CN102269823A - Wave field reconstruction method based on model segmentation - Google Patents

Abstract

The invention relates to a wave field reconstruction method for determining underground oil-gas reservoir distribution by geophysical prospecting for petroleum. The method comprises the following steps: reconstructing a wave field value of each discrete grid point at every moment by using stacked and offset sections obtained through field acquisition and a discrete stratum attribute model, and using a position wave field of a detection point at each moment as a wave field reconstruction record at the moment, and processing to obtain stacked and offset sections reconstructed according to wave field, comparing the stacked and offset sections reconstructed according to the wave field with the stacked and offset sections obtained by processing the field acquired data to determine the underground oil-gas reservoir distribution. The wave field reconstruction method is suitable for complex structure wave field reconstruction, is high in precision, high in efficiency and low in frequency dispersion, and provides a significant basis for determining the underground oil-gas reservoir.

Description

A kind of wave-field reconstruction method of cutting apart based on model

Technical field

The present invention relates to seismic exploration technique, the realization seismic wave field of high precision, high-level efficiency and low dispersion is rebuild under cluster environment specifically, is the wave-field reconstruction method of cutting apart based on model that hydrocarbon reservoir structure is descended in a kind of help definitely.

Background technology

The reflection wave seismic prospecting utilizes wave detector to accept to come from reflective information--the seismologic record of underground geologic bodies by at the ground earthquake-wave-exciting.The reflective information that has obtained is obtained formation velocity, thickness and the form of Depth Domain by seismic data data processing and explanation.Rebuild the reflective information (wave-field reconstruction) of underground geologic bodies according to the open-air earthquake data acquisition process of the layer attribute parameters simulation that obtains, the reflective information of reflective information that wave-field reconstruction is obtained and open-air actual acquisition is analyzed then, determines to handle early stage the reliability of explaining the formation velocity, thickness and the form that obtain.

Wave-field reconstruction describes for geologic interpretation, hydrocarbon reservoir structure and the hydrocarbon-bearing pool exploitation plays a very important role.The process of wave-field reconstruction can the true reappearance seismic event in the overall process of underground propagation, the affirmation of tectonic structure is had important effect.When utilizing the speed on various stratum, thickness and form to rebuild seismologic record, how describing seismic event accurately and fast is a gordian technique of wave-field reconstruction in underground propagation.

At present, generally utilize ACOUSTIC WAVE EQUATION to come the reconstruction of three-dimensional seismic wave field, be used for the correctness of geologic interpretation under the Analysis of Complex structural environment.

The three-dimensional acoustic wave equation is:

$\frac{{\∂}^{2}u}{{\∂x}^2}+\frac{{\∂}^{2}u}{{\∂y}^2}+\frac{{\∂}^{2}u}{{\∂z}^2}=\frac{1}{v^2(x,y,z)}\frac{{\∂}^{2}u}{{\∂t}^2}---\left(1\right)$

Wherein: (y t) is the pressure wave field of ground table record to u for x, z; (x, z are in length and breadth to variable medium velocity y) to v.The calculated amount of finding the solution above-mentioned partial differential equation of second order in the reality is huge, and the stock number that needs is also very big, can only do some simple tests under general cluster environment, does not reach realistic scale.Aspect the raising computational accuracy, people do a lot of work to the computational accuracy aspect that how to improve the space partial derivative, but the computational accuracy of time partial derivative is still lower, the solving equation three-dimensional acoustic wave of high precision, high-level efficiency and low dispersion how, making it to reach realistic scale and being needs the problem that solves.

Summary of the invention

The object of the invention is to provide a kind of efficient, wave-field reconstruction method that high precision descend the hydrocarbon-bearing pool distribution definitely.

The invention provides following technical scheme:

1) utilizes the field layout acquiring seismic data;

2) data processing to field acquisition obtains stack and migrated section;

3) utilize step 2) result that obtains sets up the discrete stratum attribute model that reflection hydrocarbon-bearing pool distributes;

4) utilize the field layout of step 1) and the discrete stratum attribute model of step 3), utilize following formula to rebuild each wave field value on each discrete grid block point constantly, and with each constantly geophone station position wave field as the wave-field reconstruction record in this moment;

$u(t+\mathrm{\Δt})=2u\left(t\right)-u(t-\mathrm{\Δt})+{\left(\mathrm{v\Δt}\right)}^2(\frac{{\∂}^{2}u}{{\∂x}^2}+\frac{{\∂}^{2}u}{{\∂y}^2}+\frac{{\∂}^{2}u}{{\∂z}^2})---\left(2\right)$

$+\frac{1}{12}{\left(\mathrm{v\Δt}\right)}^4(\frac{{\∂}^{4}u}{{\∂x}^4}+\frac{{\∂}^{4}u}{{\∂z}^4}+\frac{{\∂}^{4}u}{{\∂}^{4}y}+2\frac{{\∂}^{4}u}{{\∂y}^2{\∂z}^2}+2\frac{{\∂}^{4}u}{{\∂y}^2{\∂x}^2}+2\frac{{\∂}^{4}u}{{\∂x}^2{\∂z}^2})+O\left(\mathrm{\Δ}{t}^6\right)$

O (Δ t in the formula (2) ⁶) be the difference truncation error of described formula at time orientation.

