Paleotopography-based beach bar sand body quantitative description method

Abstract

The invention provides a beach bar sand body quantitative description method based on a paleotopography. The beach bar sand body quantitative description method based on the paleotopography comprises the steps that 1, the paleotopography in a certain deposition period is restored by integrating earthquake, geology and logging information; 2, selecting a plurality of representative well point samples; step 3, obtaining a reduced stratum depth value of the position of a single sample well point and drilling sand body thickness data; 4, establishing a sand body thickness prediction formula based on the reduced stratum depth; and step 5, according to the established sand body thickness prediction formula based on the reduced stratum depth, quantitatively predicting the thickness of the beach and bar sand body in the unmoved area. The beach bar sand body quantitative description method based on the paleotopography is high in prediction precision, effectively overcomes the limitation that quantitative description cannot be achieved through a conventional beach bar sand prediction method, is simple and easy to operate, and can achieve characterization of the thickness of the beach bar sand body.

Description

Technical Field

[0001] The invention relates to the technical field of unconventional oil development, and in particular to a quantitative description method of beach-bar sand bodies based on paleotopography. Background Art

[0002] Beach-bar sand is one of the most important oil and gas reservoirs in fault basins. The quantitative description of beach-bar sand bodies has always been the focus of attention of geologists at home and abroad. With the continuous advancement of the exploration process, deep beach-bar sand reservoirs have gradually become an important field of oil and gas exploration in continental fault basins in eastern my country. Taking Shengli Oilfield as an example, the cumulative proven reserves of beach-bar sandstone reported in the western oil field alone are nearly 200 million tons, with huge development potential. At present, most domestic and foreign researchers believe that the beach-bar deposition in fault lake basins is mainly controlled by "three paleo-geography", including paleo-topography, paleo-hydrodynamics and paleo-base level. Among them, paleo-topography can provide evidence for characterizing the spatial relationship between sedimentary areas and sedimentary centers, reflecting the transport channels of sediments, and is of great significance for predicting sedimentary systems. By searching domestic and foreign literature, domestic scholars have mostly made qualitative predictions in the description of beach-bar sand reservoir reservoirs, lacked applicable technical research in the quantitative prediction of sand body thickness, and have not formed an effective method to quantitatively describe the boundaries and thickness of sand bodies.

[0003] In the Chinese patent application with application number: CN201910348690.2, a method and device for predicting thin reservoirs in lacustrine beach-bar sand bodies are involved. The method includes: dividing the sequence levels of different single wells according to historical data and well logging data in the target area; comparing the sand bodies of different single wells of the same sequence level to obtain sand body comparison results; preprocessing and standardizing the well logging curves of the single wells, and selecting inversion sample curves from the well logging curves according to the lithology data of the well logging curves; bandpass filtering the seismic data according to the sand body comparison results to obtain thin reservoir seismic reflection data; waveform phase-controlled random inversion is performed according to the inversion sample curves, the acoustic wave curves and density curves in the seismic data, and the thin reservoir seismic reflection data to obtain the thin reservoir inversion results; and determining the location of the thin reservoir according to the thin reservoir inversion results. This application can improve the accuracy of predicting thin reservoirs in lacustrine beach-bar sand bodies.

[0004] In the Chinese patent application with application number: CN201710711093.2, a method and device for predicting reservoir sand bodies based on wind field, material source, and basin system is involved; wherein, the method includes: obtaining geological data of the area to be predicted; wherein, the geological data includes at least multiple of core data, paleontological data, logging data, and seismic data; inputting the geological data into the preset wind field, material source, and basin system model to generate the beach-bar sand body formation process data of the area to be predicted; wherein, the wind field, material source, and basin system model includes at least multiple of ancient material source recovery tools, ancient wind force recovery tools, ancient wind direction recovery tools, ancient landform recovery tools, and ancient water depth recovery tools; according to the beach-bar sand body formation process data, the specific distribution position of the beach-bar sand body in the area to be predicted is predicted by using geological methods and geophysical methods. The invention can effectively identify and predict the distribution position and range of shallow water thin-layer beach-bar sand bodies, and improve the feasibility and accuracy of reservoir sand body prediction methods.

