517 results about "Wave equation" patented technology

The instant invention is a method for numerically propagating waves or solving wave equations on a digital computer. This invention can be used to compute highly accurate solutions to the wave equation, in fact in some cases it computes the analytical solution, something previously considered impossible. The instant method can also propagate waves that are not described by differential equations, such as anisotropic scalar waves. The invention has the advantages that it is computationally efficient, accurate, and flexible. Of importance is the ability to propagate waves that simulate the P-wave arrivals in both isotropic and anisotropic media with a scalar as opposed to a vector equation.

Method for interpolating aliased seismic data to generate shot records at regular shot points. The method involves sorting the data into common offsets to obtain the finer sampling in the common-offset domain, then using DMO to transform the data to zero offset to eliminate azimuth and offset variations, from which densely sampled shot records are reconstructed by an efficient Log-Stretch Inverse Shot Record DMO. The method has ready application to techniques that benefit from input data that are regularly and densely sampled, such as 3-D surface related multiple elimination and shot record wave equation migration.

A method for estimating near-surface material properties in the vicinity of a locally dense group of seismic receivers is disclosed. The method includes receiving seismic data that has been measured by a locally dense group of seismic receivers. Local derivatives of the wavefield are estimated such that the derivatives are centered at a single location preferably using the Lax-Wendroff correction. Physical relationships between the estimated derivatives including the free surface condition and wave equations are used to estimate near-surface material properties in the vicinity of the receiver group. Another embodiment of the invention is disclosed wherein the physical relationships used to estimate material properties are derived from the physics of plane waves arriving at the receiver group, and the group of receivers does not include any buried receivers.

The invention discloses a method and a device for full-wave-shape inversion based on a time domain-step velocity-stress elastic wave equation, wherein the method includes: adopting an adjoint method based on the perturbation theory, and confirming the adjoint equation of the time domain-step velocity-stress elastic wave equation and a corresponding gradient expression, in regard to model parameters, of an objective functional; conforming a forward-propagating wave field according to the time domain-step velocity-stress elastic wave equation, and conforming an inverse time extrapolation adjoint wave field according to the adjoint equation; confirming the gradient, in regard to the model parameters, of the objective functional according to the forward-propagating wave field, the inverse time extrapolation adjoint wave field and the gradient expression; and using a gradient iterative algorithm to carry out multi-scale full-wave-shape inversion. According to the method for the full-wave-shape inversion, before transmitted in an inverse-time mode, a wave field residual error does not need pretreatment, the conversion problems of particle velocity and particle displacement do not need to be considered, and inversion calculation efficiency can be improved.

The invention discloses an elastic reverse time migration imaging method by combining seismic multi-component and belongs to the field of exploration geophysics. The method comprises the following steps: directly inputting seismic multi-component data; without performing the wave field separation on the input data, extrapolating forwards at inverse time based on an elastic wave equation; building an underground elastic vector seismic wave field by combining with multi-component; acquiring four elastic wave imaging results having specific physical significance, such as longitudinal wave, transverse wave, transition longitudinal wave and transition transverse wave, by applying an elastic wave cross-correlation imaging condition of lighting compensation; and suppressing the low wave number noise in the elastic reverse time migration by performing low-pass angle filtering, thereby acquiring an imaging result of final elastic wave migration. By directly inputting the seismic multi-component data and building the underground elastic vector seismic wave field by combining with multi-component, the method can be used for accurately imaging for complex earth medium.

A system and method for shallow water simulation may provide a framework for solving General Shallow Wave Equations (GSWE) to efficiently simulate 3D fluid effects on arbitrary surfaces using a height field representation. The height field representation may include height columns constructed along surface normals, which may be dependent on a condition of boundary cells adjacent to fluid cells and/or artificial viscosity effects. The framework may provide implicit schemes for solving for the effects of external forces applied to the fluid, including gravity and surface tension, and explicit schemes for solving for advection effects. The system and method may be implemented on general-purpose CPU(s) and/or GPU(s) and may be capable of simulating a variety of fluid effects including: waves, rivulets and streams, drops, and capillary events. In some embodiments, the system and method may achieve real-time fluid control and fluid shape design through user-interaction (e.g., in a graphical painting application).

An instrumentation system for assessing operation of a reciprocating pump system which produces hydrocarbons from a non-vertical or a vertical wellbore. The instrumentation system periodically produces a downhole pump card as a function of a directly or indirectly measured surface card and a friction law function from a wave equation which describes the linear vibrations in a long slender rod. A control signal or command signal is generated based on characteristics of the downhole pump card for controlling the pumping system. It also generates a pump and well analysis report that is useful for a pump operation and determination of its condition.

