Test layer selection method and device based on gas logging

Abstract

The invention relates to the technical field of oil and gas exploration, in particular to a gas logging-based test layer selection method and device.The gas logging-based test layer selection method comprises the following steps that S1, gas logging parameters and logging parameters are collected, and the C1 / C2 ratio is calculated according to the gas logging parameters; drawing a C1 / C2 change curve, an acoustic curve and a total hydrocarbon curve; s2, selecting a hydrocarbon source rock baseline according to a total hydrocarbon curve change trend, lithology and an acoustic curve; s3, comparing the C1 / C2 ratio of the gas reservoir section with the hydrocarbon source rock baseline value of the underlying mudstone section, and dividing the gas reservoir section into a good gas reservoir, a medium gas reservoir and a differential gas reservoir; preferentially selecting a good gas layer, secondly selecting a medium gas layer, and finally selecting a differential gas layer for testing. The method can significantly improve the success rate of test layer selection.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil and gas exploration, and particularly relates to a test layer selection method and device based on gas logging. BACKGROUND

[0002] Accurate determination of gas layers is a key factor to determine the success rate of drilling tests. With the continuous progress of petroleum geology theory and the continuous progress of oil and gas field exploration and development technology, the determination of drilling gas layers has developed into a comprehensive analysis technology combining logging, well logging and geology. As the most direct observation technology for formation gas content during drilling, the application of gas logging technology in gas layer determination is mainly limited to the high and low of total hydrocarbon display and its change characteristics, and the mining of geological information contained in gas logging parameters is still relatively weak.

[0003] The organic matter hydrocarbon generation evolution process and numerous oil and gas field exploration practices have confirmed that the amount of oil and gas generated at the mature-high mature stage of source rock is much higher than that at the low mature stage, and the scale of the accumulated oil and gas reservoirs is also mainly filled with oil and gas generated at the mature-high mature stage of source rock. Therefore, how to determine the depth section of the oil and gas generated at the mature-high mature stage of the source rock is related to the success or failure of exploration.

[0004] However, for complex oil and gas reservoirs that have experienced multiple stages of oil and gas migration, accumulation and charging, it is difficult to determine the favorable layer for testing by using the conventional logging parameters such as drilling time and total hydrocarbon display, and it is impossible to analyze the differences in the composition and gas abundance of the natural gas contained in the gas layer, which limits the accurate selection of the drilling test layer and is not conducive to improving the success rate of testing layer selection. SUMMARY

[0005] The present application aims to overcome the problem that the conventional testing layer selection method cannot determine the favorable layer for testing for complex oil and gas reservoirs that have experienced multiple stages of oil and gas migration, accumulation and charging, and to provide a testing layer selection method and device based on gas logging.

[0006] In a first aspect, the present application provides a testing layer selection method based on gas logging, comprising the following steps:

[0007] S1: Collecting gas logging parameters and logging parameters, the gas logging parameters including well depth, lithology, total hydrocarbon content, methane content C1 and ethane content C2, and the logging parameters including acoustic wave value; calculating the C1 / C2 ratio according to the gas logging parameters; drawing the C1 / C2 variation curve, the acoustic wave curve and the total hydrocarbon curve;

[0008] S2: Selecting the source rock baseline according to the variation trend of the total hydrocarbon curve, the lithology and the acoustic wave curve;

[0009] S3: Comparing the C1 / C2 ratio of the gas layer section with the source rock baseline value of the underlying mudstone section:

[0010] If the ratio of the gas layer section C1 / C2 increases from deep to shallow, and the ratio of the gas layer section C1 / C2 is higher than the source rock baseline value of the underlying mudstone section, the gas layer section is a good gas layer;

[0011] If the ratio of the gas layer section C1 / C2 is close to the source rock baseline value of the underlying mudstone section, the gas layer section is a medium gas layer;

[0012] If the ratio of the gas layer section C1 / C2 decreases from deep to shallow, the gas layer section is a poor gas layer;

[0013] The good gas layer is preferentially selected, then the medium gas layer, and finally the poor gas layer is selected for testing.

[0014] The test layer selection method based on gas logging provided by the application comprehensively considers the gas logging parameters and logging parameters, and can help to distinguish the natural gas from deeper high-mature source rock and the natural gas from adjacent source rock by comparing the ratio of the gas layer section C1 / C2 with the baseline value of the underlying mudstone section, thereby assisting in judging the gas abundance of the gas layer section interpreted by conventional logging or logging, providing an important basis for the exploration of complex oil and gas systems, and providing an important clue for the study of oil and gas migration and charging history, and significantly improving the success rate of test layer selection. The method provides a new idea and method for judging the gas abundance and other characteristics of the gas layer, and provides logging geological support for improving the success rate of oil and gas drilling testing.

