Method, device, storage medium and computer equipment for determining overburden porosity
By constructing a cover pressure porosity model, the problem of large porosity calculation error in the existing technology is solved, and accurate porosity calculation is achieved under cover pressure conditions, providing important data support for shale gas reservoir evaluation.
Patent Information
- Application Number
- CN202010848459.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2020-08-21
- Publication Date
- 2025-08-29
- Estimated Expiration
- 2040-08-21
AI Technical Summary
The prior art cannot accurately determine the porosity of the target reservoir, especially the porosity calculation errors under cover pressure conditions, which cannot meet the needs of shale gas exploration and development.
A cover porosity model is constructed, and the porosity of core samples under different overlay pressures is measured, a logarithmic relationship model between overlay porosity and overlay pressure is established. The pressure term coefficient and model constant are determined by using a linear fitting method to achieve accurate calculation of overlay porosity.
The rapid and accurate calculation of the cover porosity of the target reservoir under different pressures provides a data basis for shale gas reservoir evaluation and improves the accuracy and efficiency of porosity determination.
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Figure CN114077784B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of petroleum, geology and mining exploration and development, and in particular to a method, device, storage medium and computer equipment for determining overburden porosity. Background Art
[0002] In shale gas exploration and development, shale porosity is a crucial parameter for evaluating target reservoirs. Typically, core porosity, which reflects reservoir physical properties, is determined through experimental analysis at atmospheric pressure. In reality, shale is deeply buried, and factors such as formation pressure can cause porosity to differ from that determined through core analysis under conventional surface experimental conditions. Therefore, overburden pressure correction is necessary to accurately restore the true porosity characteristics of underground shale reservoirs.
[0003] A literature review revealed that existing studies on reservoir property pressure sensitivity consistently conclude that underground reservoir porosity is closely related to overburden pressure. Various researchers have investigated the porosity of rocks under dense overburden pressure. Some studies have found a trend in which porosity decreases with increasing overburden pressure, but further research is lacking, and no corresponding mathematical models have been established. Some studies have established mathematical models for target reservoir porosity, but these models offer poor accuracy in calculating target reservoirs, making them unusable in practice.
[0004] Therefore, a more accurate method for determining the porosity of the target reservoir is urgently needed. Summary of the Invention
[0005] The main purpose of the present invention is to provide a method, device, storage medium and computer equipment for determining overburden porosity, so as to accurately determine the overburden porosity of a target reservoir.
[0006] In a first aspect, the present application provides a method for determining overburden porosity, comprising the following steps: constructing an overburden porosity model of a target reservoir, wherein the overburden porosity model of the target reservoir is a logarithmic relationship model between the overburden porosity of the target reservoir and the overburden pressure; based on the overburden porosity model of the target reservoir, determining the overburden porosity of the target reservoir according to the overburden pressure and normal pressure porosity of the target reservoir.
[0007] In one embodiment, an overburden porosity model is constructed by the following steps: obtaining several core samples of the target reservoir, applying normal pressure and multiple different overburden pressures higher than normal pressure to each core sample, and measuring its normal pressure porosity at normal pressure and its overburden porosity at each different overburden pressure higher than normal pressure; establishing an initial overburden porosity model of the target reservoir, wherein the initial overburden porosity model includes a pressure term coefficient and a model constant to be determined; for each core sample, based on the initial overburden porosity model, according to its normal pressure porosity at normal pressure and its overburden porosity at each different overburden pressure higher than normal pressure, For overburden porosity, a curve fitting method is used to determine the overburden porosity model corresponding to the core sample, wherein the overburden porosity model corresponding to the core sample includes a pressure term coefficient and a model constant corresponding to the core sample; the pressure term coefficient to be determined in the overburden porosity initial model is determined based on the pressure term coefficient corresponding to each core sample, and the model constant in the overburden porosity initial model is determined based on the normal pressure porosity of each core sample and the model constant corresponding to each core sample; the overburden porosity initial model with the determined pressure term coefficient and model constant is used as the overburden porosity model of the target reservoir.
