Method and device for predicting gas sweet spots of near-source tight sandstone

Abstract

The invention provides a near-source tight sandstone gas sweet spot prediction method and device, and the method comprises the steps: recovering the regional structure evolution history according to the existing geological parameters; according to the regional structure evolution history, key periods are determined, and the key periods comprise an early CO2 main generation period and a natural gas main generation period; according to the key period, drawing a tight sandstone paleostructure geological map, and delimiting a structure conversion superposition area range to obtain a target area; and classifying the sandstone in the target area by combining the reservoir characteristics of the tight sandstone and the sedimentary facies, and determining the tight gas sweet spot distribution. The prediction method provided by the invention is simple to operate, practical and efficient, and can quickly and accurately help geologists and oil and gas companies to predict the distribution area of the tight sandstone gas sweet spots.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and natural gas exploration and development, and in particular relates to a method and a device for predicting near-source tight sandstone gas sweet spots. Background Art

[0002] Near-source tight sandstone gas is a type of energy with great potential, cleanness and high efficiency. The areas of the Carboniferous-Permian System and the Kuche Jurassic System in the Ordos Basin, which are dominated by near-source coal-bearing sandstone, have achieved large-scale industrial production and are an important part of the gradual growth of regional natural gas reserves. It has great potential in all large and medium-sized basins in my country. However, the geological conditions for the formation of tight sandstone gas are complex, and the structure is complex and diverse due to multiple stages of tectonic changes, and the gas production capacity is very different. The production of wells in geographical proximity may change greatly, and quickly transition from high-yield wells to non-gas-producing wells. How to accurately predict gas well production and sweet spots is of great significance to the exploration and development of tight gas.

[0003] At present, most of the prediction of tight sandstone gas sweet spots is mainly focused on evaluating the reservoir sweet spots in tight sandstone from the perspective of reservoir quality by using various technical means, including using sedimentary phase, diagenetic phase, seismic phase and fracture distribution to predict the area with relatively good porosity and permeability in the distribution area of ​​tight sandstone. For example, geophysical-seismic prediction technology combines sequence stratigraphic theory and effective geophysical methods to predict the reservoir sweet spots of tight sandstone gas reservoirs, and predicts the reservoir sweet spots based on the construction of three-dimensional rock physics templates. Clarify the rock physical characteristics of the sweet spot reservoir and the elastic parameters sensitive to lithology, physical properties and gas content. Consider factors such as mineral composition and content, porosity, gas saturation, etc. However, the seismic method has a low accuracy in predicting sweet spots. It also includes sweet spot screening technology that combines seismic, geological and production dynamics to summarize the geological conditions that predict favorable tight gas sweet spots: including organic matter abundance, brittle mineral content, structural location, etc., so as to determine whether an area is a possible favorable accumulation area. However, this method cannot ensure the success rate of prediction, and more importantly, it cannot determine the scale and sustainability of well production, let alone determine the problems related to reservoir formation.

[0004] Poor reservoir properties, difficulty in identifying gas and water, complex sand body distribution, and strong heterogeneity have restricted the exploration and development of tight gas reservoirs. In summary, developing a simple, practical, and efficient method for predicting near-source tight sandstone gas sweet spots can quickly and accurately help geologists and oil and gas companies predict the distribution area of ​​tight sandstone gas sweet spots, which has become an urgent problem that technicians in this field need to solve. Summary of the invention

[0005] The purpose of the present invention is to provide a prediction method and device for near-source tight sandstone gas sweet spots, which integrates the prediction of tight sandstone gas sweet spots into dynamic elements such as structure, sedimentation, hydrocarbon generation, diagenesis and reservoir formation, and realizes prediction and evaluation in multiple dimensions of space and time domains. The prediction method has high prediction accuracy and wide applicability, and is not only suitable for tapping the potential of mature exploration areas, but also suitable for the evaluation of immature exploration areas.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for predicting near-source tight sandstone gas sweet spots, the prediction method comprising:

[0008] Restore the regional tectonic evolution history based on the existing geological parameters;

[0009] According to the regional tectonic evolution history, the key periods are determined, including: the early CO2 main generation period and the natural gas main generation period;

[0010] Based on the key period, the dense sandstone paleo-structural geological map is drawn, and the scope of the structural conversion superposition area is delineated to obtain the target area;

[0011] The sandstones are graded in the target area based on the reservoir characteristics and sedimentary facies of tight sandstones to determine the distribution of tight sandstone gas sweet spots.

