A method for identifying and quantitatively describing deep-water sedimentary lithologic traps

Abstract

The application provides a method for identifying and quantitatively describing a deep-water lithologic trap, and the method comprises the following steps: (1) establishing a deep-water lithologic trap development model through structural-sedimentary slope folding and deep-water deposition analysis; (2) determining a dominant superimposition angle and obtaining reservoir identification data through elastic impedance petrophysical analysis; (3) obtaining a pseudo-elastic impedance body and identifying sandstone reservoir distribution through the reservoir identification data in step (2); (4) three-dimensionally identifying and searching for a lithologic trap target by using a relative geologic age body method and a seismic geomorphology method; and (5) quantitatively describing a lithologic trap boundary through a pinch-out model forward. The method can be used for identifying and quantitatively describing a lithologic trap in a deep-water sand-rich deposition environment, a P-wave impedance and conventional full superimposition data being difficult to accurately identify a reservoir and a sandstone-mudstone boundary being fuzzy.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of oil and gas exploration, and relates to a method for identifying and quantitatively describing deep-water sedimentary lithologic traps. BACKGROUND

[0002] Deep-water lithologic trap exploration is currently a hot and difficult point in oil and gas exploration at home and abroad. The research area as a whole presents a large monocline tectonic background, and is relatively flat, lacking large tectonic traps, and mainly seeking pure lithologic traps. The target layer is in a deep-water sand-rich sedimentary environment with multiple sedimentary bodies, and the sand bodies are vertically superimposed and widely distributed on the plane. The petrophysical characteristics and seismic responses are complex and diverse, and the conventional method cannot effectively implement the lithologic traps in the area, which seriously affects the evaluation of the exploration potential.

[0003] Generally, the deep-water sedimentary body has a clear sedimentary body under-cutting shape on the seismic profile, and has a clear amplitude anomaly on the conventional full stack data, so the interpreter directly interprets the top and bottom envelopes of the sedimentary body on the full stack data, and combines the full stack amplitude attribute to qualitatively determine the boundary range. However, when multiple sedimentary bodies are developed, the under-cutting shape is not obvious, the full stack data and the commonly used P-wave impedance and P-S wave velocity ratio parameters are difficult to distinguish sand and mud, and the trap boundary is ambiguous, the traditional method cannot implement the lithologic trap.

[0004] The specific conventional method has the following disadvantages: (1) affected by the basin overpressure, the velocity difference between the sandstone and the surrounding rock in the research area is very small, the AVO type is various, the seismic response is complex, and the seismic reflection interference caused by the internal impedance difference of the surrounding rock interferes with the identification of the reservoir, so that the effective P-wave impedance, Vp / Vs and other elastic parameters and the full stack data in the reservoir identification in other areas cannot accurately identify the reservoir in the research area; (2) multiple deep-water sedimentary bodies are developed in the research area, which cut and superimpose each other, and do not have the typical sedimentary body shape on the seismic profile, so it is difficult to interpret the sand body by using the traditional sedimentary body manual top and bottom envelope interpretation mode; (3) the sand body is widely distributed on the plane, the sand and mud boundary is ambiguous, and the conventional qualitative identification and description of the lithologic trap have strong multi-solution, which affects the effectiveness of the trap, the determination of the trap scale and the reliability of the oil and gas reservoir analysis.

[0005] Therefore, it is urgent to establish an effective deep-water sedimentary lithologic trap identification and description method to improve the accuracy of the lithologic trap description. SUMMARY

[0006] In order to solve the technical problems in the prior art, the present application provides a method for identifying and quantitatively describing deep-water sedimentary lithologic traps, which can be used for identifying and quantitatively describing the lithologic traps in the deep-water sand-rich sedimentary environment, the reservoir which cannot be accurately identified by the P-wave impedance and the conventional full stack data, and the ambiguous sand and mud boundary.

[0007] To achieve the above technical effects, the application adopts the following technical solutions:

[0008] The application provides a deep-water lithologic trap identification and quantitative description method.