[0008] In one embodiment, the pressure term coefficient to be determined in the initial model of overburden porosity is determined based on the pressure term coefficient corresponding to each core sample, including: the pressure term coefficient to be determined in the initial model of overburden porosity is equal to the average of the pressure term coefficients corresponding to each core sample.
[0009] In one embodiment, the model constants in the initial model of overburden porosity are determined based on the normal-pressure porosity of each core sample and the model constants corresponding to each core sample, including: establishing a correspondence between the model constants in the initial model of overburden porosity and the normal-pressure porosity based on the normal-pressure porosity of each core sample and the model constants corresponding to each core sample using a linear fitting method; based on the correspondence, determining the model constants in the initial model of overburden porosity of the target reservoir based on the normal-pressure porosity of the target reservoir.
[0010] In one embodiment, the initial overburden porosity model is:
[0011] Φ P =-a ln(P)+b
[0012] Among them, Φ P represents the overburden porosity of the target reservoir under the overburden pressure P, P represents the overburden pressure of the target reservoir, a represents the pressure term coefficient to be determined, and b represents the model constant.
[0013] In one embodiment, the relationship between the model constants in the initial overburden porosity model and the normal pressure porosity is the following linear relationship:
[0014] b=cΦ0+d
[0015] Where b represents the model constant, c represents the slope, Φ0 represents the normal pressure porosity of the target reservoir, and d represents a constant.
[0016] In one embodiment, the number of core samples of the target reservoir obtained is at least 12, and for each core sample, at least 6 different overburden pressures higher than normal pressure are applied.
[0017] In a second aspect, the present application provides a device for determining overburden porosity, comprising: a model construction module for constructing an overburden porosity model of a target reservoir, wherein the overburden porosity model of the target reservoir is a logarithmic relationship model between the overburden porosity of the target reservoir and the overburden pressure; a porosity determination module for determining the overburden porosity of the target reservoir based on the overburden porosity model of the target reservoir, according to the overburden pressure and normal pressure porosity of the target reservoir.
[0018] In a third aspect, the present application provides a storage medium storing a computer program, characterized in that when the computer program is executed by a processor, the steps of the method for determining the overburden porosity as described above are implemented.
[0019] In a fourth aspect, the present application provides a computer device comprising a processor and a storage medium storing program code, wherein when the program code is executed by the processor, the steps of the method for determining the overburden porosity as described above are implemented.
[0020] The present invention provides a method for determining overburden porosity, which can quickly and accurately calculate the overburden porosity of target reservoirs at different pressures. This method provides a data basis for shale gas reservoir evaluation and is of great significance for evaluating shale reservoirs and shale oil and gas reserves. It can also be used to determine porosity under overburden conditions in shale gas exploration and development evaluation in southern my country. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The accompanying drawings, which constitute a part of the present application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:
[0022] Figure 1 is a flow chart of a method for determining overburden porosity according to an exemplary embodiment of the present application;
[0023] Figure 2 Flowchart of a method for constructing an overburden porosity model of a target reservoir according to an exemplary embodiment of the present application;
[0024] Figure 3 is a flow chart of a method for determining overburden porosity according to a specific embodiment of the present application;
[0025] Figure 4 This is a comparison chart of the measured porosity of a core sample under an overburden pressure of 2 MPa according to a specific embodiment of the present application and the overburden porosity calculated using the overburden porosity model;
[0026] Figure 5 This is a comparison chart of the measured porosity of a core sample under an overburden pressure of 41.6 MPa according to a specific embodiment of the present application and the overburden porosity calculated by the overburden porosity model. DETAILED DESCRIPTION
[0027] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.
[0028] Example 1
[0029] Figure 1 FIG. 1 is a flow chart of a method for determining overburden porosity according to an exemplary embodiment of the present application. Figure 1 As shown, this embodiment provides a method for determining overburden porosity, which may include the following steps:
[0030] S100: Constructing an overburden porosity model of a target reservoir, wherein the overburden porosity model of the target reservoir is a logarithmic relationship model between the overburden porosity of the target reservoir and the overburden pressure.