[0015] Preferably, in S3, if the ratio of the gas layer section C1 / C2 is 1-1.5 times the source rock baseline value of the underlying mudstone section, the gas layer section is a medium gas layer.

[0016] Preferably, in S2, the C1 / C2 ratio of the mudstone section with no significant jump in the acoustic curve and a stable change trend of the total hydrocarbon curve is selected as the source rock baseline.

[0017] By using this method for selecting the source rock baseline, the stability of the acoustic curve reflects the uniformity and continuity of the formation, and by selecting the mudstone section with no significant jump in the acoustic curve, the influence of interlayers, fractures or other geological anomalies can be excluded, and the representativeness and accuracy of the source rock baseline are improved; the stable change trend of the total hydrocarbon curve means that the mudstone section has no obvious hydrocarbon gas anomaly. This helps to exclude the interference of external gas brought by possible fractures, microfractures or other permeation channels, and ensures that the baseline value truly reflects the original geochemical characteristics of the layer. This fine selection method of the source rock baseline greatly improves the accuracy and reliability of the entire analysis process.

[0018] Preferably, in S2, the C1 / C2 ratio of the mudstone section with a sharp peak in the acoustic curve, the peak value of the acoustic curve within the range of ±5 meters of the well depth being 2.5 times or less the minimum value of the acoustic curve, and the ratio of the minimum value to the maximum value of the total hydrocarbon curve being less than 3 is selected as the source rock baseline.

[0019] Preferably, the shale section selected for the baseline of the source rock in S2 does not contain carbon and coal seams.

[0020] Preferably, S1 further comprises: drawing a single well comprehensive column chart, the single well comprehensive column chart comprising well depth, lithology, C1 / C2 variation curve, acoustic curve, total hydrocarbon curve.

[0021] Preferably, S1 further comprises: the logging parameters comprising natural gamma value, deep lateral resistivity value, shallow lateral resistivity value, and the single well comprehensive column chart further comprising natural gamma curve, deep lateral resistivity curve, and shallow lateral resistivity curve.

[0022] By integrating various parameters in the single well comprehensive column chart, the user can comprehensively analyze multiple parameters, and the accuracy and reliability of the interpretation are greatly improved.

[0023] In a second aspect, the present application provides a device for testing and selecting layers based on gas logging, comprising at least one processor and a memory in communication connection with the at least one processor; the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the above-mentioned method for testing and selecting layers based on gas logging.

[0024] In a third aspect, the present application provides a computer readable medium having instructions executable by a processor stored thereon, wherein the instructions, when executed by the processor, cause the processor to execute the above-mentioned method for testing and selecting layers based on gas logging.

[0025] Compared with the prior art, the present application has the following beneficial effects:

[0026] 1. The method for testing and selecting layers based on gas logging provided by the present application comprehensively considers gas logging parameters and logging parameters, and by comparing the C1 / C2 ratio of the gas layer section with the baseline value of the underlying shale section, it can help to distinguish natural gas from deeper high-mature hydrocarbon source rocks and natural gas from adjacent hydrocarbon source rocks, assist in judging the gas-bearing abundance of the gas layer section interpreted by conventional logging or logging, provide an important basis for the exploration of complex oil and gas systems, and provide an important clue for the study of oil and gas migration and charging history, thereby significantly improving the success rate of testing and selecting layers. The method provides a new idea and method for judging the gas-bearing abundance and other characteristics of the gas layer, and provides logging geological support for improving the success rate of oil and gas drilling testing.

[0027] 2. The device for testing and selecting layers based on gas logging provided by the present application uses the method for testing and selecting layers based on gas logging provided by the present application, and can significantly improve the success rate of testing and selecting layers.

[0028] 3. The computer readable medium provided by the present application can run the test layer selection method based on gas logging provided by the present application, and the success rate of test layer selection is significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The single-well comprehensive column chart of the well A. DETAILED DESCRIPTION

[0030] The present application will be further described in conjunction with specific embodiments. However, it should not be understood that the scope of the above-mentioned subject matter of the present application is limited to the following embodiments, and any technology implemented based on the content of the present application falls within the scope of the present application.

