CN104793242A - Extraction method and system of pre-stack ray-parameter-field trace gather - Google Patents

Abstract

The invention discloses an extraction method and system of a pre-stack ray-parameter-field trace gather. The method comprises that time sampling points are set for a read-in earthquake data trace gather to be processed; in each time sampling point, the ray parameter coefficient is determined in the minimum error principle, ray parameters corresponding to different offsets are calculated based on the ray parameter coefficient, and distribution of the ray parameters in the time offset domain is formed; and normal moveout correction is carried out on the pre-stack trace gather, and data of sampling points whose ray parameters are the same in the normal moveout correction result of the pre-stack trace gather is superposed to extract the trace gather of common ray parameters. The extraction method and system do not rely on a velocity model, the high-precision pre-stack ray-parameter-field trace gather can be provided for pre-stack inversion of storage layer elastic parameters of earthquake data, the relation that the amplitude extracted from the earthquake pre-stack trace gather data changes with the ray parameters correctly describes the relation that the storage layer changes with the ray parameters, and the inversion precision of the storage layer elastic parameters and the predication precision of the air-containing characteristic of the storage layer are both improved.

Description

A kind of road, prestack ray parameter territory collection abstracting method and system

Technical field

The present invention relates to geophysics oil vapour exploration engineering field, particularly relate to a kind of prestack ray parameter territory road collection abstracting method and system.

Background technology

From the existing method utilizing seismic wave analysis formation lithology, in prestack common midpoint gather, Seismic Reflection Amplitude changes (AVO) with offset distance change.Prestack angle domain AVO inverting is the important technology of reservoir elastic parameter inversion and reservoir prediction, fluid prediction, can be obtained velocity of longitudinal wave, shear wave velocity, density, the important parameter such as p-wave impedance and S-wave impedance of reservoir by prestack angle domain AVO inverting.And the gordian technique of prestack angle domain AVO inverting is the conversion from offset distance to angle.Each Seismic Traces has a fixing geophone offset, and on road, different instance sample point has different reflection angle.In order to obtain the information that echo amplitude changes with incident angle, must time m-offset distance territory constant offset be converted to apart from common midpoint gather time m-angle domain the road collection of fixation reflex angle.In prior art, when being converted to angle from offset distance, ray tracing needs known speed model.Rate pattern conventional at present has following four kinds: uniform dielectric model, layered medium model, continuum Model and interlayer continuum Model.Uniform dielectric model ignores speed with change in depth relation, and suppose that from ground to the speed of position, reflection horizon be constant, ray is the straight line between reflection spot and eye point.The angle value obtained by this model is less than normal, and disappearance wide-angle, is unfavorable for prestack angle domain AVO inverting.Layered medium model hypothesis speed is phase step type change (as shown in Figure 1) with the degree of depth, and ray form is broken line.This model needs the number of plies at artificial setting speed interface, and refraction makes eye point side-play amount reverse with the reflection degree of depth, easily causes angle form partition.Continuum Model utilizes statistical method to obtain speed with change in depth relation, and ray is a smooth curve.But this model, it is considered that the general trend of velocity variations, have ignored the localized variation of speed, therefore at the position that velocity variations is violent, can not describe rightly.Interlayer continuum Model hypothesis speed be phase step type change with the degree of depth, while be again continuum Model in interlayer speed.This model had both emphasized speed localized variation and continuity thereof, maintained again the consistance of localized variation and overall variation, but also needed the number of plies at artificial setting speed interface.The precision of above-mentioned four kinds of rate patterns determines the precision being converted to angle from offset distance.Although from uniform dielectric model, continuum Model, layered medium model to interlayer continuum Model, the precision of each rate pattern progressively improves, but due to speed cannot be described exactly, when the process of actual seismic data, the error of the angle that the angle calculated based on each rate pattern and actual seismic are propagated is comparatively large, and this error directly affects the precision of precision based on prestack angle gathers inverting stratum elastic parameter and the prediction of seismic data reservoir gas-bearing property.As shown in Figure 2 A and 2B, calculate layered halfspace angle for uniform dielectric model, the angle value that this model calculates is less than normal, larger with the error of real angle, within the scope of 1.5 times of offset distances, angle relative error, up to 38%, has a strong impact on prestack angle domain AVO elastic parameter inversion precision.Although Zhang Feng in 2011 etc. propose new prestack ray impedance and elastic parameter inversion technology, improve reservoir elastic parameter inversion and reservoir prediction precision to a certain extent, but the method is in from offset distance to the transfer process in ray parameter territory, still Negotiation speed model is needed to carry out ray tracing to calculate raypath and angle, and then be ray parameter from angle and rate conversion, therefore the ray parameter of the method conversion still by the impact of rate pattern precision, can not can correctly describe Amplitudeversusangle relation.