All space derivatives in the formula (2) all are converted into second derivative, and assign to be similar to by 10 jumps of following formula:

$\frac{{\∂}^{2}f}{{\∂s}^2}=\frac{1}{{\mathrm{\Δs}}^2}\underset{m=1}{\overset{5}{\∑}}{C}_m^{\left(5\right)}[f(s+\mathrm{m\Δx})-2f\left(s\right)+(s-\mathrm{m\Δs})]---\left(3\right)$

Difference coefficient in the formula (3)

Try to achieve by following formula:

$\left[\begin{array}{ccccc}{1}^2& 2^2& 3^2& 4^2& 5^2\\ 1^4& 2^4& 3^4& 4^4& 5^4\\ 1^6& 2^6& 3^6& 4^6& 5^6\\ 1^8& 2^8& 3^8& 4^8& 5^8\\ 1^{10}& 2^{10}& 3^{10}& 4^{10}& 5^{10}\end{array}\right]\left[\begin{array}{c}{C}_1^{\left(5\right)}\\ C_2^{\left(5\right)}\\ C_3^{\left(5\right)}\\ C_4^{\left(5\right)}\\ C_5^{\left(5\right)}\end{array}\right]=\left[\begin{array}{c}1\\ 0\\ 0\\ 0\\ 0\end{array}\right]$

5) record that will obtain is according to step 2) carry out identical processing, obtain the stack and the migrated section of wave-field reconstruction;

6) stack that wave-field reconstruction is obtained and migrated section and step 2) field data collection handles stack and the migrated section contrast obtain, descends the distribution of hydrocarbon-bearing pool definitely.

The present invention also provides following technical scheme:

Step 1) obtains the wave-field reconstruction parameter and comprises that shot interval, track pitch, big gun number, road number, sampling interval, road are long.

Step 2) field data collection is handled and is comprised that the single shot record to collecting carries out static correction, normal moveout correction, velocity analysis, stack and migration processing.

The effect of invention

The present invention is under 3 D complex structure situation, rebuilds seismic wave field to descend the method for hydrocarbon reservoir structure definitely, to have to be applicable to any complex structure wave-field reconstruction and the ability of descending hydrocarbon reservoir structure definitely.Have precision height, efficient height and the low characteristics of frequency dispersion.Therefore this method can become the industrialization structure and proves the main method of software development.The present invention has comprised the strong and weak information of longitudinal wave propagation time and energy in the record that wave-field reconstruction obtains, it is the characteristic feature of hydrocarbon-bearing pool reflection seismic waves, is the important evidence of descending hydrocarbon-bearing pool definitely.

The present invention adopts the quadravalence difference approximation with second order time local derviation, has improved the precision of wave-field reconstruction.

Description of drawings

The rate pattern of Fig. 1 salt dome model 385 lines of the present invention;

The synthetic single shot record of Fig. 2 salt dome model 385 line positions of the present invention;

The wave field figure of Fig. 3 salt dome model 385 line positions of the present invention in the time of 1 second, 2 seconds, 3 seconds;

Fig. 4 salt dome model 385 line position self excitation and self receiving records of the present invention;

Fig. 5 model block diagram of the present invention;

Fig. 6 wave-field reconstruction iterative process of the present invention figure.

Embodiment

The present invention obtains the wave-field reconstruction record by finding the solution wave-field reconstruction formula (2).In order to adapt to calculator memory, model need be divided into polylith and put into different computer nodes respectively in the process of wave-field reconstruction, want overlapping ten row's grids between the adjacent block.The wave field in every moment of calculating must exchange the wave field of lap between two adjacent nodes.Carry out time iteration repeatedly, output each constantly the wave field of geophone station position promptly obtain the wave field record rebuild.

