Method, device and equipment for determining water saturation of fractured reservoir, medium and product

Abstract

The invention provides a method, a device and equipment for determining the water saturation of a fractured reservoir, a medium and a product, and relates to the technical field of oil and gas development. The method comprises the following steps: acquiring the fracture porosity of a target fractured reservoir; a first corresponding relation between the first parameter and the fracture porosity is obtained based on the fracture porosity of the target fracture-containing reservoir, the first corresponding relation is determined according to a second corresponding relation between the resistance increasing rate and the water saturation under different fracture porosities, and the first parameter is a parameter reflecting the influence of the fracture porosity on the electrical property; determining parameters of a water saturation calculation model according to the first corresponding relation and the fracture porosity of the target fractured reservoir to obtain a target water saturation calculation model; and determining the water saturation of the target fractured reservoir according to the target water saturation calculation model. According to the method, the accuracy of a water saturation calculation result is improved, and the water saturation calculation result is closer to a rock core analysis result.

Description

Technical Field

[0001] This application relates to the field of oil and gas development technology, and in particular to a method, apparatus, equipment, medium and product for determining the water saturation of fractured reservoirs. Background Technology

[0002] Water saturation is an important geological parameter that reflects the relationship between the actual amount of water present in the pores of rocks or soil and the pore capacity. In oil and gas development and reservoir evaluation, measuring water saturation can assess the reserves and recoverability of oil and gas reservoirs, and is used for resource assessment and production optimization in oil and gas exploration and development.

[0003] With the development of oil and gas exploration, heterogeneous and anisotropic complex reservoirs have gradually become the focus of exploration. These reservoirs often have well-developed fractures, and their water saturation calculation faces great challenges. Some scholars have derived a general relationship between resistivity and water saturation based on heterogeneous anisotropic formation models, and determined the form of the saturation model according to the pore type of the reservoir.

[0004] However, while the proposed saturation model solved the structural form problem of the saturation equation for fractured reservoirs, it did not provide an effective method for determining the model parameters. At present, when using it, a unified parameter is often determined to calculate the water saturation of fractured pore reservoirs. However, the accuracy of the water saturation calculated by using a water saturation calculation model with unified parameters is low and there is a large gap with the core analysis results. Summary of the Invention

[0005] This application provides a method, apparatus, equipment, medium, and product for determining the water saturation of fractured reservoirs, in order to solve the technical problem that the accuracy of water saturation calculated using a water saturation calculation model with uniform parameters is low and the results differ significantly from those obtained from core analysis.

[0006] In a first aspect, this application provides a method for determining the water saturation of fractured reservoirs, including:

[0007] Obtain the fracture porosity of the target fractured reservoir;

[0008] A first correspondence between a first parameter and fracture porosity is obtained based on the fracture porosity of the target fractured reservoir. The first correspondence is determined based on a second correspondence between the resistivity increase rate and water saturation under different fracture porosities. The first parameter is a parameter that reflects the influence of fracture porosity on electrical properties.

[0009] The parameters of the water saturation calculation model are determined based on the first correspondence and the fracture porosity of the target fractured reservoir, so as to obtain the target water saturation calculation model.

[0010] The water saturation of the target fractured reservoir is determined based on the target water saturation calculation model.

[0011] In one possible design, the first correspondence is determined based on a second correspondence between the rate of increase in resistivity and water saturation under different crack porosities, including:

[0012] Multiple digital core models are constructed, and each digital core model has a corresponding fracture porosity.

[0013] Numerical simulations were performed on each of the digital core models to obtain a second correspondence under each fracture porosity.

[0014] The second correspondence is input into the formula corresponding to the preset water saturation calculation model to determine the first parameter corresponding to the porosity of each crack;

[0015] Linear fitting is performed based on the porosity of each crack and the corresponding first parameter to obtain the first correspondence.

[0016] In one possible design, numerical simulations are performed on each digital core model to obtain a second correspondence under each fracture porosity, including:

[0017] Perform the following operations on each of the aforementioned digital core models:

[0018] Multiple preset water saturation levels are obtained, and the corresponding resistivity is simulated based on each preset water saturation level;

[0019] The resistance increase rate is calculated based on each of the resistivities to obtain a second correspondence.

[0020] In one possible design, the formula corresponding to the first correspondence is: Where p2 is the first parameter; denoted as crack porosity; a, b, and c are constants.

[0021] In one possible design, a target water saturation calculation model is determined based on a first correspondence and the fracture porosity of the target fractured reservoir, including:

[0022] Determine the saturation index of the target fractured reservoir;

[0023] Based on the first correspondence, the first parameter and the second parameter corresponding to the fracture porosity of the target fractured reservoir are determined, and the sum of the values ​​of the second parameter and the first parameter is equal to one.

[0024] The saturation index and the first and second parameters corresponding to the fracture porosity of the target fractured reservoir are input into the formula corresponding to the preset water saturation calculation model to obtain the target water saturation calculation model.

[0025] In one possible design, determining the saturation index of the target fractured reservoir includes:

[0026] Obtain different water saturation levels of the target rock core and their corresponding resistivity;

[0027] Calculate the resistance increase rate based on resistivity;

[0028] Relationship curves were plotted based on different water saturation levels and resistivity increase rates, and the absolute value of the slope of the corresponding relationship curves was determined as the saturation index.

