48 results about "Zoeppritz equations" patented technology

The invention relates to a multi-wave AVO reservoir elastic parameter inversion method based on the precise Zoeppritz equation. The method includes: a. defining amplitude scaling factors; b. counting the prior information of model parameters and calculating the covariance matrix of the relevance of the three parameters; c. building an initial elastic parameter model of the time domain; d. forward modeling the multi-wave seismic pre-stack gather based on the elastic parameter mode and the precise Zoeppritz equation and calculating the inversion residual error between the PP wave and the PS wave according to the forward modeling records and the actual records; e. building and solving the inversion objective function and obtaining the solution expression of the disturbance quantity of the model parameters; f. calculating the disturbance quantity of the model parameters according to the inversion residual error and the solution expression of the disturbance quantity; g. repeating and iterating the steps of d, e and f and obtaining an optimal model parameter. The multi-wave AVO reservoir elastic parameter inversion method based on the precise Zoeppritz equation effectively improves the calculating precision and the stability of the existing pre-stack AVO inversion method, and meets the requirement of the inversion identification of oil and gas reservoir of the seismic prestack, especially the requirement of the characterization of the shale gas reservoir.

The invention provides a shale gas reservoir brittleness earthquake prediction method and device. The method comprises the following steps: carrying out calculation by means of the generalized linear inversion thought, based on a Bayesian theory and by utilizing actual seismic data of a work area and a prior distribution function and a Zoeppritz equation of a plurality of elastic parameters, to obtain a disturbance quantity solution expression of the elastic parameters; carrying out calculation according to the solution expression and an initial model of the elastic parameters to obtain disturbance quantity value of the elastic parameters; carrying out calculation according to the disturbance quantity value and the initial model to obtain a current model of the elastic parameters; carrying out calculating based on the actual seismic data, the current model and the Zoeppritz equation of the plurality of elastic parameters to obtain seismic inversion residual error; and if the seismic inversion residual error is smaller than a set threshold value, serving the current model as the value of the elastic parameters, and carrying out calculation according to the value of the elastic parameters to obtain shale gas reservoir brittle index of the work area. The method and device can improve shale gas reservoir brittle index predication accuracy.

The invention relates to a method for performing difference AVO (amplitude versus offset) analysis by utilizing time-lapse seismic exploration data. A four-directional difference AVO expression is deduced from an approximate elastic modulus simplified formula (Bortfeld, 1961) of a Zoeppritz equation. The physical significance of difference between two time-lapse seismic AVOs is further clearly explained and the key problem of time-lapse seismic difference AVO analysis is solved. Analysis and reservoir prediction can be directly performed on amplitude difference between seismic data at two times by utilizing the expression. The difference AVO technology can be used for difference amplitude analysis of the time-lapse seismic (four-dimensional seismic) data. Changes in fluid, reflected by the difference amplitude can be fast identified. The saturation of the fluid can be further predicted.

The invention provides a method for modeling a reflection coefficient of a spherical PP wave in a viscoelastic medium and belongs to the field of geophysical prospecting for petroleum. The method comprises steps as follows: (1) a longitudinal wave phase velocity vp and a quality factor Q<-1> are calculated on the basis of a White model: the longitudinal wave phase velocity vp and the quality factor Q<-1> are calculated on the basis of the White model and reservoir parameters; (2) a reflection coefficient of a planar PP wave in a dispersive porous medium is calculated: the longitudinal wave phase velocity vp and the quality factor Q<-1> which are obtained in Step (1) are introduced in a Zoeppritz equation of the dispersive medium, and the reflection coefficient R<*>PP of the planar PP wave in the dispersive porous medium is calculated; (3) the reflection coefficient of the spherical wave is calculated: after the reflection coefficient R<*>PP of the planar PP wave is calculated in Step (2), the reflection coefficient of the spherical PP wave in the dispersive porous medium is modeled with a planar wave decomposition algorithm of the spherical wave, and the reflection coefficient R<spherical>PP of the spherical PP wave in the dispersive porous medium is calculated.