[0005] In the Chinese patent application with application number: CN202010691793.1, a beach-bar sand reservoir prediction method and device are involved, the method comprising: according to the well logging data of the target well located in the beach-bar sand study area, the reservoir corresponding to the well logging data is divided into multiple beach-bar sand sand body development stages; based on the oil and gas exploration results corresponding to each of the development stages, the development stage with the largest oil and gas content is selected as the target layer segment, and the seismic horizon data of the target layer segment is determined; the beach-bar sand development area in the beach-bar sand study area is determined according to the seismic horizon data of the target layer segment, and the beach-bar sand reservoir distribution result of the beach-bar sand study area is determined based on the beach-bar sand development area. This application can effectively improve the recognition accuracy of obtaining beach-bar sand reservoirs, can effectively improve the efficiency, reliability and accuracy of predicting beach-bar sand reservoirs, and can provide an effective and accurate data basis for beach-bar sand exploration and oil and gas production.

[0006] In the Chinese patent application with application number: CN201210212603.9, a method for establishing a beach-bar sandstone microfacies identification model is involved. This method uses well logging curves combined with geological logging data to identify sedimentary microfacies. First, the lithology is accurately identified based on the well logging curve, and then the well logging curve and lithology are combined to divide the small layer in the geological microfacies layer, and the curve value and morphological value of the small layer are extracted. Finally, the beach-bar sandstone sedimentary microfacies are accurately divided according to the curve value, morphological value and lithology, and a standard library for patterned identification of beach-bar sandstone sedimentary microfacies and a beach-bar sandstone microfacies identification model are established. The beach-bar sandstone microfacies identification model is adopted, based on the standard library for patterned identification of beach-bar sandstone sedimentary microfacies, combined with the well logging curve value and morphological value, the beach-bar sandstone sedimentary microfacies can be accurately identified. This method can be applied to all beach-bar sandstone sedimentary microfacies divisions, and can provide a basis for judging reservoir properties and oil and gas content.

[0007] The above existing technologies are greatly different from the present invention and fail to solve the technical problem we want to solve. Therefore, we have invented a new quantitative description method of beach-bar sand bodies based on paleotopography. Summary of the invention

[0008] The purpose of the present invention is to provide a quantitative description method of beach-bar sand bodies based on paleotopography which can improve prediction accuracy and is simple and easy to operate.

[0009] The object of the present invention can be achieved by the following technical measures: a quantitative description method of beach-bar sand bodies based on paleotopography, the quantitative description method of beach-bar sand bodies based on paleotopography comprising:

[0010] Step 1: Restore the ancient topography of a certain sedimentary period by integrating seismic, geological and well logging data;

[0011] Step 2, selecting a plurality of representative well point samples;

[0012] Step 3, obtaining the restored formation depth value and the drilled sand body thickness data at the location of the single sample well point;

[0013] Step 4, establishing a sand body thickness prediction formula based on the reduced formation depth;

[0014] Step 5: quantitatively predict the thickness of the beach-bar sand body in the unmoved area according to the established sand body thickness prediction formula based on the restored formation depth.

[0015] The purpose of the present invention can also be achieved by the following technical measures:

[0016] In step 1, the top and bottom interfaces of the strata that accurately represent a certain geological period are determined, and the paleotopography of the geological period is restored by the comprehensive application of residual thickness calculation, strata filling and completion, and sedimentation compaction correction methods.

[0017] In step 2, based on the analysis of paleotopographic data, multiple representative well point samples are selected from underwater highlands, underwater uplifted gentle slopes, and underwater low-lying areas.

[0018] In step 2, the ancient topography of a certain geological period is restored and classified according to different ancient topography characteristics into three categories: underwater highlands, underwater uplifted gentle slopes, and underwater low-lying areas. Then, multiple representative wells are selected at different ancient topography locations to ensure the diversity of sample quantity and improve the credibility of the analysis results.

[0019] In step 3, based on the results of ancient terrain restoration in a certain geological period, the restored stratigraphic depth value of the location of a single sample well point is counted; based on the results of fine stratigraphic comparison, the thickness value of the sand body drilled by the single sample well point in the geological period is counted.

[0020] In step 4, based on the classification of different paleotopographic locations, the correlation coefficient between the sand body thickness encountered at a single sample well point and the reduced formation depth is calculated, a sand body thickness prediction formula based on the reduced formation depth is obtained, and a fitting trend diagram of the change of sand body thickness with the reduced formation depth is drawn.