[0029] Secondly, this application provides an apparatus for determining the water saturation of a fractured reservoir, comprising:

[0030] The acquisition module is used to acquire the fracture porosity of the target fractured reservoir;

[0031] The acquisition module is further configured to acquire a first correspondence between a first parameter and fracture porosity based on the fracture porosity of the target fractured reservoir. The first correspondence is determined based on a second correspondence between the resistivity increase rate and water saturation under different fracture porosities. The first parameter is a parameter that reflects the influence of fracture porosity on electrical properties.

[0032] The determination module is used to determine the parameters of the water saturation calculation model based on the first correspondence and the fracture porosity of the target fractured reservoir, so as to obtain the target water saturation calculation model.

[0033] The determining module is further configured to determine the water saturation of the target fractured reservoir based on the target water saturation calculation model.

[0034] Thirdly, this application provides a device for determining the water saturation of a fractured reservoir, comprising: a processor, and a memory communicatively connected to the processor;

[0035] The memory stores the instructions that the computer executes;

[0036] The processor executes computer-executable instructions stored in memory to implement the method as described in any of the first aspects.

[0037] Fourthly, this application provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the method as described in any of the first aspects.

[0038] Fifthly, this application provides a computer program product, including a computer program that, when executed by a processor, implements the method as described in the first aspect.

[0039] This application provides a method, apparatus, equipment, medium, and product for determining the water saturation of fractured reservoirs. The method obtains the fracture porosity of a target fractured reservoir; based on the fracture porosity of the target fractured reservoir, it obtains a first correspondence between a first parameter and the fracture porosity, the first correspondence being determined according to a second correspondence between the resistivity increase rate and water saturation under different fracture porosities, the first parameter being a parameter reflecting the influence of fracture porosity on electrical properties; based on the first correspondence and the fracture porosity of the target fractured reservoir, it determines the parameters of a water saturation calculation model to obtain a target water saturation calculation model; and based on the target water saturation calculation model, it determines the water saturation of the target fractured reservoir. Once the fracture porosity of the target fractured reservoir is obtained, it indicates that the water saturation of the target fractured reservoir needs to be calculated. The first correspondence between the first parameter and the fracture porosity is determined in advance based on the second correspondence between the resistivity increase rate and water saturation under different fracture porosities. Therefore, after obtaining the fracture porosity of the target fractured reservoir, the water saturation can be calculated accurately and quickly based on the first correspondence. The first parameter reflects the influence of fracture porosity on electrical properties. The first correspondence can accurately reflect the relationship between fracture porosity and the first parameter. Therefore, the parameters of the target water saturation calculation model determined based on the first correspondence and the fracture porosity of the target fractured reservoir are more suitable for the target fractured reservoir. The water saturation of the target fractured reservoir determined based on the target water saturation calculation model is more accurate and closer to the core analysis results. Attached Figure Description

[0040] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0041] Figure 1 An application scenario diagram of the water saturation determination method for fractured reservoirs provided in one embodiment of this application;

[0042] Figure 2 A flowchart illustrating a method for determining the water saturation of a fractured reservoir according to an embodiment of this application;

[0043] Figure 3 This is a schematic diagram of the water saturation evaluation results of the target fractured reservoir section of Well X provided in an embodiment of this application;

[0044] Figure 4 This is a schematic diagram illustrating the second correspondence between the rate of increase in resistivity and water saturation under different crack porosities, provided in an embodiment of this application.

[0045] Figure 5 A schematic diagram illustrating the relationship between the porosity of each crack and the first parameter provided in an embodiment of this application;

[0046] Figure 6 A flowchart of a method for determining the water saturation of fractured reservoirs provided in another embodiment of this application;

[0047] Figure 7 A schematic diagram of a device for determining the water saturation of a fractured reservoir provided in an embodiment of this application;

[0048] Figure 8 A schematic diagram of a device for determining the water saturation of fractured reservoirs provided in an embodiment of this application.

[0049] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0050] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0051] To clearly understand the technical solution of this application, the solutions of the prior art will be described in detail first.

[0052] In oil and gas development and reservoir evaluation, water saturation measurement can be used to assess the reserves and recoverability of oil and gas reservoirs, and can be used for resource assessment and production optimization in oil and gas exploration and development. When the reservoir contains fractures, the commonly used water saturation calculation model is shown in Equation (1), where p1, p2, and n1 are parameters to be determined. At present, when using this model, a unified parameter value is often determined to calculate the water saturation of fractured reservoirs. However, the accuracy of the water saturation calculated by the water saturation calculation model with a unified parameter value is low, and there is a large gap with the core analysis results.

[0053]

[0054] In equation (1): I is the resistance increase rate; S w denoted as water saturation; n1 is the saturation index; p1 and p2 are parameters to be determined.

[0055] Therefore, when facing technical problems in the existing technology, in order to improve the accuracy of water saturation calculation of fractured reservoirs, the meaning of the parameters themselves is fully considered when determining the model parameters. Since the first parameter, i.e. p2 in equation (1), is a parameter reflecting the influence of fracture porosity on electrical properties, different fracture porosities should correspond to different first parameters. So, the first correspondence between the first parameter and the fracture porosity is determined firstly based on the second correspondence between the resistance increase rate and water saturation under different fracture porosities, and stored in the water saturation determination device of fractured reservoirs. After obtaining the fracture porosity of the target fractured reservoir, the parameters of the target water saturation calculation model are determined according to the first correspondence and the fracture porosity of the target fractured reservoir. The target water saturation calculation model determined in this way will have a higher degree of fit with the target fractured reservoir. Therefore, the water saturation of the target fractured reservoir determined by the target water saturation calculation model is more accurate and closer to the core analysis results.

