CN106501146B - Method and device for determining physical upper limit of tight oil reservoir - Google Patents

Abstract

The embodiment of the present application provides a method and device for determining the upper limit of physical properties of tight oil reservoirs. The method includes: performing fine reservoir description on the target low-permeability reservoir, obtaining a fine geological model of the target low-permeability reservoir; according to the fine geological model, determining the target low-permeability reservoir that meets the preset conditions The target layer section; obtain the air permeability and starting pressure gradient data of the core sample in the target layer section, and generate the relationship curve between the air permeability and the starting pressure gradient; determine the air permeability corresponding to the abrupt point in the relationship curve , the abrupt point is the point with the largest curvature in the relationship curve. The embodiment of the present application can quantitatively determine the upper limit of physical properties of tight oil reservoirs, so as to guide the scientific and reasonable selection of development methods at the operation site.

Description

A method and device for determining the upper limit of physical properties of tight oil reservoirs

technical field

This application relates to the field of exploration and development of unconventional oil and gas reservoirs, in particular to a method and device for determining the upper limit of physical properties of tight oil reservoirs.

Background technique

Throughout the world, in the third major energy transformation trend from traditional oil and gas to new energy, unconventional oil and gas resources will undoubtedly become the most realistic resource type in this transformation. Tight oil is another hot spot in global unconventional oil and gas exploration and development after shale gas, and is called "black gold" by the oil industry. Although tight oil is a very realistic resource to replace oil, because the exploration and development of tight oil and related research are still in the preliminary stage, the overall degree of exploration and geological understanding is low, and there are still many problems that need to be discussed and solved in the exploration and development.

Due to the characteristics of tight oil reservoirs, in order to obtain effective mass production, effective production measures specific to their characteristics must be adopted. At present, there is a consensus in the academic circles that only in low-permeability reservoirs below a certain upper limit of physical properties can large-area and low-abundance tight oil and gas accumulations be formed, but the specific limit has not yet been determined. standard. Although scholars at home and abroad have proposed various methods on how to determine the boundary of physical properties, these methods can be divided into three categories, one is based on exploration and development experience, and this method is greatly disturbed by human factors; The operation of this method is complex based on statistics of typical tight oil reservoir data; another method is to determine the permeability indirectly, first determine the oiliness, then determine the porosity, and finally determine the permeability. The ultimate goal of reservoir research is development, but unfortunately none of the above methods can directly and simply establish the connection between the upper limit of physical properties of tight reservoirs and effective development.

Contents of the invention

The purpose of the embodiments of the present application is to provide a method and device for determining the upper limit of physical properties of tight oil reservoirs, which can directly quantitatively determine the upper limit of physical properties of tight oil reservoirs from the perspective of effective development, so as to guide the scientific and reasonable selection of development methods at the operation site.

In order to achieve the above purpose, the embodiment of the present application provides a method for determining the upper limit of physical properties of tight oil reservoirs, the method comprising:

Carry out fine reservoir description for the target low-permeability reservoir, and obtain the fine geological model of the target low-permeability reservoir;

According to the fine geological model, determine the target section in the target low-permeability reservoir that meets the preset conditions;

Obtain the data of the air permeability and the threshold pressure gradient of the core sample in the target interval, and generate a relationship curve between the air permeability and the threshold pressure gradient;

Determine the air permeability corresponding to the abrupt point in the relationship curve, where the abrupt point is the point with the largest curvature in the relationship curve.

In order to achieve the above purpose, the embodiment of the present application also provides a device for determining the upper limit of physical properties of tight oil reservoirs, the device includes:

A description module, configured to perform fine reservoir description on the target low-permeability reservoir, and obtain a fine geological model of the target low-permeability reservoir;

The reservoir description module is used for performing fine reservoir description on the target low-permeability reservoir, and obtaining the fine geological model of the target low-permeability reservoir;

A target layer determination module, configured to determine a target interval in the target low-permeability reservoir that meets preset conditions according to the fine geological model;

An acquisition and generation module, configured to acquire the data of the air permeability and the threshold pressure gradient of the core sample in the target interval, and generate a relationship curve between the air permeability and the threshold pressure gradient;

The sudden change point determination module is used to determine the air permeability corresponding to the sudden change point in the relationship curve, and the sudden change point is the point with the largest curvature in the relationship curve.

