Abstract: This invention is a method of attenuating multiples in seismic data, particularly three-dimensional seismic data in which seafloor roughness is present. The method relies on an efficient ray-tracing procedure to determine travel-times for each multiple. The characteristics of the seismic data are used to estimate the waveform of the multiple to be attenuated. The travel-time and the estimated waveform are then used to attenuate the multiple from the original data. The method can be employed both for water-bottom multiples and for source and receiver pegleg multiples.

Abstract: The disclosed invention provides a method for recovering hydrocarbons from a subterranean formation by injecting an emulsion, comprising oil and water, into the formation. More specifically, the emulsion is stabilized using undissolved solid particles, which are preferably at least partially oleophilic. The solids-stabilized emulsion may be used either as a drive fluid for displacing hydrocarbons from the formation or to produce a barrier for diverting flow of fluids in the formation. Such solid particles may be either formation solid particles (i.e., indigenous to the formation) or nonformation solid particles (i.e., obtained from outside the formation). Nonformation solid particles may either be naturally occurring or synthetic. Some preferred solids include clays, quartz, feldspar, gypsum, coal dust, asphaltenes, and polymers.

Abstract: A method is disclosed of predicting a characteristic of a fluid-containing physical system such as a reservoir. The physical system is discretized to a plurality of gridcells. For each gridcell, nonlinear governing equations are constructed that are representative of fluid properties for each fluid. The nonlinear terms are linearized to derive linear equations at a current timestep. The linear equations are then solved to determine estimates of the solution. The estimated solution is then improved by a gridcell-by-gridcell computation wherein flows into and out of a particular gridcell are determined using linearized values of nonlinear terms in gridcells adjacent that particular gridcell. The improved solution is used to predict a property of a fluid in the physical system at end of the timestep. These calculation steps are repeated for a plurality of timesteps and the results are used to predict a property of the physical system and the fluids it contains as a function of time.

Abstract: A method for inhibiting the formation of clathrate hydrates in a fluid having hydrate forming constituents is claimed. More specifically, the method can be used in treating a petroleum fluid stream such as natural gas conveyed in a pipe to inhibit the formation of a hydrate restriction in the pipe. The hydrate inhibitors used for practicing the method comprise substantially water soluble polymers having N-vinyl amide or N-allyl amide units. Specific examples of such copolymers include, N-vinyl-N-methylacetamide (VIMA) copolymerized with acryloylpyrrolidine (APYD) or acryloylpiperidine (APID), and more preferably, VIMA copolymerized with N-substituted methacrylamides, such as N-isopropylmethacrylamide (iPMAM) and methacryloylpyrrolidine (MAPYD) to produce inhibitors for practicing the claimed method.

Abstract: This invention relates to a process for liquefying a gas stream rich in methane and having a pressure above about 3103 kPa (450 psia). The gas stream is expanded to a lower pressure to produce a gas phase and a liquid product having a temperature above about -112.degree. C. (-170.degree. F.) and a pressure sufficient for the liquid product to be at or below its bubble point. The gas phase and the liquid product are then phase separated in a suitable separator, and the liquid product is introduced to a storage means for storage at a temperature above about -112.degree. C. (-170.degree. F.).

Abstract: A method for reconstructing a selected seismic wavefield at a designated common midpoint and offset location from a set of prestack seismic data traces. The method uses actual data traces from other common midpoint and offset locations to reconstruct the selected wavefield at the designated reconstruction location. The method may be used to reconstruct any selected wavefield, including both primary reflection wavefields and secondary wavefields such as water-bottom multiple wavefields, and may be used with both 2-D and 3-D seismic data. If the reconstructed wavefield is a secondary wavefield, it may be subtracted from the prestack seismic data traces to eliminate interference between wavefields. The method may also be used to reconstruct data from missing shots to avoid spatial aliasing problems in other data processing operations.

Abstract: This invention relates to a process for liquefying a pressurized gas stream rich in methane in which the liquefication of the gas stream occurs in a heat exchanger being cooled by a cascade refrigeration system to produce a methane-rich liquid product having a temperature above about -112.degree. C. (-170.degree. F.). In this process, a pressurized gas stream is introduced into heat exchange contact with a first refrigerant cycle comprising at least one refrigeration stage whereby the temperature of the gas stream is reduced by heat exchange with a first portion of a first refrigerant to produce a cooled gas stream. The cooled gas stream is then introduced into heat exchange contact with a second refrigerant cycle comprising at least one refrigeration stage whereby the temperature of the cooled gas stream is further reduced by heat exchange with a second refrigerant to produce a liquefied methane-rich stream having a temperature above about -112.degree. C. (-170.degree. F.

Abstract: Computer-implemented methods of processing seismic data are subjected to quantitative evaluation by a computerized testing procedure. The effect of the data processing software under evaluation on attributes of the seismic data is measured and statistically evaluated. The effect of various user-selectable processing parameters of the software under evaluation is also measured and statistically evaluated. To evaluate the software effect on attributes, an attribute of known content represented by seismic data is selected. The seismic data represented by that attribute is processed by the processing software under evaluation. A test measure of the attribute is recomputed as indicated by the results of the processing. A quantitative statistical analysis of the similarities of the two attributes is then performed. For quality control of parameter estimates, a parameter-sweep test is performed on original data containing known events.