[0056] Figure 1 This is an application scenario diagram of the method for determining the water saturation of fractured reservoirs provided in one embodiment of this application, such as... Figure 1 As shown in the embodiments of this application, the application scenarios corresponding to the method for determining the water saturation of fractured reservoirs include: a terminal device 101, a server 102, and a server database 103. The server database 103 pre-stores a first correspondence between a first parameter and fracture porosity. This first correspondence is determined based on a second correspondence between the resistivity increase rate and water saturation under different fracture porosities. The first correspondence can be a formula, a table storing multiple fracture porosities and their corresponding first parameters, or other forms; this embodiment does not limit this.

[0057] Specifically, the user triggers a water saturation determination request through terminal device 101. Server 102 receives the water saturation determination request, which includes the fracture porosity of the target fractured reservoir. Then, server 102 obtains a first correspondence between a first parameter and fracture porosity from server database 103 based on the request, and determines the parameters of the water saturation calculation model according to the first correspondence and the fracture porosity of the target fractured reservoir to obtain the target water saturation calculation model. Finally, server 102 determines the water saturation of the target fractured reservoir according to the target water saturation calculation model and sends a water saturation determination request response to terminal device 101 so that the user can obtain the water saturation of the target fractured reservoir.

[0058] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0059] Figure 2 A flowchart of a method for determining the water saturation of fractured reservoirs provided in an embodiment of this application is shown below. Figure 2 As shown, the execution subject of this embodiment is a water saturation determination device for fractured reservoirs. This device can be implemented through a computer program, or through a medium storing the relevant computer program, such as a USB flash drive and / or optical disc; alternatively, it can be implemented through a physical device integrating or installing the relevant computer program, such as a chip or a water saturation determination device for fractured reservoirs. The water saturation determination method for fractured reservoirs provided in this embodiment includes the following steps:

[0060] Step 201: Obtain the fracture porosity of the target fractured reservoir.

[0061] Among them, the target fractured reservoir refers to the reservoir whose water saturation is to be determined, and different target fractured reservoirs have different fracture porosity.

[0062] The fracture porosity of the target fractured reservoir can be obtained by exploring the formation through formation microresistivity imaging logging and then processing the data using logging software; or it can be obtained by other methods, which are not limited in this embodiment.

[0063] It is understandable that during oil and gas exploration, a single well test may contain multiple reservoir segments. Each reservoir segment is formed by multiple single reservoirs stacked vertically across phases, and each single reservoir has its corresponding fracture porosity.

[0064] Optionally, the fracture porosity of the target fractured reservoir can be obtained by the user sending it to the water saturation determination device for the fractured reservoir, or by the water saturation determination device actively retrieving it from the system, or by other means. This embodiment does not limit this.

[0065] It should be noted that fracture porosity is an important factor affecting reservoir water saturation. Therefore, when initiating a water saturation determination request, users should include the fracture porosity of the target fractured reservoir to enable accurate water saturation calculation.

[0066] Step 202: Obtain the first correspondence between the first parameter and the fracture porosity based on the fracture porosity of the target fractured reservoir. The first correspondence is determined based on the second correspondence between the resistivity increase rate and water saturation under different fracture porosities. The first parameter is a parameter that reflects the influence of fracture porosity on electrical properties.

[0067] The first correspondence is the relationship between the first parameter and the fracture porosity. The first correspondence can be stored in the form of a relational formula in the water saturation determination device of the fractured reservoir, or it can be stored in the form of a table. The table can contain multiple fracture porosities and their corresponding first parameter values, or it can be stored in other forms. This embodiment does not limit this.

[0068] It is understandable that the first correspondence is determined based on the second correspondence between the resistance increase rate and water saturation under different fracture porosities. Under the same fracture porosity, when the water saturation changes, the resistance increase rate will also change. Therefore, there is a correspondence between the resistance increase rate and water saturation under different fracture porosities.

[0069] Optionally, a preset water saturation calculation model can be used to determine the first correspondence, that is, the second relationship is input into the formula corresponding to the preset water saturation calculation model to calculate the corresponding first parameter value, thereby determining the first correspondence between the first parameter and the crack porosity.

[0070] Specifically, after obtaining the fracture porosity of the target fractured reservoir, a first correspondence between the pre-stored first parameter and the fracture porosity is obtained.

[0071] Step 203: Determine the parameters of the water saturation calculation model based on the first correspondence and the fracture porosity of the target fractured reservoir, so as to obtain the target water saturation calculation model.

[0072] Among them, the target water saturation calculation model is used to calculate the water saturation of the target fractured reservoir. It is affected by the fracture porosity of the target fractured reservoir, and different fracture porosities correspond to different target water saturation calculation models.

[0073] It is understood that the target water saturation calculation model also includes another parameter, the sum of which is one with the value of the first parameter. Therefore, after determining the first parameter based on the first correspondence and the fracture porosity of the target fractured reservoir, the value of the other parameter can be determined. The target water saturation calculation model also includes a saturation index. The value of the saturation index can be obtained by conducting rock electrical experiments on core samples extracted from the target fractured reservoir, or it can be obtained through other methods. This embodiment does not limit this.

[0074] Specifically, based on the first correspondence, a first parameter corresponding to the fracture porosity of the target fractured reservoir can be determined, and a water saturation calculation model containing the value of the first parameter, the value of another parameter, and the value of the saturation index is determined as the target water saturation calculation model.