Summary of the invention

In order to solve the problems of the technologies described above, the invention provides a kind of high-precision prestack ray parameter territory road collection abstracting method and the system that can not rely on rate pattern.

The method comprises the following steps:

S100, read in pending seismic-data traces collection, treat processing seismic data road collection setup times sampled point;

S200, at each time-sampling point place, according to error minimum principle determination ray parameter coefficient, then based on the ray parameter that the different offset distance of described ray parameter coefficient calculations is corresponding, thus form ray parameter in the distribution of time migration apart from territory;

S300, carry out prestack road collection normal moveout correction, to the identical sampling number of ray parameter in prestack road collection normal moveout correction result according to superposing to extract common ray parameter road collection.

Particularly, in above-mentioned steps S100, described pending seismic-data traces integrates as compressional wave prestack common midpoint gather.

Or in above-mentioned steps S100, described pending seismic-data traces integrates as transformed wave prestack CRP gather.

In addition, above-mentioned time-sampling point is the self excitation and self receiving time point of zero-offset in pending seismic-data traces collection.

Particularly, above-mentioned steps S200 comprises following little step:

S210, be each time-sampling point t _0iselect one group of parameter coefficient { (A _j, B _j), j=1,2......;

S220, by every a pair system of parameters number (A _j, B _j) substitute into the calculating whilst on tour t that following formula calculates correspondence with it _j, and analytical calculation whilst on tour t _jand the error between real travel time t:

$t_j=t_{0i}+\frac{1}{3}{A}_j{x}^3+\frac{1}{2}{B}_j{x}^2$

In formula, x is offset distance;

S230, all parameter coefficient { (A to be obtained _j, B _j), after the error result of the calculating whilst on tour that j=1,2...... are corresponding, therefrom select the minimum parameter coefficient of error as time-sampling point t _0ithe ray parameter coefficient (A, B) at place;

S240, ray parameter coefficient (A, B) is substituted into following formula to calculate ray parameter p corresponding to different offset distance x:

p=Ax ²+Bx。

Particularly, in above-mentioned steps S300, based on known ray parameter coefficient (A, B), carry out prestack road collection normal moveout correction by following formula:

$\mathrm{\Δ}{t}_i=t-t_{0i}=\frac{1}{3}A{x}^3+\frac{1}{2}B{x}^2$

In formula, t is real travel time, and x is offset distance, Δ t _ifor with time-sampling point t _0icorresponding normal moveout.

In addition, the present invention also provides road, a kind of prestack ray parameter territory collection extraction system, it is characterized in that, comprising:

Pretreatment module, for reading in pending seismic-data traces collection, treats processing seismic data road collection setup times sampled point;

Analysis module, at each time-sampling point place, according to error minimum principle determination ray parameter coefficient, then based on the ray parameter that the different offset distance of described ray parameter coefficient calculations is corresponding, thus forms ray parameter in the distribution of time migration apart from territory;

Take out collection module, for carrying out prestack road collection normal moveout correction, the sampling number certificate identical to ray parameter in prestack road collection normal moveout correction result superposes to extract common ray parameter road collection.

