Method for evaluating oil-gas exploration potential in low-exploration-degree area

Abstract

The invention provides an oil-gas exploration potential evaluation method for a low-exploration-degree area. The oil-gas exploration potential evaluation method for the low-exploration-degree area comprises the steps that 1, main geological evaluation conditions of a research area are determined; 2, determining key geological evaluation parameters; step 3, establishing a key geological evaluation parameter grading assignment standard; 4, determining a key geological evaluation parameter weight coefficient; 5, calculating an exploration potential evaluation value; and step 6, carrying out exploration potential classification and quantitative evaluation. According to the method for evaluating the oil-gas exploration potential in the low-exploration-degree area, a basin foundation geological condition, a hydrocarbon source condition and a migration and accumulation condition are preferably selected as evaluation conditions according to the actual condition that the geological data of the low-exploration-degree area is less, and a mathematical statistical analysis technology is adopted, so that the evaluation standard and method for the oil-gas exploration potential in the low-exploration-degree area are established; therefore, the exploration potential of unknown basins or regions can be rapidly evaluated.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploration, and particularly to a method for evaluating the oil and gas exploration potential in areas with low exploration degree. Background Art

[0002] There are many oil and gas bearing basins in China, with different areas and various types. Moreover, there are a large number of areas that have not been registered for exploration by oil companies. In recent years, with the continuous deepening of geological understanding and the increasing number of exploration areas, breakthroughs in oil and gas exploration have been achieved in new areas and new fields of multiple basins, revealing that unknown basins or regions may also have great exploration value, which promotes the gradual strengthening of the work of selecting areas. Therefore, how to select favorable basins or regions for research is a difficult problem facing us. For this reason, a method for evaluating the oil and gas exploration potential in unknown areas needs to be established.

[0003] Regarding the evaluation of exploration potential in areas with low exploration degree, many methods such as the four-factor method, the eleven-parameter method, and the two-factor model method have been proposed by predecessors. Through analysis, the following disadvantages are found: ① A large number of geological parameters are selected, which is too comprehensive. Most of the parameters are classified and graded from six aspects of the oil and gas accumulation elements, namely "source, reservoir, caprock, trap, migration, and preservation". For areas with low exploration and understanding degrees, due to the limitation of geological data, it is difficult to obtain most of the indicators, and it is difficult to operate; ② Some methods can only achieve qualitative evaluation of blocks, but cannot perform quantitative evaluation; ③ For the methods for quantitative evaluation of exploration potential, the weight assignment of some indicators is unreasonable.

[0004] In the Chinese patent application with the application number: CN202210185588.7, a method for evaluating oil and gas resources in areas with low exploration degree is involved. First, the evaluation units are divided in the areas with low exploration degree, the analog scale areas similar to the evaluation units in the areas with low exploration degree are selected, and the evaluation parameters of the analog scale areas are screened. Then, the analog method is used to assign values to the corresponding evaluation parameters of the evaluation units in the areas with low exploration degree, and the parameter values are adjusted in combination with the actual situation and expert evaluation. Finally, the Monte Carlo simulation method is used to calculate the probability value of the oil and gas resource volume of the evaluation unit. This method realizes the evaluation of oil and gas resources in areas with low exploration degree in an objective and scientific way, and solves the problem of difficult accurate assessment of oil and gas resource volume in current areas with low exploration degree.

[0005] In the Chinese patent application with the application number: CN202210399990.5, it involves a method for evaluating the exploration potential of oil and gas reservoirs, belonging to the technical field of oil and gas exploration and development. The method for evaluating the exploration potential of oil and gas reservoirs of this invention includes the following steps: (1) Select quantifiable indicators that affect the formation conditions of oil and gas reservoirs in the area to be evaluated; the formation conditions include oil generation conditions, reservoir conditions, caprock conditions, trap conditions, migration conditions, and preservation conditions; (2) Calculate the weights of each selected quantifiable indicator; (3) Calculate the evaluation value Gp of the exploration potential of each single well; (4) Draw an isogram through the evaluation values of the exploration potential of each single well, and then evaluate the exploration potential of the oil and gas reservoirs in the area to be evaluated. The method for evaluating the exploration potential of oil and gas reservoirs of this invention starts from the single well information data, uses the correlations between elements such as generation, reservoir, caprock, trap, migration, and preservation, establishes a quantitative evaluation model, and quantifies the exploration potential of the oil and gas reservoirs in the evaluation area.

