Prediction method of favorable sandstone lithologic reservoirs in meandering river facies

Abstract

This invention provides a method for predicting favorable hydrocarbon accumulation areas in meandering river facies sandstone lithological oil reservoirs, comprising: statistically analyzing the oil content of the main oil-bearing sandstone groups drilled in previous wells and compiling well oil-bearing maps; performing detailed structural interpretation and compiling top structural maps of the main oil-bearing sandstone groups; identifying and plotting structural ridges on the structural maps and analyzing the relationship between well oil content and structural ridges; statistically analyzing the percentage content of sandstone in the main oil-bearing sandstone groups drilled in previous wells and compiling sandstone percentage content contour maps in conjunction with seismic attribute analysis; analyzing the matching relationship between well oil content and sandstone percentage content to determine the sandstone percentage content range of favorable hydrocarbon accumulation areas and unfavorable hydrocarbon migration areas; and predicting favorable hydrocarbon accumulation areas in meandering river facies sandstone lithological oil reservoirs. This method for predicting favorable hydrocarbon accumulation areas in meandering river facies sandstone lithological oil reservoirs can be used for exploration and development of these reservoirs, thereby improving the efficiency and success rate of exploration and development.

Description

Technical Field

[0001] This invention relates to the field of petroleum geological exploration technology, and in particular to a method for predicting favorable reservoir formation areas in meandering river facies sandstone lithology oil reservoirs. Background Technology

[0002] With the increasing sophistication of oil and gas exploration, concealed reservoirs, such as lithologic reservoirs, are playing an increasingly important role in oil and gas exploration, especially for Neogene fluvial sandstone reservoirs, which are becoming the primary targets of exploration. Neogene fluvial strata lack well-developed source rocks, and their reservoirs are all exogenous reservoirs. Oil and gas migration paths include faults, unconformities, and framework sand bodies. After migrating along faults and unconformities to the fluvial strata, oil and gas undergo lateral migration along the framework sand bodies under the influence of buoyancy. This lateral migration path is controlled by both structural and reservoir conditions. Due to the generally low sand content in meandering river sections, lateral migration of oil and gas within them presents certain difficulties. Currently, exploration methods for meandering river sandstone reservoirs are mainly based on fine reservoir characterization techniques. These methods utilize geophysical techniques to accurately characterize the sand bodies in the meandering river channel, analyze the configuration relationship between sand bodies and faults, and select favorable sand bodies for exploration deployment. This exploration method is relatively precise and is mostly applicable to the exploration and development of meandering sandstone reservoirs with relatively good oil source conditions. However, it does not analyze the path and pattern of oil and gas migration within the meandering facies section from a macroscopic perspective. In particular, for meandering sandstone reservoirs in slope zones far from faults, its exploration guidance significance is insufficient, which restricts the efficient exploration of meandering sandstone lithologic reservoirs in slope zones.

[0003] Chinese patent application CN201810190356.4 discloses a method and apparatus for determining favorable hydrocarbon accumulation areas in far-source oil and gas reservoirs in superimposed basins. The method includes: determining the key accumulation period of far-source oil and gas reservoirs in the area to be analyzed; obtaining a source-transport system distribution map of the far-source oil and gas reservoirs during the key accumulation period; identifying effective traps in the source-transport system distribution map; superimposing the effective traps onto the source-transport system distribution map to obtain a trap distribution map within the source-transport system; and determining favorable hydrocarbon accumulation areas in the far-source oil and gas reservoirs based on the source-transport system distribution map and the trap distribution map within the source-transport system. Utilizing the embodiments in this application improves the accuracy of evaluating favorable hydrocarbon accumulation areas in far-source oil and gas reservoirs in superimposed basins, providing an accurate theoretical basis for oil and gas exploration and development.

