates counters for establishing non-overlapping data gates in the respective sondes, the operation of the gates supplying the cable with the respective receiver analog signals in a sequence from bottom to top, simultaneously switching off previously gated signals until a clock reset pulse resets the entire sonde string.

Abstract: A method for producing a display of acoustic signals received during full waveform acoustic well logging. In a preferred embodiment, the signals received at the individual receiver (or receivers) of the logging tool are stacked along lines of constant acoustic velocity to produce for display a stacked signal. Preferably, the raw signals are weighted prior to the stacking step, to compensate for decreasing amplitude of the acoustic arrival of interest with increasing transmitter to receiver distance. The stacked signals produced may be displayed in various formats, such as on a linear or logarithmic scale of inverse acoustic velocity, or of formation porosity.