[0009] (1) A deep-water lithologic trap development model is established through structural-sedimentary slope folding and sedimentary analysis;

[0010] (2) The dominant superimposed angle is determined through elastic impedance petrophysical analysis, and reservoir identification data are obtained;

[0011] (3) A pseudo-elastic impedance body is obtained through the reservoir identification data in step (2), and sandstone reservoir distribution is identified;

[0012] (4) A lithologic trap target is identified and searched in three dimensions through a relative geologic age body method and a seismic geomorphology method;

[0013] (5) The lithologic trap boundary is quantitatively described through pinch-out model forward.

[0014] As a preferred technical solution of the application, the structural-sedimentary slope folding in step (1) is a stratum flexure slope folding developed on the basis of a basement protrusion, and is a multi-stage slope folding structure with multiple slope folding steps.

[0015] In the application, the specific number of slope folding steps of the multi-stage slope folding structure is determined by the specific slope folding structure of the research area, and is not specifically limited here.

[0016] Preferably, the structural-sedimentary slope folding analysis in step (1) obtains a deep-water sedimentation model of multi-stage slope folding relay delivery and step-by-step unloading.

[0017] In the application, when the deep-water sedimentary sand body is further delivered to the slope folding zone, the gravity flow sand-carrying capacity is enhanced due to the abrupt change of the topographic slope, and then the gravity flow delivers the detrital material to the next stage of the slope folding step along the slope folding zone, thereby forming a multi-stage slope folding relay delivery and step-by-step unloading deep-water sedimentation model.

[0018] Preferably, the sandstone pinch-out zone of overpass deposition is formed at each stage of the slope folding line in the deep-water sedimentation model.

[0019] In the application, in the deep-water sedimentation model, the multi-stage slope folding not only controls the sand body delivery and unloading, but more importantly, forms the sandstone pinch-out zone of overpass deposition at each stage of the slope folding line, and provides favorable geological conditions for forming pinch-out in the updip direction under the background of sand-rich deep-water deposition.

[0020] As a preferred technical solution of the application, the deep-water lithologic trap development model in step (1) is a model of structural slope folding controlling updip pinch-out and lateral plugging of muddy waterways.

[0021] In the present application, during the relative sea level rise period, a certain amount and scale of muddy waterway is developed after the sandy waterway deposition due to the gravity collapse of the continental slope and multi-stage slope break zone. The incision erosion capacity of the muddy waterway controls the scale of the lithologic trap, when the scale of the late muddy waterway is large and the incision erosion capacity is strong, the sandy waterway deposited in the early stage can be cut in the plane, thereby controlling the sealing of the lithologic trap flanks; when the scale of the muddy waterway is small and the incision erosion capacity is weak, it is difficult to separate the sandy waterway in the plane, at this time, the deep water lithologic trap mainly relies on the semi-deep sea muddy surrounding rock to seal the flanks, thereby forming the lithologic trap.

[0022] As a preferred technical scheme of the present application, the method of the elastic impedance rock physics analysis in step (2) comprises: comparing the rock physics characteristics of different angle seismic elastic parameters, and screening out the stacking angle with the largest sandstone-mudstone difference and the smallest background mudstone wave fluctuation interference.

[0023] As a preferred technical scheme of the present application, the dominant stacking angle in step (2) comprises near trace, middle trace, far trace or super far trace.

[0024] In the present application, for the research area of the present application, the dominant stacking angle is preferably far trace or super far trace. However, for other research areas, due to the change of rock physics performance, the dominant stacking angle may also be near trace or middle trace when the dominant stacking angle is determined.

[0025] In the present application, for the multi-period superposition of deep water sedimentary bodies in the research area, the wave impedance cannot accurately distinguish sandstone and mudstone, so that the conventional stacked seismic data is difficult to identify the reservoir problem. Through the elastic impedance rock physics analysis, the rock physics characteristics of different angle seismic elastic parameters are compared in detail, the stacking angle with the largest sandstone-mudstone difference and the smallest background mudstone internal difference interference is screened out, and then the seismic response data of the stacking angle is selected as the dominant angle stacking data for sand body identification.