[0006] In the Chinese patent application with the application number: CN201510117159.6, it involves a method for quantitatively dividing the exploration degree of oil and gas units. It includes collecting the 2D seismic workload and 3D seismic workload of the oil and gas unit, determining the exploration work degree coefficient Wed according to the 2D seismic workload, 3D seismic workload, and actual number of exploration wells of the oil and gas unit; calculating the ratio of the sum of the resource recognition parameters of the oil and gas unit to the total resource volume to obtain the resource determination degree coefficient Rid; calculating the exploration degree index Ied according to the exploration work degree coefficient Wed and the resource determination degree coefficient Rid. This invention can make the most of existing data to accurately divide the exploration degree. Especially for areas with low exploration degrees, it can more effectively distinguish the high and low levels of exploration degrees. This invention can make the most of existing data to accurately divide the exploration degree. Especially for areas with low exploration degrees, it can more effectively distinguish the high and low levels of exploration degrees. However, this method cannot comprehensively reflect the exploration status of evaluating oil and gas units.

[0007] The above existing technologies are all quite different from this invention and fail to solve the technical problems we want to solve. Therefore, we have invented a new method for evaluating the exploration potential of oil and gas in areas with low exploration degrees. Summary of the Invention

[0008] The purpose of this invention is to establish evaluation criteria and methods for the exploration potential of oil and gas in areas with low exploration degrees through statistical analysis of the relationship between known basin geological parameters and oil and gas shows, and provide support for the comprehensive evaluation and optimization of its exploration potential.

[0009] The purpose of this invention can be achieved by the following technical measures: A method for evaluating the exploration potential of oil and gas in areas with low exploration degrees, and this method for evaluating the exploration potential of oil and gas in areas with low exploration degrees includes:

[0010] Step 1: Determine the main geological evaluation conditions of the study area;

[0011] Step 2: Determine the key geological evaluation parameters;

[0012] Step 3: Establish the grading and assignment criteria for key geological evaluation parameters;

[0013] Step 4: Determine the weight coefficients of key geological evaluation parameters;

[0014] Step 5: Calculate the exploration potential evaluation value;

[0015] Step 6: Conduct a classified and quantitative evaluation of exploration potential.

[0016] The object of the present invention can also be achieved by the following technical measures:

[0017] In Step 1, on the basis of a large amount of literature research and data collection and analysis, determine the factors affecting hydrocarbon accumulation in the study area with low exploration degree. Generally, large basins will have large oil and gas discoveries, and the scale of oil and gas is positively correlated with the source conditions and migration and accumulation conditions.

[0018] In Step 2, select the parameters that play a decisive role in exploration potential, analyze the relationship between the basic geological conditions and petroleum geological conditions of the basin and oil and gas shows, and select the parameters that are closely related to oil and gas shows as key geological evaluation parameters.

[0019] In Step 2, the petroleum geological conditions include source conditions and migration and accumulation conditions.

[0020] In Step 3, using the method of mathematical statistics and analysis, classify each geological evaluation parameter according to the relationship between the change of single geological evaluation parameter and the oil and gas show rate.

[0021] In Step 3, classify the geological evaluation parameters into grades I, II, and III. Grade I has the highest oil and gas show rate, followed by Grade II and the lowest by Grade III; the oil and gas show rate = the number of sample points / the total number of samples × 100%.

[0022] In Step 4, the weight coefficient can reflect the relative importance degree among key geological evaluation parameters. Using the method of mathematical statistics, determine the index weight based on the analysis and comparison of the sensitivity of each key geological evaluation parameter to oil and gas shows.