The invention provides an angular part superposition seismic data-based fluid identification method, which comprises the following three steps of: 1) rapidly estimating an impedance reflection coefficient, namely starting from Shuey approximation (Shuey, 1985) in a Zoeppritz equation, deducing a formula for accurately and rapidly estimating the impedance reflection coefficient of longitudinal and shear waves, and calculating a seismic attribute used for fluid identification; 2) extracting a new fluid identification attribute based on the angle gather part superposition seismic data, namely starting from a fluid factor formula provided in Smith and Gidlow (Smith, 2003), and obtaining the combination of the angle gather part superposition seismic data for fluid identification and reservoir prediction; and 3) performing a curvelet transform and Bayesian theory-based fluid identification, namely equalizing each angle superposition gather data by using a wavelet equalization method on the basis of the steps 1) and 2) so as to remove difference of different angles and keep the difference of different angle gather data caused by the fluid, obtaining abnormality at a target layer by using Bayesian wave field separation technology in a curvelet domain, naming the abnormality as angle fluid gather, and solving various attributes to obtain the abnormality at the target layer, wherein the attribute obtained by employing various combinations of the angle gather part superposition seismic data can better distinguish gas/oil-containing and water-containing reservoirs, particularly the attribute section obtained from the third power of the angle gather can better distinguish the gas/oil-containing and water-containing reservoirs.

The invention provides a pre-stack seismic wide angle retrieval method. The pre-stack seismic wide angle retrieval method comprises the following steps: inputting at least three angle stacking seismic data volumes, at least three corresponding wavelets, longitudinal wave speeds, a transverse wave speed and an initial density model; creating a pre-stack retrieval objective function; expanding the taylor series of the pre-stack retrieval objective function; deriving parameters through the matrix form of a Zoeppritz equation to obtain the partial derivatives of a reflection coefficient to the longitudinal wave speeds, the transverse wave speed and the density; according to actual data, decreasing computing amount through matrix partitioning; computing the perturbation of a retrieval parameter; and controlling the convergence of the retrieval objective function through the computed perturbation of the retrieval parameter to obtain a pre-stack retrieval parameter. The pre-stack seismic wide angle retrieval method solves the problems that the approximate conditions of the validity of the Zoeppritz equation are difficult to met and the error is great in the prior art, and has the advantages of wide application range, small error and high retrieval precision.

The invention discloses a method and system for utilizing the inversion of modulus of elasticity parameters to predict coal bed gas. The method comprises the steps of simplifying a Zoeppritz equation set so as to obtain a modulus of elasticity approximate expression of the Zoeppritz equation set, wherein according to the modulus of elasticity approximate expression of the Zoeppritz equation set, in the expression, the lame constant relative variation, shear modulus relative variation, and relative density variation are provided; on the logging constraint condition, utilizing the modulus of elasticity approximate expression of the Zoeppritz equation set to conduct simultaneous inversion of the lame constant relative variation, the shear modulus relative variation, and the relative density variation before stacking, and predicting the coal bed gas according to the inversion results.

The invention discloses a method and system for calculating frequency change AVO response of a directionally-cracked pore medium. The method can comprise the steps of: establishing a stratigraphic model of the directionally-cracked pore medium based on a Brajanovski model, and acquiring a longitudinal wave volume modulus of the directionally-cracked pore medium; acquiring an elastic rigidity coefficient of the directionally-cracked pore medium based on the longitudinal wave volume modulus of the directionally-cracked pore medium, as well as a plurality of low-frequency limit elastic rigidity coefficients and a plurality of high-frequency limit elastic rigidity coefficients; and acquiring the frequency change AVO response of the directionally-cracked pore medium based on the elastic rigidity coefficient of the directionally-cracked pore medium and a Zoeppritz equation of a viscoelastic VTI medium.

