Method and system for determining sand-rich areas of deepwater fans without well constraints

Abstract

The present invention discloses a method and a system for determining sand-rich areas of deepwater fans without well constraints. The method for determining sand-rich areas of deepwater fans without well constraints includes the following steps: determining the top interface and the bottom interface of a target deepwater fan in 3D seismic data; drawing a planar thickness isopach map based on the depth difference value between the top interface and the bottom interface, and drawing a planar isopach map of the top interface structure based on the depth value of the top interface; determining mud-rich areas and sand-rich areas according to the planar thickness isopach map and the planar isopach map of the top interface structure. The present invention first determines the closed area, then draws the planar thickness isopach map and the planar isopach map of the top interface structure, and finally intersects the two images to obtain the distribution of mud-rich areas and sand-rich areas, and can quickly determine the sand-rich areas without drilling wells, reducing the cost of determining the sand-rich areas.

Description

Technical Field

[0001] The present invention belongs to the technical field of geological resources and geological engineering, and particularly relates to a method and system for determining sand-rich areas of deepwater fans without well constraints. Background Art

[0002] Oil and natural gas are important strategic resources for the development of the national economy. With the continuous deepening of exploration depth, oil and gas exploration has developed from structural oil and gas reservoirs to lithologic oil and gas reservoirs. Oil and gas exploration practice has confirmed that fan-shaped or cone-shaped sediment accumulations (deepwater fans) formed by sediment gravity flows in deepwater (including deep sea and deep lake) sedimentary environments can form turbidite fan lithologic oil and gas reservoirs, which are important target areas for global oil companies to efficiently increase reserves. Compared with onshore river-delta oil and gas reservoirs, deepwater fan reservoirs are more complex in terms of sedimentary composition, stacking relationship, heterogeneity, and distribution pattern. How to determine the sand-rich areas of deepwater fans is the core key to the efficient exploration and development of turbidite fan lithologic oil and gas reservoirs.

[0003] The core of the prior art of well-constrained reservoir inversion for predicting sand-rich areas is to fully exploit the elastic information of submarine fan rocks contained in drilling data, establish the corresponding relationship between the rock physical information of deepwater fans and seismic attributes, and then determine the sand-rich areas of submarine fans. However, this method highly depends on well logging data and requires well logging data as a constraint condition to obtain the wave impedance of deepwater fans. Restricted by the high operating cost of offshore drilling, the number of deepwater wells is often small or there is no drilling information available. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies of the prior art, the present invention provides a method and system for determining sand-rich areas of deepwater fans without well constraints, so as to solve the technical problem that the prior art cannot determine the sand-rich areas of deepwater fans under the condition of no well constraints.

[0005] To achieve the above object, the present invention provides a method for determining sand-rich areas of deepwater fans without well constraints, and the method for determining sand-rich areas of deepwater fans without well constraints includes the following steps:

[0006] Step S10, determining the top interface and the bottom interface of the target deepwater fan in the three-dimensional seismic data;

[0007] Step S20, drawing a plane thickness contour map according to the depth difference value between the top interface and the bottom interface, and drawing a top interface structural plane contour map according to the depth value of the top interface;

[0008] Step S30, determining the mud-rich areas and the sand-rich areas according to the plane thickness contour map and the top interface structural plane contour map.

[0009] In an embodiment of the present invention, the step S30 specifically includes:

[0010] Step S31: Determine the first area where the thickness isolines of the planar thickness isoline map are closed and the values increase numerically.

[0011] Step S32: Determine the second area where the top interface structure isolines of the top interface structure planar isoline map are densified and the values decrease numerically.

[0012] Step S33: Determine the sand-rich area according to the intersection area of the first area and the second area.

[0013] In the embodiment of the present invention, step S31 specifically includes:

[0014] Step S311: Determine the area where the thickness isolines are closed according to whether the isolines in the planar thickness isoline map are closed.

[0015] Step S312: Determine the area where the thickness isoline values increase towards the center according to whether the isoline values in the planar thickness isoline map increase from the fan periphery to the fan center.

[0016] Step S313: Determine the first area according to the intersection area of the area where the thickness isolines are closed and the area where the thickness isoline values increase towards the center.

[0017] In the embodiment of the present invention, step S32 specifically includes:

[0018] Step S321: Determine the area where the structure isolines are densified according to whether the isolines in the top interface structure planar isoline map are densified.