[0023] Step 4 includes:

[0024] ① On the basis of the grading and assignment of geological evaluation parameters, determine the oil and gas show rate corresponding to each level of a single evaluation parameter;

[0025] ② Fit a linear trend line for the oil and gas show rates at each level to characterize the positive correlation between key geological evaluation parameters and oil and gas shows;

[0026] ③ Obtain the difference between the oil and gas show rates corresponding to Grade I and Grade III of a single key geological evaluation parameter;

[0027] ④ Compare the differences in the oil and gas show rates of each key geological evaluation parameter and perform normalization processing.

[0028] In step 5, the potential evaluation value is calculated using the three-factor multiplication method. The formula for determining the potential evaluation value is:

[0029] Potential evaluation value = Basic condition evaluation value × Source rock condition evaluation value × Migration and accumulation condition evaluation value;

[0030] ① Basic condition evaluation value = ∑(Basic evaluation parameter × Parameter weight);

[0031] ② Source rock condition evaluation value = ∑(Source rock parameter × Parameter weight);

[0032] ③ Migration and accumulation condition evaluation value = ∑(Migration and accumulation parameter × Parameter weight).

[0033] In step 6, classification is carried out based on the potential evaluation value:

[0034] For Class I, the evaluation value > 0.4: The geological evaluation conditions are good, the expected reserve scale is large, and the exploration pace can be accelerated; for Class II, the evaluation value is 0.4 - 0.2: The geological evaluation conditions are medium, and further research can be carried out to verify the potential; for Class III, the evaluation value < 0.2: The geological evaluation conditions are poor, and there is no potential for oil and gas exploration.

[0035] In the method for evaluating the oil and gas exploration potential in low-exploration-degree areas of the present invention, following the principle of simplifying geological evaluation parameters as much as possible and aiming at the actual situation of scarce geological data in low-exploration-degree areas, the basic geological conditions, source rock conditions, and migration and accumulation conditions of the basin are selected as evaluation conditions, and mathematical statistics analysis techniques are used to establish the evaluation criteria and methods for the oil and gas exploration potential in low-exploration-degree areas, thereby realizing the rapid evaluation of the exploration potential of unknown basins or regions. Description of the Drawings

[0036] Figure 1 It is a schematic diagram of the statistics of oil and gas discoveries in the central and western basins in a specific embodiment of the present invention;

[0037] Figure 2 It is a diagram showing the relationship between the basin area, thickness, and oil and gas show rate in a specific embodiment of the present invention;

[0038] Figure 3 It is a flowchart of a specific embodiment of the method for evaluating the oil and gas exploration potential in low-exploration-degree areas of the present invention. Detailed Embodiments

[0039] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0040] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should also be understood that when the terms "comprise" and / or "include" are used in this specification, they specify the presence of features, steps, operations, and / or combinations thereof.

[0041] As Figure 3 shown, Figure 3 is a flowchart of a method for evaluating the potential of oil and gas exploration in areas with low exploration levels according to the present invention. The method for evaluating the potential of oil and gas exploration in areas with low exploration levels includes:

[0042] Step 101: Determine the main geological evaluation conditions of the study area.

[0043] Based on a large amount of literature research and data collection and analysis, determine the factors affecting hydrocarbon accumulation in the study area with low exploration levels. Generally, large oil and gas discoveries will be made in large basins, and the scale of oil and gas is positively correlated with source rock conditions and migration and accumulation conditions.

[0044] Step 102: Determine the key geological evaluation parameters.

[0045] Preferably select the parameters that play a decisive role in the exploration potential. Analyze the relationship between the basic geological conditions of the basin and the petroleum geological conditions (such as source rock conditions, migration and accumulation conditions, etc.) and the oil and gas shows, and preferably select the parameters that are closely related to the oil and gas shows as the key geological evaluation parameters.

[0046] Step 103: Establish a grading and assignment standard for key geological evaluation parameters.

[0047] Using the method of mathematical statistics and analysis, classify each geological evaluation parameter according to the relationship between the change of single geological evaluation parameter and the oil and gas show rate. The geological evaluation parameters are divided into grades I, II, and III. The oil and gas show rate of grade I is the highest, that of grade II is the second, and that of grade III is the lowest. The oil and gas show rate = the number of sample points / the total number of samples × 100%.

