Quasi-three-dimensional-based river channel identification method under multi-constraint condition

Abstract

The invention relates to a method for identifying a river channel under a multi-constraint condition based on quasi-three dimensions, and belongs to the technical field of oil and gas geology. The method comprises the following specific steps: determining seismic response characteristics of a river channel by utilizing seismic data, logging data and ancient landform of a research area in combination with a deposition law; carrying out amplitude consistency correction on the seismic survey lines processed in different years according to a processing and interpretation integration technology countermeasure, and carrying out quasi-three-dimensional processing on the corrected two-dimensional seismic survey lines; time window amplitude attribute prediction is carried out according to a three-dimensional mode by using the characteristic that amplitude energy of a river channel in the transverse direction has similarity, and river channel amplitude energy distribution characteristics on a two-dimensional seismic survey line are obtained; and performing interpolation extrapolation by using a quasi-three-dimensional technology to obtain river channel plane distribution conforming to the deposition law. According to the method, the consistency processing technology and the quasi-three-dimensional processing technology are utilized, and the problem that the river channel sand body in the two-dimensional seismic data area cannot be predicted is effectively solved.

Description

Technical Field

[0001] The invention relates to a river channel identification method under pseudo-three-dimensional multi-constraint conditions, belonging to the technical field of oil and gas geology. Background Art

[0002] In oilfield exploration and development, the study of river channel sand bodies is the key to improving oil and gas recovery. In particular, in the later stages of oilfield exploration and development, identifying the distribution characteristics of river channel sand bodies makes it easier to excavate oil and gas and improve oil and gas recovery. It can be seen that in order to improve oil and gas recovery, it is very important to provide a method for identifying the distribution characteristics of river channel sand bodies. In areas where two-dimensional seismic is the main method, the two-dimensional seismic lines collected and processed in different batches usually have large energy differences in the lateral direction due to different years of acquisition and processing. Therefore, the seismic response characteristics of the river channel will also vary greatly on different survey lines, making it difficult to effectively identify them. In addition, since the two-dimensional seismic network is relatively sparse, the distance between survey lines is usually more than 2 km, which makes it impossible for conventional methods to predict the planar distribution of the river channel. Therefore, it is necessary to establish a new set of river channel prediction methods to solve the problem of river channel planar distribution in two-dimensional areas. Summary of the invention

[0003] In order to solve the above problems existing in the prior art, the present invention discloses a channel identification method under multiple constraints based on quasi-three-dimensional conditions. The method utilizes seismic data, logging data, and paleomorphic features of the study area, combined with sedimentary laws, to clarify the seismic response characteristics of the channel, and performs amplitude consistency correction in accordance with the idea of ​​integrated processing and interpretation to ensure the lateral consistency of the characteristic amplitude energy of the channel. The corrected survey line is then used in a quasi-three-dimensional mode to perform time window amplitude attribute channel prediction, and interpolation and extrapolation are used to obtain the planar distribution law of the channel sand body, thereby solving the problem that the planar distribution law of the channel sand body in the two-dimensional area cannot be predicted.

[0004] The technical solution adopted by the present invention is: a river channel identification method under multiple constraints based on quasi-three-dimensional conditions, and the specific steps are as follows:

[0005] Step 1: Use seismic data, well logging data, paleo-geomorphology and sedimentary laws in the study area to clarify the seismic response characteristics of the river channel;

[0006] Step 2: According to the integrated processing and interpretation technical countermeasures, the amplitude consistency correction is performed on the seismic lines processed in different years, and the corrected two-dimensional seismic lines are processed into pseudo-three-dimensional ones;

[0007] Step 3: Using the similarity of the amplitude energy of the river channel in the lateral direction, the time window amplitude attribute prediction is carried out according to the three-dimensional model to obtain the amplitude energy distribution characteristics of the river channel on the two-dimensional seismic line;

[0008] Step 4: Based on step 3, use pseudo-3D technology to perform interpolation and extrapolation to obtain the river channel plan distribution that conforms to the sedimentary law.

[0009] Furthermore, in step 2, the integrated processing and interpretation technical countermeasure is that all two-dimensional seismic lines are corrected for amplitude consistency by seismic data processing personnel in accordance with the amplitude requirements put forward by seismic interpreters for seismic lines processed in different years to ensure that the lateral amplitude change trend of river channel characteristics on the seismic lines is consistent.

[0010] Furthermore, in step 2, the quasi-three-dimensional processing is to define the three-dimensional seismic work area according to the gridding, and then load the corrected two-dimensional seismic survey line into the newly defined three-dimensional work area.

[0011] Furthermore, in step 2, if there is a large change in the lateral energy of the river channel characteristics along the source direction on the two-dimensional seismic survey line, that is, the energy difference between adjacent seismic traces is greater than 10 times, the amplitude consistency compensation technology can be used to increase the energy level of each survey line to the same level, which is conducive to river channel identification.