Abstract: A method for enhancing zero-phase seismic data traces so that subtle geologic features are easier to identify and interpret. In a first embodiment, the method comprises enhancing the amplitudes of at least the peaks and troughs in the zero-phase seismic data traces. This enhancement can be accomplished in a variety of ways. In a second embodiment, the negative second difference is calculated at each sample point along the zero-phase seismic data trace to enhance bends or kinks in the data, as well as peaks and troughs.

Abstract: Apparatus for measurement concerning fluids in a rotor or container (2) during rotation, comprising an electric or magnetic sensor (4) mounted internally on a wall in the container (2), and means (5A, 5B) for contact-free and intermittent transmission of measurement signals from the sensor (4) to a stationary measuring unit (7) outside the container. The sensor (4) comprises an active electronic circuit (8) adapted to store measurement values that are recorded during at least a portion of a revolution of the container (2), before said transmission of corresponding measurement signals to the measuring unit (7). Electric power supply to the electronic circuit (8) is provided for by generator means comprising a stationary magnet (11) near the container (2) and a coil (12) mounted in the container so that a voltage is induced in the coil (12) during movement past the magnet (11) during the rotation of the container (2).

Abstract: A method of migrating seismic data using offset checkshot survey measurements. The offset checkshot survey measurements involve raypaths similar to the migration raypaths for the seismic data, and are used to determine direct arrival traveltimes to receivers in a borehole. Embodiments of the invention provide for direct use of the traveltimes in migration, or indirect use of the traveltimes in migration via construction of a migration velocity model. The velocity model embodiments further provide for either traveltime error correction via use of interpolated error functions or construction of migration error tables. The invention can be employed for time, depth or Kirchhoff migration, in either two or three dimension, and in either prestack or poststack applications. The invention may be used to migrate any type of seismic data, including compressional-wave, shear-wave, and converted-wave seismic data.

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 for determining a substantially optimal NMO velocity function for use in stacking a CMP gather of seismic data traces. The method begins with an initial estimate of the NMO velocity function for the CMP gather. This initial estimate is typically determined through conventional seismic velocity analysis. The method then picks a first velocity-traveltime pair falling on the initial estimate of the NMO velocity function and conducts a two-dimensional interpolative search of trial velocity-traveltime pairs in the neighborhood of the pick to find a substantially optimal velocity-traveltime pair. This substantially optimal velocity-traveltime pair is the trial velocity-traveltime pair having the highest stack response and is substituted for the pick in the NMO velocity function. The method then proceeds to find substantially optimal velocity-traveltime pairs to replace each of the other picks on the initial estimate of the NMO velocity function.

Abstract: This invention relates to a process for producing pressurized liquid rich in methane from a multi-component feed stream containing methane and a freezable component having a relative volatility less than that of methane. The multi-component feed stream is introduced into a separation system having a freezing section operating at a pressure above about 1,380 kPa (200 psia) and under solids forming conditions for the freezable component and a distillation section positioned below the freezing section. The separation system produces a vapor stream rich in methane and a liquid stream rich in the freezable component. At least a portion of the vapor stream is cooled to produce a liquefied stream rich in methane having a temperature above about -112.degree. C. (-170.degree. F.) and a pressure sufficient for the liquid product to be at or below its bubble point. A first portion of the liquefied stream is returned to the separation system to provide refrigeration to the separation system.

Abstract: This invention relates to a process for liquefying a pressurized gas stream rich in methane in which the liquefication of the gas stream occurs in a heat exchanger being cooled by a closed-loop multi-component refrigeration system to produce a methane-rich liquid product having a temperature above about -112.degree. C. (-170.degree. F.) and a pressure sufficient for the liquid product to be at or below its bubble point. The liquefied gas product is then introduced to a storage means at a temperature above about -112.degree. C. (-170.degree. F.).

Abstract: A method is disclosed for treating drilling mud discharged from a well wherein the mud contains drill cuttings and paramagnetic materials such as hematite. The drilling mud is first passed through a high-gradient magnetic separator to separate the paramagnetic materials from the drilling mud. The drilling mud is then passed through a centrifuge separator to remove the drill cuttings from the drilling mud.

Abstract: Novel maleimide copolymers have at least two monomeric units, a maleimide unit and a vinyl unit having a pendant group, the pendant group having two to twenty-one carbon atoms, at least one nitrogen atom and at least one oxygen atom. The copolymer has an average molecular weight between about 1,000 and about 6,000,000. Preferred maleimide copolymers include acrylamide/maleimide copolymers, N-vinyl amide/maleimide copolymers, vinyl lactam/maleimide copolymers, alkenyl cyclic imino ether/maleimide copolymers, and acryloylamide/maleimide copolymers. The substantially water soluble maleimide copolymers are useful for inhibiting the formation of clathrate hydrates in a fluid having hydrate-forming constituents by reducing the rate of nucleation, growth, and/or agglomeration of gas hydrate crystals in a petroleum fluid stream, thereby inhibiting the formation of a hydrate blockage in the pipe conveying the petroleum fluid stream.

Abstract: A method of installing an integrated deck onto an offshore platform substructure. The integrated deck is held by a support structure on a barge and transported to a preinstalled offshore platform substructure which is adapted to receive the barge and allow aligning of the integrated deck with the substructure for mating operations. Once the barge is positioned within the substructure, tethers are connected between the barge and anchoring foundation elements to moor the barge. Then the tethers are tensioned to minimize both vertical movement and lateral movement caused by wave action. Mating of the integrated deck and the substructure proceeds while tension loads in the tethers are maintained.