[0012] The prediction method provided by the present invention is based on the microscopic mechanism of high-quality reservoir development in tight sandstone gas areas, and at the same time based on the organic-inorganic interaction control of high-quality reservoir development, incorporating the key control and influencing factors of reservoir densification or high-quality reservoir development that can be examined, incorporating microscopic mechanisms such as the natural gas charging dynamics basis in sweet spot areas for prediction, and comprehensively considering the tight sandstone gas accumulation law and sweet spot area prediction under multi-dimensional conditions such as structure, sedimentation, hydrocarbon generation, diagenesis and accumulation time, and integrating the four histories of regional sedimentary history, tectonic evolution history, source rock hydrocarbon generation evolution history and accumulation history, thereby realizing a multi-dimensional prediction technology for near-source tight sandstone gas sweet spots.

[0013] As a preferred technical solution of the present invention, the existing geological parameters include regional stratum thickness and reflectance of vitrinite of terrigenous organic matter in the stratum.

[0014] In the present invention, for areas with relatively mature exploration and geological research, the recognized research results and previous understandings can be directly used to restore the regional tectonic evolution history; for areas with low exploration levels, the tectonic evolution history in the study area can be restored based on the thickness of the strata revealed by drilling and the maturity of the organic matter therein, and then basin simulation software is used.

[0015] As a preferred technical solution of the present invention, the early CO2 main generation period includes the low maturity stage of kerogen or source rock.

[0016] Preferably, the vitrinite reflectance Ro of the early CO2 main generation period is 0.5%-0.7% and the burial depth is 2000-4000m.

[0017] In the present invention, CO2 has two main generation periods, early and late, with the vitrinite reflectance Ro between 0.5% and 0.7% being the key period of the early CO2 main generation period. The influence range of the acidic fluid (CO2) during this period determines the high-quality development range of the reservoir.

[0018] As a preferred technical solution of the present invention, the main natural gas generation period includes the following two situations:

[0019] In areas where no uplift or erosion has occurred, the main period of natural gas generation is the present period; or

[0020] In areas where uplift and erosion have occurred, the main generation period of natural gas is the maximum ancient burial period of the source rock layer or tight sandstone.

[0021] In the present invention, the main generation period of natural gas is generally late, and different types of source rocks also have certain differences. For areas where no uplift and erosion have occurred, the present is taken as the key moment for natural gas generation. It is necessary to consider whether an overheating event has occurred in the target area. Generally, the temperature of thermal events is high, and the affected range often corresponds to the maximum paleo-geothermal conditions.

[0022] As a preferred technical solution of the present invention, the drawing of the dense sandstone paleo-structural geological map includes the following two situations:

[0023] For areas where no uplift and erosion has occurred, the dense sandstone paleo-structural geological map includes a plan distribution map of the paleo-burial depth of target strata during the early main generation period of CO2 and a plan distribution map of the paleo-burial depth of target strata during the main generation period of natural gas; or

[0024] For areas where uplift and erosion have occurred, the dense sandstone paleo-structural geological map includes a plan distribution map of the ancient burial depth of target strata during the early main CO2 generation period, a plan distribution map of the ancient burial depth of target strata during the main natural gas generation period, and a plan distribution map of the ancient burial depth of target strata in the present period.

[0025] In the present invention, the target stratum is dense sandstone.

[0026] In the present invention, if an area has experienced uplift and erosion, the structural position and geological map of the current target stratum (tight sandstone) must be considered to consider the effects of later natural gas preservation, diffusion and migration.

[0027] As a preferred technical solution of the present invention, the scope of the structural conversion overlapping area is defined in the following two cases:

[0028] In areas where no uplift and erosion has occurred, the low point range is constructed on the plane distribution map of the ancient burial depth of the target strata during the early main generation period of CO2, and the high point range is constructed on the plane distribution map of the ancient burial depth of the target strata during the main generation period of natural gas, and the overlapping area of ​​the above two ranges is defined as the target area; or

[0029] In areas where uplift and erosion have occurred, a low point range is constructed on the plane distribution map of the ancient burial depth of the target strata during the early main generation period of CO2, a high point range is constructed on the plane distribution map of the ancient burial depth of the target strata during the main generation period of natural gas, and a high point range is constructed on the plane distribution map of the ancient burial depth of the target strata in the present period. The overlapping area of ​​the above three ranges is designated as the target area.

