CN102053275B - Method for calculating relative statics correction value of combination in single-point earthquake chamber - Google Patents

Abstract

The invention belongs to the seismic data processing in geophysical exploration for oil and geological engineering survey, and in particular relates to a method for calculating relative statics correction value of combination in a single-point earthquake chamber. Aiming at the statics correction problem of the combination in a single-point high-density earthquake detector chamber, the adopted method comprises the steps of: representing first arrival time difference of adjacent demodulator probes as a linear function of refracted wave slowness and relative static correction time difference by using refraction time of refraction waves transmitted near surface and the characteristics of mantle rock seismic waves, and calculating relative static correction time differences of all detectors within a demodulator probe combination range by adopting a numerical value statistical method. According to the invention, no near surface speed models of static correction are required to be established, thus the occupied computer resources are less, the calculated quantity is little, and the problem of dependence of the first arrival position on the earthquake focus property is overcome.

Description

A kind of relative static correction amount computing method for the indoor combination of single-point earthquake

Technical field

The seismic data that the invention belongs in the investigation of geophysical prospecting for oil and Geological Engineering is processed, near-surface velocity modeling and quiet school category in seismic prospecting, the static correcting method during especially for the indoor combination of wave detector of single-point high density earthquake.

Background technology

The earthquake of single-point high density can be eliminated landform and change the combination time difference of causing due in indoor combination, has kept to greatest extent the radio-frequency component of underground signal, thereby has had higher resolution.Generally speaking, eliminate the combination time difference and can adopt static correction and two kinds of disposal routes of residual static correction: front a kind of dependence near-surface velocity model, calculate the receiver static correction amount of each geophone station according to near-surface model and reference field, then the static correction value of the interior adjacent geophone station of calculation combination scope is poor, namely the relative static correction amount; A kind of rear method is utilized phase neighboring trace waveform similarity principle, although in theory can be directly or iteration seek out the relative static correction amount, in the single-point seismologic record often relevant noise energy much larger than useful signal, at this moment with regard to the calculating of inapplicable combination relative static correction amount.Therefore, in actual applications, usually adopt the first technology.

The calculating of existing combination static calibration amount depends on the foundation of near-surface model, and it is to investigate by near surface that a class is set up near-surface model, and method commonly used has micro logging method and little refraction method, directly measures the speed of near surface with change in depth; Another kind of is the refraction information that comprises by primary wave in seismologic record, by the hypothesis of some surface structures or calculate near-surface velocity model by chromatography conversion method.The near surface investigation obtains the reliable velocity structure of observation station, but because cost is higher, generally only carries out the measurement of finite point, sets up near-surface model and need to make space interpolation; The rate pattern of first arrival inverting does not need space interpolation, but often the speed of surface layer is difficult to accurately ask for.Therefore, in the static correction of existing seismic data, no matter adopt that a kind of model, all need to carry out residual static correction and process before stack, to eliminate the inaccurate static correction value error that causes of near-surface velocity model.

Summary of the invention

The present invention has researched and developed a kind of relative static correction method to the indoor combination of single-point seismoreceiver in order to solve the technical matters that exists in prior art.The present invention is the physical property of utilizing primary wave, quiet school time difference relatively between geophone station in direct calculation combination scope of the time difference during from the walking of adjacent geophone station primary wave, the method need not to set up near-surface velocity model, and has overcome the difficulty that the ski-jump of explosive source is difficult for picking up.

The know-why that the present invention's research and development are adopted is:

Combined area when considering the indoor combination of high density single-point seismoreceiver is less, generally should be in 20 meters radius, if the velocity variations of top layer and reduction of speed layer is not too violent, so, the factor that affects the relatively quiet school time difference between geophone station is mainly topsoil speed and elevation, according to formula, the first arrival time difference of adjacent two geophone stations of identical shot point, can be expressed as Fig. 1:

Δt＝Δr/v _b+Δh/v _w (1)

In formula, Δ t is the first arrival time difference, and Δ r is that offset distance is poor, and Δ h is difference of elevation, v _bBe refractor velocity, v _wBe waste mantle speed, in formula, first, right side is the refraction time difference, and second, right side is exactly the relative static correction time difference between geophone station, considers the time error that may exist when first arrival is picked up, and (1) formula can be write as:

Δt＝sΔr+δ+ε (2)

In formula, s is the refractor slowness, and δ is exactly the relative static correction time difference between twice, and ε is error term, if error is stochastic distribution, offset distance refractor velocity within the specific limits changes little, can utilize the method for the statistics of a plurality of shot points to obtain.