The invention discloses a forward simulation method for a sand-mud interbed CO2 geology sealing time-shifting earthquake without shear wave velocity logging. The method comprises the following steps: collecting data; extracting the data layer by layer; using logging information to calculate a sandstone mineral composition curve, calibrating the longitudinal and shear wave velocity under the pressure condition after the CO2 injection, and forecasting the shear wave velocity; executing the mixed fluid to replace the longitudinal and shear wave velocity curve after the injection; reserving the logging information time-depth conversion of the thin-layer information and using a Zoeppritz equation to calculate the reflection coefficient; executing the convolution with Ricker wavelet to obtain a synthetic seismogram; and using the time-shifting forward artificial synthetic seismogram of the different injection stages and different basic frequencies before and after the CO2 injection to subtract, to obtain the difference forward earthquake response. The method is capable of, in allusion to the feature of the complicated sand-mud thin interbed, solving the mixed fluid saturation replacement problem of the different reservoir features in the CO2 oil flooding and geology sealing process better and forecasting the longitudinal and shear wave velocities of the pressure change in the CO2 injection stage.

The invention provides a prestack high-resolution fluid factor inversion method based on frequency division joint inversion. The prestack high-resolution fluid factor inversion method comprises the following steps: rewriting an accurate Zoeppritz equation in a traditional form based on a pore elasticity theory to obtain an accurate Zoeppritz equation in a new form containing a fluid factor item; constructing a multi-wave data frequency division joint inversion target function under a Bayesian framework by utilizing a frequency division processing result of actual seismic data of a work area, apriori distribution function of a plurality of reservoir parameters obtained by logging data statistics and a derived new form Zoeppritz equation; solving the target function by using Taylor series expansion to obtain a solving expression of the reservoir parameter disturbance quantity; and carrying out iterative solution on the solution expression, and carrying out iterative updating on the initial reservoir parameter value by utilizing a solution result until an iterative termination condition is reached. The prediction precision of the reservoir fluid factor can be improved.

The invention discloses a shale gas identification method based on deepest descent prestack precise equation fluid inversion. The method is characterized in that an objective function based on fluid identification parameters is constructed through the Zoeppritz equation and a porous medium rock-physics model, and an iterative equation is obtained through deduction and inversion. The method has theadvantages that prestack inversion is directly carried out through the Zoeppritz equation, so that limitations for small angles caused by a Zoeppritz approximate expression can be avoided, and large-angle seismic materials can be better utilized; through the deepest descent algorithm, the convergence efficiency can be improved, and the calculation load can be reduced; and the deepest descent inversion is carried out through the non-simplified Zoeppritz equation, so that estimated values of the fluid identification parameters can be accurately and rapidly obtained, and a more reliable basis can be further provided for shale gas identification.

The invention discloses a method and a device for nonlinear longitudinal wave AVO inversion. The device includes: obtaining pre-stack angle gather data, said pre-stack angle gather data including longitudinal wave reflection coefficients Rpp(θi) corresponding to N incident angles θi, i=1, 2,...,N; respectively expanded as The Taylor series of the P-wave velocity change rate rα, S-wave velocity change rate rβ, and density change rate rρ are substituted into the Zoeppritz equations, and the P-wave reflection coefficient is expressed as the high-order nonlinearity of P-wave velocity change rate, S-wave velocity change rate, and density change rate. Linear function; invert rα, rβ, rρ based on prestack angle gather data and this formula. By applying the invention, the change rate of the elastic parameter with high precision can be obtained by inversion, and the calculation efficiency is high.

The invention provides an accurate Zeoppritz equation seismic amplitude inversion method based on a saturated medium. According to the scheme, firstly, saturated seismic wave velocity containing fluid parameters is introduced into an elastic medium Zoeppritz equation to represent an isotropic saturated medium; then, by means of the perturbation theory and the Taylor expansion method, the problem of solving the target function is converted into the problem of solving the gradient or partial derivative of the reflection coefficient to the model parameters; an iterative least square algorithm and a Bayesian theory are combined, a model parameter iterative update expression is established, a multi-wave saturated medium fluid factor nonlinear direct inversion method based on an accurate Zoeppritz equation is provided, and finally quantitative characterization and accurate prediction containing fluid characteristics and distribution rules are achieved.