[0030] As a preferred technical solution of the present invention, the low point or high point is specifically: the distribution and depth of the dense sandstone relative to the main source rock are at a relatively low point or high point.

[0031] As a preferred technical solution of the present invention, the reservoir characteristics of the dense sandstone include the lithology, mineral composition and sedimentary environment of the sand body itself.

[0032] As a preferred technical solution of the present invention, the result of classifying the sandstone is specifically: in descending order of priority, they are divided into diversion channel sand body, diversion estuary sand bar sand body, far sand bar sand body, breach fan sand body, beach bar sand body, delta sand body, and lake sand body.

[0033] Preferably, the diversion channel sand body is the best sweet spot.

[0034] In the present invention, the diversion channel sand body is taken as the best sweet spot, and then downgraded in order; from the perspective of lithology, the physical properties of medium-coarse sandstone are obviously better than those of fine sand and siltstone, and the mud matrix content of high-quality reservoirs does not exceed 5%, so clean medium-coarse sandstone is the basis for forming high-quality reservoirs.

[0035] In the present invention, for different levels of sand body classification, priority levels can be divided and drilling can be implemented; at the same time, the gas content in the best sweet spot is relatively high, so the best sweet spot is a favorable area of ​​tight sandstone, and drilling can be implemented here for exploration deployment.

[0036] In a second aspect, the present invention provides a prediction device for near-source tight sandstone gas sweet spots, the prediction device comprising:

[0037] The first restoration module is used to restore the regional tectonic evolution history based on the existing geological parameters;

[0038] The first determination module is used to determine the key period according to the regional tectonic evolution history, and the key period includes: the early CO2 main generation period and the natural gas main generation period;

[0039] The first drawing module is used to draw a dense sandstone paleo-structural geological map based on the key period, and to delineate the scope of the structural conversion superposition area to obtain the target area;

[0040] The second determination module is used to classify the sandstone in the target area in combination with the reservoir characteristics of the tight sandstone and the sedimentary phase, and determine the distribution of the tight sandstone gas sweet spots.

[0041] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The prediction method provided by the present invention is based on the microscopic mechanism of high-quality reservoir development in tight sandstone gas areas, and based on the organic-inorganic interaction control of high-quality reservoir development, it incorporates the key control and influencing factors of reservoir densification or high-quality reservoir development that can be examined, and incorporates the microscopic mechanisms such as the natural gas charging dynamics basis in the sweet spot area for prediction. The tight sandstone gas accumulation law and sweet spot area prediction are comprehensively considered under multi-dimensional conditions such as structure, sedimentation, hydrocarbon generation, diagenesis and accumulation time, and the four histories of regional sedimentary history, structural evolution history, source rock hydrocarbon generation evolution history and accumulation history are integrated into one, realizing the multi-dimensional prediction technology of near-source tight sandstone gas sweet spots. At the same time, the prediction method is simple to operate, practical, and efficient, and can quickly and accurately help geologists and oil and gas companies predict the distribution area of ​​tight sandstone gas sweet spots. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a flow chart of the method for predicting the near-source tight sandstone gas sweet spot provided in Examples 1 and 2;

[0045] Figure 2 It is a schematic diagram of the structure of the prediction device for the near-source tight sandstone gas sweet spot provided in Example 3. DETAILED DESCRIPTION

[0046] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0047] It should be noted that the terms "first", "second", "candidate", "target", etc. in the specification and claims of the present application and the above drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0048] Example 1

[0049] This embodiment provides a method for predicting near-source tight sandstone gas sweet spots. The selected area is an area where no uplift and erosion has occurred. The prediction method can efficiently and accurately predict the distribution of near-source tight sandstone gas sweet spots. The prediction method can be executed by a prediction device for near-source tight sandstone gas sweet spots.

[0050] like Figure 1 As shown, the method provided in this embodiment includes:

[0051] S101. Restore the regional tectonic evolution history based on the existing geological parameters;

[0052] This embodiment combines the thickness of regional strata and the reflectivity of vitrinite of terrigenous organic matter in the strata to restore the regional tectonic evolution history;

[0053] For areas with relatively mature exploration and geological research, recognized research results can be directly used; for areas with low exploration levels, basin simulation software can be used to restore the structural evolution history of the study area based on the thickness of the strata revealed by drilling and the maturity of the organic matter therein.