If the combination basic point in a combined area of single-point earthquake, triangle in Fig. 2 has M geophone station on every side, and offset distance is at (R1, R2) the N big gun is arranged in scope, so just can form i big gun j geophone station with respect to the first arrival time difference and offset distance difference data collection { the Δ t of combination basic point _ij, Δ r _ij(i=1 ..., M; J=1 ..., N), utilize (2) formula and the principle of least square, can obtain:

$s=\frac{\mathrm{MN}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\mathrm{\Δ}{t}_{\mathrm{ij}}\mathrm{\Δ}{r}_{\mathrm{ij}}-\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\mathrm{\Δ}{t}_{\mathrm{ij}}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\mathrm{\Δ}{r}_{\mathrm{ij}}}{\mathrm{MN}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\mathrm{\Δ}{r}_{\mathrm{ij}}-{\left(\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\mathrm{\Δ}{r}_{\mathrm{ij}}\right)}^2}---\left(3\right)$

${\mathrm{\δ}}_i=\frac{\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\mathrm{\Δ}{t}_{\mathrm{ij}}-s\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\mathrm{\Δ}{r}_{\mathrm{ij}}}{N}---\left(4\right)$

Consider the reality that refraction wave speed increases with the increase of offset distance, the offset distance scope is excessive, and the stability of statistical computation strengthens, but because the variation of refractor slowness is larger, cause final static correction relative time error as a result the error of δ strengthen; The offset distance scope is too small, the bad stability of calculating; Simultaneously, because the primary wave energy of nearly offset distance is stronger, the first break time reliability of picking up is strong, primary wave energy a long way a little less than, the reliability of first break time is relatively poor.Amid all these factors, the maximum offset that can observe according to earthquake and the characteristics of primary wave, divide different offset distance spans to use respectively (3) formula to calculate the interior refraction wave slowness of this offset distance section, calculate at last each geophone station relatively and the quiet school time difference of combination basic point.

If be { R with the interval division of offset distance ₁, R ₂..., R _L, the offset distance scope of k section (in Rk＜=R＜Rk+1), the Nk big gun is arranged, the refraction slowness that calculates according to (3) formula is sk, and the computing formula of the relative static correction amount of geophone station becomes:

${\mathrm{\δ}}_i=\frac{\underset{k=1}{\overset{L-1}{\mathrm{\Σ}}}(\underset{j=1}{\overset{N_k}{\mathrm{\Σ}}}\mathrm{\Δ}{t}_{\mathrm{ij}}-s_k\underset{j=1}{\overset{N_k}{\mathrm{\Σ}}}\mathrm{\Δ}{r}_{\mathrm{ij}})}{\underset{k=1}{\overset{L-1}{\mathrm{\Σ}}}{N}_k}---\left(5\right)$

Because the refraction wave velocity variations of minimum offset distance is larger, do not advise adopting little offset distance first arrival to participate in calculating, the Criterion of Selecting of geophone station spacing is as follows:

Criterion one: the choosing of smallest offset distance meets transfers between divisions and is:

1. greater than 5 times of yardstick in combined area

2. greater than the distance that excites between the big gun line

3. stablize the refractor degree of depth 2 times

Criterion two: the Criterion of Selecting of offset distance spacing:

1. can adopt distribution mode equidistant and that spacing progressively strengthens with the offset distance increase.

2. in any one offset distance section, effectively excite the big gun number to be not less than 10.

3. according to near-surface velocity structure and maximum offset, offset distance can divide 5～10 sections.