[0048] Step 104: Determine the weight coefficients of key geological evaluation parameters.

[0049] The weight coefficients can reflect the relative importance of each key geological evaluation parameter. Using the method of mathematical statistics, determine the index weights based on the analysis and comparison of the sensitivity of each key geological evaluation parameter to oil and gas shows.

[0050] ① On the basis of grading and assigning values to geological evaluation parameters, determine the oil and gas show rate corresponding to each level of a single evaluation parameter;

[0051] ②Fit a linear trend line to the oil and gas display rates at all levels to characterize the positive correlation between the key geological evaluation parameters and the oil and gas display.

[0052] ③Calculate the difference between the oil and gas display rates corresponding to Class I and Class III of a single key geological evaluation parameter;

[0053] ④Compare the differences in the oil and gas display rates of each key geological evaluation parameter and perform normalization processing.

[0054] Step 105: Calculate the exploration potential evaluation value.

[0055] Calculate the potential evaluation value using the three-factor multiplication method.

[0056] Determination of the potential evaluation value:

[0057] Potential evaluation value = Basic condition evaluation value × Hydrocarbon source condition evaluation value × Migration and accumulation condition evaluation value;

[0058] ①Basic condition evaluation value = ∑(Basic evaluation parameter × Parameter weight);

[0059] ②Hydrocarbon source condition evaluation value = ∑(Source rock parameter × Parameter weight);

[0060] ③Migration and accumulation condition evaluation value = ∑(Migration and accumulation parameter × Parameter weight);

[0061] Step 106: Classify and quantitatively evaluate the exploration potential.

[0062] Classify according to the potential evaluation value:

[0063] Class I (evaluation value > 0.4): Good geological evaluation conditions, large expected reserve scale, and the exploration pace can be accelerated; Class II (evaluation value is 0.4 - 0.2): Medium geological evaluation conditions, and further research can be carried out to implement the potential; Class III (evaluation value < 0.2): Poor geological evaluation conditions and no potential for oil and gas exploration.

[0064] The following are several specific embodiments of applying the present invention

[0065] Embodiment 1:

[0066] In a specific embodiment 1 of applying the present invention, the oil and gas exploration potential evaluation method for the low exploration degree area includes the following steps:

[0067] (1) Determine the main geological evaluation conditions of the study area: Based on a large amount of literature research and data collection and analysis, by analyzing the main controlling factors of hydrocarbon accumulation in more than 20 small and medium-sized basins in the central and western regions, and combining the six elements of petroleum geology - "source, reservoir, cap, migration, trap, and preservation", it is determined that the basic geological conditions, hydrocarbon source conditions, and migration and accumulation conditions of the basin are the most important influencing factors for hydrocarbon accumulation in the study area.

[0068] (2) Determine the key geological evaluation parameters: Select the parameters that are closely related to hydrocarbon shows as the main evaluation parameters. From the basic basin conditions, select two parameters: basin area and sedimentary rock thickness; from the source rock conditions, select the distribution area, thickness, organic carbon content, organic matter type, and organic matter maturity of the source rock as evaluation parameters; from the migration and accumulation conditions, select the study area and the distance from the source area as evaluation parameters.

[0069] (3) Establish the grading and assignment criteria for key geological evaluation parameters:

[0070] Take the basic basin conditions as an example.

[0071] The hydrocarbon discoveries in 50 basins in the central and western regions were statistically analyzed ( Figure 1 ). It can be seen from Figure 1 that large basins have large discoveries. When the basin area ≥ 20,000 km 2 , the hydrocarbon show rate is about 80%; when the basin area ≤ 5,000 km 2 , there are basically no hydrocarbon discoveries. Based on this, the basin area is divided into 3 grades: Grade I ≥ 20,000 km 2 , Grade II is (5,000 - 20,000) km 2 , and Grade III < 5,000 km 2 . Basin sedimentary rock thickness: Grade I ≥ 6,000 m, Grade II is (6,000 - 2,500) m, and Grade III < 2,500 m.