Further, above-mentioned analysis module comprises with lower unit:

Pretreatment unit, for being each time-sampling point t _0iselect one group of parameter coefficient { (A _j, B _j), j=1,2......;

Analytic unit, for by every a pair system of parameters number (A _j, B _j) substitute into the calculating whilst on tour t that following formula calculates correspondence with it _j, and analytical calculation whilst on tour t _jand the error between real travel time t:

$t_j=t_{0i}+\frac{1}{3}{A}_j{x}^3+\frac{1}{2}{B}_j{x}^2$

In formula, x is offset distance;

Parameter selection unit, for from all parameter coefficient { (A _j, B _j), select the minimum parameter coefficient of error in the error result of the calculating whilst on tour that j=1,2...... are corresponding as time-sampling point t _0ithe ray parameter coefficient (A, B) at place;

Computing unit, ray parameter coefficient (A, B) is substituted into following formula to calculate ray parameter p corresponding to different offset distance x:

p=Ax ²+Bx。

Further, above-mentioned collection module of taking out comprises prestack road collection normal moveout correction unit, for based on known ray parameter coefficient (A, B), carries out prestack road collection normal moveout correction by following formula:

$\mathrm{\Δ}{t}_i=t-t_{0i}=\frac{1}{3}A{x}^3+\frac{1}{2}B{x}^2$

In formula, t is real travel time, and x is offset distance, Δ t _ifor with time-sampling point t _0icorresponding normal moveout.

Compared with prior art, method and system of the present invention can have the following advantages by tool: the present invention is based on ray parameter is the derivative of seismic wave propagation whilst on tour to offset distance, proposition directly can ask for ray parameter coefficient by the slope of reflection line-ups, because solution procedure is driven by geological data completely, therefore angle calculation is avoided in prior art to the dependence of rate pattern precision, thus provide high precision prestack ray parameter territory Dao Ji for geological data prestack inverting reservoir elastic parameter, make the variation relation correctly describing the amplitude ray parameter corresponding to reservoir from the variation relation of the amplitude ray parameter of earthquake prestack road collection extracting data, reservoir elastic parameter inversion precision and reservoir gas-bearing property precision of prediction can be improved.

Other advantages of the present invention, target and feature will be set forth to a certain extent in the following description, and to a certain extent, based on will be apparent to those skilled in the art to investigating hereafter, or can be instructed from the practice of the present invention.Target of the present invention and other advantages can by instructionss below, claims, and in accompanying drawing, specifically noted structure realizes and obtains.

Accompanying drawing explanation

Accompanying drawing is used to provide a further understanding of the present invention, and forms a part for instructions, with embodiments of the invention jointly for explaining the present invention, is not construed as limiting the invention.In the accompanying drawings:

Fig. 1 is prior art laminate dielectric model schematic diagram;

Fig. 2 A be angle and the real angle calculated based on uniform dielectric model in prior art compare schematic diagram;

Fig. 2 B is the relative error schematic diagram based on the angle of uniform dielectric model calculating shown in Fig. 2 A;

Fig. 3 is the workflow diagram of road, prestack ray parameter territory collection abstracting method in one embodiment of the invention;

Fig. 4 A be the ray parameter that calculates in one embodiment of the invention with real ray parameter compare schematic diagram;

Fig. 4 B is the relative error schematic diagram of the ray parameter calculated shown in Fig. 4 A;

Fig. 5 is the schematic diagram of the calculating whilst on tour obtained in one embodiment of the invention.

Embodiment

For making the object, technical solutions and advantages of the present invention clearly, below in conjunction with accompanying drawing, the present invention is described in further detail.

Base area seismic wave whilst on tour is theoretical, and in common midpoint gather, ray parameter p is the derivative of whilst on tour t to offset distance x:

$p=\frac{\mathrm{dt}}{\mathrm{dx}}.$

The present inventor proposes a kind of method directly obtaining ray parameter on road collection by asking for reflection line-ups slope accordingly.The method not desirably under speed prior imformation, the dependence to rate pattern precision can be avoided, there is the advantage of complete earthquake data-driven.

According to ray tracing theoretical forward simulation layered medium model whilst on tour, meet following quadratic function relation by the relation of the ray parameter p and offset distance x that analyze known different offset distance:

p=Ax ²+Bx （1）

Wherein, A and B is two unknowm coefficients.

