CN1158539C - Optimizing design method of 3D seismic observation system based on geologic geophysical model - Google Patents

Abstract

The present invention is a method for optimizing the design of a three-dimensional seismic observation system based on a geological and geophysical model, comprising the following steps: A) establishing a priori geological and geophysical model; B) designing two or more observation systems for three-dimensional seismic data acquisition; C) Using virtual spectrum method for 3D wave equation numerical simulation and 3D seismic physical model simulation combined forward modeling to complete the data acquisition work; D) Based on common reflection points, pre-stack depth migration processing was performed on the collected data, Obtaining several imaging results of seismic processing; E) performing a comprehensive comparative evaluation of imaging quality on the several imaging results of seismic processing, and determining one of the best seismic imaging results after comparison. This method has a wide range of applications and good application effects, and has practical significance for guiding the actual production of oil and gas seismic exploration and improving the success rate of oil and gas exploration.

Description

Optimal Design Method of 3D Seismic Observation System Based on Geological and Geophysical Model

technical field

The invention relates to a technical design optimization method for three-dimensional seismic exploration in petroleum and natural gas and other mineral resources and geological engineering, in particular to an optimal design method for a three-dimensional seismic observation system based on geological and geophysical models.

Background technique

The three major steps of seismic exploration are acquisition, processing and interpretation. Acquisition is the foundation; the excitation system composed of the excitation points of the seismic source on the ground and the receiving system composed of the receiving points of the geophone must pass the correct geometric distribution, that is, the optimized seismic observation system, in order to collect effective and complete underground geological structure information . Therefore, the observation system plays an important role in seismic exploration, and its design is directly related to the success or failure of the exploration task. Because of the large workload and high investment of 3D seismic, the 3D work areas are often arranged in complex structural areas, so the optimal design of the 3D observation system is extremely important.

So far, most of the 3D observation system design software widely used at home and abroad are based on the horizontal layered geological model and the common center point (CMP) superposition principle, which are not suitable for the 3D seismic technical design of complex structures and high-dip formations. . In the case of complex structures, the application of such design schemes not only cannot obtain high-quality seismic imaging, but may even result in wrong seismic imaging results.

Contents of the invention

Therefore, the object of the present invention is to provide a method for optimal design of a three-dimensional seismic observation system based on geological and geophysical models.

This method is based on the priori 3D geological and geophysical models of the exploration area, adopts the joint forward modeling technology of numerical simulation and physical simulation, according to the principle of common reflection point (CRP), and takes the high-quality seismic imaging of geological targets as the evaluation standard to integrate the 3D The design scheme of seismic acquisition technology is directly related to the imaging quality of seismic data processing, so as to realize the acquisition technology goal of optimizing the design of 3D observation system.

The optimal design method of the three-dimensional seismic observation system based on the geological geophysical model provided by the present invention comprises the following steps:

A) Establish a priori geological-geophysical model based on the existing exploration results in the exploration area, that is, the complex geological structure and complex geological body shape and its geophysical parameters; B) take the above-mentioned geological-geophysical model as the exploration target, design two or Observation system for various 3D seismic data collection; C) Using the model as the 3D seismic observation object, simulate the field seismic data collection process in the laboratory according to the technical parameters and construction graphics required by the observation system design, and obtain the simulated field original seismic records The specific method is to use the two methods of virtual spectrum method 3D wave equation numerical simulation and 3D seismic physical model simulation to complete the data acquisition work; Based on this, pre-stack depth migration processing is performed on the data, and several imaging results of seismic processing are obtained; E) The prior geological and geophysical model is used as the evaluation and comparison standard, and the signal-to-noise ratio, resolution and structural morphological characteristics are used as technical The main content is analyzed, and the imaging quality of several imaging results of seismic processing is comprehensively compared and evaluated. After comparison, one of the best seismic imaging results is determined.

Wherein step E) also comprises:

E1) If the imaging result does not meet the target requirements of seismic exploration, the original 3D observation system parameters are modified, and then the 3D seismic data acquisition and processing work is carried out again. The 3D observation system parameters include 3D seismic observation width, bin size, Coverage or illumination times, illumination, total number of seismic channels, maximum offset, where the observation width N is defined as:

$\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\frac{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\frac{{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}{{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; )</span>$

Among them: L _c /L _i - the aspect ratio of the array sheet,

n _c /n _i - the aspect ratio of the number of coverages,

C ₁ - the coefficient related to the aspect ratio of the aligned slices,

C ₂ -coefficient related to the aspect ratio of coverage times, and C ₂ =1-C ₁ , generally C ₁ =C ₂ =0.5,

  θ- the distribution range of the azimuth angle of the center panel of the sub-area (radian);

E2) If the imaging result has reached the target requirement of seismic exploration, output the flow chart of optimal design of the 3D seismic observation system.