[0031] S200: Determine the overburden porosity of the target reservoir based on the overburden porosity model of the target reservoir and the overburden pressure and normal pressure porosity of the target reservoir.
[0032] The method for determining overburden porosity provided by the present invention can quickly and accurately calculate the overburden porosity of target reservoirs under different pressures, providing a data basis for shale gas reservoir evaluation, which is of great significance for evaluating shale reservoirs and shale oil and gas reserves.
[0033] Example 2
[0034] Figure 2 FIG. 1 is a flow chart of a method for constructing an overburden porosity model of a target reservoir according to an exemplary embodiment of the present application. Figure 2 As shown in the figure, the overburden porosity model can be constructed by the following steps:
[0035] S110: Obtain several core samples of the target reservoir, apply normal pressure and multiple different overburden pressures higher than normal pressure to each core sample, and measure the normal pressure porosity under normal pressure and the overburden porosity under different overburden pressures higher than normal pressure.
[0036] S120: Establishing an initial overburden porosity model of the target reservoir, wherein the initial overburden porosity model includes a pressure term coefficient and a model constant to be determined.
[0037] The initial overburden porosity model of the target reservoir can be:
[0038] Φ P =-a ln(P)+b
[0039] Among them, Φ P represents the overburden porosity of the target reservoir under the overburden pressure P, P represents the overburden pressure of the target reservoir, a represents the pressure term coefficient to be determined, and b represents the model constant.
[0040] S130: For each core sample, based on the initial overburden porosity model, according to its normal pressure porosity at normal pressure and the overburden porosity at different overburden pressures higher than normal pressure, the overburden porosity model corresponding to the core sample is determined using a curve fitting method, wherein the overburden porosity model corresponding to the core sample includes a pressure term coefficient and a model constant corresponding to the core sample.
[0041] The number of core samples of the target reservoir obtained is at least 12, and for each core sample, at least 6 different overburden pressures higher than normal pressure are applied.
[0042] As an example, when applying multiple different overburden pressures higher than normal pressure, multiple different overburden pressures with smaller differences between each other can be applied to the core sample in a lower overburden pressure range, and multiple different overburden pressure ranges with larger differences between each other can be applied to the core sample in a higher overburden pressure range.
[0043] S140: Determine the pressure term coefficient to be determined in the initial model of overburden porosity based on the pressure term coefficient corresponding to each core sample, and determine the model constant in the initial model of overburden porosity based on the normal pressure porosity of each core sample and the model constant corresponding to each core sample.
[0044] The step of determining the pressure term coefficient to be determined in the initial model of overburden porosity based on the pressure term coefficient corresponding to each core sample may include: the pressure term coefficient to be determined in the initial model of overburden porosity being equal to the average of the pressure term coefficients corresponding to each core sample.
[0045] Among them, determining the model constants in the initial model of overburden porosity based on the normal-pressure porosity of each core sample and the model constants corresponding to each core sample can include: establishing a corresponding relationship between the model constants in the initial model of overburden porosity and the normal-pressure porosity based on the normal-pressure porosity of each core sample and the model constants corresponding to each core sample using a linear fitting method; based on the corresponding relationship, determining the model constants in the initial model of overburden porosity of the target reservoir based on the normal-pressure porosity of the target reservoir.
[0046] The relationship between the model constants in the initial overburden porosity model and the normal pressure porosity can be expressed as the following linear relationship:
[0047] b=cΦ0+d
[0048] Where b represents the model constant, c represents the slope, Φ0 represents the porosity of the target reservoir at normal pressure, and d represents a constant.
[0049] S150: The initial overburden porosity model with the determined pressure term coefficient and model constant is used as the overburden porosity model of the target reservoir.