[0021] In step 4, through rock physics simulation experiments, the formation depth values ​​of single well points at different paleotopographic positions counted in the previous step are fitted with the sand body thickness encountered, and the sand body thickness-reduced formation depth fitting trend equations of underwater highlands, underwater uplift gentle slopes, and underwater depressions are obtained respectively, and a fitting trend graph of the change of sand body thickness with reduced formation depth is drawn.

[0022] The fitting trend equation of sand body thickness-reduced formation depth in underwater highlands and underwater uplift gentle slopes is:

[0023] Y1=a1e -b1x1

[0024] Where, Y1 is the actual sand body thickness encountered by the well point, in m; x1 is the reduced formation depth at the well point, in m; a1 is the fitting coefficient between the actual sand body thickness encountered by the well point and the reduced formation depth, a constant; b1 is a constant.

[0025] In step 4, from the fitting trend equation of sand body thickness-reduced stratum depth in underwater highlands and underwater uplift gentle slopes, it can be seen that the sand thickness in underwater highlands and gentle slopes is exponentially negatively correlated with the reduced stratum depth. The higher the paleotopography, the less the thickness of the sedimentary sand body.

[0026] In step 4, the fitting trend equation of sand body thickness-reduced formation depth in the underwater low-lying area is:

[0027] Y2=a2e b2x2

[0028] Where, Y2 is the actual sand body thickness encountered by the well point in the underwater low-lying area, in m; x2 is the reduced formation depth of the well point in the underwater low-lying area, in m; a2 is the fitting coefficient between the actual sand body thickness encountered by the well point and the reduced formation depth, a constant; b2 is a constant.

[0029] In step 4, from the fitting trend equation of sand body thickness in underwater depressions and reduced stratum depth, it can be seen that the sand thickness in underwater depressions is exponentially positively correlated with the reduced stratum depth. The higher the paleotopography, the thicker the sedimentary sand body.

[0030] The quantitative description method of beach-bar sand bodies based on paleotopography in the present invention is based on seismic, geological and logging data, and is corrected by sedimentation and compaction. The comprehensive application of the method restores the paleotopography during the Sha 4 deposition period. On the basis of classifying different paleotopographic locations, the restored formation depth values ​​and drilled sand body thickness data of the locations of single sample well points are extracted respectively. The restored formation depth is used as the independent variable, and the sand body thickness drilled by the well point is used as the dependent variable. The sand body thickness prediction formula based on the restored formation depth is established by regression fitting, and then the thickness of the beach-bar sand body in the unmoved area is quantitatively predicted. Compared with the prior art, the present invention has the following beneficial effects: in view of the difficulty in describing beach-bar sand, under the guidance of the predecessors' "three ancient" sand-controlling sedimentary model, the method research is deepened, based on the results of ancient topography restoration, and the nonlinear exponential relationship between the restored stratum thickness at the location of the well point in the dense well network area and the thickness of the sand body encountered by the well point is utilized to guide the quantitative description of the sand body in the unmoved area of ​​the beach-bar, which can effectively improve the accuracy of the description of the beach-bar sand body and the reliability of the results; none of the existing methods for fine description of beach-bar sand bodies involve guiding the quantitative prediction of the thickness of beach-bar sand bodies based on the results of ancient topography restoration, and is highly innovative. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a flow chart of a specific embodiment of the method for quantitatively describing beach-bar sand bodies based on paleotopography of the present invention;

[0032] Figure 2 for Figure 1 A restored plane display of ancient terrain in a certain geological period in the embodiment;

[0033] Figure 3 for Figure 1 A fitting relationship diagram between the thickness of sand bodies encountered by well points in a certain geological period and the restored strata in the embodiment;

[0034] Figure 4 for Figure 1 Plane prediction diagram of beach-bar sand body thickness in a certain geological period in the embodiment. DETAILED DESCRIPTION

[0035] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0036] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations and / or combinations thereof.