Therefore, corresponding apart from increment dx with minor shifts time increment dt is:

dt=pdx=(Ax ²+Bx)dx （2）

Integration is carried out to formula (2) corresponding normal moveout Δ t can be obtained:

$\mathrm{\Δt}=\underset{0}{\overset{\mathrm{\Δt}}{\∫}}\mathrm{dt}=\underset{0}{\overset{x}{\∫}}\mathrm{pdx}=\underset{0}{\overset{x}{\∫}}(A{x}^2+\mathrm{Bx})\mathrm{dx}=\frac{1}{3}A{x}^3+\frac{1}{2}B{x}^2$

The reflection interval of so different offset distance meets following formula:

$t=t_0+\mathrm{\Δt}=t_0+\frac{1}{3}A{x}^3+\frac{1}{2}B{x}^2---\left(3\right)$

Wherein, t ₀it is the self excitation and self receiving time of zero-offset.

Formula (3) had both been applicable to calculate compressional wave whilst on tour, was applicable to again calculate transformed wave whilst on tour.

Thus, when known different offset distance seismic event whilst on tour, according to just drilling whilst on tour and real travel time error minimum principle, coefficient A and B of inverting ray parameter p, and then ray parameter p can be determined.

Based on above-mentioned principle, road, ray parameter territory of the present invention collection abstracting method comprises the following steps (as shown in Figure 3):

S100, read in pending seismic-data traces collection, treat processing seismic data road collection setup times sampled point:

In the specific implementation, pending seismic-data traces collection can be compressional wave prestack common midpoint gather or transformed wave prestack CRP gather, and in time-sampling point preferred road collection, the self excitation and self receiving time point of zero-offset, is designated as t _0i, i ,=12.......

S200, at each time-sampling point place, according to error minimum principle determination ray parameter coefficient, then based on the ray parameter that the different offset distance of described ray parameter coefficient calculations is corresponding, thus form ray parameter in the distribution of time migration apart from territory.Specifically can comprise the following steps S210 ~ S240:

S210, be each time-sampling point t _0iselect one group of parameter coefficient { (A _j, B _j), j=1,2......;

S220, by every a pair system of parameters number (A _j, B _j) substitute into the calculating whilst on tour t that following formula calculates correspondence with it _j, and analytical calculation whilst on tour t _jand the error between real travel time t:

$t_j=t_{0i}+\frac{1}{3}{A}_j{x}^3+\frac{1}{2}{B}_j{x}^2$

In formula, x is offset distance;

S230, all parameter coefficient { (A to be obtained _j, B _j), after the error result of the calculating whilst on tour that j=1,2...... are corresponding, therefrom select the minimum parameter coefficient of error as time-sampling point t _0ithe ray parameter coefficient (A, B) at place;

S240, ray parameter coefficient (A, B) is substituted into following formula to calculate the ray parameter p corresponding to different offset distance x:

p=Ax ²+Bx。

S300, carry out prestack road collection normal moveout correction, to the identical sampling number of ray parameter in prestack road collection normal moveout correction result according to superposing to extract common ray parameter road collection.Specifically can comprise the following steps S310 ~ S320:

S310, carry out prestack road collection normal moveout correction:

Treat all time-samplings point completing steps S200, form ray parameter after the distribution in time migration distance territory, based on known ray parameter coefficient (A, B), carry out prestack road collection normal moveout correction by following formula:

$\mathrm{\Δ}{t}_i=t-t_{0i}=\frac{1}{3}A{x}^3+\frac{1}{2}B{x}^2$

In formula, t is real travel time, Δ t _ifor with time-sampling point t _0icorresponding normal moveout.

S320, extraction ray parameter road collection altogether:

In the prestack road collection normal moveout correction result of step S310, the sampling number certificate identical to ray parameter p superposes to form cascode line parameter p road, is also the prestack ray parameter territory Dao Ji that the present invention needs.