[0012] Furthermore, in step 3, the time window amplitude attribute prediction is carried out in a three-dimensional mode, specifically, the small time window amplitude attribute is extracted for each two-dimensional seismic line by utilizing the medium-weak amplitude peak reflection characteristics of the river channel, and the amplitude energy value of the river channel sand body of a single two-dimensional seismic line is obtained.

[0013] Furthermore, in step 4, the pseudo-three-dimensional technology is used to first establish a pseudo-three-dimensional seismic work area, and then the two-dimensional seismic survey line river channel amplitude value extracted in the third step is extrapolated and interpolated using the inverse distance weighted method to obtain the river channel plane distribution.

[0014] Furthermore, the spacing between the three-dimensional seismic network in the working area is consistent with that of the two-dimensional seismic network or is smaller than that of the two-dimensional seismic network.

[0015] The present invention discloses a channel identification method under multiple constraints based on quasi-three-dimensional conditions. The beneficial effect is that the method utilizes seismic data, well logging data, paleo-geomorphological features, and sedimentary laws as constraints, and utilizes consistency processing technology and quasi-three-dimensional processing technology. The method effectively solves the problem that channel sand bodies in two-dimensional seismic data areas cannot be predicted. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0017] Figure 1 Shown is the seismic profile of the river channel response in the study area;

[0018] Figure 2 Shown is the paleo-geomorphology of the study area;

[0019] Figure 3 Shown is the plan distribution diagram of the amplitude attributes of the river channel in the study area predicted by the present invention.

[0020] Specific implementation methods

[0021] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] In order to further understand the content of the present invention, the present invention is further described below in conjunction with specific implementation methods.

[0023] Example 1: Figures 1 to 3 As shown in the figure, a river channel identification method based on quasi-three-dimensional multi-constraint conditions is shown in the figure. The specific steps are as follows:

[0024] Step 1: If Figure 1 As shown, the seismic response characteristics of the river channel are clarified by using seismic data, well logging data, paleo-geomorphology and sedimentary laws in the study area.

[0025] This example takes the western slope area in the southern part of the Songliao Basin as an example:

[0026] According to the river channel characteristics revealed by existing drilling in the study area, using the synthetic records of the well side channels, it is clear that the river channel in the study area is a medium-weak amplitude wave crest reflection, and it also shows complex wave characteristics on the seismic profile.

[0027] Using the impression method, the paleo-geomorphology of the study area was confirmed. Figure 2 As shown in the figure, it can be seen that there are two grooves with a large extension length on the paleo-geomorphology map. According to the concept of groove controlling sand, it is believed that the river channel in the study area develops along the two grooves, and the seismic response characteristics of the river channel along the groove direction should be similar, and the lateral change trend of the amplitude is relatively consistent.

[0028] Step 2: According to the integrated processing and interpretation technical countermeasures, all 2D seismic lines are corrected for amplitude consistency by seismic data processors according to the amplitude requirements of seismic interpreters, to ensure that the lateral amplitude change trend of river channel characteristics on the seismic lines is consistent. At the same time, the corrected 2D seismic lines are pseudo-3D, that is, the 3D seismic work area is defined according to a 50m x 50m grid, and then the corrected 2D seismic lines are loaded into the newly defined 3D work area;

[0029] There are many 2D seismic lines in the study area, and the annual span of acquisition and processing is large. The energy difference of processing results between different years is large, which is not conducive to river channel identification. Therefore, according to the technical countermeasures of integrated processing and interpretation, all survey lines in the study area are uniformly processed and corrected for amplitude consistency, so that the amplitude change trend of 2D seismic lines in the lateral direction is basically consistent. The difference in amplitude of individual 2D seismic lines is the seismic response of geological phenomena.

[0030] Step 3: Taking advantage of the similarity of the amplitude energy of the river channel in the lateral direction, the time window amplitude attribute river channel prediction is carried out in a three-dimensional mode to obtain the amplitude energy distribution characteristics of the river channel on the two-dimensional seismic line.

[0031] Utilizing the reflection characteristics of medium-weak amplitude wave crests in the river channel, the amplitude attribute extraction of the small window is performed for each two-dimensional seismic line, wherein the time window size is adjusted according to the thickness of the sand body, that is, the time window size needs to include the longitudinal change of the sand body. In this embodiment, the drilling has been completed and revealed that the thickness of the river channel sand body is generally 3-10 meters, and 1 millisecond represents 2 meters in the earthquake. If the sand body is 3 meters thick, a 1.5 millisecond time window is sufficient. In this embodiment, the maximum thickness of the sand body is 10 meters. Considering the lateral continuity and longitudinal thickness change of the sand body, therefore, when extracting seismic attributes, the time window size is 5 milliseconds, which can include the longitudinal change of the river channel sand body. Therefore, the 5 millisecond time window in the earthquake includes the longitudinal change of the river channel sand body. Using this feature, according to the seismic response characteristics of the river channel on each two-dimensional seismic line, the amplitude attribute extraction of the 5 millisecond time window is performed to obtain the amplitude energy value of the river channel sand body of a single two-dimensional seismic line. The size of the time window is critical. If the time window is too large, false information is introduced. If the time window is too small, the river channel characteristics cannot be fully reflected.