[0026] In the present application, the elastic impedance calculation formula is as follows (Connlly, 1999):

[0027] EI(θ)=V p a V s b ρ c , wherein, θ is the incidence angle, a=1+sin 2 θ, b=-8Ksin 2 θ, c=1-4Ksin 2 θ, K is a constant, usually taking the average value of (Vs / Vp) 2 .

[0028] As a preferred technical scheme of the present application, the method for identifying the distribution of sandstone reservoirs in step (3) comprises: performing dominant superimposed angle pseudo-elastic impedance volume inversion, and identifying deep water sedimentary sand bodies with weak velocity difference by using the dominant superimposed angle pseudo-elastic impedance volume.

[0029] In the present application, the method for identifying the distribution of sandstone reservoirs effectively converts seismic interface information into stratigraphic information, and can significantly improve the identification ability of sand bodies compared with conventional seismic reflecting interface information.

[0030] As a preferred technical scheme of the present application, the method for obtaining the relative geologic time volume in step (4) comprises: calculating isochronous stratigraphic slices by using a method for generating a relative geologic time volume based on a global optimization algorithm.

[0031] As a preferred technical scheme of the present application, after obtaining the isochronous stratigraphic slices, under the constraint of a fine isochronous stratigraphic framework, isochronous stratigraphic slice attribute extraction is carried out on the dominant superimposed angle pseudo-elastic impedance volume effectively characterizing sand bodies.

[0032] In the present application, the method for using a relative geologic time volume and the method of seismic geomorphology are used, and the relative isochronous interface envelope interpretation mode makes seismic interpretation in a sand-rich environment more reliable, reduces the multi-solution nature of trap implementation, and simultaneously realizes multi-oil and gas field and multi-target continuous interpretation and research in a block.

[0033] As a preferred technical scheme of the present application, the pinch-out model forward in step (5) comprises: establishing a stratigraphic model in which sand body thickness gradually changes until pinch-out according to actual drilling and logging data, carrying out dominant superimposed angle seismic forward simulation for the model, and counting the change curve of seismic amplitude and sand body thickness.

[0034] As a preferred technical scheme of the present application, the method for quantitatively depicting the boundary of the lithologic trap in step (5) comprises: taking the amplitude value when the sand body thickness is zero as the threshold value of the trap boundary according to the change curve of seismic amplitude and sand body thickness, delineating the trap range through the threshold value, and completing the quantitative depiction of the trap boundary.

[0035] Compared with the prior art, the present application has at least the following beneficial effects:

[0036] (1) The distribution range of sandstone reservoirs that cannot be identified by the prior art and full superimposed data is identified by analyzing and selecting dominant data.

[0037] (2) The present application breaks through the traditional sedimentary body top and bottom envelope interpretation trap implementation mode, and is more suitable for deep water sedimentary lithologic trap implementation in a complex sedimentary environment and a profile without obvious sedimentary body shape.

[0038] (3) make sand body boundary description from qualitative to quantitative, accurately describe the trap range, reduce the multi-solution of traditional manual trap boundary setting;

[0039] (4) under the guidance of trap development mode, the lithologic trap is more reliable;

[0040] (5) a set of lithologic trap identification and description technology combination suitable for deepwater sand-rich sedimentary environment is established. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 For the structural and stratigraphic development characteristics of the study area map;

[0042] Figure 2a For the seismic reflection characteristics of the deepwater sedimentary body of the conventional (a block in West Africa) deepwater sedimentary body;

[0043] Figure 2b For the seismic reflection characteristics of the deepwater sedimentary body of the study area (a block in South America) deepwater sedimentary body;