[0037] The quantitative description method of beach-bar sand bodies based on paleotopography in the present invention is based on seismic, geological and well logging data, and restores the paleotopography of a certain sedimentary period through the comprehensive application of residual thickness calculation, formation filling and filling, and sediment compaction correction methods; based on the analysis of paleotopographic data, multiple representative well point samples are selected from underwater highlands, underwater uplifted gentle slopes, and underwater low-lying areas to obtain the restored formation depth value and drilled sand body thickness data of the location of a single sample well point; on the basis of the classification of different paleotopographic locations, the sand body thickness-restored formation depth fitting trend equation is established according to the correlation coefficient between the sand body thickness and the restored formation depth of a single sample well point obtained by experimental calculation, and the thickness of the beach-bar sand body in the unmoved area is quantitatively predicted according to the fitting trend equation. The method of the present invention has high prediction accuracy, effectively overcomes the limitation that conventional beach-bar sand prediction methods cannot be quantitatively described, is simple and easy to operate, and can achieve the characterization of beach-bar sand body thickness.

[0038] The following are several specific embodiments of the present invention.

[0039] Example 1

[0040] In the specific embodiment 1 of the present invention, Figure 1 As shown, Figure 1 The flowchart of the method for quantitatively describing beach-bar sand bodies based on paleotopography of the present invention is as follows:

[0041] Step 101, integrating seismic, geological and well logging data to restore the ancient topography of a certain sedimentary period;

[0042] Step 102, based on the analysis of paleotopographic data, multiple representative well point samples are selected from underwater highlands, underwater uplifted gentle slopes, and underwater low-lying areas;

[0043] Step 103, obtaining the restored formation depth value and drilled sand body thickness data of the location of the single sample well point;

[0044] Step 104, based on the classification of different paleo-topographic locations, the restored stratum depth is used as an independent variable, and the sand body thickness encountered by the well point is used as a dependent variable, and regression fitting is used to establish a sand body thickness prediction formula based on the restored stratum depth, and a fitting trend diagram of the change of sand body thickness with the restored stratum depth is drawn;

[0045] Step 105, quantitatively predicting the thickness of the beach-bar sand body in the unmoved area according to the established sand body thickness prediction formula based on the restored formation depth.

[0046] The ancient topography of a certain sedimentary period is restored by integrating seismic, geological and logging data, specifically including: determining the top and bottom interfaces of the strata that accurately represent a certain geological period, and restoring the ancient topography of that geological period through the comprehensive application of residual thickness calculation, strata filling and completion, and sedimentation compaction correction methods.

[0047] Based on the analysis of paleotopographic data, a number of representative well point samples were selected from underwater highlands, underwater uplifted gentle slopes, and underwater depressions. Specifically, professional software was used to restore the paleotopography of a certain geological period, and the paleotopography was classified according to different paleotopographic features into three categories: underwater highlands, underwater uplifted gentle slopes, and underwater depressions. Then, a number of representative wells were selected at different paleotopographic locations to ensure the diversity of sample quantity and improve the credibility of the analysis results.

[0048] The restored stratigraphic depth value and drilled sand body thickness data of the location of a single sample well point are obtained, specifically including: based on the results of ancient topography restoration in a certain geological period, using professional software to count the restored stratigraphic depth value of the location of a single sample well point; based on the results of fine stratigraphic comparison, counting the sand body thickness value encountered by a single sample well point in the geological period.

[0049] Based on the classification of different paleo-topographic locations, the correlation coefficient between the sand body thickness encountered by a single sample well point and the depth of the restored formation is calculated, and a sand body thickness prediction formula based on the depth of the restored formation is obtained, and a fitting trend diagram of the change of sand body thickness with the depth of the restored formation is drawn. Specifically, the formation depth values ​​of the single well points at different paleo-topographic locations statistically calculated in the previous step are fitted with the sand body thickness encountered, and the fitting trend equations of sand body thickness-reduced formation depth in underwater highlands, underwater uplifted gentle slopes, and underwater depressions are obtained respectively, and a fitting trend diagram of sand body thickness-reduced formation depth is drawn. Among them, the fitting trend equation of sand body thickness-reduced formation depth in underwater highlands / underwater uplifted gentle slopes is:

[0050] Y1=a1e -b1x1

[0051] Where Y1 is the actual sand body thickness encountered by the well point, in m; x1 is the restored formation depth at the well point, in m.

[0052] From the fitting trend equation of the underwater highland / underwater uplift gentle slope sand body thickness-reduced stratum depth, it can be seen that the sand thickness in the underwater highland and gentle slope zone is exponentially negatively correlated with the reduced stratum depth. The higher the ancient topography, the less the thickness of the sedimentary sand body.