The present invention relates to a method of processing data representing energy propagating through a medium (e.g., acoustic, elastic or electromagnetic energy) and describes an efficient and flexible e approach to forward modeling and inversion of such energy for a given medium. The representation theorem for the wave-equation is used, in combination with time-reversal invariance and reciprocity, to express the Green's function between two points in the interior of the model as an integral over the response in those points due to sources regularly distributed on a surface surrounding the medium and the points.

A staggered grid 3D seismic prestack reverse time migration imaging method based on GPU small storage capacity is a very important technology for 3D prestack depth migration imaging of complex structures. The reverse time migration method based on the two-way wave equation has been realized, which can accurately image the rotary wave and the large-angle reflected wave, and at the same time solve the problem of the large amount of calculation of this method. Utilizing parallel computing technology based on GPU hardware, staggered grid difference format, checkpoint storage and other technologies, and relying on Laplace imaging conditions, the pre-stack reverse time migration imaging of 3D seismic data is realized, which greatly shortens the computing time. The efficiency has been increased hundreds of times, and the imaging accuracy has been significantly improved.

Solving wave equation with damp calculates rate of change from swabbing parameters including stroke, number of strokes, diameter of pump, depth of pump, diameter and length of sucker rod etc. to system effectiveness. Sorting rate of change is carried out according to magnitude of absolute value. Under limiting conditions of well yield, load, torque moment etc, analyzing degree of sensitivity of swabbing parameters, the invention optimizes a group of optimal swabbing parameters for oil pumping well system. The method can calculate out polished rod horsepower, efficiencies of sucker rod, and oil pipe difficult to calculate out before. Carrying out quantitative analysis for each factor affecting system effectiveness, the invention solves issue of designing complex parameters so as to raise system effectiveness. The invention is applicable to oil pumping well system composed of inclined well or straight well, different typed pumping units and electric motor.

A migration method using hybrid one-way and full-way (HOF) wave equation propagation. The HOF method extrapolates seismic wavefields in less complex media with a one-way wave equation propagator and extrapolates seismic wavefields in extremely complex media with a full-way wave equation propagator. For prestack depth migration, the HOF extrapolates source-side and receiver-side wavefields independently. Frequency-space domain and time-space domain imaging conditions are applied to the one-way and the full-way extrapolated wavefields, respectively. A suitable amplitude matching factor is introduced to combine the one-way and full-way images. The HOF method is a cost-effective migration that produces superior image quality with less noises and less computational resources.

According to a preferred aspect of the instant invention, there is provided herein a system and method for extending zero-offset or stacked wave-equation illumination analysis into the angle-gather domain, where it becomes an appropriate tool for assessing the effects of complex overburden on AVA response. A preferred method for doing this involves first creating an angle gather that has a perfect AVA response (i.e. a constant amplitude as a function of angle). This gather is then preferably used as a reflectivity map that is fed into a demigration process which creates modeled data that by construction carries with it a completely flat reflectivity signature. Remigration of such a data set then results in a gather on which any amplitude variation is more likely to be a measure of illumination effects alone. The resulting AVA signature on the gather can then be used to assess the validity of the AVA response on modeled or actual data, resulting in a useful AVA risk analysis.

A method of three-dimensional preserved-amplitude pre-stack time migration which is applied to reflected seismic data treatment in seismic prospecting is a pre-stack migration imaging method aiming at the three-dimensional collected seismic data. The technical scheme comprises three aspects: 1) performing the migration amplitude calculation by using a weight coefficient acquired according to a one-way wave equation and the reverse convolution imaging condition of the depth migration, 2) confirming the time varying three-dimensional migration aperture according to the biggest incidence formed underground, and 3) automatically suppressing the migration voice by performing strip attenuation method on the edge of the migration aperture. The method of the invention realizes high-efficient, high SNR (Signal to Noise Ratio) and preserved-amplitude migration imaging by improving the migration aperture, providing a weight coefficient of the preserved-amplitude and suppressing the migration voice in the imaging process. The preserved-amplitude reflective spot collection generated by using the method of the invention can better serve for the oil gas and fluid detection technique for pre-stack inversion. The method of the invention has high application value to oil gas and mine resource exploration.

