Abstract: This method and system for estimating Earth environmental effects in relation to planetary orbital dynamics provides for integrating seemingly diverse data input sources gathered from historical data, field data, meteorological sensors, satellites, and the like for geophysical, meteorological, archeological and astrophysical purposes to perform comparison, correlation, time and date determinations for historical analysis and future event prediction. Computer systems which are used to collect and store necessary data are linked by the most appropriate transmission means given the location and data transmission characteristics to be networked. A data base module is used to store historical or archival data as well as large input current data.

Abstract: Aspects for reporting faults in a redundant power converter are described. An exemplary method aspect includes monitoring at least one node within the redundant power converter. The method further includes tracking values of the at least one node during a predetermined time period, and predicting when a specification of the redundant power converter will be exceeded based on the tracked values.

Abstract: A seismic sensor pod is provided for coupling to a seismic cable and establishing a substantially water tight connection between the seismic cable and a seismic sensor. The pod includes a housing for holding the seismic sensor. The forward section of the housing includes a substantially sealed chamber. One or more conductors from the seismic cable are cut and the cut ends are projected into the chamber. Electrical connection between the cut ends of the conductors and the seismic sensor is established by a connector member. The pod provides a water resistant pathway between the conductors of the seismic cable and the seismic sensor, and a streamlined housing to hold the seismic sensor.

Abstract: A method of processing seismic signals for the analysis of moveout is presented in which waves are transmitted in a medium, reflected, received by receivers and recorded in the form of seismic traces. A string of N integers is defined having indices j lying between two limits (j.sub.min, j.sub.max) and representative of the moveouts of at least one predetermined gather of traces. A focus depth time t.sub.p for each value of j is calculated. A string of P integer numbers u is defined which determines an interval (P-1).DELTA.X. For each value of j, each trace identified by its parameters X.sub.0 and h is copied as many times as there are integer numbers u in the interval (P-1).DELTA.X. At least one static correction (dt) is applied to each of the copied traces, dependent at least on the parameters j, h and u .DELTA.X. Copying and static correction are repeated for all the values of X.sub.0 and of j.

Abstract: A magnetic drive device couples the drive motor of a depth control device or bird, with the axle of the depth control wings. The magnetic drive includes a plurality of permanent magnet pieces mounted in respective drive blocks on either side of a magnetically permeable membrane of the main body of the drive mechanism. The magnet pieces are mounted side by side in alternating polarity to capture as much of the magnetic flux of the magnets as possible to minimize stray flux from escaping the drive. Pole pieces either side of the drive blocks also serve to capture stray flux. To the maximum extent possible within the constraints of mechanical durability, the drive mechanism is made of non-magnetic or non-ferrous materials which would interfere with the heading sensor of the bird. Thus, this invention avoids reducing the accuracy of the heading sensor of the bird, while eliminating a major source of seawater inleakage into the bird.

Abstract: Methods and apparatus are described for seismic signal acquisition utilizing an odd number of vibratory sources arranged in line and positioning the sources for one sweep cycle at positions occupied by other sources during the previous sweep cycle. The method has advantages in particular for marine seismic acquisitions.

Abstract: A process for separating waves in borehole seismics for walkaway-type acquisitions. Waves are generated in a medium from several positions of a source. The waves are received at at least three sensors along axes V, H.sub.1, H.sub.2. Collections of C traces are formed with a common source. On the basis of the trace collection, collections of residual C traces and C signals, a pivot trace is selected from the collection of residual C traces. A straight line of variable slope p is plotted at each sampled point of the pivot trace. The amplitudes of the seismic events located at the intersections of the traces with the straight line are summed along the straight line. The amplitude sums are then transferred to a domain (.tau., p). A synthetic seismogram is made from the domain (.tau., p) and iterations are performed until the synthetic seismogram is acceptable in terms of the data of the collection of residual C traces.

Abstract: A method for performing a seismic survey with even fold. An inline direction and a crossline direction are selected. Seismic signals are generated at a plurality of source locations positioned along one or more source lines. The source locations are substantially equally spaced, and the source lines are substantially parallel to each other. Seismic signals are detected at a plurality of receiver locations positioned along a plurality of receiver paths having longitudinal axes parallel to the inline direction, and substantially equally spaced in each receiver path. Each receiver path is positioned along its axis, and extends in a regular pattern on both sides of the axis. The axes are substantially parallel to each other. A desired fold, F.sub.i, is determined in the inline direction, and a desired fold, F.sub.x, is determined in the crossline direction. A number of receiver channels, NC.sub.i, per receiver path in the inline direction, a spacing, RI.sub.

Abstract: A method and system for simulating and optimizing land seismic survey operations. The method and system utilizes spatially referenced data and nonspatial data relevant to land seismic survey operations such as high resolution satellite and airborne imagery and uses discrete event information about land seismic survey operation to simulate a land seismic survey. The output of the simulation is a detailed list of survey events. Mathematical optimization techniques are used to enhance the efficiency of the survey execution via optimal route planning and optimal allocation of survey logistical components. The invention uses a discrete event simulator which is an object-oriented software program with survey geometry objects that represent the survey design, resources objects that represent resources needed to conduct survey operations and manager objects to coordinate the resource objects within the specified survey geometry.

Abstract: A method for seismic data interpretation for the purposes of identification of oil, gas and water accumulation locations and delineation of their contours uses a model of discrete media with inhomogeneous stresses. For a selected reflection horizon, the relative value of overall pressure gradient is calculated on the basis of instantaneous amplitudes and frequencies of seismic signals using a derived relationship between the reflection coefficients of elastic waves and the stress condition parameter. The calculation technique uses estimates of instantaneous amplitudes and frequencies smoothed over the entire seismic horizon or its fragment. A generalized model of normal (lithostatic) pressure is excluded, and the final interpreted parameters have the sense of relative estimates of anomalous pressure caused by basin dynamics.