As shown in Figure 4 A and 4 B shown in FIG., comparative result and the relative error thereof of ray parameter and the real ray parameter calculated according to formula (1) is respectively illustrated.As seen from the figure, formula (1) calculate ray parameter and real angle basically identical, and within the scope of 1.5 times of offset distances, ray parameter relative error is no more than 1.5%.As shown in Figure 5, the calculating whilst on tour (black bold dashed lines) obtained according to the present invention with utilize Fig. 1 layered medium forward modeling seismic channel set whilst on tour basically identical, correctly describe amplitude ray parameter variation relation.In addition, by known to the application of rich Canyon multi-wave seismic data, the present invention is compared with conventional angle domain elastic parameter inversion method, four sections of reservoir velocity of longitudinal waves inverting rate of coincideing must bring up to 0.62 from 0.57, S-wave velocity inversion rate of coincideing brings up to 0.67 from 0.57, inversion of Density rate of coincideing brings up to 0.72 from 0.46, thus further demonstrate, the present invention can provide high precision prestack ray parameter territory Dao Ji for geological data prestack inverting reservoir elastic parameter, make the variation relation correctly describing the amplitude ray parameter corresponding to reservoir from the variation relation of the amplitude ray parameter of earthquake prestack road collection extracting data, improve reservoir elastic parameter inversion precision and reservoir gas-bearing property precision of prediction.

Those skilled in the art should be understood that, above-mentioned of the present invention each step can realize with general calculation element, they can concentrate on single calculation element, or be distributed on network that multiple calculation element forms, alternatively, they can realize with the executable program code of calculation element, thus, they can be stored and be performed by calculation element in the storage device, or they are made into each integrated circuit modules respectively, or the multiple module in them or step are made into single integrated circuit module to realize.Like this, the present invention is not restricted to any specific hardware and software combination.

Therefore, the present invention also provides a kind of system adopting road, above-mentioned prestack ray parameter territory collection abstracting method.This system comprises:

Pretreatment module, for reading in pending seismic-data traces collection, treats processing seismic data road collection setup times sampled point;

Analysis module, at each time-sampling point place, according to error minimum principle determination ray parameter coefficient, then based on the ray parameter that the different offset distance of described ray parameter coefficient calculations is corresponding, thus forms ray parameter in the distribution of time migration apart from territory;

Take out collection module, for carrying out prestack road collection normal moveout correction, the sampling number certificate identical to ray parameter in prestack road collection normal moveout correction result superposes to extract common ray parameter road collection.

Further, above-mentioned analysis module can comprise with lower unit:

Pretreatment unit, for being each time-sampling point selection one group of parameter coefficient;

Analytic unit, for calculating calculating whilst on tour corresponding with it for every a pair system of parameters number, and the error between analytical calculation whilst on tour and real travel time;

Parameter selection unit, for selecting the minimum parameter coefficient of error, as the ray parameter coefficient at time-sampling point place in the error result from calculating whilst on tour corresponding to all parameter coefficients;

Computing unit, based on the ray parameter that the different offset distance of ray parameter coefficient calculations is corresponding.

Further, above-mentioned collection module of taking out can comprise prestack road collection normal moveout correction unit, for based on known ray parameter coefficient, carries out prestack road collection normal moveout correction.

Although the embodiment disclosed by the present invention is as above, the embodiment that described content just adopts for the ease of understanding the present invention, and be not used to limit the present invention.Technician in any the technical field of the invention; under the prerequisite not departing from the spirit and scope disclosed by the present invention; any amendment and change can be done what implement in form and in details; but scope of patent protection of the present invention, the scope that still must define with appending claims is as the criterion.

Claims (9)

1. road, a prestack ray parameter territory collection abstracting method, comprises the following steps:

S100, read in pending seismic-data traces collection, treat processing seismic data road collection setup times sampled point;

S200, at each time-sampling point place, according to error minimum principle determination ray parameter coefficient, then based on the ray parameter that the different offset distance of described ray parameter coefficient calculations is corresponding, thus form ray parameter in the distribution of time migration apart from territory;

S300, carry out prestack road collection normal moveout correction, to the identical sampling number of ray parameter in prestack road collection normal moveout correction result according to superposing to extract common ray parameter road collection.