[0072] The grading methods for other geological evaluation parameters are similar to the above, and the grading evaluation criteria for each parameter are as follows.

[0073] Source rock area: Grade I ≥ 2,500 km 2 , Grade II is (1,500 - 2,500) km 2 , and Grade III < 1,500 km 2 .

[0074] Source rock thickness: Grade I ≥ 300 m, Grade II is (100 - 300) m, and Grade III < 100 m.

[0075] Organic carbon content: Grade I ≥ 2.0%, Grade II is (0.5 - 2.0)%, and Grade III < 0.5%.

[0076] Organic matter type: Grade I is mainly type I, with a small amount of type II; Grade II is mainly type II, and Grade III is mainly type III.

[0077] Organic matter maturity: Grade I is mainly mature and highly mature; Grade II is mainly low mature and over mature, and Grade III is mainly immature.

[0078] Study area in the migration and accumulation conditions: Grade I ≥ 6,000 km 2 , Grade II is (4,000 - 6,000) km2 , Class III < 4000 km 2 .

[0079] Distance from the source area: Class I < 1 km, Class II is (1 - 20) km, Class III > 20 km.

[0080] (4) Determine the weight coefficients of key geological evaluation parameters:

[0081] Take the basin area and sedimentary thickness as examples.

[0082] ① Calculate the oil and gas show rate corresponding to each level of a single geological evaluation parameter ( Figure 2 ).

[0083] Basin area: The oil and gas show rate of Class I is 76.5%, that of Class II is 40.9%, and that of Class III is 16.7%.

[0084] Thickness of basin sedimentary rocks: The oil and gas show rate of Class I is 100%, that of Class II is 57%, and that of Class III is 0%.

[0085] ② Fit a linear trend line for the oil and gas show rates of the three levels.

[0086] After calculation, for the basin area: The oil and gas show rate of Class I is 74.6%, that of Class II is 44.7%, and that of Class III is 14.8%. For the thickness of basin sedimentary rocks: The oil and gas show rate of Class I is 100%, that of Class II is 52.1%, and that of Class III is 2.1%.

[0087] ③ Calculate the difference between the oil and gas show rates corresponding to Class I and Class III of a single key geological evaluation parameter after fitting, and perform normalization processing to determine the weight coefficient;

[0088] Basin area: I - III = 74.6% - 14.8% = 59.8% ≈ 0.6

[0089] Basin thickness: I - III = 100% - 2.1% = 97.9% ≈ 1

[0090]

[0091] The determination methods of the weight coefficients of other geological evaluation parameters are the same as above. The weight coefficients of each key geological evaluation parameter are as shown in the following table (Table 1). Thus, an evaluation standard and method for the oil and gas exploration potential in areas with low exploration degree are established.

[0092] Table 1 Evaluation standard table for the oil and gas exploration potential in areas with low exploration degree

[0093]

[0094] Example 2:

[0095] Taking Area A in the western part of China as an example. The basin where this area is located has an area of 15,000 square kilometers and is a sedimentary basin mainly composed of Cenozoic strata, with the thickness of sedimentary rocks being approximately 5,000 m. Area A has an area of 6,100 square kilometers, and there are only 2 gravity and magnetic profiles and 2 electrical method profiles within the area, without seismic data and drilling wells. In the outcrops of this basin, Paleogene and Neogene lacustrine dark mudstones are found, with a cumulative thickness of up to 141.4 m. It is speculated that the area of source rocks in Area A reaches 2,000 square kilometers, and the thickness of source rocks is 250 m. From the analysis and testing results of outcrop samples, the organic carbon content of the source rocks is 0.4% - 1.32%, with an average of 0.65%. The organic matter type is mainly Type II, and the maturity is 0.5% - 0.72%, with an average of 0.55%, being in the low maturity stage. Area A is located in the relatively middle position of the basin, and the underlying source rocks are well-developed.

