Method and system for evaluating Archie cementation index of two-dimensional multi-fracture rock

Abstract

The embodiment of the invention provides a two-dimensional multi-crack rock Archie cementation index evaluation method and system, and belongs to the technical field of data processing. The method comprises the following steps: acquiring crack data; according to the crack data, constructing a double-hole medium two-dimensional rock model containing multiple cracks; according to the multi-crack-containing double-hole medium two-dimensional rock model, the resistivity of the segmentation module is obtained; acquiring the resistivity of the whole rock module according to the resistivity of the segmentation module; and obtaining the Archie cementation index according to the resistivity of the whole rock module. According to the method, the cementation index of the multi-crack two-dimensional rock can be quickly calculated.

Description

Technical Field

[0001] The present application relates to the field of data processing technology, and in particular to a method and system for evaluating the Archie cementation index of two-dimensional multi-fracture rocks. Background Art

[0002] In the field of oil and gas exploration and development, reservoir pore structure has a crucial impact on fluid storage and flow. Reservoir porosity is directly related to oil and gas reserves, production, and ultimately, recovery. Among various reservoir types, dual-porosity reservoirs have attracted considerable attention due to their complex pore structure and fracture network. Dual-porosity reservoirs typically contain matrix pores and fracture pores, with fracture pores serving as the primary fluid flow pathways and significantly influencing reservoir permeability. In particular, in dual-porosity reservoirs with intersecting dual fractures, the presence and distribution of fractures are crucial for assessing reservoir permeability and fluid saturation. Fractures not only provide highly permeable pathways for oil and gas flow, but their complex network structure also increases the complexity of reservoir fluid dynamics. Traditional reservoir evaluation methods, such as the Archie cementation index model, are primarily applicable to single fractures or groups of parallel fractures. In intersecting dual-fracture reservoirs, the applicability and accuracy of these models are limited because they fail to fully account for the interactions between fractures and the complex effects of fractures on matrix pores. There are not only two cracks in rocks under natural conditions. Existing technology still has no solution to the situation of three cracks, four cracks and multiple cracks. Summary of the Invention

[0003] The main purpose of the embodiments of the present application is to provide a method and system for evaluating the Archie cementation index of two-dimensional multi-fracture rock.

[0004] The technical solution adopted by the present invention is:

[0005] In one aspect, an embodiment of the present invention provides a method for evaluating the Archie cementation index of a two-dimensional multi-fracture rock, the method comprising the following steps:

[0006] Obtain crack data;

[0007] constructing a two-dimensional rock model of a dual-porosity medium containing multiple fractures based on the fracture data;

[0008] Obtaining the resistivity of the segmentation module according to the two-dimensional rock model of the dual-porosity medium containing multiple fractures;

[0009] Obtaining the resistivity of the entire rock module according to the resistivity of the segmentation module;

[0010] Based on the resistivity of the entire rock module, the Archie cementation index is obtained.

[0011] Furthermore, the acquisition of crack data includes the following steps:

[0012] Get the location of the crack intersection;

[0013] Get the angle between the crack and the horizontal line;

[0014] Crack data are obtained according to the positions of the crack intersections and the angles between the cracks and the horizontal line.

[0015] Furthermore, constructing a two-dimensional rock model of a dual-porosity medium containing multiple fractures based on the fracture data comprises the following steps:

[0016] According to the fracture data, if there are double intersecting fractures, a two-dimensional rock model of double fractures and double porosity media is established with the intersection of the double fractures as the model center;

[0017] According to the crack data, if the number of cracks is greater than two, the cracks are translated until all the cracks intersect at the same point, thereby obtaining a multi-crack intersection point;

[0018] Taking the intersection of the multiple fractures as the model center, a two-dimensional rock model of the multiple fractures and dual-porosity medium is established;

[0019] A two-dimensional rock model of a dual-porosity medium containing multiple fractures is obtained according to the two-dimensional rock model of the dual-fracture dual-porosity medium and the two-dimensional rock model of the multi-fracture dual-porosity medium.