Implementer's case of the present invention (Fig. 3) scheme,

1. read first arrival data and each focal point and acceptance point coordinate from single-point seismological observation data;

2. seismic observation system and array mode data after the default combination

3. to the offset distance segmentation;

4. to making up rear earthquake reception channel circulation, the single-point earthquake acceptance point of selection and this road space length minimum is as the combination basic point;

5. search for the geophone station in combined area, and in the calculation combination area, all big guns of each geophone station are relatively poor with the first arrival time difference and the offset distance of combination basic point;

6. adopt following formula (3) to calculate the refraction wave slowness of each offset distance section:

$s=\frac{\mathrm{MN}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\mathrm{\Δ}{t}_{\mathrm{ij}}\mathrm{\Δ}{r}_{\mathrm{ij}}-\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\mathrm{\Δ}{t}_{\mathrm{ij}}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\mathrm{\Δ}{r}_{\mathrm{ij}}}{\mathrm{MN}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\mathrm{\Δ}{r}_{\mathrm{ij}}-{\left(\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\mathrm{\Δ}{r}_{\mathrm{ij}}\right)}^2}---\left(3\right)$

7. adopt the relatively quiet school time difference of the geophone station in following formula (5) analytical calculation combined area:

${\mathrm{\δ}}_i=\frac{\underset{k=1}{\overset{L-1}{\mathrm{\Σ}}}(\underset{j=1}{\overset{N_k}{\mathrm{\Σ}}}\mathrm{\Δ}{t}_{\mathrm{ij}}-s_k\underset{j=1}{\overset{N_k}{\mathrm{\Σ}}}\mathrm{\Δ}{r}_{\mathrm{ij}})}{\underset{k=1}{\overset{L-1}{\mathrm{\Σ}}}{N}_k}---\left(5\right)$

8. search obtains next combination basic point, repeating step 4., until finish;

9. export the result of calculation of relative static correction amount.

Described the 3. in the step foundation to the offset distance segmentation as follows,

The choosing of smallest offset distance that is used for calculating meets the following requirements:

1. greater than 5 times of yardstick in combined area;

2. greater than the distance that excites between the big gun line;

3. stablize the refractor degree of depth 2 times;

And choosing of each offset distance spacing meets the following requirements:

1. can adopt distribution mode equidistant and that spacing progressively strengthens with the offset distance increase;

2. in any one offset distance section, effectively excite the big gun number to be not less than 10;

3. according to near-surface velocity structure and maximum offset, offset distance can divide 5～10 sections.

the general data that the present invention relates to is the poor and various offset distance of first break time, offset distance is to determine when measuring in the open air, first arrival is manually to pick up or the computing machine automatic Picking, in computation process, first break time has only adopted relative variation, therefore, no matter the first arrival position is the ski-jump at energy, or at Wave crest and wave trough, not impact of net result on this programme, during actual computation, can adopt the ceiling capacity of primary wave as first break time, the automatic Picking that more is conducive to first break time, reduce processing time and human cost, overcome simultaneously the defective that explosive source must be picked up ski-jump.

Simultaneously, the technical scheme of the present invention design has been avoided earth's surface elevation and near-surface velocity field problem, with the final static correction relative time error of their comprehensive one-tenth, calculate the inverting near-surface model with respect to current static correction value, EMS memory occupation is few, and calculated amount reduces greatly, and microcomputer just can be realized, and might directly realize in the process of earthquake data acquisition monitoring.

Description of drawings

Fig. 1 is adjacent geophone station refraction wave path schematic diagram;

Fig. 2 is the receiver pattern schematic diagram;

Fig. 3 is calculation flow chart of the invention process;

Above-mentioned each width accompanying drawing is illustrated in connection with summary of the invention and embodiment.

Embodiment

Fig. 1 is the refraction wave path schematic diagram of same shot point adjacent geophone station; 1. waste mantle 2. the reduction of speed layer 3. tear open and penetrate layer

Fig. 2 is receiver pattern and offset distance segmentation schematic diagram, and this figure illustrates that intuitively offset distance in implementation step 6 participates in geophone station and the sp location of calculating between R1 and R2; Wherein Δ makes up the shot point that the geophone station sp location ■ in the basic point combined area chooses;

Fig. 3 is calculation flow chart of the invention process;

Described method comprises the steps,

1. read first arrival data and each focal point and acceptance point coordinate from single-point seismological observation data;

2. seismic observation system and array mode data after the default combination;

3. to the offset distance segmentation;

4. to making up rear earthquake reception channel circulation, the single-point earthquake acceptance point of selection and this road space length minimum is as the combination basic point;

5. search for the geophone station in combined area, and in the calculation combination area, all big guns of each geophone station are relatively poor with the first arrival time difference and the offset distance of combination basic point;

6. adopt following formula (3) to calculate the refraction wave slowness of each offset distance section:

$s=\frac{\mathrm{MN}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\mathrm{\Δ}{t}_{\mathrm{ij}}\mathrm{\Δ}{r}_{\mathrm{ij}}-\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\mathrm{\Δ}{t}_{\mathrm{ij}}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\mathrm{\Δ}{r}_{\mathrm{ij}}}{\mathrm{MN}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\mathrm{\Δ}{r}_{\mathrm{ij}}-{\left(\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\mathrm{\Δ}{r}_{\mathrm{ij}}\right)}^2}---\left(3\right)$

7. adopt the relatively quiet school time difference of the geophone station in following formula (5) analytical calculation combined area:

${\mathrm{\δ}}_i=\frac{\underset{k=1}{\overset{L-1}{\mathrm{\Σ}}}(\underset{j=1}{\overset{N_k}{\mathrm{\Σ}}}\mathrm{\Δ}{t}_{\mathrm{ij}}-s_k\underset{j=1}{\overset{N_k}{\mathrm{\Σ}}}\mathrm{\Δ}{r}_{\mathrm{ij}})}{\underset{k=1}{\overset{L-1}{\mathrm{\Σ}}}{N}_k}---\left(5\right)$

8. search obtains next combination basic point, repeating step 4., until finish;

9. output calibration result.

Directly calculate the relative static correction between geophone station from direct wave time difference that the single-point earthquake receives and plane space position

Foundation to the offset distance segmentation in described the 2nd step is:

The choosing of smallest offset distance that is used for calculating meets the following requirements:

1. greater than 5 times of yardstick in combined area;

2. greater than the distance that excites between the big gun line;

3. stablize the refractor degree of depth 2 times;

And choosing of each offset distance spacing meets the following requirements:

1. can adopt distribution mode equidistant and that spacing progressively strengthens with the offset distance increase;

2. in any one offset distance section, effectively excite the big gun number to be not less than 10;

3. according to near-surface velocity structure and maximum offset, offset distance can divide 5～10 sections.

Claims (1)

1. relative static correction amount computing method that are used for the indoor combination of single-point earthquake, it is characterized in that, the feature of refraction time and waste mantle seismic event when described method utilizes the near surface of refraction wave to propagate, the first arrival time chart of adjacent geophone station is shown the linear function of refraction wave slowness and the relative quiet school time difference, and adopts the numerical statistic method to obtain the relatively quiet school time difference of each wave detector in the geophone station combination range;

Described method comprises the steps,

1. read first arrival data and each focal point and acceptance point coordinate from single-point seismological observation data;

2. preset the rear seismic observation system of combination and array mode data;

3. to the offset distance segmentation;

4. to making up rear earthquake reception channel circulation, the single-point earthquake acceptance point of selection and this road space length minimum is as the combination basic point;

5. search for the geophone station in combined area, and in the calculation combination area, all big guns of each geophone station are poor with respect to the first arrival time difference and the offset distance of combination basic point;

6. adopt following formula (3) to calculate the refraction wave slowness of each offset distance section:

The implication of M is that detection is counted; The implication of N is the shot point number;

△ t _ijImplication be i big gun j geophone station with respect to first arrival time difference of combination basic point;

△ r _ijImplication to be i big gun j geophone station poor with respect to the offset distance of combination basic point;

The implication of s is the refraction wave slowness;

7. adopt the relatively quiet school time difference of the geophone station in following formula (5) analytical calculation combined area:

s _kImplication be k section refraction wave slowness; N _kImplication be k section shot point number;

△ t _ijImplication be i big gun j geophone station with respect to first arrival time difference of combination basic point;

△ r _ijImplication to be i big gun j geophone station poor with respect to the offset distance of combination basic point;

The implication of L is segments;

8. search obtains next combination basic point, turns back to step and 4. begins the order execution, until finish;

9. output calibration result;

Described the 3. in the step foundation to the offset distance segmentation be:

The choosing of smallest offset distance that is used for calculating meets the following requirements:

1. greater than 5 times of yardstick in combined area;

2. greater than the distance that excites between the big gun line;

3. stablize the refractor degree of depth 2 times;

And choosing of each offset distance spacing meets the following requirements:

1. adopt distribution mode equidistant and that spacing progressively strengthens with the offset distance increase;

2. in any one offset distance section, effectively excite the big gun number to be not less than 10;

3. according to near-surface velocity structure and maximum offset, offset distance divides 5～10 sections.

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