[0075] Step 204: Determine the water saturation of the target fractured reservoir based on the target water saturation calculation model.

[0076] Specifically, after obtaining the target water saturation calculation model, the characteristic data of the target fractured reservoir required in the calculation model are input into the model to calculate the water saturation of the target fractured reservoir.

[0077] For example, Figure 3 This is a schematic diagram illustrating the water saturation evaluation results of the target fractured reservoir section in Well X, as shown below. Figure 3 As shown, the lithology, depth, resistivity, porosity, imaging, and dip angle data are all from well logging data, while the porosity is calculated based on the well logging data. The last two columns of the figure show that the water saturation of fractured reservoirs calculated using the traditional method (Archie formula) has a low correlation with core analysis results and poor accuracy. In contrast, the water saturation of fractured reservoirs calculated using the method provided in this embodiment is closer to the core analysis results and has higher accuracy.

[0078] The method for determining the water saturation of fractured reservoirs provided in this embodiment involves: obtaining the fracture porosity of the target fractured reservoir; obtaining a first correspondence between a first parameter and the fracture porosity based on the fracture porosity of the target fractured reservoir, wherein the first correspondence is determined based on a second correspondence between the resistivity increase rate and the water saturation under different fracture porosities, and the first parameter is a parameter reflecting the influence of fracture porosity on electrical properties; determining the parameters of the water saturation calculation model based on the first correspondence and the fracture porosity of the target fractured reservoir to obtain the target water saturation calculation model; and determining the water saturation of the target fractured reservoir based on the target water saturation calculation model. Once the fracture porosity of the target fractured reservoir is obtained, it indicates that the water saturation of the target fractured reservoir needs to be calculated. After obtaining the fracture porosity of the target fractured reservoir, the water saturation can be calculated accurately and quickly based on the first correspondence relationship. The first parameter reflects the influence of fracture porosity on electrical properties. The first correspondence relationship can accurately reflect the relationship between fracture porosity and the first parameter. Therefore, the parameters of the target water saturation calculation model determined based on the first correspondence relationship and the fracture porosity of the target fractured reservoir are more suitable for the target fractured reservoir. The water saturation of the target fractured reservoir determined based on the target water saturation calculation model is more accurate and closer to the core analysis results.

[0079] As an optional implementation, based on the above embodiments, the first correspondence is determined according to the second correspondence between the resistivity increase rate and water saturation under different crack porosities, including:

[0080] Multiple digital core models were constructed, each with a corresponding fracture porosity.

[0081] Numerical simulations were performed on each digital core model to obtain the second correspondence under each fracture porosity.

[0082] The second correspondence is input into the formula corresponding to the preset water saturation calculation model to determine the first parameter corresponding to the porosity of each crack;

[0083] Linear fitting is performed based on the porosity of each crack and the corresponding first parameter to obtain the first correspondence.

[0084] Among them, the digital core model is a virtual three-dimensional core structure model constructed using specialized tools, such as 3D modeling tools.

[0085] The formula corresponding to the preset water saturation calculation model is:

[0086]

[0087] In the formula: I is the rate of increase in resistance; S w denoted as water saturation; n1 is the saturation index; p1 is the second parameter; p2 is the first parameter.

[0088] It should be noted that the relationship between the first parameter and the second parameter is: p1 = 1 - p2.

[0089] Specifically, before determining the water saturation, it is necessary to first determine the first correspondence. First, the size characteristic data of the target core in the target fractured reservoir should be obtained. Using a special tool, such as a 3D modeling tool, the size characteristic data of the target core should be input into the tool to construct the shape structure of the digital core model. The fracture porosity should be adjusted as needed to obtain multiple digital core models, that is, each digital core model has a corresponding fracture porosity. Then, numerical simulations should be performed on the multiple constructed digital core models to simulate the resistivity corresponding to different water saturations, so as to obtain the second correspondence between the resistance increase rate and the water saturation under different fracture porosities. Then, the second correspondence should be input into the formula shown in Equation (2) to calculate the first parameter corresponding to each fracture porosity. Finally, data analysis software, such as Origin, should be used to linearly fit each fracture porosity and its corresponding first parameter to obtain the first correspondence.

[0090] Among them, the target core refers to the core located in the target fractured reservoir. The target core is extracted from the target fractured reservoir to determine the water saturation of the target fractured reservoir. The target core is a full-diameter core without fractures in the reservoir section where the target fractured reservoir is located. The diameter of the target core can be selected according to the mining situation, but the diameter of the target core should be as large as possible to improve the ability to reflect the heterogeneity of the reservoir.

[0091] The size characteristics of the target rock core can be obtained in advance through three-dimensional X-CT scanning or through other methods; this embodiment does not limit this.

[0092] For example, when constructing a digital core model, the fracture porosity can be set to 0.0006, 0.001, 0.003, and 0.005. Then, the second correspondence between the resistivity increase rate and water saturation under different fracture porosities obtained after numerical simulation can be as follows: Figure 4 As shown in Table 1, after inputting the second correspondence into the formula corresponding to the preset water saturation calculation model, the first parameters corresponding to the porosity of each fracture are obtained; the relationship diagram after linear fitting based on the porosity of each fracture and the corresponding first parameters is shown in Table 1. Figure 5 As shown.

[0093] Table 1. First parameters corresponding to the porosity of each crack.