The invention belongs to the technical field of natural gas hydrate reservoir exploration, and discloses a natural gas hydrate reservoir information evaluation method and application thereof. Generating a plurality of natural gas hydrate reservoir models from the microcosmic mode, reservoir porosity, hydrate saturation and reservoir thickness of the natural gas hydrate based on a biphasic medium theory; a Brekhovski equation is used for accurately describing an AVO curve of a natural gas hydrate model, indirect relation between typical hydrate reservoir AVO marks and reservoir rock physical parameters is established, and therefore prediction and evaluation of a hydrate reservoir are achieved. According to the method, a Brekhovski equation considering the thickness of the thin layer is usedas a basic formula, the limitation of semi-infinite medium hypothesis of a Zoeppritz equation is avoided, the calculation of the AVO curve of the thin layer is more accurate, and the prediction and evaluation precision of the hydrate reservoir is improved.

The invention provides a design method of a converted wave-highlighted VSP observation system, and belongs to the field of seismic exploration in the petroleum industry. The design method comprises the following steps: (1) according to physical parameters of an exploration target layer, solving a Zoeppritz equation to obtain relationships between a P wave reflecting coefficient and a PSV wave reflecting coefficient of the target layer and incident angles; according to change rules of the reflecting coefficients, determining the effective incident angle theta P1-theta P2 of the P wave and the effective incident angle theta S1-theta S2 of the PSV wave of the target layer; (2) according to conditions of an exploration task and a VSP acquisition device, determining arrangement depths the of wave detectors in a well and intervals between the wave detectors; (3) for each CCP surface element, tracing and calculating a ray in a PSV wave receiving point-CCP-shot point direction according to the superposition times required by the task, and calculating a shot point position at which the incident angle is within the effective incident angle theta S1-theta S2 of the PSV wave to generate a density figure at the shot point position of the PSV wave.

The invention discloses a four-parameter coalbed methane predicting method and device and relates to the technical field of coalbed methane exploration and development. The method comprises the following steps that: a Zoeppritz equation set is simplified, so that an elastic modulus approximate expression of the Zoeppritz equation set can be obtained, wherein the elastic modulus approximate formulaof the Zoeppritz equation set is described in the descriptions of the invention, delta k/M in the approximate formula is a volume modulus relative change factor, delta lambda/M in the approximate formula is a lame constant relative change factor, delta mu/M in the approximate formula is a shear modulus relative change factor, and delta rho/rho in the approximate formula is a density relative change factor; under a logging constraint condition, a pre-stack maximum likelihood statistical method is used for carrying out simultaneous inversion on the pre-stack volume modulus relative change factor, the lame constant relative change factor, the shear modulus relative change factor and the density relative change factor; and coalbed methane is predicted according to inversion results.

The invention relates to a pre-stack seismic multi-parameter synchronous inversion nonlinear method based on a hybrid Markov neighborhood. The inversion method uses an accurate Zoeppritz equation instead of an approximate formula to realize pre-stack seismic inversion, and introduces two constraint conditions, thereby overcoming instability during solving at different angles caused by huge difference of orders of magnitudes in multi-parameter inversion. Then minimization of a target function is solved by using a rapid simulated annealing algorithm, so that inversion results of three parameters, namely longitudinal wave speed, transverse wave speed and density, can be synchronously and accurately obtained. The neighborhood of the hybrid Markov random field (MRF) is used for boundary protection regularization, so that the precision of the inversion result is improved, the stability of the inversion result is controlled, and the timeliness of the inversion process is improved. When the method is used for inversion of the synthetic seismic data, a satisfactory result is obtained, and compared with traditional prestack seismic inversion, the inversion effect is obviously improved.

The invention provides a viscoelastic medium seismic inversion method based on a Zoeppritz equation. The method comprises the following steps: acquiring seismic data and logging data; obtaining angle-dependent seismic wavelets according to the obtained seismic data; obtaining prior data of a geologic horizon model according to the obtained logging data; obtaining geologic horizon model parameter initial values according to the obtained prior data; obtaining geologic horizon model parameters according to the obtained geologic horizon model parameter initial values, the angle-dependent seismic wavelets and a preset viscoelastic medium Zeoppritz reflection coefficient equation, and obtaining an inversion result according to the obtained model parameters; according to the method, inversion is carried out based on the accurate Zeoppritz equation of a seismic pre-stack viscoelastic medium AVO, the inversion calculation precision is high, the inversion parameter purposiveness is high, and accumulative errors caused by step-by-step inversion or indirect calculation are avoided.