[0020] Furthermore, obtaining the resistivity of the segmentation module according to the two-dimensional rock model of the dual-porosity medium containing multiple fractures includes the following steps:

[0021] Based on the two-dimensional rock model of the dual-porosity medium with multiple fractures, multiple rounds of segmentation processing are performed. In the first round of segmentation processing, the following steps are performed:

[0022] Establishing a first vertical dividing line and a first horizontal dividing line to obtain a first dividing module group, wherein the first dividing module group includes four different first dividing modules; an intersection of the first vertical dividing line and the first horizontal dividing line coincides with a center of the two-dimensional rock model of the dual-porosity medium containing multiple fractures;

[0023] If there is only one crack in the first segmentation module, the resistivity of the first segmentation module is calculated using the equivalent medium theory to obtain a first resistivity;

[0024] If two different first segmentation modules are centrosymmetric, their first resistivities are the same;

[0025] In the nth round of segmentation processing, it includes:

[0026] If the number of cracks in the n-1th segmentation module is greater than one, an nth vertical segmentation line and an nth horizontal segmentation line are established for the n-1th segmentation module to obtain an nth segmentation module group, wherein the nth segmentation module group includes four different nth segmentation modules; the intersection of the nth vertical segmentation line and the nth horizontal segmentation line coincides with the center of the n-1th segmentation module;

[0027] The cracks in the n-1th segmentation module are translated or symmetrically moved along the nth vertical segmentation line until all the cracks in the n-1th segmentation module intersect at the center of the n-1th segmentation module and a certain nth segmentation module has only one crack;

[0028] Calculating the resistivity of the nth segmented module having only one crack to obtain an nth resistivity;

[0029] Wherein n is an integer greater than or equal to two;

[0030] The resistivity of each segmentation module is obtained according to the first resistivity and the nth resistivity.

[0031] Furthermore, if there is only one crack in the first segmentation module, the resistivity of the first segmentation module is calculated using the equivalent medium theory to obtain a first resistivity, and the formula used includes:

[0032] R Afβ =R w F Afβ ;

[0033] R Dfβ =R w F Dfβ ;

[0034] R Afβ =R Dfβ ;

[0035] Among them, R Afβ Represents the first resistivity of module A; R Dfβ represents the first resistivity of the D module; the A module and the D module are different first segmentation modules; the A module and the D module are centrally symmetrical and both contain a crack with an inclination angle of β; F Afβ Represents the formation factor of the A module; R w Indicates the resistivity of formation water; F Sfβ Represents the formation factor of the D module.

[0036] Furthermore, obtaining the resistivity of the entire rock module according to the resistivity of the segmentation module includes the following steps:

[0037] According to the resistivity of each segmented module, the resistivity of the entire rock module is calculated using the series and parallel connection rule of resistors.

[0038] Furthermore, obtaining the Archie cementation index according to the resistivity of the entire rock module comprises the following steps:

[0039] The Archie cementation index is calculated based on the resistivity of the entire rock module and combined with the Archie formula.

[0040] Furthermore, the method for evaluating the Archie cementation index of two-dimensional multi-fracture rock further includes the following steps:

[0041] Obtain matrix porosity data;

[0042] Obtain fracture porosity data;

[0043] The changes of the matrix porosity data and the fracture porosity data in response to the Archie cementation index are analyzed to obtain cementation index change analysis data.

[0044] On the other hand, an embodiment of the present invention also provides an Archie cementation index evaluation device for two-dimensional multi-fracture rock, including a memory, a processor, and a computer program stored in the memory and runnable on the processor. When the processor executes the computer program, it implements the Archie cementation index evaluation method for two-dimensional multi-fracture rock as described above.

[0045] On the other hand, an embodiment of the present invention further provides a computer-readable storage medium storing computer-executable instructions, which are used to enable a computer to execute the Archie cementation index evaluation method for two-dimensional multi-fracture rock as described above.