[0031] In the description of the specific embodiments of the present application, the orientation or positional relationship terms such as "up", "down", "left", "right", "center", "inner", "outer", and the like appearing without special indication are expressed based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the product / equipment / device of the present application is usually used. These orientation or positional relationship terms are only for the convenience of describing the present application scheme or simplifying the description in the specific embodiments, for the convenience of the technical personnel to quickly understand the scheme, and are not intended to indicate or imply that a specific device / component / element must have a specific orientation or be constructed and operated in a specific positional relationship, and therefore cannot be understood as a limitation on the present application.

[0032] In addition, if the terms "horizontal", "vertical", "overhang", "parallel", and the like appear, it does not mean that the corresponding device / component / element must be absolutely horizontal or vertical or overhanging or parallel, but can be slightly inclined or deviated. For example, "horizontal" only means that its direction is relatively more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined. Alternatively, it can be simplified to understand that the corresponding device / component / element is set in the "horizontal", "vertical", "overhanging", "parallel" direction, and can have an error / deviation of ±10% with respect to the corresponding direction setting, more preferably an error / deviation of ±8% or less, more preferably an error / deviation of ±6% or less, more preferably an error / deviation of ±5% or less, and more preferably an error / deviation of ±4% or less. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its role in the scheme of the present application.

[0033] In addition, the terms "first", "second", "third", and the like appearing in the terms are only used to distinguish the description of the same or similar parts, and should not be understood as emphasizing or implying the relative importance of the specific parts.

[0034] In addition, in the description of the embodiments of the present application, "several" "a plurality of" "several" represents at least 2. It can be 2, 3, 4, 5, 6, 7, 8, 9, etc. Any case, it can even be more than 9 cases.

[0035] In addition, in the description of the technical solutions of the present application, unless otherwise specified / limited / limited, the terms "set", "install", "connect", "connect", "set", "lay", "arrange" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrally connected, such as welding, riveting, bolting, screwing, etc. The connection means commonly used in the art. Such connection can be mechanical connection, or electrical connection or communication connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be connected inside two elements.

[0036] Embodiment 1

[0037] The embodiment provides a test layer selection method based on gas logging, which is used for improving the success rate of layer selection of complex oil and gas reservoirs which have experienced multi-stage oil and gas migration and charging.

[0038] The test layer selection method based on gas logging provided by the embodiment comprises the following steps:

[0039] S1: Collect gas logging parameters and logging parameters, the gas logging parameters include well depth, lithology, total hydrocarbon content (TG), C1 (methane) content, C2 (ethane) content, and the logging parameters include acoustic value (AC), natural gamma value (GR), deep lateral resistivity value (RD), and shallow lateral resistivity value (RS);

[0040] According to the gas logging parameters, the C1 / C2 ratio is calculated;

[0041] Draw a single-well comprehensive column chart, which includes well depth, lithology, C1 / C2 change curve, acoustic curve, total hydrocarbon curve, natural gamma curve, deep lateral resistivity curve and shallow lateral resistivity curve; by integrating various parameters in the single-well comprehensive column chart, it is helpful for users to conduct comprehensive analysis of multiple parameters, for example, by using the logging interpretation method commonly used in industrial production to interpret the well section, and by cooperating the logging interpretation result with the test layer selection method based on gas logging provided by the embodiment, the accuracy and reliability of layer selection are improved.

[0042] S2: According to the total hydrocarbon curve change trend, lithology and acoustic curve, the hydrocarbon source rock baseline is selected, and mudstone or shale can be used as the hydrocarbon source rock;

[0043] Specifically, when the C1 / C2 ratio in the mudstone section is abnormally high in a sharp peak shape, it is usually caused by lithology or fracture development. The C1 / C2 ratio in a section with developed coal seams or carbonaceous shale is usually abnormally high due to the influence of carbon, and does not represent the true C1 / C2 ratio in the source rock series. If the acoustic curve shows a significant jump, it indicates that the mudstone section has developed fractures, and the C1 / C2 ratio is high due to the influence of the fractures, and also does not represent the true C1 / C2 ratio in the source rock series.

[0044] Therefore, the C1 / C2 ratio of the mudstone section with no significant jump in the acoustic curve and a stable change trend in the total hydrocarbon curve can be selected as the source rock baseline. Specifically, the acoustic curve has no significant jump, that is, the acoustic curve is in a sharp peak shape, and the peak value of the acoustic curve within a range of ±5 meters of the well depth is 2.5 times or less than the minimum value of the acoustic curve. Specifically, the total hydrocarbon curve has a stable change trend, that is, the ratio of the minimum value to the maximum value of the total hydrocarbon curve within a range of ±5 meters of the well depth is less than 3.