[0050] This embodiment constructs an overburden porosity model of the target reservoir by studying the relationship between the core physical properties of the target reservoir and the overburden pressure, and establishes a logarithmic relationship between the overburden porosity of the target reservoir and the overburden pressure. Compared with the existing technology, the overburden porosity model of the target reservoir of this embodiment can more accurately calculate the overburden porosity of the target reservoir through the overburden pressure of the target reservoir.
[0051] Example 3
[0052] Figure 3 Flowchart of a method for determining overburden porosity according to a specific embodiment of the present application.
[0053] The method for determining the overburden porosity provided in this embodiment may include the following steps:
[0054] The first step is to select several core samples from the Wufeng-Longmaxi Formation shale in the south, conduct atmospheric pressure tests on these core samples, and obtain experimental results, including the atmospheric pressure porosity of the core samples. In this example, 12 core samples are used as an example. The atmospheric pressure is 0.10133 MPa.
[0055] The second step is to conduct an overburden pressure test on the core samples that have undergone the atmospheric pressure test and obtain the test results, which include the overburden porosity of the core samples. In this example, overburden pressure tests are conducted on each core sample using six different overburden pressures, and the overburden porosity of each core sample under each different overburden pressure is obtained.
[0056] The experimental results obtained are shown in Table 1. In Table 1, TOC (Total Organic Carbon) represents total organic carbon, and Rb represents asphalt reflectivity.
[0057] Table 1
[0058]
[0059] The third step is to establish an initial overburden porosity model of the target reservoir, wherein the initial overburden porosity model includes a pressure term coefficient and a model constant to be determined.
[0060] The initial overburden porosity model of the target reservoir can be:
[0061] Φ P =-a ln(P)+b
[0062] Among them, Φ P represents the overburden porosity of the target reservoir under the overburden pressure P, P represents the overburden pressure of the target reservoir, a represents the pressure term coefficient to be determined, and b represents the model constant.
[0063] The fourth step is to determine the a and b values in the initial model of overburden porosity.
[0064] First, for each core sample, based on the established initial overburden porosity model, the overburden porosity model corresponding to that core sample was determined using a curve fitting method, based on the normal pressure porosity of each core sample at atmospheric pressure and the overburden porosity at six different overburden pressures above atmospheric pressure. The overburden porosity model corresponding to each core sample includes the corresponding pressure term coefficient and model constant (as shown in the two rightmost columns of Table 1, respectively, for A and B values).
[0065] In this example, the overburden porosity model corresponding to each core sample is obtained as follows:
[0066] Sample model No. 1: Φ P =-0.511ln(P)+4.3404, R2=0.8508;
[0067] Sample model No. 2: Φ P =-0.379ln(P)+3.5884, R2=0.9902;
[0068] Sample model No. 3: Φ P =-0.329ln(P)+3.3392, R 2 =0.9359;
[0069] Sample model No. 4: Φ P=-0.322ln(P)+3.5331, R 2 =0.9141;
[0070] Sample model No. 5: Φ P =-0.69ln(P)+4.4064, R 2 =0.9964;
[0071] Sample model No. 6: Φ P =-0.483ln(P)+6.6533, R 2 =0.9901;
[0072] Sample model No. 7: Φ P =-0.754ln(P)+7.7577, R 2 =0.9752;
[0073] Sample model No. 8: Φ P =-0.504ln(P)+5.3064,R 2 =0.9978;
[0074] Sample model No. 9: Φ P =-0.322ln(P)+6.5015, R 2 =0.9986;
[0075] Sample model No. 10: Φ P =-0.172ln(P)+6.7673, R 2 =0.7613;
[0076] Sample model No. 11: Φ P =-0.325ln(P)+6.6521,R 2 =0.9906;
[0077] Sample model No. 12: Φ P =-0.625ln(P)+5.9842, R 2 =0.9488.
[0078] Among them, R 2 Represents the correlation coefficient.