[0054] S102, determining the key period according to the regional tectonic evolution history, wherein the key period includes: the early CO2 main generation period and the natural gas main generation period;

[0055] In this embodiment, the early CO2 main generation period includes the low maturity stage of kerogen or source rock; further, the vitrinite reflectance Ro of the early CO2 main generation period is 0.5-0.7%, and the burial depth is 2000-4000m;

[0056] The main natural gas generation period in this embodiment is the present period. If overheating occurs in the target area, it corresponds to the maximum paleo-geothermal period.

[0057] S103. Draw a dense sandstone paleo-structural geological map based on the key period, and define the scope of the structural conversion superposition area to obtain the target area;

[0058] In this embodiment, the dense sandstone target stratum is taken as the main object, that is, the regional tectonic evolution history and burial history are considered, and the dense sandstone paleo-tectonic geological map includes the dense sandstone paleo-burial depth plane distribution map in the early CO2 main generation period and the dense sandstone paleo-burial depth plane distribution in the natural gas main generation period;

[0059] In this embodiment, a low point range is constructed on the plane distribution map of the ancient burial depth of dense sandstone in the early main generation period of CO2, and a high point range is constructed on the plane distribution map of the ancient burial depth of dense sandstone in the main generation period of natural gas, and the overlapping area of ​​the above two ranges is defined as the target area; wherein the low point or high point is specifically: the distribution and depth of dense sandstone relative to the main source rock are at a relative low point or high point.

[0060] S104. Classify the sandstone in the target area based on the reservoir characteristics and sedimentary facies of the tight sandstone to determine the distribution of gas sweet spots in the tight sandstone;

[0061] The reservoir characteristics of the tight sandstone in this embodiment include the lithology, mineral composition and depositional environment of the sand body itself;

[0062] The result of classifying the sandstone in this embodiment is specifically as follows: in descending order of priority, they are distributary channel sand body, distributary estuary sand bar sand body, far sand bar sand body, breach fan sand body, beach bar sand body, delta sand body, and lake sand body, among which the distributary channel sand body is the best sweet spot.

[0063] Example 2

[0064] This embodiment provides a method for predicting near-source tight sandstone gas sweet spots. The selected area is an area where uplift and erosion have occurred. The prediction method can efficiently and accurately predict the distribution of near-source tight sandstone gas sweet spots. The prediction method can be executed by a prediction device for near-source tight sandstone gas sweet spots.

[0065] like Figure 1 As shown, the method provided in this embodiment includes:

[0066] S101. Restore the regional tectonic evolution history based on the existing geological parameters;

[0067] This embodiment combines the thickness of regional strata and the reflectivity of vitrinite of terrigenous organic matter in the strata to restore the regional tectonic evolution history;

[0068] For areas with relatively mature exploration and geological research, recognized research results can be directly used; for areas with low exploration levels, basin simulation software can be used to restore the structural evolution history of the study area based on the thickness of the strata revealed by drilling and the maturity of the organic matter therein.

[0069] S102, determining the key period according to the regional tectonic evolution history, wherein the key period includes: the early CO2 main generation period and the natural gas main generation period;

[0070] In this embodiment, the early CO2 main generation period includes the low maturity stage of kerogen or source rock; further, the vitrinite reflectance Ro of the early CO2 main generation period is 0.5-0.7%, and the burial depth is 2000-4000m;

[0071] The main generation period of natural gas in this embodiment is the maximum ancient burial period of the source rock layer or dense sandstone.

[0072] S103. Draw a dense sandstone paleo-structural geological map based on the key period, and define the scope of the structural conversion superposition area to obtain the target area;

[0073] In this embodiment, the dense sandstone target stratum is taken as the main object, that is, the regional tectonic evolution history and burial history are considered, and the dense sandstone paleo-tectonic geological map includes the dense sandstone paleo-burial depth plane distribution map of the early CO2 main generation period, the dense sandstone paleo-burial depth plane distribution map of the natural gas main generation period, and the dense sandstone paleo-burial depth plane distribution map of the present period;

[0074] In this embodiment, a low point range is constructed on the plane distribution map of the ancient burial depth of tight sandstone in the early main generation period of CO2, a high point range is constructed on the plane distribution map of the ancient burial depth of tight sandstone in the main generation period of natural gas, and a high point range is constructed on the plane distribution map of the ancient burial depth of tight sandstone in the present period, and the overlapping area of ​​the above three ranges is delineated as the target area; wherein the low point or high point is specifically: the distribution and depth of tight sandstone relative to the main source rock are at a relative low point or high point.