[0045] Further, since the C1 / C2 ratio in a section with developed coal seams or carbonaceous shale is usually abnormally high due to the influence of carbon, the mudstone section used to select the source rock baseline in the present embodiment should not contain carbon, and the mudstone section used to select the source rock baseline in the present embodiment should not contain coal seams.

[0046] Using this method for selecting the source rock baseline, the stability of the acoustic curve reflects the uniformity and continuity of the formation, and by selecting a mudstone section with no significant jump in the acoustic curve, the influence of interlayers, fractures or other geological anomalies can be excluded, and the representativeness and accuracy of the source rock baseline can be improved. The stable change trend of the total hydrocarbon curve means that the mudstone section has no obvious hydrocarbon gas anomaly. This helps to exclude the interference of possible fractures, micro-fractures or other permeation channels, and ensures that the baseline value truly reflects the original geochemical characteristics of the horizon. This refined method for selecting the source rock baseline greatly improves the accuracy and reliability of the entire analysis process.

[0047] S3: Compare the C1 / C2 ratio of the gas layer section with the source rock baseline value of the underlying mudstone section to determine the level of the gas layer section.

[0048] If the C1 / C2 ratio of the gas layer section shows an increasing trend from deep to shallow, and the C1 / C2 ratio of the gas layer section adjacent to the underlying mudstone section is higher than the source rock baseline value of the underlying mudstone section, it represents that the natural gas maturity of the set of gas layer sections is higher than that of the underlying adjacent mudstone, and is rich in natural gas generated from deeper source rocks, and has high gas abundance, so the gas layer section is a good gas layer.

[0049] If the C1 / C2 ratio of the gas layer section is close to the source rock baseline value of the underlying mudstone section, that is, if the C1 / C2 ratio of the gas layer section is 1-1.5 times the source rock baseline value of the underlying mudstone section, the gas maturity of the gas layer section is relatively consistent with the underlying source rock, and the natural gas mainly comes from the underlying source rock, and the gas layer section is a medium gas layer.

[0050] If the C1 / C2 ratio of the gas layer section shows a decreasing trend from deep to shallow, it means that the gas maturity of the gas layer section is lower than the underlying source rock, and the gas abundance is lower, and the gas layer section is a poor gas layer.

[0051] According to the level of the gas layer section, the good gas layer is selected first, the medium gas layer is selected second, and the poor gas layer is selected last for testing.

[0052] The test layer selection method of gas logging provided in the embodiment provides a basis for the judgment of the characteristics of the gas layer according to the gas logging parameters, combined with the full hydrocarbon display and logging curve parameters. The method provides a new idea and method for the judgment of the characteristics such as gas abundance of the gas layer, and provides geological support for improving the success rate of oil and gas drilling testing.

[0053] The test layer selection method based on gas logging provided in the embodiment comprehensively considers the gas logging parameters and logging parameters, and can help to distinguish the natural gas from the deeper high-mature source rock and the natural gas from the adjacent source rock by comparing the C1 / C2 ratio of the gas layer section with the baseline value of the underlying mudstone section, and assist in judging the gas abundance of the gas layer section interpreted by conventional logging or logging. The method provides an important basis for the exploration of complex oil and gas systems and an important clue for the study of oil and gas migration and charging history, and significantly improves the success rate of test layer selection. The method provides a new idea and method for the judgment of the characteristics such as gas abundance of the gas layer, and provides geological support for improving the success rate of oil and gas drilling testing.

[0054] Embodiment 2

[0055] As Figure 1 A single well comprehensive column chart of well A of a gas field in the Sichuan Basin is shown.

[0056] According to Figure 1 The rightmost logging display and conventional logging interpretation show that the well A develops multiple sets of gas layers in the vertical direction, and the gas layers in the 5380m-5420m well section are continuously distributed and have a large thickness, which is better than the 5520m-5640m well section. However, it is found by using the test layer selection method based on gas logging provided in embodiment 1 that:

[0057] The C1 / C2 ratio of the 5520m-5615m well section shows an increasing trend from deep to shallow, as shown by the dashed arrow in ① in the figure, and the C1 / C2 ratio of the well section is higher than the source rock baseline value of the underlying mudstone section. Figure 1The fourth black vertical line from the right to the left at the bottom indicates that the gas layer is a good gas layer.

[0058] The 5400m to 5430m well section, as shown by the dashed arrow at point ② in the figure, shows a decreasing C1 / C2 ratio from deep to shallow, indicating that the gas-bearing section is classified as a poor gas layer.