[0046] The embodiments of the present application have at least the following beneficial effects: This application provides a method and system for evaluating the Archie cementation index of two-dimensional, multi-fractured rock. The steps of the present invention include acquiring fracture data; constructing a two-dimensional rock model of a dual-porosity medium containing multiple fractures based on the fracture data; acquiring the resistivity of segmented modules based on the two-dimensional rock model of the dual-porosity medium containing multiple fractures; acquiring the resistivity of the entire rock module based on the resistivity of the segmented modules; and obtaining the Archie cementation index based on the resistivity of the entire rock module. The present invention can rapidly calculate the cementation index of two-dimensional rock containing multiple fractures. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Schematic diagram of the Archie cementation index evaluation method for two-dimensional multi-fracture rock provided by an embodiment of the present invention;

[0048] Figure 2 Schematic diagram of a method for calculating a two-dimensional rock multi-fracture cementation index according to an embodiment of the present invention;

[0049] Figure 3 A two-dimensional rock model with intersecting double fractures and its equivalent model diagram provided by an embodiment of the present invention;

[0050] Figure 4 A two-dimensional rock model with three intersecting fractures and its equivalent model diagram provided by an embodiment of the present invention;

[0051] Figure 5 A two-dimensional rock model with four intersecting fractures and its equivalent model diagram provided by an embodiment of the present invention;

[0052] Figure 6 This is a model diagram of four intersecting cracks provided by an embodiment of the present invention after symmetry processing about the dotted line portion;

[0053] Figure 7 This is a model diagram of three cross cracks provided by an embodiment of the present invention after symmetry processing about the dotted line portion;

[0054] Figure 8 This is a schematic diagram of a model of a three-crack B module provided by an embodiment of the present invention after translation and symmetry processing;

[0055] Figure 9 Schematic diagram of a model of the four-crack B module provided by an embodiment of the present invention after translation and symmetry processing;

[0056] FIG10( a ) is a schematic diagram showing the effect of matrix porosity on the cementation index of a two-dimensional rock module with three cross fractures and a fracture azimuth angle of 1°, provided by an embodiment of the present invention;

[0057] FIG10( b ) is a schematic diagram showing the effect of matrix porosity on the cementation index of a two-dimensional rock module with three cross fractures and a fracture azimuth angle of 10°, provided by an embodiment of the present invention;

[0058] FIG10( c ) is a schematic diagram showing the effect of matrix porosity on the cementation index of a two-dimensional rock module with three cross fractures and a fracture azimuth angle of 40°, provided by an embodiment of the present invention;

[0059] FIG10( d ) is a schematic diagram showing the effect of matrix porosity on the cementation index of a two-dimensional rock module with three cross fractures and a fracture azimuth angle of 70°, provided by an embodiment of the present invention;

[0060] FIG11( a ) is a schematic diagram showing the effect of fracture porosity on cementation index in a two-dimensional rock module with three cross fractures and a fracture azimuth angle of 1°, provided by an embodiment of the present invention;

[0061] FIG11( b ) is a schematic diagram showing the effect of fracture porosity on the cementation index of a two-dimensional rock module with three cross fractures and a fracture azimuth angle of 10°, provided by an embodiment of the present invention;

[0062] FIG11( c ) is a schematic diagram showing the effect of fracture porosity on the cementation index of a two-dimensional rock module with three cross fractures and a fracture azimuth angle of 10° provided by an embodiment of the present invention;

[0063] FIG11( d ) is a schematic diagram showing the effect of fracture porosity on the cementation index of a two-dimensional rock module with three cross fractures and a fracture azimuth angle of 70° provided by an embodiment of the present invention;

[0064] FIG12( a ) is a schematic diagram showing the effect of matrix porosity on the cementation index of a two-dimensional rock module with four cross fractures and a fracture azimuth angle of 1°, provided by an embodiment of the present invention;

[0065] FIG12( b ) is a schematic diagram showing the effect of matrix porosity on the cementation index of a two-dimensional rock module with four cross fractures and a fracture azimuth angle of 10°, provided by an embodiment of the present invention;

[0066] FIG12( c ) is a schematic diagram showing the effect of matrix porosity on the cementation index of a two-dimensional rock module with four cross fractures and a fracture azimuth angle of 40°, provided by an embodiment of the present invention;

[0067] FIG12( d ) is a schematic diagram showing the effect of matrix porosity on the cementation index of a two-dimensional rock module with four cross fractures and a fracture azimuth angle of 70° provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0068] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the embodiments of the present application. They are merely examples of devices and methods consistent with some aspects of the embodiments of the present application as detailed in the appended claims.