[0044] Figure 3 For the study area P-wave impedance and P-wave to S-wave velocity ratio parameter petrophysical crossplot analysis map;

[0045] Figure 4 The deepwater sedimentary lithologic trap identification and quantitative description method flowchart provided by the present application;

[0046] Figure 5 The deepwater clastic rock lithologic trap development mode map in the embodiment;

[0047] Figure 6a The sandstone and mudstone elastic impedance map at different angles in the embodiment;

[0048] Figure 6b The near-trace elastic impedance and far-trace elastic impedance crossplot in the embodiment;

[0049] Figure 7a The full stack, near-trace, mid-trace, far-trace and other different angle stack data over well seismic section in the embodiment;

[0050] Figure 7b The full stack and far-trace different angle stack data over well seismic section and plane attribute map in the embodiment;

[0051] Figure 8a The far-trace stack data in the embodiment;

[0052] Figure 8b The pseudo-elastic impedance body inversion data in the embodiment;

[0053] Figure 9a The relative isochronous interface envelope interpretation deepwater sedimentary body section in the embodiment;

[0054] Figure 9b This example illustrates the planar distribution of sediments based on planar properties.

[0055] Figure 10 These are cross-sectional views of seismic reflection types at the boundaries of two sandstone reservoirs in the examples;

[0056] Figure 11a This is a wedge model diagram based on actual well data in the embodiment;

[0057] Figure 11b This is a diagram showing the forward modeling results of the wedge model in the embodiment;

[0058] Figure 12 The example uses an amplitude threshold to depict the closed boundary map.

[0059] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims. Detailed Implementation

[0060] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0061] The research area of ​​the specific embodiments of this invention is a deep-water area of ​​a calm, passive continental margin basin on the west coast of the Atlantic Ocean.

[0062] like Figure 1 As shown, the study area presents a large monocline tectonic setting with relatively flat strata and a lack of large tectonic traps, with the search primarily focused on pure lithological traps. The target layer is located in a deep-water, sandy-rich sedimentary environment with multiple sedimentary phases, where sand bodies are vertically superimposed and distributed in contiguous areas in the plane.

[0063] As shown in Figure 2(a), conventional deep-water sedimentary bodies exhibit obvious anomalies in shape and amplitude on conventional full-stack seismic profiles, allowing for the identification and confirmation of traps by interpreting the top and bottom envelopes of the sedimentary bodies. As shown in Figure 2(b), the study area is located in a sand-rich deep-water fan sedimentary environment. The sedimentary bodies lack distinct shape characteristics, are stacked in multiple phases vertically, intersected in planar planes, and have blurred boundaries. Seismic interpretation makes it difficult to identify reservoir distribution, posing a significant challenge to trap confirmation.

[0064] like Figure 3 As shown, the P-wave impedance and P-wave velocity ratio parameters, which are effective in reservoir prediction in other areas, are difficult to distinguish between sandstone and mudstone in the study area. There are many overlapping areas between sandstone and mudstone on the cross plot, and reservoir identification has strong ambiguity.

[0065] Example

[0066] This embodiment provides a method for identifying and quantitatively characterizing deep-water sedimentary lithological traps, the method comprising the following steps:

[0067] (1) Establish a deep-water lithological trap development model through tectonic-sedimentary slope break analysis and sedimentary analysis;