[0079] Next, the pressure term coefficient to be determined in the initial model of overburden porosity (i.e., the a value) is determined based on the pressure term coefficient corresponding to each core sample (i.e., the A value in Table 1), and the model constant (i.e., the b value) in the initial model of overburden porosity is determined based on the normal pressure porosity (Φ0) of each core sample and the model constant corresponding to each core sample (i.e., the B value in Table 1).
[0080] Among them, determining the pressure term coefficient to be determined in the initial model of overburden porosity (i.e., the a value) based on the pressure term coefficient corresponding to each core sample (i.e., the A value in Table 1) may include: the pressure term coefficient to be determined in the initial model of overburden porosity is equal to the average value of the pressure term coefficient corresponding to each core sample.
[0081] Specifically, the mean model of 12 samples: Φ P =-0.451ln(P)+5.4025, R 2 =0.9978, then a=0.451.
[0082] Among them, determining the model constants in the initial model of overburden porosity based on the normal-pressure porosity of each core sample and the model constants corresponding to each core sample can include: establishing a corresponding relationship between the model constants in the initial model of overburden porosity and the normal-pressure porosity based on the normal-pressure porosity of each core sample and the model constants corresponding to each core sample using a linear fitting method; based on the corresponding relationship, determining the model constants in the initial model of overburden porosity of the target reservoir based on the normal-pressure porosity of the target reservoir.
[0083] Linear fitting of the atmospheric porosity of each core sample and its corresponding model constant yields: b = 0.8157Φ0 + 0.1184, R 2 =0.8766.
[0084] Finally, the initial overburden porosity model with the determined pressure term coefficient and model constant is used as the overburden porosity model of the target reservoir. That is, the overburden porosity model of the target reservoir is:
[0085] Φ P =-0.451ln(P)+0.8157Φ0+0.1184
[0086] This model is a logarithmic relationship model between the overburden porosity and overburden pressure of the target reservoir.
[0087] When the overburden pressure and normal-pressure porosity of the target reservoir are measured, the overburden porosity of the target reservoir can be determined based on the overburden pressure and normal-pressure porosity of the target reservoir based on the constructed overburden porosity model of the target reservoir.
[0088] Figure 4 This is a comparison chart of the measured porosity of a core sample under an overburden pressure of 2 MPa according to a specific embodiment of the present application and the overburden porosity calculated by the overburden porosity model. Figure 5 This is a comparison chart of the measured porosity of a core sample under an overburden pressure of 41.6 MPa according to a specific embodiment of the present application and the overburden porosity calculated by the overburden porosity model.
[0089] pass Figure 4 and Figure 5 It can be seen that the porosity measured for the target reservoir is highly consistent with the overburden porosity obtained through the constructed overburden porosity model.
[0090] The present invention provides a method for determining overburden porosity, which can quickly and accurately calculate the overburden porosity of target reservoirs at different pressures. This method provides a data basis for shale gas reservoir evaluation and is of great significance for evaluating shale reservoirs and shale oil and gas reserves. It can also be used to determine porosity under overburden conditions in shale gas exploration and development evaluation in southern my country.
[0091] Example 4
[0092] This embodiment provides a device for determining overburden porosity, including: a model construction module for constructing an overburden porosity model of a target reservoir, wherein the overburden porosity model of the target reservoir is a logarithmic relationship model between the overburden porosity of the target reservoir and the overburden pressure; and a porosity determination module for determining the overburden porosity of the target reservoir based on the overburden porosity model of the target reservoir, the overburden pressure of the target reservoir, and the normal pressure porosity of the target reservoir.
[0093] In this embodiment, the device for determining overburden porosity may also include: a processor and a memory, wherein the processor is used to execute the following program modules stored in the memory: a model building module and a porosity determination module, to determine the overburden porosity of the target reservoir based on the overburden pressure and normal pressure porosity of the target reservoir.