[0004] Chinese patent application CN201710505449.7 discloses a method and apparatus for quantitatively predicting favorable exploration zones for structural oil and gas reservoirs in superimposed basins. The method includes: obtaining the reservoir-controlling probabilities of source sites, paleo-uplifts, sedimentary facies, and regional caprocks within a specified area; determining the probability distribution of favorable reservoir-forming zones for structural oil and gas reservoirs within the specified area based on these probabilities; obtaining the preservation probability distribution of structural oil and gas reservoirs within the specified area; and superimposing the preservation probability distribution with the favorable reservoir-forming zone probability distribution to obtain the probability distribution of favorable exploration zones for structural oil and gas reservoirs within the specified area. This application embodiment can achieve quantitative prediction of favorable exploration zones for structural oil and gas reservoirs in superimposed basins.

[0005] Chinese patent application CN201910115510.6 discloses a method for selecting development zones in tight sandstone oil reservoirs. The method comprises the following steps: obtaining normalized geological characterization parameters based on the geological characterization parameters of the target oil well in the test area; establishing a production capacity prediction model for the target oil well based on the production capacity data from the target oil well's production data and the normalized geological characterization parameters; obtaining the predicted production capacity data of the target oil well based on the production capacity prediction model; determining the production capacity prediction contour map of the target oil well based on the predicted production capacity data; and determining the development zone selection area of ​​the test area based on the production capacity prediction contour map of the target oil well and the development zone selection criteria of the test area. This invention improves upon the single-factor overlap method for development zone selection, increasing the efficiency of development zone selection and the drilling success rate of high-yield oil wells.

[0006] The existing technologies described above are significantly different from the present invention and have failed to solve the technical problem we want to address. Therefore, we have invented a new method for predicting favorable reservoir formation areas in meandering river facies sandstone lithology oil reservoirs. Summary of the Invention

[0007] The purpose of this invention is to provide a method for predicting favorable hydrocarbon accumulation zones in meandering river facies sandstone lithology reservoirs by analyzing the controlling effect of tectonic ridges and sandstone percentages on hydrocarbon migration and accumulation.

[0008] The objective of this invention can be achieved through the following technical measures: a method for predicting favorable hydrocarbon accumulation zones in meandering river facies sandstone reservoirs, wherein the method for predicting favorable hydrocarbon accumulation zones in meandering river facies sandstone reservoirs includes:

[0009] Step 1: Analyze the oil content of the main oil-bearing sand groups in the drilled wells and compile the oil content map of the wells;

[0010] Step 2: Conduct detailed structural interpretation and compile a structural diagram of the top surface of the main oil-bearing sand formation;

[0011] Step 3: Identify and plot the structural ridges on the structural map, and analyze the relationship between well oil content and structural ridges;

[0012] Step 4: Calculate the percentage content of sandstone in the main oil-bearing sand groups of drilled wells, and compile a sandstone percentage content contour map based on seismic attribute analysis;

[0013] Step 5: Analyze the matching relationship between well oil content and sandstone percentage content to determine the sandstone percentage content range in areas favorable for oil and gas accumulation and areas unfavorable for oil and gas migration.

[0014] Step 6: Taking into account the relationship between the percentage content of structural ridges and sandstone and the oil-bearing properties of wells, predict the favorable oil-forming areas of meandering river facies sandstone lithology reservoirs.

[0015] The objective of this invention can also be achieved through the following technical measures:

[0016] In step 1, based on the comprehensive oil testing results, well logging interpretation results, and comprehensive well logging display results, the oil content of the main oil-bearing sand groups that have been drilled is statistically analyzed, and the statistical results are marked on the plan view to compile a well oil content map.

[0017] In step 2, using drilling and seismic data, the drilled wells are finely divided into stratigraphic units and the synthetic seismic records are calibrated. The seismic reflection axes at the top of the main oil-bearing sand groups are finely interpreted, and a structural map of the top of the main oil-bearing sand groups is compiled.

[0018] In step 3, structural ridges are identified on the top surface structural map of the main oil-bearing sandstone group, which are the ridge lines of positive structures formed by changes in the attitude of the rock strata. The structural ridges are marked with thick lines with arrows. The drilling oil-bearing map obtained in step 1 is superimposed with the top surface structural map of the main oil-bearing sandstone group obtained in step 2 to analyze the relationship between drilling oil-bearing properties and structural ridges.