From the technical solutions provided by the above embodiments, it can be seen that this embodiment generates the relationship curve between the air permeability and the threshold pressure gradient of the target low-permeability reservoir through the data of the core samples. The point with the largest curvature in the air permeability and threshold pressure gradient curve of the target low-permeability reservoir is the point where the threshold pressure gradient changes abruptly. Combined with the fact that only in low-permeability reservoirs below a certain upper limit of physical properties can large-area and low-abundance tight oil and gas accumulations be formed, and that tight oil and gas reservoirs can only produce economic output under relatively large displacement pressures, That is to say, because of the large threshold pressure gradient, it can be determined that the air permeability at the sudden change point of the threshold pressure gradient should correspond to the upper limit of physical properties of tight oil reservoirs. Air permeability is closely related to the effective development of oil and gas. Choosing air permeability as the upper limit of physical properties is beneficial to scientific and reasonable guidance for later development. In the examples of this application, the air permeability is directly obtained without indirect acquisition by other means, and the operation is simple.

Description of drawings

The drawings described here are used to provide further understanding of the embodiments of the present application, constitute a part of the embodiments of the present application, and do not limit the embodiments of the present application. In the attached picture:

Fig. 1 is a schematic flow chart of a method for determining the upper limit of physical properties of tight oil reservoirs according to an embodiment of the present application;

Figure 2 is a schematic diagram of the relationship between air permeability and starting pressure gradient in the embodiment of the present application;

Fig. 3 is a schematic flowchart of another method for determining the upper limit of physical properties of tight oil reservoirs according to an embodiment of the present application;

Fig. 4 is a schematic diagram of a device for determining an upper limit of physical properties of a tight oil reservoir according to an embodiment of the present application.

Detailed ways

In order to make the purpose, technical solutions, and advantages of the embodiments of the present application clearer, the embodiments of the present application will be further described in detail below in conjunction with the embodiments and the accompanying drawings. Here, the schematic embodiments and descriptions of the embodiments of the present application are used to explain the embodiments of the present application, but are not intended to limit the embodiments of the present application.

The specific implementation manners of the embodiments of the present application will be further described in detail below in conjunction with the accompanying drawings.

Fig. 1 is a schematic flowchart of a method for determining the upper limit of physical properties of tight oil reservoirs according to an embodiment of the present application. As shown in Fig. 1, a method for determining the upper limit of physical properties of tight oil reservoirs may include:

S101. Perform fine reservoir description on the target low-permeability reservoir, and obtain a fine geological model of the target low-permeability reservoir.

The low-permeability reservoir generally refers to a reservoir with a reservoir permeability ≤ 50×10 ^-3 μm ² , which has the characteristics of low permeability, low abundance and low productivity of a single well.

The fine reservoir description refers to the process of fine geological feature research and remaining oil distribution description after the oilfield is put into development, with the deepening of the exploitation degree and the increase of dynamic and static data, and the process of continuously improving the geological model for reservoir prediction . The fine geological model may be a data body for geological description of the target oil reservoir.

The detailed reservoir description for the target low-permeability reservoir may include the following steps. Wherein, the target low-permeability reservoir may be a low-permeability reservoir in the area to be studied.

(1) Firstly, obtain the geological, seismic, well logging, oil test and production data of the target low-permeability reservoir.

(2) Combining the geological, seismic, well logging and oil testing and production testing data to carry out fine reservoir description.

S102. According to the refined geological model, determine target intervals in the target low-permeability reservoir that meet preset conditions.

The overall geological characteristics of the target low-permeability reservoir and the detailed geological characteristics of each target interval will be reflected in the refined geological model obtained from the reservoir description. Wherein, the geological feature does not only refer to a specific feature, but a collection of many features. In an embodiment of the present application, the geological characteristics may include: formation, structure, lithology, sedimentation, heterogeneity, reservoir physical properties, fluid physical properties and other characteristics of the reservoir. The satisfying of the preset condition may be that the detailed geological feature data of the target interval is the closest to the overall geological feature of the overall target low-permeability reservoir, that is, the target interval is the most representative target interval in the target oil reservoir.

In one embodiment of the present application, the determination of the target interval in the target low-permeability reservoir that satisfies preset conditions may include the following steps.

First, based on the reservoir analysis of the target low-permeability reservoir, a fine geological model data body is obtained, and the data in the data body can reflect the overall geological characteristics of the target reservoir.

Then, according to the detailed geological characteristics of the specific target interval in the fine geological model, the position of the target interval closest to the overall characteristic value of the target reservoir is determined.