[0096] Evaluation value of basic conditions = ∑(basic evaluation parameters × parameter weights) = 0.4×0.6 + 0.6×0.6 = 0.6;

[0097] Evaluation value of source rock conditions = ∑(source rock parameters × parameter weights) = 0.2×0.5 + 0.2×0.6 + 0.15×0.4 + 0.15×0.6 + 0.3×0.6 = 0.55

[0098] Evaluation value of migration and accumulation conditions = ∑(migration and accumulation parameters × parameter weights) = 0.4×0.75 + 0.6×1 = 0.9;

[0099] Evaluation value of potential = Evaluation value of basic conditions × Evaluation value of hydrocarbon source conditions × Evaluation value of migration and accumulation conditions = 0.6×0.55×0.9 = 0.297.

[0100] After calculation, the resource potential value of Area A is 0.297, belonging to Class II area. It is considered that the geological evaluation conditions are medium, with certain exploration potential, and it can be further studied to further verify the potential.

[0101] Table 2 Resource Potential Evaluation Table of Area A in the Western Part of China

[0102]

[0103]

[0104] Example 3:

[0105] Taking Area B in the eastern part of China as an example. The depression where this area is located has an area of 4,000 square kilometers and is a sedimentary basin mainly composed of Cenozoic strata, with the thickness of sedimentary rocks being more than 6,500 m. Area B has an area of 2,700 square kilometers, and there are only 6 2D seismic lines and 6 exploration wells in the area, with a low exploration degree. According to research, the fourth member of the Shahejie Formation - Kongdian Formation is the main hydrocarbon source rock series in this depression. The source rock area reaches 1,500 square kilometers, the maximum thickness of the source rock is 300 - 400 m, the average thickness is 150 m, the organic carbon content is 0.4% - 0.6%, with an average of 0.5%, and the organic matter type is mainly type III, being in the mature stage.

[0106] Evaluation value of basic conditions = ∑(basic evaluation parameters × parameter weights) = 0.4 × 0.2 + 0.6 × 0.75 = 0.53;

[0107] Evaluation value of source rock conditions = ∑(source rock parameters × parameter weights) = 0.2 × 0.3 + 0.2 × 0.4 + 0.15 × 0.3 + 0.15 × 0.2 + 0.3 × 0.8 = 0.455

[0108] Evaluation value of migration and accumulation conditions = ∑(migration and accumulation parameters × parameter weights) = 0.4 × 0.2 + 0.6 × 1 = 0.68;

[0109] Evaluation value of potential = Evaluation value of basic conditions × Evaluation value of hydrocarbon source conditions × Evaluation value of migration and accumulation conditions = 0.53 × 0.455 × 0.68 = 0.164.

[0110] After calculation, the resource potential value of Area B is 0.164, belonging to Class III area, indicating that the geological evaluation conditions are poor and it does not have the potential for oil and gas exploration.

[0111] Table 3 Resource Potential Evaluation Table of Area B in the Eastern Part of China

[0112]

[0113]

[0114] Example 4:

[0115] Taking Area C in the western part of China as an example. The basin where this area is located has an area of 11,000 square kilometers and is a Mesozoic - Cenozoic sedimentary basin, with the thickness of sedimentary rocks being 6,000 m. Area C has an area of 2,500 square kilometers. According to research, the Middle Jurassic Yaojie Formation is the main hydrocarbon source rock series in this basin. The source rock area is 1,900 square kilometers, the source rock thickness is 50 - 170 m, the average organic carbon content is 2.62%, and the organic matter type is mainly type II, being in the mature and highly mature stages.

[0116] After calculation, the resource potential value of Area C is 0.224, belonging to Class II area, indicating that the geological evaluation conditions are medium and it has a certain exploration potential, and can be further studied to further verify the potential.

[0117] Finally, it should be noted that the above are only preferred embodiments of the present invention and are 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 perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

[0118] Except for the technical features described in the specification, the rest are known technologies to those skilled in the art.