The present invention will be described in detail below in conjunction with the accompanying drawings, so as to further understand the above-mentioned purpose, characteristics and advantages of the present invention.

Description of drawings

Fig. 1 is the flow chart of the three-dimensional seismic observation system optimization design method based on geological geophysical model of the present invention;

Figure 2(a) is the physical model of Qianmiqiao buried hill structure based on prior data;

Figure 2(b) is a two-dimensional geological profile of the 337 survey line passing through the top of the buried hill in the north-south direction;

Fig. 3 is the seismic record obtained by using the virtual spectrum method 3D wave equation forward modeling and 3D seismic physical simulation respectively on the 337 survey line;

Figure 4 is the horizontal superposition imaging results (337 lines) of seismic data collected by three observation systems, in which Figure 4(a) is an observation system with 8 lines, 2 shots, 24 times and 1 time horizontally; Figure 4(b) is an observation system with 8 lines and 4 24 vertical and 2 horizontal observation systems of the cannon; Figure 4(c) is an 8-line, 8 cannon vertical, 24 vertical and 2 horizontal observation system;

Fig. 5 is the seismic data migration imaging results of three-dimensional acquisition with different widths (horizontal slice image of the top of the dome), in which Fig. 5(a) is the seismic data migration of narrow three-dimensional acquisition, and Fig. 5(b) is the wide Migration of seismic data acquired in 3D.

Detailed ways

The Geophysical Key Laboratory of China National Petroleum Corporation began to explore a new three-dimensional acquisition technology design method based on CRP seismic imaging targeting at the specific complex geological structure of the exploration area in 1996. The work flow of this method is shown in the figure 1.

First, based on the existing exploration results in the exploration area (complex geological structure and shape of complex geological bodies and their geophysical parameters), a priori geological and geophysical model is established, usually the seismic velocity model of the underground medium is established; the second step is based on the above geological and geophysical The model is the exploration target, and two or more observation systems for 3D seismic data acquisition are designed; in the third step, the model is used as the 3D seismic observation object, and the field seismic data is simulated in the laboratory according to the technical parameters and construction graphics required by the observation system design Acquisition process, this method is characterized by using two methods of mathematical calculation and physical experiment to simulate the field earthquake construction, and obtain the simulated field original seismic record (see Figure 3), specifically the three-dimensional wave equation numerical simulation and three-dimensional earthquake physical model Simulate two methods to complete this data collection work; the fourth step is to process the collected data for 3D seismic data. The processing principle is based on common reflection points (CRP), and the core technology is pre-stack depth migration processing. , that is, a currently popular seismic imaging technology, so as to obtain several imaging results of seismic processing; the fifth step is to use the prior geological and geophysical model as the evaluation and comparison standard, and use the signal-to-noise ratio, resolution and structural features as the technical Analyze the main content, conduct a comprehensive comparative evaluation of the imaging quality of several imaging results of seismic processing, and determine one of the best seismic imaging results after comparison; if this imaging result has not yet reached the target requirements of seismic exploration, the original 3D Observation system parameters (design scheme), and then re-acquisition and processing of 3D seismic data; if the imaging result has reached the target requirements of seismic exploration, the corresponding 3D observation system is the final result of the optimal design of 3D seismic exploration in this area, Then output the 3D seismic observation system optimization design work flow chart. At this time, the entire optimization design work is also announced to be completed.

The main content of the design of the 3D seismic observation system is the selection of the 3D observation template (several lines, several processings) and the parameter design of the 3D observation system. 3D observation system parameters mainly include 3D seismic observation width, bin size, coverage or illumination times, illumination, total number of seismic traces, maximum offset, etc. When determining the width N of 3D seismic observation, the following formula proposed by the applicant is used:

$\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\frac{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\frac{{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}{{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; )</span>$

Among them: L _c /L _I - the aspect ratio of the array sheet,

n _c /n _I - aspect ratio of number of coverages,

C ₁ - the coefficient related to the aspect ratio of the aligned slices,

C ₂ -coefficient related to the aspect ratio of coverage times, and C ₂ =1-C ₁ , generally C ₁ =C ₂ =0.5,

    θ - distribution range of the azimuth angle of the center surface of the sub-area (radian).