[0019] In step 3, the relationship between well oil content and structural ridges is analyzed to obtain the oil and gas distribution pattern: oil flow wells, oil layer wells and oil and gas show wells in fault zones are located within structural traps; in slope zones where faults are not well developed, oil flow wells, oil layer wells and oil and gas show wells are distributed in and around structural ridges, that is, located above the dominant oil and gas migration channels.

[0020] In step 4, the thickness of sandstone and formation of the main oil-bearing sand groups drilled are statistically analyzed, and the percentage content of sandstone is calculated. Based on the calculated percentage content of sandstone, and combined with seismic attribute data, a sandstone percentage content contour map is compiled.

[0021] In step 4, based on the sandstone percentage content formula: sandstone percentage content = sandstone thickness / formation thickness, the sandstone percentage content value of each well is calculated and marked on the plan map; based on the calculated sandstone percentage content value, combined with seismic attribute data and root mean square amplitude attributes, a sandstone percentage content contour map is compiled, and the well oil-bearing map is overlaid on the sandstone percentage content contour map.

[0022] In step 5, the well oil-bearing map obtained in step 1 is overlaid with the sandstone percentage content contour map obtained in step 4 to analyze the matching relationship between well oil-bearing properties and sandstone percentage content, and to determine the boundary range of sandstone percentage content in oil and gas favorable accumulation areas and oil and gas unfavorable migration areas.

[0023] In step 5, areas with a higher percentage of sandstone content can become favorable areas for oil and gas accumulation, while areas with a lower percentage of sandstone content are mostly unfavorable areas for oil and gas accumulation.

[0024] In step 6, the drilling oil-bearing map obtained in step 1 is superimposed with the top surface structural map of the main oil-bearing sand group obtained in step 2 and the sandstone percentage content contour map obtained in step 4. The coupling relationship between structural ridges, sandstone percentage content and drilling oil-bearing properties is comprehensively analyzed. The area above the structural ridge with high sandstone percentage content is depicted with a closed curve. This area is the favorable formation area of ​​the meandering river sandstone oil reservoir. Other areas are mostly unfavorable formation areas of the meandering river sandstone oil reservoir. Based on this, the favorable formation areas of the meandering river facies sandstone lithology oil reservoir are predicted.

[0025] This invention presents a method for predicting favorable hydrocarbon accumulation zones in meandering fluvial sandstone reservoirs. From the perspective of hydrocarbon migration, it analyzes the coupling relationship between structural ridges and sandstone percentage content and well oil-bearing potential. Specifically, for slope zones lacking direct oil sources, a method for predicting favorable hydrocarbon accumulation zones in meandering fluvial sandstone reservoirs is established. After predicting favorable hydrocarbon accumulation zones in slope zones using this method, detailed exploration can be conducted using channel sand body description technology, which can effectively improve the well success rate in meandering fluvial sandstone reservoir exploration. Attached Figure Description

[0026] Figure 1 A flowchart illustrating a specific embodiment of the method for predicting favorable reservoir formation areas in meandering river facies sandstone lithology oil reservoirs according to the present invention;

[0027] Figure 2 This is a drilling oil-bearing distribution map in a specific embodiment of the present invention;

[0028] Figure 3 This is a structural diagram of the top of the main oil-bearing sand formation marked with a structural ridge in a specific embodiment of the present invention;

[0029] Figure 4This is a contour map showing the percentage content of sandstone in the main oil-bearing sandstone group in a specific embodiment of the present invention;

[0030] Figure 5 This is a prediction map of favorable reservoir formation areas for meandering river facies sandstone lithology oil reservoirs in a specific embodiment of the present invention. Detailed Implementation

[0031] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0032] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, and / or combinations thereof.