For example, in a specific embodiment of the present application, if the target interval that is closest to the characteristic value reflected by the fine geological model is 1500-1800m, then it is considered that the target interval of 1500-1800m is the target interval in the target oil reservoir that meets the requirements. The target interval of setting conditions, that is, the most representative target interval. Here, selecting the position of the target interval that is closest to the various characteristic values of the overall geological characteristics of the target reservoir can ensure that the subsequent experimental data can reflect the overall properties of the target low-permeability reservoir.

S103. Obtain air permeability and threshold pressure gradient data of the core sample in the target interval, and generate a relationship curve between air permeability and threshold pressure gradient.

In one embodiment of the present application, the acquisition of the air permeability and threshold pressure gradient data of the core samples in the target interval specifically includes the following steps.

(1) Acquiring a preset number of core samples in the target interval.

The process of obtaining a core sample refers to obtaining a core sample by taking a core.

(2) Obtain the data of air permeability and threshold pressure gradient obtained from the core displacement experiment of each of the core samples.

The core samples are subjected to a core displacement experiment, and the data of air permeability and threshold pressure gradient of each core sample are obtained.

A set of starting pressure gradient and air permeability data corresponding to each core sample is measured by the core water flooding experiment, and the starting pressure gradient and air permeability of each core sample are plotted in a relationship chart, and the air can be obtained. Experimental results for the relationship between permeability and threshold pressure gradient.

S104. Determine the air permeability corresponding to a sudden change point in the relationship curve, where the sudden change point is a point with the largest curvature in the relationship curve.

The air permeability corresponding to the abrupt change point may be the upper limit of physical properties of the tight oil reservoir in the study area where the target low-permeability oil reservoir is located. Although scholars at home and abroad do not have a unified opinion on the upper limit of physical properties of tight oil reservoirs, there is a consensus that everyone agrees on. That is, tight oil reservoirs require a larger start-up pressure gradient than ordinary low-permeability oil reservoirs. On the other hand, there is also a consensus that there is a certain functional relationship between the starting pressure gradient and the air permeability, and the air permeability is a physical quantity related to production and development practices. Therefore, the air permeability corresponding to the point where the threshold pressure gradient increases sharply in the graph of the relationship between threshold pressure gradient and air permeability can be used as the upper limit of physical properties of tight oil reservoirs.

From the embodiment shown in FIG. 1 , it can be seen that the relationship between the start pressure and the air permeability is generated through the core samples of the low-permeability reservoir to be studied, and the relationship between the two is obtained. Then, according to the principle that tight oil reservoirs require a larger start-up pressure gradient than ordinary low-permeability oil reservoirs, the air permeability corresponding to the point where the pressure increases sharply in the relationship chart is selected as the upper limit of physical properties of tight oil reservoirs, Therefore, the upper limit of physical properties of tight oil reservoirs is finally determined, which can provide reference for subsequent production and development.

In an embodiment of the present application, S104 is specifically implemented. First, according to the threshold pressure gradient and air permeability data obtained from the experiment, the specific functional relationship between the threshold pressure gradient and air permeability is obtained. Then calculate the position of the maximum curvature point in the curve according to the specific functional relationship, so as to obtain the air permeability of the sudden change point, and use this value as the upper limit of the physical properties of tight oil reservoirs.

In an embodiment of the present application, the starting pressure gradient and the air permeability satisfy a power function relationship. According to the power function expression obtained by fitting, the point with the largest curvature in the curve is calculated, so as to obtain the value of air permeability corresponding to this point.

According to the threshold pressure gradient and air permeability satisfying a certain relationship, and the threshold pressure gradient value of the tight oil reservoir is relatively large, in this embodiment, the point where the threshold pressure gradient value changes abruptly in the threshold pressure gradient and air permeability curve, that is, the point with the largest curvature The air permeability corresponding to the point is used as the upper limit of physical properties of tight oil reservoirs. And the air permeability is a quantity related to production practice, and choosing the air permeability as the upper limit of physical properties can provide a reference for subsequent development.

In an embodiment of the present application, when coring is performed on target intervals that meet preset conditions, the number of cores to be taken is not less than 10. In this embodiment, the number of cores taken is not less than 10 to ensure the accuracy when drawing the graph of the relationship between the air permeability and the start-up pressure gradient. If the amount of data is too small, the error will be relatively large during fitting, which will lead to a decrease in the accuracy of the final upper limit of air permeability.