Claims

1. Oil and gas exploration potential evaluation method for areas with low exploration degree, characterized in that, the oil and gas exploration potential evaluation method for areas with low exploration degree includes: Step 1: Determine the main geological evaluation conditions of the study area; Step 2: Determine the key geological evaluation parameters; Step 3: Establish the grading and assignment criteria for key geological evaluation parameters; Step 4: Determine the weight coefficients of key geological evaluation parameters; Step 5: Calculate the exploration potential evaluation value; Step 6: Conduct classification and quantitative evaluation of exploration potential.

2. The oil and gas exploration potential evaluation method for areas with low exploration degree according to claim 1, characterized in that, in Step 1, on the basis of a large amount of literature research and data collection and analysis, determine the factors affecting hydrocarbon accumulation in the study area with low exploration degree. Generally, large oil and gas discoveries will be made in large basins, and the scale of oil and gas is positively correlated with source rock conditions and migration and accumulation conditions.

3. The oil and gas exploration potential evaluation method for areas with low exploration degree according to claim 1, characterized in that, in Step 2, select the parameters that play a decisive role in exploration potential, analyze the relationship between the basic geological conditions and petroleum geological conditions of the basin and hydrocarbon shows, and select the parameters closely related to hydrocarbon shows as the key geological evaluation parameters.

4. The oil and gas exploration potential evaluation method for areas with low exploration degree according to claim 3, characterized in that, in Step 2, the petroleum geological conditions include source rock conditions and migration and accumulation conditions.

5. The oil and gas exploration potential evaluation method for areas with low exploration degree according to claim 1, characterized in that, in Step 3, use the method of mathematical statistics analysis to classify each geological evaluation parameter according to the relationship between the change of single geological evaluation parameter and hydrocarbon show rate.

6. The oil and gas exploration potential evaluation method for areas with low exploration degree according to claim 5, characterized in that, in Step 3, divide the geological evaluation parameters into grades I, II, and III. Grade I has the highest hydrocarbon show rate, grade II is the second, and grade III is the lowest; hydrocarbon show rate = number of sample points / total number of samples × 100%.

7. The oil and gas exploration potential evaluation method for areas with low exploration degree according to claim 1, characterized in that, in Step 4, the weight coefficient can reflect the relative importance degree among key geological evaluation parameters. Use the method of mathematical statistics to determine the index weight based on the analysis and comparison of the sensitivity of each key geological evaluation parameter to hydrocarbon shows.

8. The oil and gas exploration potential evaluation method for areas with low exploration degree according to claim 1, characterized in that, Step 4 includes: ① On the basis of grading and assignment of geological evaluation parameters, determine the hydrocarbon show rate corresponding to each level of a single evaluation parameter; ② Fit a linear trend line for the hydrocarbon show rates at each level to characterize the positive correlation between key geological evaluation parameters and hydrocarbon shows; ③ Calculate the difference between the hydrocarbon show rates corresponding to grade I and grade III of a single key geological evaluation parameter; ④ Compare the differences in hydrocarbon show rates of each key geological evaluation parameter and conduct normalization processing.

9. The oil and gas exploration potential evaluation method for areas with low exploration degree according to claim 1, characterized in that, in Step 5, use the three-factor multiplication method to calculate the exploration potential evaluation value. The formula for determining the exploration potential evaluation value is: Exploration potential evaluation value = basic condition evaluation value × source rock condition evaluation value × migration and accumulation condition evaluation value; ①Basic condition evaluation value = ∑(basic evaluation parameter × parameter weight); ②Source rock condition evaluation value = ∑(source rock parameter × parameter weight); ③Migration and accumulation condition evaluation value = ∑(migration and accumulation parameter × parameter weight).

10. The method for evaluating the oil and gas exploration potential in a low exploration degree area according to claim 1, characterized in that, in step 6, classification is carried out according to the potential evaluation value: For Class I, the evaluation value > 0.4: The geological evaluation conditions are good, the expected reserve scale is large, and the exploration pace can be accelerated; for Class II, the evaluation value is 0.4 - 0.2: The geological evaluation conditions are medium, and further research can be carried out to implement the potential; for Class III, the evaluation value < 0.2: The geological evaluation conditions are poor, and there is no potential for oil and gas exploration.

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