[0033] This invention provides a method for predicting favorable hydrocarbon accumulation areas in meandering river facies sandstone lithological oil reservoirs, relating to the exploration and development of such reservoirs. The method includes the following steps: statistically analyzing the oil content of the main oil-bearing sandstone groups drilled in previous wells and compiling well oil-bearing maps; performing detailed structural interpretation and compiling top structural maps of the main oil-bearing sandstone groups; identifying and plotting structural ridges on the structural maps and analyzing the relationship between well oil content and structural ridges; statistically analyzing the percentage content of sandstone in the main oil-bearing sandstone groups drilled in previous wells and compiling sandstone percentage content contour maps based on seismic attribute analysis; analyzing the matching relationship between well oil content and sandstone percentage content to determine the sandstone percentage content ranges of favorable hydrocarbon accumulation areas and unfavorable hydrocarbon migration areas; and comprehensively considering the matching relationship between structural ridges, sandstone percentage content, and well oil content to predict favorable hydrocarbon accumulation areas in meandering river facies sandstone lithological oil reservoirs. This invention, from the perspective of hydrocarbon migration, analyzes the migration patterns of hydrocarbons in meandering fluvial sandstones through multi-factor overlay evaluation, and predicts favorable hydrocarbon accumulation zones in meandering fluvial sandstone lithologic reservoirs. This method allows for a simple and intuitive prediction of favorable hydrocarbon accumulation zones in meandering fluvial sandstone lithologic reservoirs. After using readily available and mature fluvial sandstone body fine description technology to identify and describe individual fluvial sandstones, exploration and development of meandering fluvial sandstone lithologic reservoirs can commence, thereby improving the efficiency and success rate of exploration and development of these reservoirs.

[0034] The following are several specific embodiments of the application of the present invention.

[0035] Example 1

[0036] In a specific embodiment 1 of the present invention, the method for predicting favorable reservoir formation areas in meandering river facies sandstone lithology includes the following steps:

[0037] Step 1: Analyze the oil content of the main oil-bearing sand groups that have been drilled and compile an oil content map of the wells;

[0038] Based on the comprehensive oil testing results, well logging interpretation results, and comprehensive logging data, the oil content of the main oil-bearing sand groups in the drilled wells is statistically analyzed, and the statistical results are marked on the plan view to compile a drilling oil content map.

[0039] Step 2: Perform detailed structural interpretation of the seismic reflection axis on the top surface of the main oil-bearing sand formation and compile a structural map of the top surface of the main oil-bearing sand formation;

[0040] Using drilling and seismic data, we conducted detailed stratigraphic division and synthetic seismic record calibration of drilled wells, performed detailed stratigraphic interpretation of the seismic reflection axis at the top of the main oil-bearing sand formations, and compiled a structural map of the top of the main oil-bearing sand formations.

[0041] Step 3: Identify and plot the structural ridges on the top surface structural map of the main oil-bearing sand groups, and analyze the relationship between well oil-bearing properties and structural ridges.

[0042] Identify structural ridges on the structural map, which are the ridge lines of positive structures formed by changes in the attitude of rock strata, and mark the structural ridges with thick lines with arrows. Overlay the well oil-bearing map obtained in step 1 with the top surface structural map of the main oil-bearing sand group obtained in step 2, and analyze the relationship between well oil-bearing properties and structural ridges.

[0043] Step 4: Calculate the percentage content of sandstone in the main oil-bearing sand groups of drilled wells, and combine it with seismic attribute analysis to compile contour maps of the percentage content of sandstone in the main oil-bearing sand groups;

[0044] The thickness of sandstone and formation of the main oil-bearing sand groups drilled were statistically analyzed, and the percentage content of sandstone was calculated. Based on the calculated percentage content of sandstone, and combined with data such as seismic attributes, a sandstone percentage content contour map was compiled.

[0045] Step 5: Analyze the matching relationship between the oil content of the main oil-bearing sandstone groups and the percentage content of sandstone to determine the boundary range of sandstone percentage content in oil and gas favorable accumulation areas and oil and gas unfavorable migration areas.