In a specific embodiment of the present application, the target low-permeability reservoir is the Triassic Yanchang Formation reservoir in Changqing Oilfield. This reservoir is an important low-permeability reservoir exploration and development unit in the Ordos Basin. The tight oil in the Yanchang Formation in the Ordos Basin is mainly developed in the semi-deep lacustrine-deep lacustrine facies area, and the tight sandstone of the 7th member of the Yanchang Formation and the 6th member of the Yanchang Formation in the middle of the lake basin are the most typical. Based on the above knowledge, the Yanchang Formation reservoir can omit the two steps of reservoir description and determination of representative target intervals. By taking cores from the target intervals and carrying out core displacement experiments, 15 sets of air permeability and threshold pressure gradient data were obtained. Using Excel software, the relationship curve between air permeability and threshold pressure gradient of the Yanchang Formation reservoir in the Ordos Basin is drawn, as shown in Fig. 2. After fitting, the fitting expression of the curve is:

y= ^0.22x-1.212 (1)

In the formula, x represents the air permeability, and y represents the starting pressure gradient.

The curvature formula is:

Among them, K represents the curvature.

According to the above curvature formula, the curvature formula of the fitting expression of air permeability and threshold pressure gradient can be obtained as:

Let f(x)=k, if the maximum value of K is required, the root of f'(x)=0 needs to be obtained.

Let f'(x)=0, that is:

This gives X = 0.551268.

Therefore, when the air permeability is 0.551268mD, the curvature of the air permeability-threshold pressure gradient curve is the largest, and the upper limit of physical properties of Yanchang Formation tight oil reservoirs in the Ordos Basin can be determined as the air permeability of 0.551268mD.

In the above examples, the relationship curve between air permeability and threshold pressure gradient is obtained by carrying out displacement experiments on core samples of typical target intervals in the Yanchang Formation in the Ordos Basin. Combined with the principle that tight oil reservoirs require a larger start-up pressure gradient than general low-permeability oil reservoirs, the air permeability corresponding to the point where the pressure increases sharply in the relationship chart is selected as the upper limit of physical properties of tight oil reservoirs. Therefore, the upper limit of physical properties of tight oil reservoirs is finally determined, which can provide reference for subsequent production and development.

As shown in FIG. 3 , another method for determining the upper limit of physical properties of tight oil reservoirs is provided in an embodiment of the present application, and the method may include the following steps.

S301. Perform fine reservoir description on the target low-permeability reservoir, and obtain a fine geological model of the target low-permeability reservoir.

S302. Correct the fine geological model to obtain a corrected fine geological model.

On the basis of the fine geological model, using fine reservoir numerical simulation means, fully inspecting the dynamic and static data to carry out reservoir simulation research on the fine geological model to repeatedly correct and improve, so that the corrected fine Geological models represent the actual reservoir as closely as possible. Among them, the static data can be various geological maps, rock and fluid physical property data, seismic data, well logging data, core and outcrop data, etc.; the dynamic data can be well test, oil test, production test data, injection-production Well monthly/daily production data, well history data, etc.

S303. According to the corrected fine geological model, determine the target interval in the target low-permeability reservoir that meets the preset condition.

S304. Obtain air permeability and threshold pressure gradient data of the core sample in the target interval, and generate a relationship curve between air permeability and threshold pressure gradient.

S305. Determine the air permeability corresponding to the abrupt point in the relationship curve, where the abrupt point is the point with the largest curvature in the relationship curve.

In the above embodiments, when determining the target layer of the target reservoir, the obtained fine geological model is corrected, so that the revised fine geological model can represent the actual reservoir as much as possible, so as to ensure that the subsequent The samples determined by the model can more truly reflect the actual situation of the reservoir and increase the accuracy of the results.

The embodiments of the present application also provide a device for determining the upper limit of physical properties of tight oil reservoirs, as described in the following embodiments. Since the problem-solving principle of the device is similar to a method for determining the upper limit of physical properties of tight oil reservoirs, the implementation of the device can refer to the implementation of a method for determining the upper limit of physical properties of tight oil reservoirs, and the repetition will not be repeated.

Referring to Fig. 4, a device for determining the upper limit of physical properties of tight oil reservoirs provided by the embodiment of the present application may include:

The reservoir description module 401 is configured to perform fine reservoir description on the target low-permeability reservoir, and obtain a fine geological model of the target low-permeability reservoir.

The low-permeability reservoir generally refers to a reservoir with a reservoir permeability ≤ 50×10 ^-3 μm ² , which has the characteristics of low permeability, low abundance and low productivity of a single well.