[0068] Specifically, this embodiment studies four types of slope breaks in the study area: fault slope breaks, sedimentary slope breaks, flexural slope breaks, and tectonic-sedimentary slope breaks. Among them, the tectonic-sedimentary slope breaks developed in the deep-water terrestrial slope area are as follows: Figure 5 As shown, this is a tectonic-sedimentary composite slope break, closely related to the formation of lithological traps. Controlled by regional compressive stress, the strata in the continental slope area formed an uplift structure trending approximately NW-SE, followed by inherited sedimentary slope breaks in the overlying strata, thus forming multi-level slope break zones. Meanwhile, the strata in the middle-lower continental slope where the study area is located are relatively gentle, with a dip angle of only about 1°, while the slope break zone strata dip angle reaches 3–10°. This results in multiple slope break steps in the middle-lower continental slope area. These gentle slope break steps become excellent sites for unloading deep-water sand bodies, forming deep-water sediments dominated by weakly confined to unconfined channels and lobes with good internal sand body connectivity and minimal downcutting erosion. As the deep-water sedimentary sand bodies further advance and are transported to the slope break zone, the abrupt change in topographic slope enhances the sand-carrying capacity of gravity flows, thus transporting clastic material along the slope break zone to the next lower slope break step, forming a multi-level slope break "relay transport, step-by-step unloading" deep-water sedimentary model. In this depositional pattern, multi-level slope breaks not only control sand transport and unloading, but more importantly, they form sandstone pinch-out zones through the slope breaks at each level. In the context of sand-rich deep-water deposition, this provides favorable geological conditions for pinch-outs to form in the updip direction.

[0069] During periods of relative sea-level rise, the gravity collapse of continental slopes and multi-level slope breaks leads to the development of numerous and large-scale muddy channels following the deposition of sandy channels. The downcutting erosion capacity of these muddy channels controls the size of lithological traps. When late-stage muddy channels are large and have strong downcutting erosion capacity, they can create planar cuts in the previously deposited sandy channels, thus controlling the flank sealing of lithological traps. When muddy channels are small and have weak downcutting erosion capacity, they are unable to planarly separate the sandy channels. In this case, deep-water lithological traps mainly rely on the flank sealing of semi-deep-sea muddy surrounding rocks to form lithological traps.

[0070] Based on tectonic-sedimentary slope breaks and comprehensive sedimentary analysis, a deep-water lithological trap development model was established, characterized by "tectonic-sedimentary slope breaks controlling updip pinch-outs and lateral blocking of muddy channels".

[0071] (2) By using elastic impedance rock physics analysis, the dominant superposition angle is determined and reservoir identification data is obtained;

[0072] Specifically, as shown in Figure 6(a), on the P-wave impedance vs. burial depth crossplot commonly used in reservoir identification, the sandstone and mudstone have high overlap degree and are difficult to be accurately distinguished, and there is obvious impedance difference in the mudstone, which will cause strong amplitude reflection interference sandstone reservoir identification. The P-wave impedance mainly reflects the elastic characteristics at the incident angle of zero, while the elastic impedance can reflect the elastic characteristics at different incident angles, and the elastic impedance at different incident angles has different sensitivities to the reservoir. As shown in Figure 6(a), in the near trace, i.e. the incident angle range of 3°-16°, the sandstone and mudstone are slightly better distinguished than the P-wave impedance, but it is still difficult to distinguish them; in the middle trace, i.e. the incident angle range of 16°-25°, the sandstone and mudstone are further better distinguished; and in the far trace or super far trace elastic impedance, the sandstone and mudstone are most obviously distinguished, and the mudstone presents the baseline characteristics, the impedance difference between the mudstones is small, and the background reflection interference is small, which is the dominant angle for identifying the reservoir. As shown in Figure 6(b), the sandstone and mudstone which are difficult to distinguish in the conventional P-wave impedance (abscissa) impedance superposition are better distinguished in the far trace elastic impedance (ordinate), and therefore, the dominant superposition angle for reservoir identification is selected by the elastic impedance petrophysical driving.

[0073] As shown in Figure 7(a), the reservoir response is weak in the full stack, near trace and middle trace in the research area, and the sandstone and mudstone are not obviously distinguished, while the sandstone reservoir response is obvious in the preferred far trace data sensitive to the reservoir.

[0074] As shown in Figure 7(b), the research area shows strong amplitude and obvious sediment shape characteristics in the near trace plane attribute, but well1 well is confirmed to be mudstone, and the weak amplitude on the far trace profile represents mudstone reflection, which confirms that the preferred far trace method for distinguishing sandstone and mudstone is effective; the regions with strong amplitude anomalies in the far trace, well2 and well3, are confirmed to be sandstone reservoirs.