[0053] The fitting trend equation of sand body thickness-reduced formation depth in underwater low-lying areas is:

[0054] Y2=a2e b2x2

[0055] Where, Y3 is the actual sand body thickness encountered by the well point in the underwater depression, in meters; x3 is the reduced formation depth of the well point in the underwater depression, in meters.

[0056] From the fitting trend equation of sand body thickness in underwater depressions-reduced stratum depth, it can be seen that the sand thickness in underwater depressions is exponentially positively correlated with the reduced stratum depth. The higher the paleotopography, the thicker the sedimentary sand body.

[0057] Example 2

[0058] The method for quantitatively describing beach-bar sand bodies based on paleotopography in this embodiment includes the following steps:

[0059] 1. Based on the comprehensive seismic, geological and logging data, the paleotopography of a certain area during the Sha-4 deposition period was restored by using the residual thickness calculation, stratum filling and sediment compaction correction methods. Figure 2 As shown, it can accurately depict favorable paleotopography such as underwater uplift gentle slope zones, underwater highlands and tectonic turning zones, and the sources of materials are distributed from southwest to northeast.

[0060] 2. A prediction formula for sand body thickness based on the restored formation depth was established by regression fitting, with the restored formation depth as the independent variable and the sand body thickness encountered by the well point as the dependent variable.

[0061] Based on the analysis of paleotopographic data, multiple representative well point samples were selected from underwater highlands, underwater uplifted gentle slopes, and underwater low-lying areas to obtain the restored stratigraphic depth value and drilled sand body thickness data of the location of each sample well point;

[0062] Based on the classification of different paleotopographic locations, the restored stratum depth was used as the independent variable, and the sand body thickness encountered by the well point was used as the dependent variable. The regression fitting was used to establish the sand body thickness prediction formula based on the restored stratum depth, and a fitting trend diagram of the change of sand body thickness with the restored stratum depth was drawn, as shown in Figure 2. Figure 3 As shown. Among them, the fitting trend equation of sand body thickness-reduced formation depth in the underwater uplift gentle slope zone is:

[0063] Y1=2.638e -0.005x1

[0064] R 2 =0.9568

[0065] Where, Y1 is the actual sand body thickness encountered by the well point in the underwater uplift gentle slope zone, in meters; x1 is the reduced formation depth of the well point in the underwater uplift gentle slope zone, in meters; R 2 is the correlation between the actual sand body thickness encountered by the well point in the gentle slope zone of the underwater uplift and the reduced formation depth, a constant.

[0066] The fitting trend equation of sand body thickness-reduced formation depth at underwater highlands is:

[0067] Y2=1.996e -0.005x2

[0068] R 2 =0.9266

[0069] Where, Y2 is the actual sand body thickness encountered by the well at the underwater highland, in meters; x2 is the reduced formation depth at the underwater highland, in meters; R 2 is the correlation between the actual sand body thickness encountered at the well point in the underwater highland and the reduced formation depth, a constant.

[0070] The fitting trend equation of sand body thickness-reduced formation depth in underwater low-lying areas is:

[0071] Y3=1529.5e 0.009x3

[0072] R 2 =0.9699

[0073] Where, Y3 is the actual sand body thickness encountered by the well point in the underwater depression, in meters; x3 is the reduced formation depth of the well point in the underwater depression, in meters; R 2 It is the correlation between the actual sand body thickness encountered by the well point in the underwater low-lying area and the depth of the reduced formation, a constant.

[0074] 3. Draw a prediction map of sand body thickness distribution

[0075] According to the sand body thickness prediction formula, a sand body thickness plane distribution prediction diagram is drawn, such as Figure 4 As shown. From the fitting trend diagram of the change of sand body thickness with the depth of the restored stratum, it can be seen that the sand body thickness at different locations of the paleotopography is significantly different, and the thickness of the sedimentary sandstone is from large to small: underwater uplift gentle slope zone > underwater highland > underwater depression. In the research example, the sand thickness in the underwater low-lying zone is exponentially positively correlated with the depth of the restored stratum. The higher the paleotopography, the thicker the sedimentary sand body; the sand thickness in the underwater highland and the gentle slope zone is exponentially negatively correlated with the depth of the restored stratum. The higher the paleotopography, the thinner the sedimentary sand body.