The fine reservoir description refers to the process of fine geological feature research and remaining oil distribution description after the oilfield is put into development, with the deepening of the exploitation degree and the increase of dynamic and static data, and the process of continuously improving the geological model for reservoir prediction . The fine geological model may be a data body for geological description of the target oil reservoir.

The detailed reservoir description for the target low-permeability reservoir may include the following steps. Wherein, the target low-permeability reservoir may be a low-permeability reservoir in the area to be studied.

(1) Firstly, obtain the geological, seismic, well logging, oil test and production data of the target low-permeability reservoir.

(2) Combining the geological, seismic, well logging and oil testing and production testing data to carry out fine reservoir description.

The target layer determination module 402 is configured to determine the target interval in the target low-permeability reservoir that meets the preset conditions according to the fine geological model.

The overall geological characteristics of the target low-permeability reservoir and the detailed geological characteristics of each target interval will be reflected in the refined geological model obtained from the reservoir description. Wherein, the feature does not only refer to a specific feature, but a collection of many features. In an embodiment of the present application, the characteristics may include: formation, structure, lithology, deposition, heterogeneity, reservoir physical properties, fluid physical properties and other characteristics of the reservoir. The satisfaction of the preset condition may be that the detailed geological feature data of the target interval is the closest to the overall geological feature of the overall target low-permeability reservoir.

In one embodiment of the present application, the determination of the target interval in the target low-permeability reservoir that satisfies preset conditions may include the following steps.

First, based on the reservoir analysis of the target low-permeability reservoir, a fine geological model data body is obtained, and the data in the data body can reflect the overall geological characteristics of the target reservoir.

Then, according to the detailed geological characteristics of the specific target interval in the fine geological model, the position of the target interval closest to the overall characteristic value of the target reservoir is determined.

The acquiring and generating module 403 is configured to acquire the data of the air permeability and the threshold pressure gradient of the core sample in the target interval, and generate a relationship curve between the air permeability and the threshold pressure gradient.

In one embodiment of the present application, the acquiring and generating module specifically includes the following submodules.

A sample acquisition module, configured to acquire a preset number of core samples in the target interval.

The process of obtaining a core sample refers to obtaining a core sample by taking a core.

The data acquisition module is used to acquire the data of air permeability and threshold pressure gradient obtained from the core displacement experiment of each of the core samples.

The core samples are subjected to a core displacement experiment, and the data of air permeability and threshold pressure gradient of each core sample are obtained.

The abrupt point determination module 404 is configured to determine the air permeability corresponding to the abrupt point in the relationship curve, where the abrupt point is the point with the largest curvature in the relationship curve.

In the above-mentioned embodiment, a graph of the relationship between the threshold pressure gradient and the air permeability is generated through the sample of the low-permeability reservoir to be studied, and the relationship between the two is obtained. Then, according to the principle that tight oil reservoirs require a larger start-up pressure gradient than general low-permeability oil reservoirs, the air permeability corresponding to the point where the start-up pressure gradient increases sharply in the relationship chart is selected as the physical property of tight oil reservoirs The upper limit of physical properties of tight oil reservoirs is finally determined, which can provide a reference for subsequent production and development.

In one embodiment of the present application, the mutation point determination module specifically includes the following submodules:

A fitting module, configured to fit the relational curve to obtain a fitting expression;

A determining module, configured to determine the air permeability at the point of maximum curvature in the relational curve according to the fitting expression.

The air permeability value at the point of maximum curvature is the upper limit of physical properties of tight oil reservoirs.

In an embodiment of the present application, the starting pressure gradient and the air permeability satisfy a power function relationship. According to the power function expression obtained by fitting, the point with the largest curvature in the curve is calculated, so as to obtain the value of air permeability corresponding to this point.

According to the threshold pressure gradient and air permeability satisfying a certain relationship, and the threshold pressure gradient value of the tight oil reservoir is relatively large, in this embodiment, the point where the threshold pressure gradient value changes abruptly in the threshold pressure gradient and air permeability curve, that is, the point with the largest curvature The air permeability corresponding to the point is used as the upper limit of physical properties of tight oil reservoirs. And the air permeability is a quantity related to production practice, and choosing the air permeability as the upper limit of physical properties can provide a reference for subsequent development.