[0019] Step S322: Determine the area where the structure isolines decrease towards the center according to whether the isoline values in the top interface structure planar isoline map decrease from the fan periphery to the fan center.

[0020] Step S322: Determine the second area according to the intersection area of the area where the structure isolines are densified and the area where the structure isolines decrease towards the center.

[0021] In the embodiment of the present invention, after step S30, the following is further included:

[0022] Step S40: Evaluate the sand-rich degree of the sand-rich area according to the top convex amplitude.

[0023] In the embodiment of the present invention, the top convex amplitude is obtained according to the following calculation formula:

[0024] A b = D / H,

[0025] A b is the top convex amplitude,

[0026] D is the actual length of the top interface of the sand-rich area,

[0027] H is the linear distance from the outer edge of the sand-rich area.

[0028] In the embodiment of the present invention, the specific evaluation of the sand-rich degree is as follows:

[0029] When 2.0 ≤ A b the sand area ratio ≤ 30%, and the sand-rich degree is low;

[0030] When 2.0 < A b < 2.5, 30% ≤ the sand area ratio ≤ 50%, and the sand-rich degree is medium;

[0031] When 2.5 ≤ A b the sand area ratio ≥ 50%, and the sand-rich degree is high.

[0032] In the embodiment of the present invention, the step S10 specifically includes:

[0033] Step S11, obtaining a typical seismic profile of the target deepwater fan by using the 3D seismic data;

[0034] Step S12, determining the top interface and the bottom interface with the same seismic facies characteristics in the typical seismic profile by using the envelope surface method.

[0035] In the embodiment of the present invention, the step S10 further includes:

[0036] Step S13, tracking and comparing the top interface and the bottom interface in the source-following and vertical-source directions and realizing the 3D space closure of the top interface and the bottom interface.

[0037] The present invention also proposes a system for determining the sand-rich area of a deepwater fan without well constraints. The system for determining the sand-rich area of a deepwater fan without well constraints includes:

[0038] A graphics processing module for determining the top interface and the bottom interface of the target deepwater fan in the seismic data,

[0039] A graphics drawing module for drawing a plane thickness contour map according to the depth difference value between the top interface and the bottom interface, and drawing a top interface structure plane contour map according to the depth value of the top interface;

[0040] An evaluation module for determining the mud-rich area and the sand-rich area according to the plane thickness contour map and the top interface structure plane contour map.

[0041] Through the above technical solutions, the method for determining the sand-rich area of a deepwater fan without well constraints provided by the embodiment of the present invention has the following beneficial effects:

[0042] First, confirm the top and bottom interfaces of the target deepwater fan. A closed area is formed by closing the top and bottom interfaces to facilitate subsequent evaluation operations. Then, draw a planar thickness isopach map and a top interface structural plane isopach map based on the depth difference value between the top and bottom interfaces. The distribution of the mud-rich area and the sand-rich area is obtained by analyzing the intersection of the two images. Compared with the existing method for determining the sand-rich area, there is no need to drill wells, and only the existing 3D seismic data needs to be processed. The image drawing and the determination of the top and bottom interfaces can be obtained by inputting parameters into the computer. By first determining the closed area, then drawing the planar thickness isopach map and the top interface structural plane isopach map, and finally obtaining the distribution of the mud-rich area and the sand-rich area by intersecting the two images, the sand-rich area can be quickly determined without drilling wells, reducing the cost of determining the sand-rich area.

[0043] Other features and advantages of the present invention will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The drawings are used to provide an understanding of the present invention and constitute a part of the specification. They are used together with the following specific implementation to explain the present invention, but do not constitute a limitation to the present invention. In the drawings:

[0045] Figure 1 is a flowchart of the first embodiment of the method for determining the sand-rich area of a deepwater fan without well constraints;

[0046] Figure 2 is a flowchart of the second embodiment of the method for determining the sand-rich area of a deepwater fan without well constraints;

[0047] Figure 3 is a typical seismic cross-section according to an embodiment of the present invention;

[0048] Figure 4 is a planar thickness isopach map of the target deepwater fan;

[0049] Figure 5 is a top interface structural plane isopach map of the target deepwater fan;

[0050] Figure 6 is a sand-rich area division map of the target deepwater fan;

[0051] Figure 7 is a schematic diagram of the top convex amplitude of different sand-rich areas. DETAILED DESCRIPTION OF THE INVENTION

[0052] The following is a detailed description of the specific embodiments of the present invention with reference to the drawings. It should be understood that the specific embodiments described herein are only for explaining and illustrating the present invention and are not used to limit the present invention.