[0075] S104. Classify the sandstone in the target area based on the reservoir characteristics and sedimentary facies of the tight sandstone to determine the distribution of gas sweet spots in the tight sandstone;

[0076] The reservoir characteristics of the tight sandstone in this embodiment include the lithology, mineral composition and depositional environment of the sand body itself;

[0077] The result of classifying the sandstone in this embodiment is specifically as follows: in descending order of priority, they are distributary channel sand body, distributary estuary sand bar sand body, far sand bar sand body, breach fan sand body, beach bar sand body, delta sand body, and lake sand body, among which the distributary channel sand body is the best sweet spot.

[0078] Example 3

[0079] This embodiment provides a prediction device for near-source tight sandstone gas sweet spots. Figure 2 As shown, the prediction device includes: a first recovery module 101, a first determination module 102, a first drawing module 103, and a second determination module 104, wherein:

[0080] The first restoration module 101 is used to restore the regional tectonic evolution history based on the existing geological parameters;

[0081] The first determination module 102 is used to determine the key period according to the regional tectonic evolution history, and the key period includes: the early CO2 main generation period and the natural gas main generation period;

[0082] The first drawing module 103 is used to draw a dense sandstone paleo-structural geological map according to the key period, and to define the scope of the structural conversion superposition area to obtain the target area;

[0083] The second determination module 104 is used to classify the sandstone in the target area in combination with the reservoir characteristics and sedimentary phase of the tight sandstone, and determine the distribution of gas sweet spots in the tight sandstone.

[0084] In the first recovery module 101, the existing geological parameters include regional stratum thickness and vitrinite reflectance of terrigenous organic matter in the stratum.

[0085] In the first determination module 102, the early CO2 main generation period includes the low maturity stage of kerogen or source rock; the vitrinite reflectance Ro of the early CO2 main generation period is 0.5-0.7% and the burial depth is 2000-4000m;

[0086] The main natural gas generation period includes the following two situations:

[0087] In areas where no uplift or erosion has occurred, the main period of natural gas generation is the present period; or

[0088] In areas where uplift and erosion have occurred, the main generation period of natural gas is the maximum ancient burial period of the source rock layer or tight sandstone.

[0089] In the first drawing module 103, the drawing of the dense sandstone paleo-structural geological map includes the following two situations:

[0090] For areas where no uplift and erosion has occurred, the dense sandstone paleo-tectonic geological map includes a plan distribution map of the paleo-burial depth of dense sandstone during the main generation period of early CO2 and a plan distribution map of the paleo-burial depth of dense sandstone during the main generation period of natural gas; or

[0091] For areas where uplift and erosion have occurred, the dense sandstone paleo-tectonic geological map includes a plan distribution map of the ancient burial depth of dense sandstone during the early CO2 main generation period, a plan distribution map of the ancient burial depth of dense sandstone during the main natural gas generation period, and a plan distribution map of the ancient burial depth of dense sandstone in the present period;

[0092] The scope of the structural conversion superposition area is defined in the following two cases:

[0093] In areas where no uplift and erosion has occurred, the low point range on the plane distribution map of the ancient burial depth of tight sandstone during the main generation period of early CO2 and the high point range on the plane distribution map of the ancient burial depth of tight sandstone during the main generation period of natural gas are constructed, and the overlapping area of ​​the above two ranges is defined as the target area; or

[0094] In areas where uplift and erosion have occurred, the low point range on the plane distribution map of the ancient burial depth of tight sandstone in the early main generation period of CO2, the high point range on the plane distribution map of the ancient burial depth of tight sandstone in the main generation period of natural gas, and the high point range on the plane distribution map of the ancient burial depth of tight sandstone in the present period are constructed, and the overlapping area of ​​the above three ranges is designated as the target area.

[0095] In the second determination module 104, the reservoir characteristics of the tight sandstone include the lithology, mineral composition and depositional environment of the sand body itself;

[0096] The results of classifying the sandstone are as follows: in descending order of priority, they are diversion channel sand body, diversion estuary sand bar sand body, far sand bar sand body, breach fan sand body, beach bar sand body, delta sand body, and lake sand body; among them, the diversion channel sand body is the best sweet spot.