[0046] By overlaying the well oil-bearing map obtained in step 1 with the sandstone percentage content contour map obtained in step 4, the matching relationship between well oil-bearing properties and sandstone percentage content is analyzed. The boundary range of sandstone percentage content between favorable oil and gas accumulation areas and unfavorable oil and gas migration areas is obtained. Areas with a larger sandstone percentage content can become favorable oil and gas accumulation areas, while areas with a smaller sandstone percentage content are mostly unfavorable oil and gas accumulation areas.

[0047] Step 6: Based on the conclusions drawn from Step 3 and Step 5, and considering the configuration relationship of hydrocarbon accumulation elements such as structural ridges and sandstone percentage content, predict the favorable hydrocarbon accumulation areas of meandering river facies sandstone lithology.

[0048] The well oil-bearing map obtained in step 1 is superimposed with the top surface structural map of the main oil-bearing sand group obtained in step 2 and the sandstone percentage content contour map obtained in step 4. The coupling relationship between structural ridges, sandstone percentage content and well oil-bearing properties is comprehensively analyzed. The area above the structural ridge with high sandstone percentage content is depicted with a closed curve. This area is the favorable formation area of ​​the meandering river sandstone oil reservoir. Other areas are mostly unfavorable formation areas of the meandering river sandstone oil reservoir. Based on this, the favorable formation areas of the meandering river facies sandstone lithology oil reservoir are predicted.

[0049] Example 2

[0050] In a specific embodiment 2 of the present invention, such as Figure 1 As shown, Figure 1 This is a flowchart illustrating the method for predicting favorable hydrocarbon accumulation zones in meandering river facies sandstone reservoirs according to the present invention. The method for predicting favorable hydrocarbon accumulation zones in meandering river facies sandstone reservoirs includes the following steps:

[0051] Step 1: Statistically analyze the oil content of the main oil-bearing sand groups that have been drilled and compile a drilling oil content map. Based on logging data, well interpretation results, and oil testing data, statistically analyze the oil content of the main oil-bearing sand groups that have been drilled and mark the statistical results on the plan view using standard symbols to compile a drilling oil content map.

[0052] Step 2: Perform detailed structural interpretation of the seismic reflection axis at the top of the main oil-bearing sand formation and compile a structural map of the top of the main oil-bearing sand formation; using drilling and seismic data, perform detailed stratigraphic division and synthetic seismic record calibration on the drilled wells, perform detailed stratigraphic interpretation of the seismic reflection axis at the top of the main oil-bearing sand formation, and compile a structural map of the top of the main oil-bearing sand formation.

[0053] Step 3: Identify and mark the structural ridges on the top surface structural map of the main oil-bearing sandstone formation, and analyze the relationship between well oil-bearing properties and structural ridges; identify structural ridges on the structural map, that is, the ridge lines of positive structures formed by changes in the attitude of rock strata, and mark the structural ridges with thick lines with arrows; overlay the well oil-bearing property map with the top surface structural map of the main oil-bearing sandstone formation, analyze the relationship between well oil-bearing properties and structures, and obtain the oil and gas distribution pattern.

[0054] Step 4: Calculate the percentage content of sandstone in the main oil-bearing sand groups of drilled wells, and compile a contour map of the percentage content of sandstone in the main oil-bearing sand groups based on seismic attribute analysis; calculate the sandstone thickness and formation thickness of the main oil-bearing sand groups of drilled wells, and calculate the percentage content of sandstone. Based on the calculated percentage content of sandstone, and in conjunction with seismic attribute data, compile a contour map of the percentage content of sandstone.

[0055] Step 5: Analyze the matching relationship between the oil-bearing properties of the main oil-bearing sandstone groups and the sandstone percentage content to determine the boundary range of sandstone percentage content between favorable oil and gas accumulation areas and unfavorable oil and gas migration areas. Overlay the well oil-bearing property map with the sandstone percentage content contour map to analyze the matching relationship between well oil-bearing properties and sandstone percentage content, and determine the boundary range of sandstone percentage content between favorable oil and gas accumulation areas and unfavorable oil and gas migration areas. Areas with a higher sandstone percentage content can be considered favorable oil and gas accumulation areas, while areas with a lower sandstone percentage content are mostly unfavorable oil and gas accumulation areas.