The embodiments of the present application disclose a method for acquiring a converted wave, an electronic device, and a readable storage medium, wherein the method for acquiring a converted wave comprises: acquiring a relational expression between a P-wave reflection coefficient and an incident angle by Zoeppritz equation; simplifying the relational expression between the P-wave reflection coefficient and the incident angle; calculating a derivative for the simplified relational expression between the P-wave reflection coefficient and the incident angle, to obtain an expression of a wave to be converted; correcting parameters in the expression of the wave to be converted to obtain a converted wave.

The invention discloses a well section gas layer identification method and system based on pre-stack and post-stack joint inversion. The method comprises the steps of obtaining the pre-stack seismic data of a well section, wherein the pre-stack seismic data comprises a two-dimensional seismic profile, obtaining an angle gather of a well section in the two-dimensional seismic profile, selecting anangle wavelet from the angle gather, performing pre-stack seismic inversion on the wavelet of each angle to obtain a corresponding transverse wave speed, matching the transverse wave speed with logging data, and selecting an optimal angle wavelet according to a matching result, calculating a reflection coefficient of the well section through a Zoeppritz equation, conducting convolution on the reflection coefficient and the optimal angle wavelet to obtain a direct inversion transverse wave speed, calculating according to the direct inversion transverse wave speed and a constraint formula to obtain a longitudinal and transverse wave speed ratio, calculating the gas saturation of the two-dimensional seismic profile according to the longitudinal and transverse wave speed ratio and the gas saturation of the single well logging in the two-dimensional seismic profile, and identifying the gas layer through the gas saturation of the two-dimensional seismic section.

The invention provides an oil and gas detection method of a deep river channel sand body based on a decompaction effect. The method includes steps: 1) editing and correcting a logging curve; 2) taking accurate interval transit times of a mudstone formation and a sandstone formation from shallow to deep, and respectively establishing normal compaction trend curves of mudstone and sandstone; 3) subtracting the compaction trend from a speed curve above a well to obtain a well speed curve after removing the compaction trend; 4) calculating parameters including the p-wave impedance, the s-wave impedance, and the Poisson's ratio etc. based on decompaction, further calculating inversely proportional Poisson's ratio parameters, and determining a threshold for containing coil and gas of a reservoir through crossed analysis; and 5) performing pre-stack simultaneous inversion based on a Zoeppritz equation, obtaining a plurality of elastic parameter bodies, further calculating inversely proportional Poisson's ratio parameter bodies, and predicting the oil-gas bearing property of the reservoir. According to the method, the influence of the formation compaction effect is eliminated so that the sensitivity of fluid parameters of the reservoir is improved; besides, the limitation of oil and gas detection of the deep river channel sand body by many oil and gas detection methods is broken through, the prediction precision of the reservoir fluid is improved, and oil and gas exploration risks are reduced.

The invention discloses an AVO inversion method and system based on Bayesian and series inversion theories. The method can comprise the steps that according to a Zoeppritz equation and a Gassmann theory, a fluid item high-order AVO expression based on incidence angle approximation is obtained; according to a series theory, parameters of the fluid item high-order AVO expression are calculated, anda fluid item high-order AVO formula is obtained; according to a Bayesian theory, an inversion objective function is obtained; and according to the fluid item high-order AVO formula and the inversion objective function, a prestack longitudinal wave high-order AVO inversion formula is constructed. According to the AVO inversion method and system based on the Bayesian and series inversion theories, based on the Zoeppritz equation and the Gassmann theory, the prestack longitudinal wave high-order AVO inversion formula is constructed by combining the Bayesian theory and the series inversion theory,actual work area reservoir fluid recognition with high precision, high stability, high noise immunity and high efficiency can be achieved, and the method and system have extremely high industrial practical value and application and popularization prospects.