2. road as claimed in claim 1 collection abstracting method, is characterized in that:

In described step S100, described pending seismic-data traces integrates as compressional wave prestack common midpoint gather.

3. road as claimed in claim 1 collection abstracting method, is characterized in that:

In described step S100, described pending seismic-data traces integrates as transformed wave prestack CRP gather.

4. the road collection abstracting method as described in claims 1 to 3 any one, is characterized in that:

Described time-sampling point is the self excitation and self receiving time point of zero-offset in pending seismic-data traces collection.

5. the road collection abstracting method as described in claims 1 to 3 any one, is characterized in that, described step S200 comprises following little step:

S210, be each time-sampling point t _0iselect one group of parameter coefficient { (A _j, B _j), j=1,2......;

S220, by every a pair system of parameters number (A _j, B _j) substitute into the calculating whilst on tour t that following formula calculates correspondence with it _j, and analytical calculation whilst on tour t _jand the error between real travel time t:

$t_j=t_{0i}+\frac{1}{3}{A}_j{x}^3+\frac{1}{2}{B}_j{x}^2$

In formula, x is offset distance;

S230, all parameter coefficient { (A to be obtained _j, B _j), after the error result of the calculating whilst on tour that j=1,2...... are corresponding, therefrom select the minimum parameter coefficient of error as time-sampling point t _0ithe ray parameter coefficient (A, B) at place;

S240, ray parameter coefficient (A, B) is substituted into following formula to calculate ray parameter p corresponding to different offset distance x:

p=Ax ²+Bx。

6. the road collection abstracting method as described in claims 1 to 3 any one, is characterized in that:

In described step S300, based on known ray parameter coefficient (A, B), carry out prestack road collection normal moveout correction by following formula:

$\mathrm{\Δ}{t}_i=t-t_{0i}=\frac{1}{3}A{x}^3+\frac{1}{2}B{x}^2$

In formula, t is real travel time, and x is offset distance, Δ t _ifor with time-sampling point t _0icorresponding normal moveout.

7. road, a prestack ray parameter territory collection extraction system, is characterized in that, comprising:

Pretreatment module, for reading in pending seismic-data traces collection, treats processing seismic data road collection setup times sampled point;

Analysis module, at each time-sampling point place, according to error minimum principle determination ray parameter coefficient, then based on the ray parameter that the different offset distance of described ray parameter coefficient calculations is corresponding, thus forms ray parameter in the distribution of time migration apart from territory;

Take out collection module, for carrying out prestack road collection normal moveout correction, the sampling number certificate identical to ray parameter in prestack road collection normal moveout correction result superposes to extract common ray parameter road collection.

8. system as claimed in claim 7, it is characterized in that, described analysis module comprises further with lower unit:

Pretreatment unit, for being each time-sampling point t _0iselect one group of parameter coefficient { (A _j, B _j), j=1,2......;

Analytic unit, for by every a pair system of parameters number (A _j, B _j) substitute into the calculating whilst on tour t that following formula calculates correspondence with it _j, and analytical calculation whilst on tour t _jand the error between real travel time t:

$t_j=t_{0i}+\frac{1}{3}{A}_j{x}^3+\frac{1}{2}{B}_j{x}^2$

In formula, x is offset distance;

Parameter selection unit, for from all parameter coefficient { (A _j, B _j), select the minimum parameter coefficient of error in the error result of the calculating whilst on tour that j=1,2...... are corresponding as time-sampling point t _0ithe ray parameter coefficient (A, B) at place;

Computing unit, ray parameter coefficient (A, B) is substituted into following formula to calculate ray parameter p corresponding to different offset distance x:

p=Ax ²+Bx。

9. as claimed in claim 7 or 8 system, is characterized in that, described in take out collection module and comprise prestack road collection normal moveout correction unit, for based on known ray parameter coefficient (A, B), carry out prestack road collection normal moveout correction by following formula:

$\mathrm{\Δ}{t}_i=t-t_{0i}=\frac{1}{3}A{x}^3+\frac{1}{2}B{x}^2$

In formula, t is real travel time, and x is offset distance, Δ t _ifor with time-sampling point t _0icorresponding normal moveout.