[0053] The following describes the method for determining the sand-rich area of a deepwater fan without well constraints according to the present invention with reference to the drawings.

[0054] As Figure 1 shown, in an embodiment of the present invention, a method for determining a sand-rich area of a deepwater fan without well constraints is provided. In the first embodiment of the method for determining a sand-rich area of a deepwater fan without well constraints provided by the present invention, the method for determining a sand-rich area of a deepwater fan without well constraints includes the following steps:

[0055] Step S10: Determine the top and bottom interfaces of the target deepwater fan in the 3D seismic data;

[0056] Step S20: Draw a plane thickness isopach map according to the depth difference value between the top and bottom interfaces, and draw a top interface structural plane isopach map according to the depth value of the top interface;

[0057] Step S30: Determine the mud-rich area and the sand-rich area according to the plane thickness isopach map and the top interface structural plane isopach map.

[0058] In this embodiment, first, the top and bottom interfaces of the target deepwater fan are confirmed, and a closed area is formed by closing the top and bottom interfaces to facilitate subsequent evaluation operations. Then, a plane thickness isopach map and a top interface structural plane isopach map are drawn according to the depth difference value between the top and bottom interfaces, and the distributions of the mud-rich area and the sand-rich area are obtained by analyzing the intersection of the two images. Compared with the existing methods for determining the sand-rich area, there is no need to drill wells, and only the existing 3D seismic data needs to be processed. The image drawing and the determination of the top and bottom interfaces can be obtained by inputting parameters into the computer. In this embodiment, by first determining the closed area, then drawing the plane thickness isopach map and the top interface structural plane isopach map, and finally intersecting the two images to obtain the distributions of the mud-rich area and the sand-rich area, the sand-rich area can be quickly determined without drilling wells, reducing the cost of determining the sand-rich area.

[0059] As Figure 2 shown, further, a second embodiment of the method for determining a sand-rich area of a deepwater fan without well constraints is proposed according to the first embodiment of the method for determining a sand-rich area of a deepwater fan without well constraints provided by the present invention. In the embodiment of the present invention, the step S30 specifically includes:

[0060] Step S31: Determine the first area where the thickness isolines of the plane thickness isopach map are closed and increase numerically;

[0061] Step S32: Determine the second area where the top interface structural isolines of the top interface structural plane isopach map are encrypted and decrease numerically;

[0062] Step S33: Determine the sand-rich area according to the intersection area of the first area and the second area.

[0063] Specifically, in this embodiment, by identifying the first region where the thickness contour lines in the planar thickness contour image are closed and digitally increasing, and the second region where the top interface structure contour lines in the top interface structure planar contour map are encrypted and the values are decreasing, and then determining the sand-rich area through the intersection method, the remaining non-intersected areas are mud-rich areas. Specifically, the closure of the thickness contour lines, the digital increase, the encryption of the top interface structure contour lines, and the decrease in values can be obtained from the line trends of the scanned images.

[0064] According to the second embodiment of the method for determining the sand-rich area of a deepwater fan without well constraints provided by the present invention, a third embodiment of the method for determining the sand-rich area of a deepwater fan without well constraints is proposed. In the embodiment of the present invention, step S31 specifically includes:

[0065] Step S311: Determine the area where the thickness contour lines are closed based on whether the contour lines in the planar thickness contour map are closed.

[0066] Step S312: Determine the area where the thickness contour values increase towards the center based on whether the contour line values in the planar thickness contour map increase from the fan periphery towards the fan center.

[0067] Step S313: Determine the first region based on the intersection region of the area where the thickness contour lines are closed and the area where the thickness contour values increase towards the center.

[0068] In this embodiment, the first region can be determined by first determining the area where the contour lines are closed, then determining the area where the thickness contour values increase towards the center, and finally intersecting the two regions. The first region can be accurately obtained, facilitating the subsequent determination of the sand-rich area and the mud-rich area.

[0069] According to the second embodiment of the method for determining the sand-rich area of a deepwater fan without well constraints provided by the present invention, a fourth embodiment of the method for determining the sand-rich area of a deepwater fan without well constraints is proposed. In the embodiment of the present invention, step S32 specifically includes:

[0070] Step S321: Determine the area where the structure contour lines are encrypted based on whether the contour lines in the top interface structure planar contour map are encrypted.