[0069] It will be understood that the terms "first", "second", etc. used in this application may be used herein to describe various concepts, but unless otherwise specified, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another. For example, without departing from the scope of the embodiments of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the words "if" and "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0070] The terms "at least one", "plurality", "each", "any", etc. used in this application include "at least one", "two" or more, "plurality" or "each", "any" or "any one", "each" or "any one" as used herein.

[0071] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein are for the purpose of describing the embodiments of this application only and are not intended to limit this application.

[0072] Before explaining the embodiments of the present application in detail, some of the nouns and terms involved in the embodiments of the present application are first explained. The nouns and terms involved in the embodiments of the present application are subject to the following explanations.

[0073] 1) Archie formula, which is used to establish the quantitative relationship between rock resistivity, porosity and water saturation;

[0074] 2) Maxwell-Garnett mixing rule, Maxwell-Garnett mixing rule, an equivalent medium theory.

[0075] The present invention takes into account that accurately assessing the characteristics of fractures is crucial for the development and production strategies of oil and gas fields. Traditional reservoir evaluation methods, such as the Archie cementation index model, are mainly applicable to single fractures or groups of parallel fractures. These models are based on Archie's equation and evaluate the pore structure and fluid distribution of the reservoir by relating the resistivity of the reservoir to the porosity and fluid saturation. However, the applicability and accuracy of these models are limited in intersecting double-fracture reservoirs because they fail to fully consider the interaction between the fractures and the complex impact of the fractures on the matrix pores. In practical applications, the morphology, distribution, and connectivity of the fractures have a significant impact on the permeability and fluid saturation of the reservoir. For example, the inclination and azimuth of the fractures affect the direction and efficiency of fluid flow, while the porosity of the fractures affects their ability to serve as fluid channels. In addition, the angle and relative position between the fractures also affect the overall permeability of the reservoir. Therefore, developing a new model that can comprehensively consider these factors is of great significance for improving the accuracy and reliability of reservoir evaluation. Although some studies have attempted to improve the Archie cementation index model through numerical simulations and experimental data, these studies have primarily focused on the case of single or parallel fractures. For intersecting dual-fracture reservoirs, these models often fail to provide accurate assessment results due to the complex interactions of the fractures. Furthermore, due to the high brittleness and fragility of fractured rock samples, direct experimental measurement of their cementation index presents significant challenges. Therefore, it is necessary to develop a new computational model that comprehensively considers the geometric and physical characteristics of the fractures, as well as the interactions between the fractures and matrix pores, to accurately assess the cementation index of intersecting dual fractures in dual-porosity reservoirs. The development of such a model would help improve the accuracy of reservoir fluid saturation assessments, optimize oil and gas field development strategies, increase oil and gas recovery rates, and reduce development costs, possessing significant practical application value and broad market prospects. Natural rocks contain more than just two fractures; existing technologies still fail to address the case of three, four, and even multiple fractures. The present invention aims to address the cementation index calculation process for two-dimensional rocks containing multiple fractures, enabling rapid calculation of the cementation index for such rocks.

[0076] The embodiments of the present invention are further described below with reference to the accompanying drawings.

[0077] On the one hand, the embodiment of the present invention provides a method for evaluating the Archie cementation index of a two-dimensional multi-fracture rock, referring to Figure 1 The Archie cementation index evaluation method for two-dimensional multi-fracture rock includes the following steps:

[0078] S100, obtaining crack data;

[0079] S200, constructing a two-dimensional rock model of a dual-porosity medium containing multiple fractures based on the fracture data;

[0080] S300, obtaining the resistivity of the segmentation module according to the two-dimensional rock model of the dual-porosity medium containing multiple fractures;

[0081] S400, obtaining the resistivity of the entire rock module according to the resistivity of the segmented module;

[0082] S500. Based on the resistivity of the entire rock module, the Archie cementation index is obtained.

[0083] Acquiring crack data in S100 disclosed in an embodiment of the present invention includes the following steps:

[0084] S110, obtaining the position of the crack intersection;

[0085] S120, obtaining an angle between the crack and the horizontal line;

[0086] S130 , obtaining crack data according to the position of the crack intersection and the angle between the crack and the horizontal line.