[0056] Step 6: Based on the conclusions drawn from Step 3 and Step 5, and considering the configuration relationship of hydrocarbon accumulation elements such as structural ridges and sandstone percentage content, predict the favorable hydrocarbon accumulation areas of meandering river facies sandstone lithology.

[0057] By overlaying the well oil-bearing map with the top structural map of the main oil-bearing sandstone group and the sandstone percentage content contour map, the coupling relationship between structural ridges, sandstone percentage content and well oil-bearing properties is comprehensively analyzed. The area above the structural ridge with high sandstone percentage content is depicted with a closed curve. This area is the favorable formation area of ​​the meandering river sandstone oil reservoir. Other areas are mostly unfavorable formation areas of the meandering river sandstone oil reservoir. Based on this, the favorable formation areas of the meandering river facies sandstone lithology oil reservoir are predicted.

[0058] Example 3

[0059] In a specific embodiment 3 of the present invention, the Kendong region is located in the transitional zone between the Kendong Uplift and the Yellow River Estuary Depression in the Bohai Bay Basin. It can be divided into secondary tectonic units such as the northern fault zone, the central main zone, and the southeastern slope zone. The upper section of the Guantao Formation is the main exploration stratum, with a meandering fluvial sedimentary facies. Oil and gas from the northern Yellow River Estuary Depression migrated to the northern part of the region along major faults or regional unconformities, and then continued southward through the Guantao Formation framework sand bodies. Influenced by factors such as faults, structures, and lithology, the types of oil and gas reservoirs differ in different secondary tectonic units. The northern fault zone is well-developed, with structural oil reservoirs being the main type; the central tectonic zone has less developed faults, with fault-nose structural oil reservoirs only formed in the south due to the influence of the Kendong 38 fault, while other areas are lithological oil reservoirs; the southeastern slope zone has fewer faults and is dominated by lithological oil reservoirs. The Guanshang Formation 5 is the main oil-bearing sandstone formation in the Guanshang Formation. Currently, discovered oil and gas reservoirs are primarily structural reservoirs, concentrated in the northern fault zone and the nose zone of the Kendong 38 fault in the central part. Sporadic drilling has also been conducted in the main belt and southeastern slope zone, but the accumulation patterns are unclear, and favorable accumulation areas are unknown, hindering the exploration and development of meandering sandstone lithological oil reservoirs in this area. Numerous wells have encountered the Guanshang Formation 5 in the area, and their distribution is relatively even, providing a good data foundation. Therefore, this invention takes the Guanshang Formation 5 in northeastern Kendong as an example, analyzing the coupling relationship between structural ridges and sandstone percentage content and well oil-bearing properties from the perspective of hydrocarbon migration. For slope zone areas lacking direct oil source conditions, a prediction method for favorable accumulation areas in meandering sandstone lithological oil reservoirs is established. The specific implementation process is as follows:

[0060] Step 1: Based on the comprehensive oil testing results, well logging interpretation results, and overall well logging information, statistically analyze the oil content of the upper 5 sand groups of the drilled wells. This can be further subdivided into industrial oil flow wells, low-production oil flow wells, oil layer wells, oil and gas show wells, and dry wells. These are then marked with different symbols on the plan view to create a drilling oil content map. Figure 2 ).

[0061] Step 2: Using drilling and seismic data, perform detailed stratigraphic division and synthetic seismic record calibration on the drilled wells. Based on this, perform detailed stratigraphic interpretation and velocity mapping on the top seismic reflection axis of the 5th sandstone group in the upper section of Guanshan. Based on the oil-bearing map of the drilling wells, compile a structural map of the top surface of the main oil-bearing sandstone group and mark the structural traps. Figure 3 ).