[0071] Step S322: Determine the area where the structure contour lines decrease towards the center based on whether the contour line values in the top interface structure planar contour map decrease from the fan periphery towards the fan center.

[0072] Step S322: Determine the second region based on the intersection region of the area where the structure contour lines are encrypted and the area where the structure contour lines decrease towards the center.

[0073] In this embodiment, specifically, the second region is obtained by first determining the contour encryption region, then determining the region where the structural contour decreases towards the center, and finally taking the intersection region of the contour encryption region and the region where the structural contour decreases towards the center. In another embodiment, the region where the structural contour decreases towards the center can be determined first, and then the contour encryption region can be determined, and finally the intersection region can be obtained. In this embodiment, the second region is obtained by the intersection of the two regions, which can quickly and effectively determine the second region.

[0074] In one embodiment, after the step S30, the following steps are further included:

[0075] Step S40, evaluating the sand-rich degree of the sand-rich area according to the top convex amplitude.

[0076] In this embodiment, after determining the sand-rich area and the mud-rich area, the sand-rich degree of the sand-rich area is evaluated according to the top convex amplitude, which can quickly identify the sand-rich area of the target deep-water fan and quickly evaluate its sand-rich property, and has great practical significance for the efficient exploration and development of turbidite fan lithologic oil and gas reservoirs.

[0077] In the embodiment of the present invention, the top convex amplitude is obtained according to the following calculation formula:

[0078] A b = D / H

[0079] A b is the top convex amplitude,

[0080] D is the actual length of the top interface of the sand-rich area,

[0081] H is the straight-line distance of the outer edge of the sand-rich area.

[0082] In this embodiment, the top convex amplitude of the sand-rich area is digitally calculated specifically through the actual length of the top interface of the sand-rich area and the straight-line distance of the outer edge of the sand-rich area, making the evaluation of the sand-rich degree of the sand-rich area more accurate, and involving fewer data types, and the sand-rich degree data can be obtained quickly and effectively.

[0083] As Figure 7 shown, in one embodiment, the specific evaluation of the sand-rich degree is:

[0084] When 2.0 ≤ A b , the sand-to-ground ratio ≤ 30%, and the sand-rich degree is low;

[0085] When 2.0 < A b < 2.5, 30% ≤ sand-to-ground ratio ≤ 50%, and the sand-rich degree is medium;

[0086] When 2.5 ≤ A b , 50% ≤ sand-to-ground ratio, and the sand-rich degree is high.

[0087] In this embodiment, the amplitude of the top convexity corresponds to three levels of sand richness, enabling the rapid acquisition of the sand richness level in the sand-rich area and making the evaluation of sand richness more efficient.

[0088] Specifically, step S10 specifically includes:

[0089] Step S11, obtaining a typical seismic profile of the target deepwater fan using the 3D seismic data;

[0090] Step S12, using the envelope surface method to determine the top interface and the bottom interface within the typical seismic profile that have the same seismic facies characteristics.

[0091] Specifically, the 3D seismic data in this embodiment can be obtained by scanning radar scanning. The seismic facies characteristics include seismic reflection amplitude, seismic reflection frequency, and seismic reflection continuity. Among them, the seismic reflection amplitude has three levels: strong, medium, and weak, which can be determined according to the color depth of the seismic reflection layer. The darker the color, the stronger the amplitude, and the lighter the color, the weaker the amplitude. The seismic reflection frequency has three levels: high, medium, and low, which can be judged according to the thickness of a single seismic reflection layer. The greater the thickness, the smaller the frequency, and the smaller the thickness, the greater the frequency. The seismic reflection continuity has three levels: good, medium, and poor, which can be determined according to the lateral continuity of the seismic reflection layer. The higher the lateral continuity, the better the continuity, and the lower the lateral continuity, the worse the continuity. In this embodiment, a typical seismic profile is obtained through preliminary graphic processing to facilitate the identification of seismic facies characteristics. The envelope surface method is used to determine the top interface and the bottom interface within the typical seismic profile that have the same seismic facies characteristics, enabling a relatively accurate and effective division of the area.