[0075] (3) The pseudo-elastic impedance body is obtained from the reservoir identification data in step (2), and the sandstone reservoir distribution is identified;

[0076] Specifically, Figure 8(a) is the far trace identification data of the research area, and Figure 8(b) is the pseudo-elastic impedance body inversion data. As shown in Figures 8(a) and 8(b), the seismic event troughs and peaks at the dominant superposition angle correspond to the top and bottom of the sandstone, respectively, and the event zero phase at the dominant superposition angle pseudo-elastic impedance body has good correspondence with the sandstone. When the sandstone resolution is less than or close to the seismic resolution, and the upper and lower surrounding rock thickness is greater than one-quarter wavelength, the pseudo-elastic impedance body inversion can be realized by using the -90° phase shift technology.

[0077] (4) The method of relative geologic time body and the method of seismic geomorphology are used to identify and search the lithologic trap in three dimensions;

[0078] Specifically, the research area is located in a multi-stage superimposed sandy submarine fan deposition environment, and develops multi-stage channel deposition bodies. The deposition bodies are distributed in series in the plane and cut and superimpose each other. In the traditional seismic interpretation, the horizon is mainly interpreted based on manual picking or automatic tracking. This workflow is not only very time-consuming but also difficult to accurately interpret the deposition bodies in the complex sedimentary environment of the research area.

[0079] In this embodiment, 1) isochronous stratigraphic slices are calculated using a method for generating a relative geochronological volume based on a global optimization algorithm. Specifically, based on the minimization of a cost function, horizon interpretation and stratigraphic modeling are automatically realized by computer global iterative optimization. The cost function depends on the amplitude similarity between seismic grid points and the distance between seismic grid points. The best model corresponds to the minimum cost function. The generated stratigraphic model is relatively isochronous for each layer. The stratigraphic model is a relative geochronological volume. 2) Under the constraint of a fine isochronous stratigraphic framework, isochronous stratigraphic slice attributes are extracted from a pseudo-elastic impedance volume that effectively characterizes the advantage of superimposed sand bodies. Specifically, isochronous stratigraphic slices that are continuous in the vertical direction can be extracted from the relative geochronological volume. Amplitude attributes are extracted from an optimally selected reservoir identification data volume along a certain isochronous stratigraphic slice, i.e., the planar attribute along the isochronous stratigraphic slice is obtained. 3) Three-dimensional stereoscopic identification and search of lithologic traps are completed using the seismic geomorphological characteristics of the sedimentary body. Specifically, seismic sedimentology is based on three-dimensional seismic data. The horizontal resolution of seismic data is higher than the vertical resolution, which allows thin reservoirs that cannot be identified in the vertical direction to be identified in the plane. According to the shape characteristics of amplitude anomalies and combined with sedimentary knowledge, potential lithologic trap targets are searched layer by layer quickly and efficiently on the isochronous stratigraphic slice planar attribute.

[0080] As shown in FIGS. 9(a) and 9(b), according to the relative isochronous principle, sequence boundary attribute algorithms under the Wheeler domain are used to carry out full three-dimensional isochronous framework sequence interface tracking interpretation. Then, the distribution range of the sand body is determined through interlayer attribute.

[0081] (5) Quantitative description of lithologic traps is carried out through pinch-out model forward modeling;

[0082] Specifically, a stratigraphic model in which the thickness of the sand body gradually changes until pinch-out is established according to the actual drilling and logging data. Seismic forward modeling is carried out for the model, and the change curve of seismic amplitude and sand body thickness is counted. According to the change curve of seismic amplitude and sand body thickness, the amplitude value when the sand body thickness is zero is taken as the threshold value of the trap boundary. The trap range is circled through the threshold value, and the quantitative description of the trap is completed, as shown in FIGS. 11(a) and 11(b).