[0087] S200 disclosed in the embodiment of the present invention constructs a two-dimensional rock model of a dual-porosity medium containing multiple fractures based on fracture data, including the following steps:

[0088] S210, based on the fracture data, if there are double intersecting fractures, establish a two-dimensional rock model of a double-fracture double-porosity medium with the intersection of the double fractures as the model center;

[0089] S220, based on the crack data, if the number of cracks is greater than two, performing translation processing on the cracks until all cracks intersect at the same point, thereby obtaining a multi-crack intersection point;

[0090] S230, establishing a two-dimensional rock model of a multi-fracture dual-porosity medium with the intersection of the multiple fractures as the model center;

[0091] S240 , obtaining a two-dimensional rock model of a dual-porosity medium with multiple fractures based on the two-dimensional rock model of the dual-porosity medium with multiple fractures and the two-dimensional rock model of the dual-porosity medium with multiple fractures.

[0092] S300 disclosed in an embodiment of the present invention obtains the resistivity of a segmentation module based on a two-dimensional rock model of a dual-porosity medium containing multiple fractures, including the following steps:

[0093] S310, performing multiple rounds of segmentation processing based on the two-dimensional rock model of the dual-porosity medium with multiple fractures. In the first round of segmentation processing, the following steps are included:

[0094] S311, establishing a first vertical dividing line and a first horizontal dividing line to obtain a first dividing module group, the first dividing module group including four different first dividing modules; the intersection of the first vertical dividing line and the first horizontal dividing line coincides with the center of the two-dimensional rock model of the dual-porosity medium containing multiple fractures;

[0095] S312: If there is only one crack in the first segmented module, calculate the resistivity of the first segmented module using the equivalent medium theory to obtain a first resistivity;

[0096] S313: If two different first segmentation modules are centrosymmetric, then their first resistivities are the same;

[0097] S320: In the nth round of segmentation processing, the following steps are included:

[0098] S321: If the number of cracks in the n-1th segmentation module is greater than one, establish an nth vertical segmentation line and an nth horizontal segmentation line for the n-1th segmentation module to obtain an nth segmentation module group, where the nth segmentation module group includes four different nth segmentation modules; the intersection of the nth vertical segmentation line and the nth horizontal segmentation line coincides with the center of the n-1th segmentation module;

[0099] S322, the cracks in the n-1th segmentation module are translated or moved symmetrically along the nth vertical segmentation line until all the cracks in the n-1th segmentation module intersect at the center of the n-1th segmentation module and an nth segmentation module has only one crack;

[0100] S323, calculating the resistivity of the nth segmentation module having only one crack to obtain the nth resistivity;

[0101] S324, wherein n is an integer greater than or equal to two;

[0102] S330 : Obtain the resistivity of each segmentation module according to the first resistivity and the nth resistivity.

[0103] As an optional implementation manner, the equivalent medium theory of the embodiment of the present invention includes the Maxwell-Garnett mixing rule.

[0104] In step S312 disclosed in the embodiment of the present invention, if there is only one crack in the first segmentation module, the resistivity of the first segmentation module is calculated using the equivalent medium theory to obtain a first resistivity. The formula used includes:

[0105] R Afβ =R w F Afβ ;

[0106] R Dfβ =R w F Dfβ ;

[0107] R Afβ =R Dfβ ;

[0108] Among them, R AfβRepresents the first resistivity of module A; R Dfβ represents the first resistivity of module D; module A and module D are different first segmentation modules; module A and module D are symmetrical in center and both contain a crack with an inclination angle of β; F Afβ Represents the formation factor of module A; R w Indicates the resistivity of formation water; F Dfβ Indicates the formation factor of the D module.

[0109] S400 disclosed in the embodiment of the present invention obtains the resistivity of the entire rock module based on the resistivity of the segmentation module, including the following steps:

[0110] S410. Calculate the resistivity of the entire rock module based on the resistivity of each segmented module using the resistor series-parallel rule.

[0111] The S500 disclosed in the embodiment of the present invention obtains the Archie cementation index based on the resistivity of the entire rock module, including the following steps:

[0112] S510. Based on the resistivity of the entire rock module and in combination with the Archie formula, the Archie cementation index is calculated and derived.