Abstract: A system and survey method for estimating the geodetic position of acoustic sensors placed at fixed but unknown locations on the seafloor is disclosed. Bottom mounted sensors are surveyed using an extension of the well known trilateration survey technique, i.e., making ranging measurements from reference points to the point to be surveyed. For acoustic sensors, these ranging measurements are obtained by transmitting an acoustic signal from a near surface projector and making corresponding timing and/or position measurements, requiring calculation of the Effective Sound Velocity. Bias errors are precluded from propagating to the sensor coordinates by considering timing and sound velocity biases, in addition to the sensor coordinates, as parameters to be estimated.

Abstract: A method for recording seismic data in deep water. A plurality of seismic data recorders are attached to a wire stored on a seismic vessel. A free end of the wire is deployed into the water, and the recorders are attached at selected positions along the wire. The wire and recorders are lowered into the water as the vessel moves to control the recorder deployment. The wire controls recorder location and establishes the recorder spacing interval. After the recorders are operated to record seismic data, the wire and attached recorders can be retrieved to the water surface. The recorders can be detached from the wire to facilitate storage and data retrieval from each recorder.

Abstract: A method and computer system for correcting seismic signals in a seismic survey, sensed in horizontal and vertical directions at receiver locations, is disclosed. According to the disclosed method and system, the horizontal and vertical seismic signal traces are processed in prestack gathers, after normal move-out correction. For each reflection event indicated in the prestack gathers, a performance function is evaluated over a range of zero-offset directivity and directivity slope values, using the horizontal and vertical pressure wave components sensed at the receivers. The zero-offset directivity and directivity slope values that return the maximum performance function are stored in connection with the gather and the reflection event, as indicative of the zero-offset dip and offset-dependent directivity of the reflective surface corresponding to the reflected event.

Abstract: Processes are described for providing a data set useful for performing analysis of reflection attribute variation among traces in a window of three-dimensional seismic data, wherein the traces have a reflection point assigned thereto and wherein the traces represent recordings from shot-receiver pairs having various azimuth angles. According to one embodiment, the process comprises: assigning an offset value to a plurality of traces; fitting a substantially conical surface having a major and a minor axis to the data of the traces within the window, wherein: the major axis of the cone represents the azimuth direction having the lowest variation in the reflection attribute, and the minor axis of the cone represents the azimuth direction having the highest variation in the reflection attribute; assigning a coordinate set to the surface, wherein the coordinate set is related to a survey geometry of the data; and comparing the reflection attribute variation as a function of offset and azimuth.

Abstract: An improved method for gathering traces in a 3-D seismic survey is disclosed. In one configuration, receiver lines having equally spaced geophone receivers stations are run in one direction, and lines of equally spaced shotpoint stations run orthogonal to the receiver station lines. The station spacing in each shotpoint and receiver lines is selected to produce a desired spatial resolution, and the individual lines are spaced apart by a distance equal to at least two times the station intervals. In this method, a series of common mid point gathers centered about source/receiver line intersection, referred to as "hybrid gathers" is made, where each hybrid gather includes traces from a designated number of shots in the shotpoint line of the selected intersection that are directed into a designated number of geophone receivers in the receiver line of the selected intersection.

Abstract: The present invention provides a system for drilling boreholes having a downhole subassembly which contains an acoustic measurement-while-drilling system. It uses the acoustic velocity through the formations surrounding the borehole and an acoustic transmitter and a set of receivers for determining the bed boundaries surrounding the borehole formation. Semblance of the data is determined in a slowness/intercept-time domain. Coherence and semblance filtering methods are used to differentiate between reflection signals and noise. The position and orientation of the bed boundary relative to the tool are determined. A further processing step uses the relative position and orientation determined for a number of tool positions to further discriminate against noise and obtain an absolute position and depth of the bed boundaries.

Abstract: The objective of this invention is to provide a method for estimating, in the frequency domain, deconvolution operators for removing spurious resonant coupling responses from the cross-line and the vertical seismic signal components in OBC surveys. The purpose is to balance the spectral response of the respective signal component in amplitude and phase in a manner consistent with the field geometry.

Abstract: The present invention provides a method of migrating seismic records that retains the information in the seismic records and allows migration with significant reductions in computing cost. The present invention comprises phase encoding seismic records and combining the encoded seismic records before migration. Phase encoding can minimize the effect of unwanted cross terms while still allowing significant reductions in the cost to migrate a number of seismic records.

Abstract: A method for determining water bottom reflectivities whereby pressure signals and velocity signals are combined to generate combined signals having signal components representing downwardly-travelling energy substantially removed. The pressure and velocity signals correspond to seismic waves generated at source locations n in a water layer and detected by co-located pressure and velocity receivers at receiver locations m in the water layer. The combined signals correspond to each pairing of source location n and receiver location m. The combined signals are transformed from the time domain to the frequency domain, generating transformed signals. A source peg-leg term and a receiver peg-leg term is calculated for each transformed signal, generating filtered signals. An optimization algorithm is applied to the filtered signals, using the corresponding source and receiver peg-leg terms to determine the water bottom reflectivity values R.sub.n and R.sub.

Abstract: A method for operating a computer to reduce the memory needed to store seismic data. The seismic measurements are first organized into a multi-dimensional data array. The multi-dimensional data array is than sub-band coded to form a coded data array by applying a one-dimensional transformation corresponding to each dimension of the data array to that dimension of the data array. The transformation is determined by the frequency content of the corresponding dimension of the data array. The sub-band coded data array is then quantized to provide a compacted data array.