[0083] The method for circling the trap range through the threshold value is that the threshold amplitude is taken as the trap boundary of the sandstone pinch-out on the interlayer planar attribute, and the area outside the threshold amplitude is determined as the background mudstone.

[0084] like Figure 12 As shown, in a multi-lobed development zone, it is difficult to determine whether sandstone reservoirs develop in the weak amplitude areas between and at the edges of lobes. By using quantitative threshold characterization of trap boundaries, the problem of ambiguous sandstone-mudstone boundaries and difficulty in manual identification is solved. The shift from qualitative to quantitative methods reduces the ambiguity in trap identification.

[0085] The applicant declares that the detailed structural features of the present invention are illustrated through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components selected in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0086] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0087] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0088] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for identifying and quantitatively characterizing deep-water depositional lithologic traps, characterized in that, The method comprises the following steps: (1) establishing a deep-water lithologic trap development model through structural-sedimentary slope break and deep-water sedimentation analysis; (2) determining a dominant stacking angle and obtaining reservoir identification data through elastic impedance petrophysical analysis; (3) identifying sandstone reservoir distribution through pseudo-elastic impedance volume obtained from the reservoir identification data in step (2); (4) three-dimensionally identifying and searching for lithologic trap targets by using a relative geologic time volume method and a seismic geomorphology method; (5) quantitatively delineating the boundary of the lithologic trap through pinch-out model forward modeling. The method for identifying sandstone reservoir distribution in step (3) comprises: performing pseudo-elastic impedance volume inversion of the dominant stacking angle data, and identifying deep-water sedimentary sand bodies with weak velocity difference by using the pseudo-elastic impedance volume of the dominant stacking angle data.

2. The method of claim 1, wherein, The structural-sedimentary slope break in step (1) is a stratum flexure slope break developed in an inherited manner on the basis of a basement bulge, and is a multi-stage slope break structure with multiple slope break steps.

3. The method of claim 1, wherein, The structural-sedimentary slope break analysis in step (1) obtains a deep-water sedimentation model of multi-stage slope break force transmission and step-by-step unloading.

4. The method of claim 3, wherein, The sandstone pinch-out zone of overpass deposition is formed at each stage of the slope break line under the deep-water sedimentation model.

5. The method of claim 1, wherein, The deep-water lithologic trap development model in step (1) is a model in which structural-sedimentary slope breaks control updip pinch-out and lateral sealing of muddy waterways.

6. The method of claim 1, wherein, The method of elastic impedance petrophysical analysis in step (2) comprises: comparing the petrophysical characteristics of seismic elastic parameters at different angles, and selecting a stacking angle with the largest difference between sandstone and mudstone and the smallest background mudstone wave fluctuation interference.

7. The method of claim 1, wherein, The dominant stacking angle in step (2) comprises near, middle, far or super-far traces.

8. The method of claim 1, wherein, The method of relative geologic time volume in step (4) comprises: calculating isochronous stratum slices by using a method of generating a relative geologic time volume based on a global optimization algorithm.

9. The method of claim 8, wherein, After the isochronous stratum slices are obtained, under the constraint of a fine isochronous stratum framework, isochronous stratum slice attribute extraction is carried out on the pseudo-elastic impedance volume of the dominant stacking angle which effectively characterizes sand bodies.

10. The method of claim 1, wherein, The pinch-out model forward modeling in step (5) comprises: establishing a stratum model in which sand body thickness gradually changes until pinch-out according to actual drilling and logging data, carrying out seismic forward modeling of the dominant stacking angle for the model, and counting the change curve of seismic amplitude and sand body thickness.

11. The method of claim 10, wherein, The method for quantitatively delineating the boundary of the lithologic trap in step (5) comprises: taking the amplitude value when the sand body thickness is zero as the threshold value of the trap boundary according to the change curve of the seismic amplitude and the sand body thickness, delineating the trap range through the threshold value, and completing the quantitative delineation of the trap boundary.

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