[0076] Example 3

[0077] In the specific embodiment 3 of the present invention, the following steps are included:

[0078] 1. Based on the comprehensive application of seismic, geological and logging data, the paleotopography of a certain block during the Sha 4 deposition period was restored through the comprehensive application of residual thickness calculation, stratum filling and completion, and sediment compaction correction methods, including favorable paleotopography such as underwater uplift gentle slope belts and underwater highlands.

[0079] 2. A prediction formula for sand body thickness based on the restored formation depth was established by regression fitting, with the restored formation depth as the independent variable and the sand body thickness encountered by the well point as the dependent variable.

[0080] Based on the analysis of paleotopographic data, multiple representative well point samples were selected from underwater highlands, underwater uplifted gentle slopes, and underwater low-lying areas to obtain the restored stratigraphic depth value and drilled sand body thickness data of the location of each sample well point;

[0081] On the basis of the classification of different paleotopographic positions, the restored stratum depth was taken as the independent variable, and the sand body thickness encountered by the well point was taken as the dependent variable. The regression fitting was used to establish the sand body thickness prediction formula based on the restored stratum depth, and the fitting trend diagram of the change of sand body thickness with the restored stratum depth was drawn. Among them, the fitting trend equation of sand body thickness-restored stratum depth in the gentle slope zone of underwater uplift is:

[0082] Y1=3.726e -0.005x1

[0083] R 2 =0.9007

[0084] Where, Y1 is the actual sand body thickness encountered by the well point in the underwater uplift gentle slope zone, in meters; x1 is the reduced formation depth of the well point in the underwater uplift gentle slope zone, in meters; R 2 is the correlation between the actual sand body thickness encountered by the well point in the gentle slope zone of the underwater uplift and the reduced formation depth, a constant.

[0085] The fitting trend equation of sand body thickness-reduced formation depth at underwater highlands is:

[0086] Y2=2.132e -0.005x2

[0087] R 2 =0.9308

[0088] Where, Y2 is the actual sand body thickness encountered by the well at the underwater highland, in meters; x2 is the reduced formation depth at the underwater highland, in meters; R 2 is the correlation between the actual sand body thickness encountered at the well point in the underwater highland and the reduced formation depth, a constant.

[0089] The fitting trend equation of sand body thickness-reduced formation depth in underwater low-lying areas is:

[0090] Y3=1426.3e 0.009x3

[0091] R 2 =0.9661

[0092] Where, Y3 is the actual sand body thickness encountered by the well point in the underwater depression, in meters; x3 is the reduced formation depth of the well point in the underwater depression, in meters; R 2 It is the correlation between the actual sand body thickness encountered by the well point in the underwater low-lying area and the depth of the reduced formation, a constant.

[0093] 3. Draw a prediction map of sand body thickness distribution

[0094] According to the sand body thickness prediction formula, a sand body thickness plane distribution prediction diagram is drawn. From the fitting trend diagram of the change of sand body thickness with the depth of the restored stratum, it can be seen that the sand body thickness at different locations of paleotopography is significantly different, and the thickness of sedimentary sandstone is from large to small: underwater uplift gentle slope zone > underwater highland > underwater depression. In the research example, the sand thickness in the underwater low-lying zone is exponentially positively correlated with the depth of the restored stratum. The higher the paleotopography, the thicker the sedimentary sand body; the sand thickness in the underwater highland and gentle slope zone is exponentially negatively correlated with the depth of the restored stratum. The higher the paleotopography, the less the sedimentary sand body thickness.

[0095] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions recorded in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0096] Except for the technical features described in the specification, all other technical features are known technologies to those skilled in the art.

Claims

1. A quantitative description method of beach-bar sand bodies based on paleotopography, characterized in that: The quantitative description method of beach-bar sand bodies based on paleotopography includes: Step 1: Restore the ancient topography of a certain sedimentary period by integrating seismic, geological and well logging data; Step 2, selecting a plurality of representative well point samples; Step 3, obtaining the restored formation depth value and the drilled sand body thickness data at the location of the single sample well point; Step 4, establishing a sand body thickness prediction formula based on the reduced formation depth; Step 5: quantitatively predict the thickness of the beach-bar sand body in the unmoved area according to the established sand body thickness prediction formula based on the restored formation depth.