[0094]

[0095] The method for determining the water saturation of fractured reservoirs provided in this embodiment determines a first correspondence based on a second correspondence between the resistivity increase rate and water saturation under different fracture porosities. This includes: constructing multiple digital core models, each with a corresponding fracture porosity; performing numerical simulations on each digital core model to obtain the second correspondence under each fracture porosity; inputting the second correspondence into the formula corresponding to a preset water saturation calculation model to determine the first parameter corresponding to each fracture porosity; and performing linear fitting based on each fracture porosity and the corresponding first parameter to obtain the first correspondence. By constructing digital core models, the digital core models more closely resemble real core dimensions, thereby quickly generating multiple simulation scenarios. Numerical simulations of these models can accurately simulate the relationship between the resistivity increase rate and water saturation under different fracture porosities, which is more accurate than traditional experimental methods. Furthermore, inputting the second correspondence into the formula corresponding to the preset water saturation calculation model and performing linear fitting on each fracture porosity and the corresponding first parameter makes the obtained first correspondence more reliable and has wider applicability.

[0096] As an optional implementation, based on the above embodiments, numerical simulations are performed on each digital core model to obtain a second correspondence under each fracture porosity, including:

[0097] Perform the following operations for each digital core model:

[0098] Multiple preset water saturation levels are obtained, and the corresponding resistivity is simulated based on each preset water saturation level;

[0099] The resistance increase rate is calculated based on each resistivity to obtain a second correspondence.

[0100] The preset water saturation is the water saturation value pre-stored in the water saturation determination device for fractured reservoirs. It can be set according to requirements, such as 90% or 80%, etc. This embodiment does not limit this.

[0101] Specifically, when performing numerical simulation on the digital core model, multiple preset water saturation levels need to be obtained. Each preset water saturation level can be input into a preset numerical simulation software. The preset numerical simulation software can be used to simulate the resistivity under different water saturation levels. Then, the resistivity corresponding to each preset water saturation level is output in sequence. Based on each resistivity, the corresponding resistance increase rate is calculated using the formula shown in Equation (3). The second correspondence between the resistance increase rate and water saturation under each fracture porosity is determined in sequence using the above method.

[0102]

[0103] In the formula: I is the rate of increase in resistance; R t R0 represents the resistivity corresponding to different water saturation levels; R0 represents the resistivity corresponding to a water saturation level of 100%.

[0104] Among them, the preset numerical simulation software is software that is pre-configured in the water saturation determination device of fractured reservoirs and is used to perform numerical simulation of digital core models, such as finite element analysis software.

[0105] Alternatively, numerical simulations of each digital core model can be performed in other ways, but this implementation does not limit this method.

[0106] The method for determining the water saturation of fractured reservoirs provided in this embodiment performs numerical simulations on various digital core models to obtain a second correspondence under different fracture porosities. This includes performing the following operations for each digital core model: obtaining multiple preset water saturations and simulating the corresponding resistivity based on each preset water saturation; calculating the corresponding resistance increase rate based on each resistivity to obtain the second correspondence. By simulating the corresponding resistivity based on the preset water saturations and then calculating the corresponding resistance increase rate based on each resistivity, the obtained second correspondence has higher accuracy and indirectly improves the accuracy of the water saturation determination results.

[0107] As an optional implementation, based on the above embodiments, the formula corresponding to the first correspondence is: Where p2 is the first parameter; denoted as crack porosity; a, b, and c are constants.

[0108] Where a can be 8.8770, b can be 0.4714, c can be 0.0077, or other values ​​obtained through simulation fitting. This embodiment does not limit these values.

[0109] Specifically, different fracture porosities correspond to different first parameter values. Once the fracture porosity of the target fractured reservoir is obtained, the corresponding first parameter can be obtained using the formula corresponding to the first correspondence.

[0110] The method for determining the water saturation of fractured reservoirs provided in this embodiment uses the following formula corresponding to the first correspondence: Where p2 is the first parameter; Here, represents fracture porosity; a, b, and c are constants. The formula corresponding to the preset pore compression model can accurately reconstruct the porosity of the coal sample under its original underground storage condition, resulting in a more precise calculation of the free gas content. The target water saturation calculation model determined by the formula corresponding to the first correspondence is more suitable for the target fractured reservoir, thus the calculated water saturation is more accurate and closer to the core analysis results.

[0111] As an optional implementation, based on the above embodiments, a target water saturation calculation model is determined according to the first correspondence and the fracture porosity of the target fractured reservoir, including:

[0112] Determine the saturation index of the target fractured reservoir;

[0113] Based on the first correspondence, the first parameter and the second parameter corresponding to the fracture porosity of the target fractured reservoir are determined, and the sum of the values ​​of the second parameter and the first parameter is equal to one.

[0114] The saturation index and the first and second parameters corresponding to the fracture porosity of the target fractured reservoir are input into the formula corresponding to the preset water saturation calculation model to obtain the target water saturation calculation model.

[0115] Specifically, when determining the target water saturation model, the values ​​of the saturation index, the first parameter, and the second parameter need to be determined. After obtaining the first correspondence, the fracture porosity of the target fractured reservoir can be input into the formula corresponding to the first correspondence to obtain the corresponding first parameter value. Since the sum of the second parameter and the first parameter value equals one, the second parameter value can be obtained. The determined saturation index, the first parameter value, and the second parameter value are input into the formula corresponding to the preset water saturation calculation model to obtain the target water saturation calculation model.

[0116] Optionally, when determining the saturation index of the target fractured reservoir, rock electrical experiments can be conducted on the target core extracted from the target fractured reservoir to obtain different water saturation and their corresponding resistivity. The saturation index can then be determined using the Archie formula, as shown in equation (4).