[0097] The prediction device provided in this embodiment can execute the prediction method for near-source tight sandstone gas sweet spots provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0098] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for predicting near-source tight sandstone gas sweet spots, characterized in that: The prediction method comprises: Restore the regional tectonic evolution history based on the existing geological parameters; According to the regional tectonic evolution history, the key periods are determined, including: the early CO2 main generation period and the natural gas main generation period; Based on the key period, the dense sandstone paleo-structural geological map is drawn, and the scope of the structural conversion superposition area is delineated to obtain the target area; The sandstones are graded in the target area based on the reservoir characteristics and sedimentary facies of tight sandstones to determine the distribution of tight sandstone gas sweet spots.

2. The prediction method according to claim 1, characterized in that: The existing geological parameters include regional stratum thickness and vitrinite reflectance of terrigenous organic matter in the stratum.

3. The prediction method according to claim 1 or 2, characterized in that: The early CO2 main generation period includes the low maturity stage of kerogen or source rock; Preferably, the vitrinite reflectance Ro of the early CO2 main generation period is 0.5-0.7% and the burial depth is 2000-4000m.

4. The prediction method according to any one of claims 1 to 3, characterized in that: The main natural gas generation period includes the following two situations: In areas where no uplift or erosion has occurred, the main period of natural gas generation is the present period; or In areas where uplift and erosion have occurred, the main generation period of natural gas is the maximum ancient burial period of the source rock layer or tight sandstone.

5. The prediction method according to any one of claims 1 to 4, characterized in that: The drawing of the dense sandstone paleo-structural geological map includes the following two situations: For areas where no uplift and erosion has occurred, the dense sandstone paleo-structural geological map includes a plan distribution map of the paleo-burial depth of target strata during the early main generation period of CO2 and a plan distribution map of the paleo-burial depth of target strata during the main generation period of natural gas; or For areas where uplift and erosion have occurred, the dense sandstone paleo-structural geological map includes a plan distribution map of the ancient burial depth of target strata during the early main CO2 generation period, a plan distribution map of the ancient burial depth of target strata during the main natural gas generation period, and a plan distribution map of the ancient burial depth of target strata in the present period.

6. The prediction method according to any one of claims 1 to 5, characterized in that: The scope of the structural conversion superposition area is defined in the following two cases: In areas where no uplift and erosion has occurred, the low point range is constructed on the plane distribution map of the ancient burial depth of the target strata during the early main generation period of CO2, and the high point range is constructed on the plane distribution map of the ancient burial depth of the target strata during the main generation period of natural gas. The overlapping area of ​​the above two ranges is defined as the target area; or In areas where uplift and erosion have occurred, a low point range is constructed on the plane distribution map of the ancient burial depth of the target strata during the early main generation period of CO2, a high point range is constructed on the plane distribution map of the ancient burial depth of the target strata during the main generation period of natural gas, and a high point range is constructed on the plane distribution map of the ancient burial depth of the target strata in the present period. The overlapping area of ​​the above three ranges is designated as the target area.

7. The prediction method according to claim 6, characterized in that: The low point or high point specifically refers to that the distribution and depth of the dense sandstone relative to the main source rock are at a relatively low point or high point.

8. The prediction method according to any one of claims 1 to 7, characterized in that: The reservoir characteristics of the tight sandstone include the lithology, mineral composition and depositional environment of the sand body itself.

9. The prediction method according to any one of claims 1 to 8, characterized in that: The results of classifying the sandstone are as follows: in descending order of priority, the sand bodies are distributary channel sand bodies, distributary estuary sand bar sand bodies, far sand bar sand bodies, breach fan sand bodies, beach bar sand bodies, delta sand bodies, and lake sand bodies; Preferably, the diversion channel sand body is the best sweet spot.

10. A prediction device for near-source tight sandstone gas sweet spots, characterized in that: The prediction device comprises: The first restoration module is used to restore the regional tectonic evolution history based on the existing geological parameters; The first determination module is used to determine the key period according to the regional tectonic evolution history, and the key period includes: the early CO2 main generation period and the natural gas main generation period; The first drawing module is used to draw a dense sandstone paleo-structural geological map based on the key period, and to delineate the scope of the structural conversion superposition area to obtain the target area; The second determination module is used to classify the sandstone in the target area in combination with the reservoir characteristics of the tight sandstone and the sedimentary phase, and determine the distribution of the tight sandstone gas sweet spots.

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