[0094] Example 5
[0095] This embodiment provides a storage medium storing a computer program, wherein when the computer program is executed by a processor, the steps of the method for determining the overburden porosity described above are implemented:
[0096] Constructing an overburden porosity model of the target reservoir, wherein the overburden porosity model of the target reservoir is a logarithmic relationship model between the overburden porosity of the target reservoir and the overburden pressure;
[0097] Based on the overburden porosity model of the target reservoir, the overburden porosity of the target reservoir is determined according to the overburden pressure and normal pressure porosity of the target reservoir.
[0098] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods or computer program products. Therefore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.
[0099] The present invention is described with reference to flowcharts of methods and computer program products according to embodiments of the present invention. It should be understood that each process in the flowcharts and combinations of processes in the flowcharts can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts. Figure 1 A device that specifies functions in a process or multiple processes.
[0100] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A function specified in a process or multiple processes.
[0101] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 The steps of a specified function in a process or multiple processes.
[0102] Storage media include permanent and non-permanent, removable and non-removable media, and can be implemented by any method or technology to store information. Information can be computer-readable instructions, data structures, program modules, or other data.
[0103] Examples of storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that can be accessed by a computing device.
[0104] Example 6
[0105] This embodiment provides a computer device, including a processor and a storage medium storing program code. When the program code is executed by the processor, the steps of the method for determining the overburden porosity described above are implemented:
[0106] Constructing an overburden porosity model of the target reservoir, wherein the overburden porosity model of the target reservoir is a logarithmic relationship model between the overburden porosity of the target reservoir and the overburden pressure;
[0107] Based on the overburden porosity model of the target reservoir, the overburden porosity of the target reservoir is determined according to the overburden pressure and normal pressure porosity of the target reservoir.
[0108] In one example, a computer device may include one or more processors (CPUs), input / output interfaces, network interfaces, and memory.
[0109] Memory may include non-permanent storage in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash memory (FLASH RAM). Memory is an example of a computer-readable medium.
[0110] 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 application. When the terms "include" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or their combinations.
[0111] It should be noted that the terms "first," "second," and the like in the specification, claims, and drawings of this application are used to distinguish similar objects, and are not used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, such that the embodiments of the application described herein can, for example, be implemented in an order other than that illustrated or described herein.
[0112] It should be understood that the exemplary embodiments described in this specification may be implemented in a variety of different forms and should not be construed as being limited to the embodiments described herein. These embodiments are provided to make the disclosure of this application thorough and complete and to fully convey the concepts of these exemplary embodiments to those skilled in the art, and should not be construed as limiting the present invention.
Claims
1. A method for determining overburden porosity, characterized in that: The following steps are involved: Constructing an overburden porosity model of the target reservoir, wherein the overburden porosity model of the target reservoir is a logarithmic relationship model between the overburden porosity of the target reservoir and the overburden pressure; Based on the overburden porosity model of the target reservoir, the overburden porosity of the target reservoir is determined according to the overburden pressure and normal pressure porosity of the target reservoir; The overburden porosity model is constructed by the following steps: Obtain several core samples from the target reservoir, apply normal pressure and multiple different overburden pressures higher than normal pressure to each core sample, and measure the normal pressure porosity at normal pressure and the overburden porosity at different overburden pressures higher than normal pressure; Establishing an initial overburden porosity model of the target reservoir, wherein the initial overburden porosity model includes a pressure term coefficient and a model constant to be determined; For each core sample, based on the initial overburden porosity model, according to its normal pressure porosity at normal pressure and the overburden porosity at various overburden pressures higher than normal pressure, a curve fitting method is used to determine the overburden porosity model corresponding to the core sample, wherein the overburden porosity model corresponding to the core sample includes a pressure term coefficient and a model constant corresponding to the core sample; Determining the pressure term coefficient to be determined in the initial model of overburden porosity based on the pressure term coefficient corresponding to each core sample, and determining the model constant in the initial model of overburden porosity based on the normal pressure porosity of each core sample and the model constant corresponding to each core sample; The initial overburden porosity model with determined pressure term coefficients and model constants is used as the overburden porosity model of the target reservoir; The model constants in the initial overburden porosity model are determined based on the normal pressure porosity of each core sample and the model constants corresponding to each core sample, including: According to the normal pressure porosity of each core sample and the model constant corresponding to each core sample, the corresponding relationship between the model constant in the initial overburden porosity model and the normal pressure porosity is established by using the linear fitting method; Based on the corresponding relationship, the model constants in the initial overburden porosity model of the target reservoir are determined according to the normal pressure porosity of the target reservoir.