2. The method for quantitative description of beach-bar sand bodies based on paleotopography according to claim 1, characterized in that: In step 1, the top and bottom interfaces of the strata that accurately represent a certain geological period are determined, and the paleotopography of the geological period is restored by the comprehensive application of residual thickness calculation, strata filling and completion, and sedimentation compaction correction methods.

3. The method for quantitative description of beach-bar sand bodies based on paleotopography according to claim 1, characterized in that: In step 2, based on the analysis of paleotopographic data, multiple representative well point samples are selected from underwater highlands, underwater uplifted gentle slopes, and underwater low-lying areas.

4. The method for quantitative description of beach-bar sand bodies based on paleotopography according to claim 3, characterized in that: In step 2, the ancient topography of a certain geological period is restored and classified according to different ancient topography characteristics into three categories: underwater highlands, underwater uplifted gentle slopes, and underwater low-lying areas. Then, multiple representative wells are selected at different ancient topography locations to ensure the diversity of sample quantity and improve the credibility of the analysis results.

5. The method for quantitative description of beach-bar sand bodies based on paleotopography according to claim 1, characterized in that: In step 3, based on the results of paleotopography restoration in a certain geological period, the restored stratigraphic depth value of the location of a single sample well point is counted; Based on the results of detailed stratigraphic comparison, the thickness of the sand bodies encountered by individual sample well points during this geological period was statistically analyzed.

6. The method for quantitative description of beach-bar sand bodies based on paleotopography according to claim 1, characterized in that: In step 4, based on the classification of different paleotopographic locations, the correlation coefficient between the sand body thickness encountered at a single sample well point and the reduced formation depth is calculated, a sand body thickness prediction formula based on the reduced formation depth is obtained, and a fitting trend diagram of the change of sand body thickness with the reduced formation depth is drawn.

7. The method for quantitative description of beach-bar sand bodies based on paleotopography according to claim 6, characterized in that: In step 4, through rock physics simulation experiments, the formation depth values ​​of single well points at different paleotopographic positions counted in the previous step are fitted with the sand body thickness encountered, and the sand body thickness-reduced formation depth fitting trend equations of underwater highlands, underwater uplift gentle slopes, and underwater depressions are obtained respectively, and a fitting trend graph of the change of sand body thickness with reduced formation depth is drawn.

8. The method for quantitative description of beach-bar sand bodies based on paleotopography according to claim 7, characterized in that: In step 4, the fitting trend equation of sand body thickness-reduced formation depth in underwater highland and underwater uplift gentle slope zone is: Y1=a1e -b1x1 Where, Y1 is the actual sand body thickness encountered by the well point, in m; x1 is the restored formation depth at the well point, in m; a1 is the fitting coefficient between the actual sand body thickness encountered by the well point and the restored formation depth, a constant; b1 is a constant.

9. The method for quantitative description of beach-bar sand bodies based on paleotopography according to claim 8, characterized in that: In step 4, from the fitting trend equation of sand body thickness-reduced stratum depth in underwater highlands and underwater uplift gentle slopes, it can be seen that the sand thickness in underwater highlands and gentle slopes is exponentially negatively correlated with the reduced stratum depth. The higher the paleotopography, the less the thickness of the sedimentary sand body.

10. The method for quantitative description of beach-bar sand bodies based on paleotopography according to claim 7, characterized in that: In step 4, the fitting trend equation of sand body thickness-reduced formation depth in the underwater low-lying area is: Y2=a2e b2x2 Where, Y2 is the actual thickness of the sand body encountered by the well point in the underwater low-lying area, in m; x2 is the restored formation depth of the well point in the underwater low-lying area, in m; a2 is the fitting coefficient between the actual thickness of the sand body encountered by the well point and the restored formation depth, a constant; b2 is a constant.

11. The method for quantitative description of beach-bar sand bodies based on paleotopography according to claim 10, characterized in that: In step 4, from the fitting trend equation of sand body thickness in underwater depressions and reduced stratum depth, it can be seen that the sand thickness in underwater depressions is exponentially positively correlated with the reduced stratum depth. The higher the paleotopography, the thicker the sedimentary sand body.

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