[0059] The 5380m–5400m well section is shown by the dashed arrow at point ③ in the figure. The C1 / C2 ratio is related to the baseline value of the underlying mudstone section's source rock. Figure 1 The top black vertical line of the fourth line from right to left is close to (the C1 / C2 ratio is 1 to 1.5 times the baseline value of the underlying mudstone section's source rock), indicating that the gas layer is classified as a medium-sized gas layer.

[0060] Therefore, when using the gas logging-based test layer selection method provided in Example 1, priority should be given to testing fractured gas layers in the 5520m–5640m depth range, where the lower gas layer is classified as a good gas layer. The gas layer range in the 5380m–5420m depth range, primarily consisting of poor and medium-quality gas layers, should be considered later. Subsequently, gas testing was conducted in the 5520m–5640m depth range, yielding a high-yield industrial gas flow of 526,000 cubic meters per day, further verifying that the gas logging-based test layer selection method provided in Example 1 can effectively improve the success rate of test layer selection.

[0061] Example 3

[0062] This embodiment provides a test layer selection device based on gas logging, including at least one processor and a memory communicatively connected to the at least one processor; the memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the test layer selection method based on gas logging provided in Embodiment 1.

[0063] Example 4

[0064] This embodiment provides a computer-readable medium storing instructions executable by a processor, which, when executed by the processor, cause the processor to perform the test layer selection method based on gas logging provided in Embodiment 1.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for testing selected intervals based on gas logging, characterized in that, The method comprises the following steps: S1: collecting gas logging parameters and logging parameters, the gas logging parameters comprising well depth, lithology, total hydrocarbon content, methane content C1, ethane content C2, and the logging parameters comprising acoustic wave value; According to the gas logging parameters, the C1 / C2 ratio is calculated; C1 / C2 variation curve, acoustic curve and total hydrocarbon curve are drawn; S2: selecting source rock baseline according to total hydrocarbon curve variation trend, lithology and acoustic curve; S3: comparing C1 / C2 ratio of gas layer section with source rock baseline value of underlying mudstone section: If C1 / C2 ratio of gas layer section shows an increasing trend from deep to shallow well depth, and C1 / C2 ratio of gas layer section is higher than source rock baseline value of underlying mudstone section, the gas layer section is a good gas layer; If C1 / C2 ratio of gas layer section is close to source rock baseline value of underlying mudstone section, the gas layer section is a moderate gas layer; If C1 / C2 ratio of gas layer section shows a decreasing trend from deep to shallow well depth, the gas layer section is a poor gas layer; Good gas layer is selected first, moderate gas layer second, and poor gas layer last for testing.

2. The method of testing and selecting zones based on gas logging according to claim 1, wherein, In S3, if C1 / C2 ratio of gas layer section is 1-1.5 times of source rock baseline value of underlying mudstone section, the gas layer section is a moderate gas layer.

3. The method of testing and selecting zones for drilling based on gas logging according to claim 1, wherein, In S2, C1 / C2 ratio of mudstone section with no significant acoustic wave jump, stable total hydrocarbon curve variation trend is selected as source rock baseline.

4. The method of testing and selecting zones based on gas logging according to claim 3, wherein, In S2, C1 / C2 ratio of mudstone section with sharp acoustic curve, acoustic curve peak value within ±5 meters of well depth being 2.5 times or less of acoustic curve minimum value, and ratio of total hydrocarbon curve minimum value to maximum value being less than 3 is selected as source rock baseline.

5. The method of testing and selecting zones for drilling based on gas logging according to claim 2, wherein, In S2, mudstone section selected as source rock baseline does not contain carbon and coal seam.

6. The method of testing and selecting zones for drilling based on gas logging according to claim 1, wherein, S1 further comprises drawing single well comprehensive columnar graph, the single well comprehensive columnar graph comprising well depth, lithology, C1 / C2 variation curve, acoustic curve and total hydrocarbon curve.

7. The method of testing and selecting zones for logging based on gas logging according to claim 6, wherein, S1 further comprises that logging parameters comprise natural gamma value, deep lateral resistivity value and shallow lateral resistivity value, and the single well comprehensive columnar graph further comprises natural gamma curve, deep lateral resistivity curve and shallow lateral resistivity curve.

8. A gas logging based test selection device, characterized in that, The method comprises at least one processor, and a memory connected with the at least one processor in communication; the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the method for selecting layer for testing based on gas logging according to any one of claims 1-7.

9. A computer readable medium having stored thereon instructions executable by a processor, the instructions comprising: The instructions, when executed by the processor, enable the processor to execute the method for selecting layer for testing based on gas logging according to any one of claims 1-7.

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