[0117]

[0118] In the formula: I is the rate of increase in resistance; R t R0 is the resistivity corresponding to different water saturation levels; S0 is the resistivity corresponding to 100% water saturation. w denoted as water saturation; n is the saturation index; b is a lithology-related constant.

[0119] The method for determining the water saturation of fractured reservoirs provided in this embodiment determines a target water saturation calculation model based on a first correspondence and the fracture porosity of the target fractured reservoir. The method includes: determining the saturation index of the target fractured reservoir; determining a first parameter and a second parameter corresponding to the fracture porosity of the target fractured reservoir based on the first correspondence, wherein the sum of the second parameter and the first parameter is equal to one; and inputting the saturation index, the first parameter, and the second parameter corresponding to the fracture porosity of the target fractured reservoir into the formula corresponding to the preset water saturation calculation model to obtain the target water saturation calculation model. By determining the first parameter and the second parameter corresponding to the fracture porosity of the target fractured reservoir based on the first correspondence and inputting the determined saturation index, the first parameter, and the second parameter into the formula corresponding to the preset water saturation calculation model, the determined target water saturation calculation model can more accurately describe the distribution state of fluids in the reservoir, thereby improving the accuracy of water saturation calculation. Furthermore, the parameter values ​​can be flexibly adjusted according to actual conditions to obtain different target water saturation calculation models applicable to different types of reservoirs, enhancing the model's universality and applicability.

[0120] As an optional implementation, based on the above embodiments, determining the saturation index of the target fractured reservoir includes:

[0121] Obtain different water saturation levels of the target rock core and their corresponding resistivity;

[0122] Calculate the resistance increase rate based on resistivity;

[0123] Intersection curves were plotted based on different water saturation levels and resistivity increase rates, and the absolute value of the slope of the corresponding curves was determined as the saturation index.

[0124] The different water saturations of the target core and their corresponding resistivity can be obtained through rock electrical experiments and stored in the water saturation determination device for fractured reservoirs.

[0125] Understandably, the target rock core needs to be pretreated before conducting rock electric experiments. This includes processing the end face of the target rock core to meet the requirements of the rock electric experiment holder, and washing the target rock core with oil, salt, and brine saturation.

[0126] Among them, the rock electrical experiment involves changing the gas drive pressure on the target rock core after it has been saturated with brine, recording the water saturation corresponding to different pressures, and measuring the resistivity value of the target rock core at different water saturations.

[0127] Specifically, different water saturations and their corresponding resistivity are obtained from the target core stored in the water saturation determination device for fractured reservoirs. Then, the resistance increase rate is calculated using equation (4). The relationship curve between different water saturations and their corresponding resistance increase rate is plotted on a double logarithmic coordinate system. The absolute value of the slope of the relationship curve is determined as the saturation index.

[0128] It should be noted that the saturation index determined by the target core can be used to determine the target water saturation calculation model for all target fractured reservoirs in the reservoir section where the target core is located. Only the first and second parameters need to be determined based on the fracture porosity of the target fractured reservoir.

[0129] The method for determining the water saturation of fractured reservoirs provided in this embodiment determines the saturation index of the target fractured reservoir. This includes: obtaining different water saturations of the target core and their corresponding resistivity; calculating the resistance increase rate based on the resistivity; plotting an intersection curve based on different water saturations and resistance increase rates, and determining the absolute value of the slope of the intersection curve as the saturation index. By obtaining the resistivity of the target core at different water saturations and calculating the resistance increase rate accordingly, more accurate and reliable data can be obtained. By plotting the intersection curve and calculating the slope to determine the saturation index, a quantitative description of reservoir properties is achieved, indirectly improving the accuracy of the water saturation determination results.

[0130] Figure 6 A flowchart of a method for determining the water saturation of fractured reservoirs provided in another embodiment of this application is shown below. Figure 6 As shown, the method for determining the water saturation of fractured reservoirs provided in this embodiment includes a specific process for determining the first correspondence. Therefore, the method for determining the water saturation of fractured reservoirs provided in this embodiment includes the following steps:

[0131] Step 601: Obtain the size characteristic data of the target core in the target fractured reservoir.

[0132] Step 602: Based on the size characteristic data, construct multiple digital core models by changing the fracture porosity.

[0133] Step 603: Perform numerical simulations on each digital core model to obtain the second correspondence under each fracture porosity.

[0134] Step 604: Input the second correspondence into the formula corresponding to the preset water saturation calculation model to determine the first parameter corresponding to the porosity of each crack.

[0135] Step 605: Perform linear fitting based on the porosity of each fracture and the corresponding first parameter to obtain the first correspondence and store it in the water saturation determination device for fractured reservoirs.

[0136] Step 606: Obtain the fracture porosity of the target fractured reservoir.

[0137] Step 607: Based on the fracture porosity of the target fractured reservoir, obtain the first correspondence between the first parameter and the fracture porosity, and the different water saturation and corresponding resistivity of the target core.

[0138] Step 608: Calculate the resistance increase rate based on resistivity.

[0139] Step 609: Plot a relationship curve based on different water saturation and resistivity increase rates, and determine the absolute value of the slope of the relationship curve as the saturation index.

[0140] Step 610: Determine the first parameter and the second parameter corresponding to the fracture porosity of the target fractured reservoir based on the first correspondence.

[0141] Step 611: Input the saturation index and the first and second parameters corresponding to the fracture porosity of the target fractured reservoir into the formula corresponding to the preset water saturation calculation model to obtain the target water saturation calculation model.