[0062] Step 3: Identify the structural ridges on the structural diagram and mark them with thick lines bearing arrows. Figure 3Structural ridges are ridges of positive structures, typically representing dominant channels for oil and gas migration. The arrows indicate the direction of oil and gas migration. Analyzing the relationship between well oil-bearing properties and structural ridges reveals the following oil and gas distribution patterns: Oil-flowing wells, oil-bearing wells, and oil and gas showing wells in fault zones are mostly located within structural traps; in slope zones with underdeveloped faults, oil-flowing wells, oil-bearing wells, and oil and gas showing wells are mostly distributed along and around structural ridges, i.e., located above dominant oil and gas migration channels.

[0063] Step 4: Calculate the sandstone thickness and formation thickness of the five sandstone groups in the upper section of the drilled wells. Using the sandstone percentage content formula: Sandstone percentage content = Sandstone thickness / Formation thickness, calculate the sandstone percentage content value for each well and mark it on the plan view. Extract seismic attributes such as the root mean square amplitude of the five sandstone groups in the upper section of the drilled wells. Based on the actual sandstone percentage content values ​​of the drilled wells, combine the root mean square amplitude attributes to create a sandstone percentage content isoline map. Overlay the well oil-bearing map onto the sandstone percentage content isoline map. Figure 4 ).

[0064] Step 5: Overlay the oil-bearing properties of wells in the Guanshang Section 5 sandstone group and the top structural map onto the sandstone percentage isopleth map to analyze the matching relationship between oil-bearing properties and structural ridges and sandstone percentages. Generally, when the sandstone percentage is high, oil and gas can migrate along structural ridges and accumulate in favorable channel sand bodies (lithological traps); when the sandstone percentage is low, oil and gas cannot migrate along structural ridges. In the example, the structural ridge area with a sandstone percentage of 20%-50% is a favorable oil and gas accumulation area, and wells in this area show good oil-bearing properties. Figure 5 Area A; structural ridges with sandstone content less than 20% are unfavorable for oil and gas migration. Wells drilled in these areas have poor oil-bearing properties and are mostly dry wells. Figure 5 Region B. Furthermore, as... Figure 5 region C ( Figure 5 Even though it is located in a structural ridge area and the sandstone content is 20%-50%, the oil and gas cannot be effectively migrated to this area due to the obstruction of the unfavorable oil and gas migration zone B. All exploration wells in the area are dry wells, which is also an unfavorable oil and gas migration zone.

[0065] Step 6: Based on the conditions for favorable hydrocarbon accumulation areas obtained in Step 5: 1) Located on a tectonic ridge, a dominant hydrocarbon migration channel; 2) Sandstone content of 20%-50%; 3) Excluding tectonic ridge areas at higher elevations of unfavorable hydrocarbon migration zones. Using a closed curve to depict the range of favorable hydrocarbon accumulation areas according to the relationship between tectonic ridges and sandstone content, predict the favorable hydrocarbon accumulation areas for meandering river facies sandstone lithology oil reservoirs. Figure 5 ).

[0066] Finally, it should be noted that the above description is merely 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 foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0067] Except for the technical features described in the specification, all other technologies are known to those skilled in the art.