[0092] In one embodiment, step S10 further includes:

[0093] Step S13, tracking and comparing the top interface and the bottom interface in the direction along the sediment source and perpendicular to the sediment source, and realizing the 3D spatial closure of the top interface and the bottom interface.

[0094] In this embodiment, the closing method of the bottom interface and the top interface specifically uses the similarity method to track and compare in the direction along the sediment source and perpendicular to the sediment source, enabling the rapid and accurate determination of the closed area. The specific similarity is determined according to a preset similarity threshold.

[0095] The present invention also proposes a system for determining the sand-rich area of a deepwater fan without well constraints. The system includes:

[0096] A graphic processing module for determining the top interface and the bottom interface of the target deepwater fan in the seismic data,

[0097] The graphic drawing module is used to draw the plane thickness isopach map according to the depth difference value between the top interface and the bottom interface, and draw the top interface structural plane isopach map according to the depth value of the top interface;

[0098] The evaluation module is used to determine the muddy-rich area and the sand-rich area according to the plane thickness isopach map and the top interface structural plane isopach map.

[0099] In this embodiment, first, the graphic processing module is used to confirm the top interface and the bottom interface of the target deep-water fan, and a closed area is formed by closing the top interface and the bottom interface to facilitate subsequent evaluation operations. Then, the graphic drawing module is used to draw the plane thickness isopach map and the top interface structural plane isopach map according to the depth difference value between the top interface and the bottom interface, and the evaluation module analyzes the intersection of the two images to obtain the distribution of the muddy-rich area and the sand-rich area. Compared with the existing method for determining the sand-rich area, there is no need to drill wells, and only the existing 3D seismic data needs to be processed. The image drawing and the determination of the top interface and the bottom interface can be obtained by inputting parameters into the computer. In this embodiment, by first determining the closed area, then drawing the plane thickness isopach map and the top interface structural plane isopach map, and finally intersecting the two images to obtain the distribution of the muddy-rich area and the sand-rich area, the sand-rich area can be quickly determined without drilling wells, reducing the cost of determining the sand-rich area.

[0100] In one embodiment, the sand-rich area of a certain deep-water fan in the lower member of the Dong 2 section of the Oligocene in the Bozhong Sag is determined by the method for determining the sand-rich area of the deep-water fan without well constraints. First, using the 3D seismic data, a typical seismic profile as shown in Figure 3 is obtained. The target deep-water fan is mainly characterized by the seismic facies features of mound-shaped medium-strong amplitude-medium-poor continuity-medium-low frequency seismic reflections. The top envelope surface ( Figure 3 the double-dot dash line in) of the mound-shaped medium-strong amplitude-medium-poor continuity-medium-low frequency seismic facies is the top interface, and its bottom envelope surface ( Figure 3 the thick solid line in) is the bottom interface. Based on the top interface and the bottom interface, the target deep-water fan is traced and compared to achieve 3D spatial closure.

[0101] Then, according to the difference between the depth of the bottom interface and the depth of the top interface, the computer is used to draw the plane thickness isopach map of the deep-water fan as shown on the left in Figure 4 . On the plane thickness isopach map, according to "whether the isoline is closed and whether the isoline value increases from the periphery of the fan body to the center of the fan body", the first area is determined, as shown by the double-dot dash line on the right in Figure 4 ; according to the top interface, the top interface structural plane isopach map is obtained, as shown on the left in Figure 5 , and on the top interface structural plane isopach map, the second area where the isolines are encrypted and the values decrease is determined, as shown by the dotted line on the right in Figure 5 . The intersection area of "the thickness isoline is closed and the value increases" and "the structural isoline is closed and the value decreases" is obtained as the sand-rich area of the deep-water fan, as shown inFigure 6 as shown in the solid line area on the right side.

[0102] Finally, based on the amplitude of the top convexity, the sand-rich degree of the deep-water fan sand-rich area was determined. A total of three sand-rich areas were identified, as Figure 6 shown, the three areas indicated by the thick solid lines. Furthermore, the amplitude of the top convexity of these three sand-rich areas was calculated using the top convexity amplitude calculation formula. Among them, the amplitude of the top convexity of the first sand-rich area is 2.07 < A b < 2.22"; the calculated amplitudes of the top convexity of the second and third sand-rich areas are: 2.68 < A b .