2. The method for determining overburden porosity according to claim 1, characterized in that: The pressure term coefficient to be determined in the initial model of overburden porosity is determined based on the pressure term coefficient corresponding to each core sample, including: The pressure term coefficient to be determined in the initial overburden porosity model is equal to the mean value of the pressure term coefficient corresponding to each core sample.
3. The method for determining overburden porosity according to claim 1, characterized in that: The initial model of overburden porosity is: Φ P =-aln(P)+b Among them, Φ P represents the overburden porosity of the target reservoir under the overburden pressure P, P represents the overburden pressure of the target reservoir, a represents the pressure term coefficient to be determined, and b represents the model constant.
4. The method for determining overburden porosity according to claim 3, characterized in that: The relationship between the model constant in the initial overburden porosity model and the normal pressure porosity is the following linear relationship: b=cΦ0+d Where b represents the model constant, c represents the slope, Φ0 represents the normal pressure porosity of the target reservoir, and d represents a constant.
5. The method for determining overburden porosity according to claim 1, characterized in that: The number of core samples of the target reservoir obtained is at least 12, and for each core sample, at least 6 different overburden pressures higher than normal pressure are applied.
6. A device for determining overburden porosity, characterized in that: include: A model building module is used to build an overburden porosity model of the target reservoir, wherein the overburden porosity model of the target reservoir is a logarithmic relationship model between the overburden porosity of the target reservoir and the overburden pressure; A porosity determination module is used to determine the overburden porosity of the target reservoir based on the overburden porosity model of the target reservoir and the overburden pressure and normal pressure porosity of the target reservoir; The model building module is further configured to obtain a plurality of core samples of the target reservoir, apply normal pressure and multiple different overburden pressures higher than normal pressure to each core sample, and measure the normal pressure porosity at normal pressure and the overburden porosity at each different overburden pressure higher than normal pressure; Establishing an initial overburden porosity model of the target reservoir, wherein the initial overburden porosity model includes a pressure term coefficient and a model constant to be determined; For each core sample, based on the initial overburden porosity model, according to its normal pressure porosity at normal pressure and the overburden porosity at various overburden pressures higher than normal pressure, a curve fitting method is used to determine the overburden porosity model corresponding to the core sample, wherein the overburden porosity model corresponding to the core sample includes a pressure term coefficient and a model constant corresponding to the core sample; Determining the pressure term coefficient to be determined in the initial model of overburden porosity based on the pressure term coefficient corresponding to each core sample, and determining the model constant in the initial model of overburden porosity based on the normal pressure porosity of each core sample and the model constant corresponding to each core sample; The initial overburden porosity model with determined pressure term coefficients and model constants is used as the overburden porosity model of the target reservoir; The model building module is further used to determine the model constants in the initial overburden porosity model according to the normal pressure porosity of each core sample and the model constants corresponding to each core sample, including: According to the normal pressure porosity of each core sample and the model constant corresponding to each core sample, the corresponding relationship between the model constant in the initial overburden porosity model and the normal pressure porosity is established by using the linear fitting method; Based on the corresponding relationship, the model constants in the initial overburden porosity model of the target reservoir are determined according to the normal pressure porosity of the target reservoir.
7. A storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method for determining overburden porosity according to any one of claims 1 to 6 are implemented.
8. A computer device comprising a processor and a storage medium storing program code, wherein when the program code is executed by the processor, the steps of the method for determining overburden porosity according to any one of claims 1 to 6 are implemented.