When: N<0.5, it is a narrow azimuth observation system;

When N≥0.5, it is a wide-azimuth observation system;

When N≥0.85, it is an omnidirectional observation system;

Combined with the oil and gas exploration tasks in the complex areas in the east and west of my country, the Key Laboratory of Geophysical Prospecting of China National Petroleum Corporation (CNPC) has applied this method to the actual 3D seismic technology design many times, such as the buried hill model of Dagang Qianmi Bridge, Xinjiang Che The overthrust fault zone model in Paizi area, the Yiqikelik fold-thrust zone model in Xinjiang, and the complex fault block models in Jurong and Hongze in Jiangsu have achieved very good results. The following is a brief introduction to this method by taking the optimal design of the 3D seismic observation system for the Qianmiqiao buried hill structure in Dagang as an example.

Figure 2(a) is a physical model of the Qianmiqiao buried hill structure based on prior data, and Figure 2(b) is a two-dimensional 337-line geological section through the top of the buried hill in the north-south direction. Figure 3 shows the seismic records obtained by using the virtual spectrum method 3D wave equation forward modeling and 3D seismic physical simulation respectively on the 337 survey line. Comparing the two records, it can be considered that they are similar. Several different observation systems were used to collect 3D seismic data in this area, and different seismic imaging results were obtained through processing (see Figure 4 and Figure 5). Then use the geological target as the standard to evaluate various imaging results and optimize the design of the observation system. For example, the signal-to-noise ratio of the image in Figure 4(c) is higher than that in Figure 4(b) and Figure 4(a), then it should be considered that the observation system corresponding to Figure 4(c) is the best among them; another example is Figure 5( b) The imaging at the top of the dome is better, and the focus quality is higher than that in Figure 5(b), indicating that a wide-azimuth 3D observation system should be selected for seismic construction. Some practical applications mentioned above show that this method has a wide range of applications and good application effects, and it has practical significance for guiding the actual production of oil and gas seismic exploration and improving the success rate of oil and gas exploration.

Claims (1)

1, a kind of optimizing design method of 3 D seismic observation system based on geologic geophysical model may further comprise the steps:

A) according to the existing exploration achievement in exploratory area, i.e. complex geological structure and complicated geological volume morphing and geophysical parameters thereof are set up the geologic geophysical model of priori;

B) be exploration targets with above-mentioned geologic geophysical model, design the recording geometry that two or more 3D seismic datas are gathered;

C) with this model as the 3-D seismics object of observation, design desired technical parameter and construction figure in the open-air earthquake data acquisition process of laboratory simulation according to recording geometry, obtain the open-air original seismic data of simulation, the concrete practice is to adopt the simulation of the three-dimensional fluctuation of empty spectrometry equation number value just drilling with two kinds of method associatings of 3-D seismics physical model simulation to finish this data collection task;

D) data of above-mentioned collection are carried out 3D seismic data and handle,,, obtain earthquake and handle several imaging results the data of the gathering preceding depth shift processing that change wherein based on common reflection point;

E) with the geologic geophysical model of priori as estimating and contrast standard, with signal to noise ratio (S/N ratio), resolution and structural feature feature as the technical Analysis main contents, the comprehensive comparative evaluation that several imaging results are carried out image quality is handled in described earthquake, through contrast, determine one of them best earthquake imaging results; Step e wherein) also comprise:

E1) if imaging results does not also reach the target call of seismic prospecting, then revise original stereo observing system parameter, again carry out the work of 3D seismic data acquisition process subsequently, described stereo observing system parameter comprises 3-D seismics observation width degree, bin size, covering or illumination number of times, illuminance, seismic trace sum, maximum offset, wherein observes width degree N be defined as:

$N=\frac{\mathrm{\&theta;}}{2\mathrm{\&pi;}}(C_1\frac{L_c}{L_i}+C_2\frac{n_c}{n_i})$

Wherein: Lc/Li-arranges the horizontal vertical ratio of sheet,

The horizontal vertical ratio of nc/ni-degree of covering,

C1-and the relevant coefficient of the arrangement horizontal vertical ratio of sheet,

C2-and the relevant coefficient of the horizontal vertical ratio of degree of covering, and C2=1-C1 generally get C1=C2=0.5,

θ-center, subarea bin azimuthal distribution scope (radian);

E2), then export 3 D seismic observation system optimal design process flow diagram if imaging results has reached the target call of seismic prospecting.

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