The specific embodiment of the present invention is:

1) utilizes the field layout acquiring seismic data;

2) data processing (comprising that the single shot record to collecting carries out a series of processing such as static correction, normal moveout correction, velocity analysis, stack and skew) of field acquisition is obtained the stack and the migrated section that conform to this area's subsurface geologic structures;

3) utilize the result that step 2 obtains to set up the discrete stratum attribute model (Fig. 1) that reflection hydrocarbon-bearing pool distributes, and put into different computer nodes according to the piecemeal principle of Fig. 5 stratum attribute model that will disperse;

4) utilize the field layout (comprising: shot interval, track pitch, big gun number, road number, sampling interval, road length) of step 1 and the discrete stratum attribute model of step 3, utilize formula (2), by iterative process shown in Figure 6, rebuild the wave field value (Fig. 3) on each each discrete grid block point of the moment, and each moment geophone station position wave field is write down (Fig. 2) as this wave-field reconstruction constantly;

5) record that will obtain is according to step 2) carry out identical processing, obtain the stacked section (Fig. 4) of wave-field reconstruction;

6) stack that wave-field reconstruction is obtained and migrated section and step 2) field data collection handles stack and the migrated section contrast obtain, determines the rationality of geologic structure and layer attribute (Fig. 1), and then definite hydrocarbon occurrence, oil and gas reserves and development plan.

Claims (3)

1. wave-field reconstruction method of cutting apart based on model is characterized in that adopting following steps:

1) utilizes the field layout acquiring seismic data;

2) data processing to field acquisition obtains stack and migrated section;

3) result of utilizing step 2 to obtain is set up the discrete stratum attribute model that reflection hydrocarbon-bearing pool distributes;

4) utilize the field layout of step 1 and the discrete stratum attribute model of step 3, utilize following formula to rebuild each wave field value on each discrete grid block point constantly, and with each constantly geophone station position wave field as the wave-field reconstruction record in this moment;

$u(t+\mathrm{\Δt})=2u\left(t\right)-u(t-\mathrm{\Δt})+{\left(\mathrm{v\Δt}\right)}^2(\frac{{\∂}^{2}u}{{\∂x}^2}+\frac{{\∂}^{2}u}{{\∂y}^2}+\frac{{\∂}^{2}u}{{\∂z}^2})---\left(2\right)$

$+\frac{1}{12}{\left(\mathrm{v\Δt}\right)}^4(\frac{{\∂}^{4}u}{{\∂x}^4}+\frac{{\∂}^{4}u}{{\∂z}^4}+\frac{{\∂}^{4}u}{{\∂}^{4}y}+2\frac{{\∂}^{4}u}{{\∂y}^2{\∂z}^2}+2\frac{{\∂}^{4}u}{{\∂y}^2{\∂x}^2}+2\frac{{\∂}^{4}u}{{\∂x}^2{\∂z}^2})+O\left({\mathrm{\Δt}}^6\right)$

O (Δ t in the formula (2) ⁶) be the difference truncation error of described formula at time orientation.

All space derivatives in the formula (2) all are converted into second derivative, and assign to be similar to by 10 jumps of following formula:

$\frac{{\∂}^{2}f}{{\∂s}^2}=\frac{1}{{\mathrm{\Δs}}^2}\underset{m=1}{\overset{5}{\mathrm{\Σ}}}{C}_m^{\left(5\right)}[f(s+\mathrm{m\Δx})-2f\left(s\right)+f(s-\mathrm{m\Δs})]---\left(3\right)$

Difference coefficient in the formula (3) Try to achieve by following formula:

$\left[\begin{array}{ccccc}{1}^2& 2^2& 3^2& 4^2& 5^2\\ 1^4& 2^4& 3^4& 4^4& 5^4\\ 1^6& 2^6& 3^6& 4^6& 5^6\\ 1^8& 2^8& 3^8& 4^8& 5^8\\ 1^{10}& 2^{10}& 3^{10}& 4^{10}& 5^{10}\end{array}\right]\left[\begin{array}{c}{C}_1^{\left(5\right)}\\ C_2^{\left(5\right)}\\ C_3^{\left(5\right)}\\ C_4^{\left(5\right)}\\ C_5^{\left(5\right)}\end{array}\right]=\left[\begin{array}{c}1\\ 0\\ 0\\ 0\\ 0\end{array}\right]$

5) record that will obtain is according to step 2) carry out identical processing, obtain the stack and the migrated section of wave-field reconstruction;

6) stack that wave-field reconstruction is obtained and migrated section and step 2) field data collection handles stack and the migrated section contrast obtain, descends the distribution of hydrocarbon-bearing pool definitely.

2. a kind of wave-field reconstruction method of cutting apart based on model according to claim 1, it is characterized in that: step (1) obtains the wave-field reconstruction parameter, comprising: shot interval, track pitch, big gun number, road number, sampling interval, road are long.

3. a kind of wave-field reconstruction method of cutting apart based on model according to claim 1 is characterized in that: the data processing of step (2) comprises that the single shot record to collecting carries out static correction, normal moveout correction, velocity analysis, stack and migration processing.

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