[0103] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0104] In the present invention, unless otherwise clearly defined and limited, the terms "installed", "connected", "connected to", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection, an electrical connection, or communicable with each other; it may be directly connected, or indirectly connected through an intermediate medium, and may be the communication inside two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0105] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0106] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for determining sand-rich areas in deep-water fans without well constraints, characterized in that The method for determining the sand-rich area of a deepwater fan without well constraints includes the following steps: Step S10: Determine the top and bottom interfaces of the target deepwater fan in the 3D seismic data, and form a closed area by closing the top and bottom interfaces; Step S20: Draw a planar thickness isopach map based on the depth difference value between the top and bottom interfaces, and draw a top interface structural planar isopach map based on the depth value of the top interface; Step S30: Determine the mud-rich area and the sand-rich area based on the planar thickness isopach map and the top interface structural planar isopach map; The specific content of step S30 includes: Step S31: Determine the first area where the thickness isopach lines of the planar thickness isopach map are closed and increase numerically; Step S32: Determine the second area where the top interface structural isopach lines of the top interface structural planar isopach map are densified and decrease numerically; Step S33: Determine the sand-rich area according to the intersection area of the first area and the second area; 2. The method for determining the sand-rich area of a deepwater fan without well constraints according to claim 1, wherein The specific content of step S31 includes: Step S311: Determine the thickness isopach line closed area according to whether the isopach lines in the planar thickness isopach map are closed; Step S312: Determine the area where the thickness isopach numerical value increases towards the center according to whether the isopach line numerical value in the planar thickness isopach map increases from the fan periphery to the fan center; Step S313: Determine the first area according to the intersection area of the thickness isopach line closed area and the area where the thickness isopach numerical value increases towards the center; 3. The method for determining the sand-rich area of the deep-water fan without well constraints according to claim 1, wherein The specific content of step S32 includes: Step S321: Determine the structural isopach line densified area according to whether the isopach lines in the top interface structural planar isopach map are densified; Step S322: Determine the area where the structural isopach line decreases towards the center according to whether the isopach line numerical value in the top interface structural planar isopach map decreases from the fan periphery to the fan center; Step S322: Determine the second area according to the intersection area of the structural isopach line densified area and the area where the structural isopach line decreases towards the center; 4. The method for determining a sand-rich area of a deepwater fan without well constraints according to any one of claims 1 to 3, characterized in that, After step S30, the following steps are also included: Step S40: Evaluate the sand-rich degree of the sand-rich area based on the top convex amplitude; 5. The method for determining the sand-rich area of the deep-water fan without well constraints according to claim 4, characterized in that The top convex amplitude is obtained according to the following calculation formula: A b = D / H, A b is the top convex amplitude, D is the actual length of the top interface of the sand-rich area, H is the straight-line distance of the outer edge of the sand-rich area.

6. The method for determining the sand-rich area of the deep-water fan without well constraints according to claim 5, characterized in that The specific evaluation of the sand-rich degree is: When 2.0 ≤ A b the sand content ratio ≤ 30%, and the sand richness degree is low; 2.0 < A b When 2.5 > A > 2.0, 50% ≥ sand ratio ≥ 30%, and the sand richness is medium; 2.5 ≤ A b When this is the case, the sand ratio is ≥ 50%, indicating a high degree of sand abundance.

7. The method for determining a sand-rich area of a deepwater fan without well constraints according to any one of claims 1 to 3, characterized in that, The specific content of step S10 includes: Step S11: Obtain the typical seismic profile of the target deepwater fan using the 3D seismic data; Step S12: Use the envelope surface method to determine the top and bottom interfaces with the same seismic facies characteristics in the typical seismic profile; 8. The method for determining the sand-rich area of a deepwater fan without well constraints according to claim 7, wherein Step S10 also includes: Step S13: Trace and compare the top and bottom interfaces in the source-following and perpendicular-to-source directions and achieve the 3D spatial closure of the top and bottom interfaces; 9. A system for determining a sand-rich area of a deepwater fan without well constraints for the method of determining a sand-rich area of a deepwater fan without well constraints according to any one of claims 1 to 8, characterized in that, The system includes: A graphics processing module for determining the top and bottom interfaces of the target deepwater fan in the seismic data, A graphics drawing module for drawing a planar thickness isopach map based on the depth difference value between the top and bottom interfaces, and drawing a top interface structural planar isopach map based on the depth value of the top interface; An evaluation module for determining the mud-rich area and the sand-rich area based on the plane thickness isogram and the top interface structure plane isogram.

Images