In an embodiment of the present application, when performing coring, the number of corings to be taken is not less than 10. In this embodiment, the number of cores taken is not less than 10 to ensure the accuracy when drawing the graph of the relationship between the air permeability and the start-up pressure gradient. If the amount of data is too small, the error will be relatively large during fitting, which will lead to a decrease in the accuracy of the final upper limit of air permeability.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above descriptions are only specific embodiments of the embodiments of the present application, and are not intended to limit this application. Within the protection scope of the application, any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the application shall be included in the protection scope of the application.

Claims (12)

1. A method for determining the upper limit of the physical property of a tight oil reservoir is characterized by comprising the following steps:

performing fine reservoir description on a target low-permeability reservoir to obtain a fine geological model of the target low-permeability reservoir;

determining a target interval meeting preset conditions in the target low-permeability reservoir according to the fine geological model; the meeting of the preset conditions comprises: the detail geological feature data of the target interval is closest to the overall geological feature of the overall target low-permeability reservoir;

Acquiring data of the air permeability and the starting pressure gradient of the core sample in the target interval, and generating a relation curve of the air permeability and the starting pressure gradient;

Determining the air permeability corresponding to a mutation point in the relation curve, wherein the mutation point is the point with the maximum curvature in the relation curve; and the air permeability corresponding to the mutation point is the physical upper limit of the compact oil reservoir in the research area of the target low-permeability oil reservoir.

2. The method of claim 1, wherein the air permeability and the actuation pressure gradient satisfy a power function relationship.

3. the method of claim 2, wherein the determining the air permeability corresponding to the discontinuity in the relationship curve comprises:

Fitting the relation curve to obtain a fitting expression;

And determining the air permeability at the position with the maximum curvature in the relation curve according to the fitting expression.

4. The method according to claim 1, wherein the obtaining of the air permeability and the startup pressure gradient data of the core sample in the interval of interest specifically comprises:

Obtaining a preset number of core samples in the target interval;

and acquiring data of air permeability and starting pressure gradient obtained by the core displacement experiment of each core sample.

5. The method of claim 4, wherein the predetermined number is not less than 10.

6. The method of claim 1, further comprising, prior to said determining, from the refined geological model, a target interval of interest in the target low-permeability reservoir that meets a preset condition:

correcting the fine geological model to obtain a corrected fine geological model;

correspondingly, determining a target interval meeting preset conditions in the target low-permeability reservoir according to the fine geological model, specifically:

And determining a target interval meeting preset conditions in the target low-permeability reservoir according to the corrected fine geological model.

7. A tight reservoir physical upper limit determining apparatus, comprising:

The oil reservoir description module is used for carrying out fine oil reservoir description on the target low-permeability oil reservoir and obtaining a fine geological model of the target low-permeability oil reservoir;

The target interval determining module is used for determining a target interval meeting preset conditions in the target low-permeability reservoir according to the fine geological model; the meeting of the preset conditions comprises: the detail geological feature data of the target interval is closest to the overall geological feature of the overall target low-permeability reservoir;

The acquisition and generation module is used for acquiring data of the air permeability and the starting pressure gradient of the core sample in the target interval and generating a relation curve of the air permeability and the starting pressure gradient;

The abrupt point determining module is used for determining the air permeability corresponding to the abrupt point in the relation curve, wherein the abrupt point is the point with the maximum curvature in the relation curve; and the air permeability corresponding to the mutation point is the physical upper limit of the compact oil reservoir in the research area of the target low-permeability oil reservoir.

8. the apparatus of claim 7, wherein the air permeability and the actuation pressure gradient satisfy a power function relationship.

9. The apparatus of claim 8, wherein the mutation point determining module specifically comprises:

The fitting submodule is used for fitting the relation curve to obtain a fitting expression;

And the air permeability determining submodule is used for determining the air permeability at the position with the maximum curvature in the relation curve according to the fitting expression.

10. The apparatus of claim 7, wherein the acquisition generation module specifically comprises:

The sample acquisition submodule is used for acquiring a preset number of rock core samples in the target interval;

And the data acquisition submodule is used for acquiring the data of the air permeability and the starting pressure gradient obtained by the core displacement experiment of each core sample.

11. the apparatus of claim 10, wherein the predetermined number is not less than 10.

12. The apparatus of claim 7, further comprising:

The correction module is used for correcting the fine geological model obtained by the oil reservoir description module to obtain a corrected fine geological model;

Correspondingly, the target interval determining module is used for determining the target interval meeting preset conditions in the target low-permeability reservoir according to the corrected fine geological model.