[0142] Step 612: Determine the water saturation of the target fractured reservoir based on the target water saturation calculation model.

[0143] In this embodiment, the implementation method and technical effect of steps 601-612 are similar to those of the corresponding solutions in the above embodiments, and will not be repeated here.

[0144] Figure 7 A schematic diagram of the structure of a device for determining the water saturation of fractured reservoirs provided in an embodiment of this application is shown below. Figure 7 As shown, the water saturation determination device for fractured reservoirs provided in this embodiment is located within the water saturation determination equipment for fractured reservoirs. Therefore, the water saturation determination device 70 for fractured reservoirs provided in this embodiment includes: an acquisition module 71 and a determination module 72.

[0145] The acquisition module 71 is used to acquire the fracture porosity of the target fractured reservoir; the acquisition module 71 is also used to acquire a first correspondence between a first parameter and the fracture porosity based on the fracture porosity of the target fractured reservoir, the first correspondence being determined based on a second correspondence between the resistivity increase rate and water saturation under different fracture porosities, the first parameter being a parameter reflecting the influence of fracture porosity on electrical properties; the determination module 72 is used to determine the parameters of the water saturation calculation model based on the first correspondence and the fracture porosity of the target fractured reservoir, thereby acquiring the target water saturation calculation model; the determination module 72 is also used to determine the water saturation of the target fractured reservoir based on the target water saturation calculation model.

[0146] The device for determining the water saturation of fractured reservoirs provided in this embodiment can perform... Figure 2 The implementation principles and technical effects of the methods shown are similar, and will not be repeated here.

[0147] Optionally, the water saturation determination device for fractured reservoirs provided in this embodiment further includes a construction module, a simulation module, an input module, and a fitting module.

[0148] Accordingly, the module is used to construct multiple digital core models, each with a corresponding fracture porosity; the simulation module is used to perform numerical simulations on each digital core model to obtain a second correspondence under each fracture porosity; the input module is used to input the second correspondence into the formula corresponding to the preset water saturation calculation model to determine the first parameter corresponding to each fracture porosity; and the fitting module is used to perform linear fitting based on each fracture porosity and the corresponding first parameter to obtain the first correspondence.

[0149] Optionally, the simulation module, when performing numerical simulation on each digital core model to obtain the second correspondence under each fracture porosity, specifically performs the following operations for each digital core model: obtaining multiple preset water saturation levels and simulating the corresponding resistivity based on each preset water saturation level; calculating the corresponding resistance increase rate based on each resistivity to obtain the second correspondence.

[0150] Optionally, the formula corresponding to the first correspondence is: Where p2 is the first parameter; denoted as crack porosity; a, b, and c are constants.

[0151] Optionally, the determining module 73, when determining the target water saturation calculation model based on the first correspondence and the fracture porosity of the target fractured reservoir, is specifically used for: determining the saturation index of the target fractured reservoir; determining the first parameter and the second parameter corresponding to the fracture porosity of the target fractured reservoir based on the first correspondence, wherein the sum of the values ​​of the second parameter and the first parameter equals one; and inputting the saturation index, the first parameter and the second parameter corresponding to the fracture porosity of the target fractured reservoir into the formula corresponding to the preset water saturation calculation model to obtain the target water saturation calculation model.

[0152] Optionally, module 73, when determining the saturation index of the target fractured reservoir, is specifically used for: obtaining different water saturation levels of the target core and their corresponding resistivity; calculating the resistance increase rate based on the resistivity; plotting a relationship curve based on different water saturation levels and resistance increase rates, and determining the absolute value of the slope of the relationship curve as the saturation index.

[0153] Figure 8 A schematic diagram of a device for determining the water saturation of fractured reservoirs provided in an embodiment of this application is shown below. Figure 8 As shown, the water saturation determination device 80 for fractured reservoirs provided in this embodiment includes: a processor 81 and a memory 82 communicatively connected to the processor.

[0154] The memory 82 stores computer-executed instructions; the processor 81 executes the computer-executed instructions stored in the memory 82 to implement the method for determining the water saturation of fractured reservoirs provided in any of the above embodiments. Related explanations can be understood by referring to the relevant descriptions and effects corresponding to the steps in the accompanying drawings, and will not be elaborated further here.

[0155] The program may include program code, which includes computer-executable instructions. Memory 82 may include high-speed RAM, and may also include non-volatile memory, such as at least one disk storage device.

[0156] In this embodiment, the memory 82 and the processor 81 are connected via a bus. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. The bus can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 8 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0157] This application also provides a computer-readable storage medium storing computer-executable instructions. When executed by a processor, these instructions are used to implement the method for determining the water saturation of fractured reservoirs provided in any of the above embodiments. For example, the computer-readable storage medium may be a ROM, random access memory (RAM), CD-ROM, magnetic tape, floppy disk, or optical data storage device.

[0158] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the method for determining the water saturation of fractured reservoirs provided in any of the above embodiments.

[0159] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are all optional embodiments, and the actions and modules involved are not necessarily essential to this application.

[0160] It should be further noted that although the steps in the flowchart are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowchart may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the sub-steps or stages of other steps.

[0161] It should be understood that the above-described device embodiments are merely illustrative, and the device of this application can also be implemented in other ways. For example, the division of units / modules in the above embodiments is only a logical functional division, and there may be other division methods in actual implementation. For example, multiple units, modules, or components may be combined, or integrated into another system, or some features may be ignored or not executed.