[0032] Step 4: In this embodiment, a quasi-3D seismic work area is first established. The spacing between the survey networks in the 3D seismic work area is kept consistent with that of the 2D seismic network or is smaller than that of the 2D seismic network to ensure that each 2D seismic line has a corresponding survey network. If the spacing between the survey networks is too large, some 2D data will be lost. On this basis, the amplitude energy values ​​of the river attributes of the 2D seismic lines are extrapolated and interpolated using the inverse distance weighted method to obtain the river plan distribution. That is to say, in the 3D mode, the inverse distance weighted method of the quasi-3D technology is used to extrapolate the difference for the amplitude energy values ​​of the river attributes of the 2D lines to obtain the river plan distribution that conforms to the sedimentary law, such as Figure 3 The final prediction result is shown in Figure 3 The red and yellow colors represent sand body development areas, and the blue represents mudstone development areas. It can be seen from the figure that five large river channels are developed in the area, which is consistent with the wells that have been drilled, indicating that the predicted river channel distribution conforms to the laws of geological deposition.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A river channel identification method based on quasi-three-dimensional multi-constraint conditions, comprising the following steps: Step 1: Use seismic data, well logging data, paleo-geomorphology and sedimentary laws in the study area to clarify the seismic response characteristics of the river channel; Step 2: According to the integrated processing and interpretation technical countermeasures, the amplitude consistency correction is performed on the seismic lines processed in different years, and the corrected two-dimensional seismic lines are processed into pseudo-three-dimensional ones; Step 3: Using the similarity of the amplitude energy of the river channel in the lateral direction, the time window amplitude attribute prediction is carried out according to the three-dimensional model to obtain the amplitude energy distribution characteristics of the river channel on the two-dimensional seismic line; Step 4: Based on step 3, use pseudo-3D technology to perform interpolation and extrapolation to obtain the river channel plan distribution that conforms to the sedimentary law.

2. According to claim 1, a river channel identification method based on quasi-three-dimensional multi-constraint conditions is characterized in that: In step 1, the integrated processing and interpretation technical countermeasure is to perform amplitude consistency correction on all 2D seismic lines processed in different years to ensure that the lateral amplitude change trend of the river channel characteristics on the seismic lines is consistent.

3. According to the method for river channel identification under multiple constraints based on quasi-three-dimensional conditions in claim 1, it is characterized in that: In step 2, the quasi-3D processing is to define the 3D seismic work area according to the gridding, and then load the corrected 2D seismic survey lines into the newly defined 3D work area.

4. According to the method for river channel identification under multiple constraints based on quasi-three-dimensional conditions in claim 1, it is characterized in that: In step 2, if the lateral energy of the river channel characteristics along the source direction on the 2D seismic line varies greatly, that is, the energy difference between adjacent seismic traces is more than 10 times, the amplitude consistency compensation technology is used to increase the energy level of each 2D seismic line to the same level.

5. The method for river channel identification under multiple constraints based on quasi-three-dimensional conditions according to claim 1 is characterized in that: In step 3, the time window amplitude attribute prediction is carried out in accordance with the three-dimensional mode. Specifically, the small time window amplitude attribute is extracted for each two-dimensional seismic line by utilizing the medium-weak amplitude peak reflection characteristics of the river channel to obtain the amplitude energy value of the river channel sand body of a single two-dimensional seismic line.

6. The method for river channel identification under multiple constraints based on quasi-three-dimensional conditions according to claim 5 is characterized in that: In step 4, the pseudo-3D technology is used to first establish a pseudo-3D seismic work area, and then the river channel amplitude values ​​of the two-dimensional seismic survey line extracted in the third step are extrapolated and interpolated using the inverse distance weighted method to obtain the planar distribution of the river channel.

7. The method for river channel identification under multiple constraints based on quasi-three-dimensional conditions according to claim 6 is characterized in that: In step 4, the spacing between the 3D seismic network and the 2D seismic network is kept consistent.

8. The method for river channel identification under multiple constraints based on quasi-three-dimensional conditions according to claim 6 is characterized in that: In step 4, the spacing between the three-dimensional seismic network in the working area is smaller than that between the two-dimensional seismic network.

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