Claims

1. A method for predicting favorable hydrocarbon accumulation zones in meandering river facies sandstone lithology reservoirs, characterized in that, The methods for predicting favorable hydrocarbon accumulation zones in meandering fluvial sandstone reservoirs include: Step 1: Compile statistics on the oil content of the main oil-bearing sand groups in the drilled wells and create an oil-bearing map of the wells. Step 2: Conduct detailed structural interpretation and compile a structural diagram of the top surface of the main oil-bearing sand formation; Step 3: Identify and plot the structural ridges on the structural map, and analyze the relationship between well oil content and structural ridges; Step 4: Calculate the percentage content of sandstone in the main oil-bearing sand groups of drilled wells, and compile a sandstone percentage content contour map based on seismic attribute analysis; Step 5: Analyze the matching relationship between well oil content and sandstone percentage content to determine the sandstone percentage content range in areas favorable for oil and gas accumulation and areas unfavorable for oil and gas migration. Step 6: Taking into account the relationship between the percentage content of structural ridges and sandstone and the oil-bearing properties of wells, predict the favorable oil-forming areas of meandering river facies sandstone lithology reservoirs; In step 4, the thickness of sandstone and formation of the main oil-bearing sand groups drilled are statistically analyzed, and the percentage content of sandstone is calculated. Based on the calculated percentage content of sandstone, combined with seismic attribute data, a sandstone percentage content contour map is compiled. In step 4, based on the sandstone percentage content formula: sandstone percentage content = sandstone thickness / formation thickness, the sandstone percentage content value of each well is calculated and marked on the plan map; based on the calculated sandstone percentage content value, combined with seismic attribute data and root mean square amplitude attributes, a sandstone percentage content contour map is compiled, and the well oil-bearing map is overlaid on the sandstone percentage content contour map; In step 5, the well oil content map obtained in step 1 is superimposed with the sandstone percentage content contour map obtained in step 4 to analyze the matching relationship between well oil content and sandstone percentage content, and to obtain the boundary range of sandstone percentage content in oil and gas favorable accumulation areas and oil and gas unfavorable migration areas. In step 5, areas with a higher percentage of sandstone content can become favorable areas for hydrocarbon accumulation, while areas with a lower percentage of sandstone content are mostly unfavorable areas for hydrocarbon migration. In step 6, the drilling oil-bearing map obtained in step 1 is superimposed with the top surface structural map of the main oil-bearing sand group obtained in step 2 and the sandstone percentage content contour map obtained in step 4. The coupling relationship between structural ridges, sandstone percentage content and drilling oil-bearing properties is comprehensively analyzed. The area above the structural ridge with high sandstone percentage content is depicted with a closed curve. This area is the favorable reservoir formation area of ​​the meandering river sandstone reservoir. Other areas are mostly unfavorable reservoir formation areas of the meandering river sandstone reservoir. Based on this, the favorable reservoir formation areas of the meandering river facies sandstone lithology reservoir are predicted.

2. The method for predicting favorable reservoir formation areas in meandering river facies sandstone lithology reservoirs according to claim 1, characterized in that, In step 1, based on the comprehensive oil testing results, well logging interpretation results, and comprehensive well logging display results, the oil content of the main oil-bearing sand groups that have been drilled is statistically analyzed, and the statistical results are marked on the plan view to compile a well oil content map.

3. The method for predicting favorable reservoir formation areas in meandering river facies sandstone lithology reservoirs according to claim 1, characterized in that, In step 2, using drilling and seismic data, the drilled wells are finely divided into stratigraphic units and the synthetic seismic records are calibrated. The seismic reflection axes at the top of the main oil-bearing sand groups are finely interpreted, and a structural map of the top of the main oil-bearing sand groups is compiled.

4. The method for predicting favorable reservoir formation areas in meandering river facies sandstone lithology reservoirs according to claim 1, characterized in that, In step 3, structural ridges are identified on the top surface structural map of the main oil-bearing sandstone group, which are the ridge lines of positive structures formed by changes in the attitude of the rock strata. The structural ridges are marked with thick lines with arrows. The drilling oil-bearing map obtained in step 1 is superimposed with the top surface structural map of the main oil-bearing sandstone group obtained in step 2 to analyze the relationship between drilling oil-bearing properties and structural ridges.

5. The method for predicting favorable reservoir formation areas in meandering river facies sandstone lithology oil reservoirs according to claim 4, characterized in that, In step 3, the relationship between well oil content and structural ridges is analyzed to obtain the oil and gas distribution pattern: oil flow wells, oil layer wells and oil and gas show wells in fault zones are located within structural traps; in slope zones where faults are not well developed, oil flow wells, oil layer wells and oil and gas show wells are distributed in and around structural ridges, that is, located above the dominant oil and gas migration channels.

Images