[0162] Furthermore, unless otherwise specified, the functional units / modules in the various embodiments of this application can be integrated into one unit / module, or each unit / module can exist physically separately, or two or more units / modules can be integrated together. The integrated units / modules described above can be implemented in hardware or as software program modules.

[0163] When integrated units / modules are implemented in hardware, the hardware can be digital circuits, analog circuits, etc. The physical implementation of the hardware structure includes, but is not limited to, transistors, memristors, etc. Unless otherwise specified, the processor can be any suitable hardware processor, such as a CPU, GPU, FPGA, DSP, and ASIC, etc. Unless otherwise specified, the storage unit can be any suitable magnetic or magneto-optical storage medium, such as Resistive Random Access Memory (RRAM), Dynamic Random Access Memory (DRAM), Static Random Access Memory (SRAM), Enhanced Dynamic Random Access Memory (EDRAM), High-Bandwidth Memory (HBM), Hybrid Memory Cube (HMC), etc.

[0164] If the integrated unit / module is implemented as a software program module and sold or used as an independent product, it can be stored in a computer-readable storage device (CMD). Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a memory and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned memory includes various media capable of storing program code, such as a USB flash drive, read-only memory (ROM), random access memory (RAM), portable hard drive, magnetic disk, or optical disk.

[0165] In the above embodiments, the descriptions of each embodiment have their own emphasis. Parts not described in detail in a particular embodiment can be referred to in the relevant descriptions of other embodiments. The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as these combinations of technical features do not contradict each other, they should be considered within the scope of this specification. Those skilled in the art, upon considering the specification and practicing the invention disclosed herein, will readily conceive of other embodiments of this application. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary technical means in the art not disclosed in this application. The specification and embodiments are considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0166] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A method for determining the water saturation of fractured reservoirs, characterized in that, The method includes: Obtain the fracture porosity of the target fractured reservoir; A first correspondence between a first parameter and fracture porosity is obtained based on the fracture porosity of the target fractured reservoir. The first correspondence is determined based on a second correspondence between the resistivity increase rate and water saturation under different fracture porosities. The first parameter is a parameter that reflects the influence of fracture porosity on electrical properties. The parameters of the water saturation calculation model are determined based on the first correspondence and the fracture porosity of the target fractured reservoir, so as to obtain the target water saturation calculation model. The water saturation of the target fractured reservoir is determined based on the target water saturation calculation model.

2. The method according to claim 1, characterized in that, The first correspondence is determined based on the second correspondence between the resistivity increase rate and water saturation under different fracture porosities, including: Multiple digital core models are constructed, and each digital core model has a corresponding fracture porosity. Numerical simulations were performed on each of the digital core models to obtain a second correspondence under each fracture porosity. The second correspondence is input into the formula corresponding to the preset water saturation calculation model to determine the first parameter corresponding to the porosity of each crack; Linear fitting is performed based on the porosity of each crack and the corresponding first parameter to obtain the first correspondence.

3. The method according to claim 2, characterized in that, The step of performing numerical simulations on each of the digital core models to obtain a second correspondence under each fracture porosity includes: Perform the following operations on each of the aforementioned digital core models: Multiple preset water saturation levels are obtained, and the corresponding resistivity is simulated based on each preset water saturation level; The resistance increase rate is calculated based on each of the resistivities to obtain a second correspondence.

4. The method according to claim 2, characterized in that, The formula corresponding to the first correspondence is: Where p2 is the first parameter; denoted as crack porosity; a, b, and c are constants.

5. The method according to claim 2, characterized in that, The step of determining the target water saturation calculation model based on the first correspondence and the fracture porosity of the target fractured reservoir includes: Determine the saturation index of the target fractured reservoir; Based on the first correspondence, a first parameter and a second parameter corresponding to the fracture porosity of the target fractured reservoir are determined, and the sum of the values ​​of the second parameter and the first parameter is equal to one. The saturation index and the first and second parameters corresponding to the fracture porosity of the target fractured reservoir are input into the formula corresponding to the preset water saturation calculation model to obtain the target water saturation calculation model.

6. The method according to claim 5, characterized in that, Determining the saturation index of the target fractured reservoir includes: Obtain the different water saturation levels of the target rock core and their corresponding resistivity; Calculate the resistance increase rate based on the resistivity; A relationship curve is plotted based on the different water saturation levels and the increase in resistivity, and the absolute value of the slope of the relationship curve is determined as the saturation index.

7. A device for determining the water saturation of a fractured reservoir, characterized in that, include: The acquisition module is used to acquire the fracture porosity of the target fractured reservoir; The acquisition module is further configured to acquire a first correspondence between a first parameter and fracture porosity based on the fracture porosity of the target fractured reservoir. The first correspondence is determined based on a second correspondence between the resistivity increase rate and water saturation under different fracture porosities. The first parameter is a parameter that reflects the influence of fracture porosity on electrical properties. The determination module is used to determine the parameters of the water saturation calculation model based on the first correspondence and the fracture porosity of the target fractured reservoir, so as to obtain the target water saturation calculation model. The determining module is further configured to determine the water saturation of the target fractured reservoir based on the target water saturation calculation model.

8. A device for determining the water saturation of fractured reservoirs, characterized in that, include: A processor, and a memory communicatively connected to the processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory to implement the method as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the method as described in any one of claims 1 to 6.

10. A computer program product, characterized in that, Includes a computer program that, when executed by a processor, implements the method described in any one of claims 1 to 6.

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