A method for generating an illumination map. The method includes receiving an earth model that represents one or more properties of the earth. The method then includes receiving a target area in the earth model and propagating one or more wavefields from the target area to a potential seismic data acquisition region in the earth model. After propagating the wavefields, the method includes decomposing the propagated wavefields into one or more subsets of the propagated wavefields and creating the illumination map based on the subsets of the propagated wavefields. The illumination map may indicate one or more contributions of one or more synthetic source and receiver pairs for illuminating the target area in the earth model. The method may then include creating a seismic survey design based on the contributions.

A one-return wave equation migration is used to extrapolate both down-going and up-going waves. Followed by a properly designed imaging condition, the partial image contributed form turning waves is correctly reconstructed. Numerical examples show that this method can significantly enhance definition of an overhanging salt boundary and a geological structure with vertical features.

The invention is a prestack depth migration method for seismic data processing of a relief land surface, determining an imaging reference plane according to the highest point of a collection region, and projecting the relief land surface to a regular grid to fill a constant speed approaching to the near land surface in the relief land surface; using Fourier finite extrapolation operators of one-way wave equation to make wave field extrapolation on shot seismic source wave fields and detector received wave fields along the depth axis, and keeping the wave field between input and output datum equal to zero; imaging the extrapolated shot and detector wave field record by conjugate related imaging conditions, and stacking the related results of each frequency and processing the imaging result into a section image by routine display software, and the invention has an obvious imaging effect of complex construction on the condition of relief land surface.

The invention relates to an anisotropic reverse time migration method for a quasi-P wave equation in a transverse isotropy with a vertical axis of symmetry (VTI) medium. The method comprises the following steps of: (1) performing discrete differentiation on a first-order quasi-P wave equation in a two-dimensional VTI medium and a perfect matched layer (PML) absorption layer boundary equation by adopting staggered meshes to obtain high-order difference formats of forward continuation and reverse continuation of the two equations; (2) performing numeric calculation to obtain a forwards-continued wave field of a shot point and a reverse time continued wave field of a receiver point, and performing normalized correlation operation on the two wave fields to obtain a migration imaging result of each imaging point in a model; and (3) extracting common imaging point gathers from migration results to obtain a final migration profile. By the method, a problem about the migration imaging of intensive transverse speed variation and a high dip angle stratum can be solved; and the influence of anisotropy of the medium is also taken into account, and the good imaging effect of longitudinal wave data acquired from an anisotropic region can be achieved by an anisotropy-theory-based migration method.

The invention provides a time domain analysis method for a transient response of lossy nonuinform multi-conductor transmission lines and aims to solve the problem that the coupling among the lossy nonuniform multi-conductor transmission lines interferes with the computation in the field of integrity of electronic circuit signals. The method comprises the following steps of: performing differential dispersion on space differential operators in an electric wave equation; and integrating time differential operators in the electrical wave equation by a trapezoidal integration method to ensure that the oscillation, which is caused by a central difference method, of a computed result can be eliminated effectively, voltage and current transient response waveforms of any point on the transmissionlines can be acquired; and the transient analysis of the transmission lines in a longer time period is effective, the waveforms can be analyzed in a longer duration without large errors, and the coupled transmission lines are not needed to be decoupled when a model of the transmission lines is built. By the method, the computational load is reduced, and the simulation efficiency is improved. The method can be used for analyzing the transient response of the lossy nonuinform multi-conductor transmission lines.

The invention relates to the prestack depth migration technique during the data processing of petroleum seismic prospecting, including the following concrete steps: establishing depth rate pattern of prestack seismic data; well designing observation grids, and solving wave equation in sphere coordinate system to simulate the communication process of seismic waves; changing and converting the calculated seismic wave field of a frequency domain into a time domain, and fitting the Green function energy spectrum of the seismic wave field in the time domain to detect the arriving time and the vibration amplitude when the maximum energy arrives; transferring the travel time and the vibration amplitude field calculated in the sphere coordinate system to a rectangular coordinate system; accomplishing the maximum energy integral prestack depth migration according to the well calculated travel time and the vibration amplitude; analyzing the operation of speed to the imaging gather of the prestack depth migration to modify the depth rate pattern; and modifying the depth rate pattern by iteration, and outputting the ultimate result until the migration result meets the precision requirement. The invention provides the self-adapting variation difference grid calculation technique so as to achieve the purpose that the difference grids are automatically and gradually thinned along with radius increase, thereby guaranteeing the finite difference calculation precision.