[0113] The method for evaluating the Archie cementation index of two-dimensional multi-fracture rock disclosed in an embodiment of the present invention further includes the following steps:

[0114] S600, obtaining matrix porosity data;

[0115] S700, obtaining fracture porosity data;

[0116] S800: Analyze the changes of matrix porosity data and fracture porosity data to Archie cementation index to obtain cementation index change analysis data.

[0117] As an optional implementation, refer to Figure 2 The embodiment of the present invention provides a method for quickly calculating the cementation index (Archi cementation index) of a two-dimensional multi-fracture rock, comprising the following steps:

[0118] A. Construct a two-dimensional rock model of dual-porosity media with multiple fractures;

[0119] B. Conductivity calculation and processing method for each module of a two-dimensional rock model of dual-porosity media with multiple fractures;

[0120] C. Calculation steps for the cementation index of a two-dimensional rock model of dual-porosity media with multiple fractures;

[0121] D. Simulate and analyze the characteristics of cementation index under different physical conditions.

[0122] Step A includes: Figure 3It is a two-dimensional rock model of double-fracture double-porosity medium. By analogy with the two-dimensional rock model of double-fracture double-porosity medium, a two-dimensional rock model of double-porosity medium with multiple fractures is constructed (e.g. Figure 4 and Figure 5 shown), where Figure 4 represents a two-dimensional rock model with three fractures and two porosities, Figure 5 Represents a two-dimensional model of dual-porosity media with four fractures. The two-dimensional rock model of dual-porosity media with multiple fractures refers to the two-dimensional model of dual-porosity media with three fractures and the two-dimensional model of dual-porosity media with four fractures.

[0123] for Figure 3 and Figure 4 (a) to (b) represent the translation of the fractures, which translates the fractures to the center point where they intersect the two-dimensional rock model. This operation does not change the conductive properties of the rock. Figure 5 Omit the crack treatment process.

[0124] Step B includes: in order to more conveniently calculate the conductivity of each module, the rock module is processed based on step A. The processing method is to process the crack symmetrically about the two dotted lines (vertical dividing line and horizontal dividing line) in the rock sample (the two dotted lines refer to the two dotted lines that divide the rock sample into A, B, C, and D). The operation is stopped when the module A and module D parts in the rock module are processed until only one crack remains. Figure 6 and Figure 7 As shown. After processing, the A module part only contains one crack, so the effective conductivity of the A module part can be directly calculated using the Maxwell-Garnett mixing rule. The D module part and the A module part are centrally symmetrical, so the effective conductivity of the D module part is the same as that of the A module part. The effective conductivity processing method of the B module part is that for the three-cross cracks, there are still two cracks left in the B module part. Therefore, the present invention continues to perform translation and symmetry processing on the two cracks in the B module part, and the processing method is as follows: Figure 8 As shown, processed to Figure 8 After the e module part, there is only one crack left in each module, so the Maxwell-Garnett mixing rule can be used to directly calculate the effective conductivity of each module. What needs to be noted here is that after the B module is divided into four modules, after the resistivity of each module part is obtained, the resistivity of the four module parts needs to be calculated according to the series-parallel rule, and finally the effective resistivity of the B module part is obtained. Among the three cracks, the 1.1 module part and the 1.2 module part are in series, the 1.3 module part and the 1.4 module part are also in series, the 1.1, 1.2 and 1.3, 1.4 module parts are in parallel, and the C module part and the B module part are also centrally symmetrical, so the processing method is the same as the B module part. The four-crack processing method imitates the three-crack processing idea, the difference is that the four cracks need to be processed once more, such as Figure 9 As shown in the figure, the resistivity calculation of each module is the same as that of the three-crack treatment. The multi-crack treatment method is also the same, imitating the treatment method of three and four cracks.

[0125] Step C includes: Calculating the cementation index of a two-dimensional rock module with three cross fractures: first, using the Maxwell-Garnett mixing rule to calculate the resistivity of each module individually, then using the series-parallel resistance law to calculate the resistivity of the entire rock module, and finally using the Archie formula to calculate the cementation index of the entire rock module. The specific solution formula is as follows:

[0126] R Afβ =R w F Afβ (1)

[0127] R Dfβ =R w F Dfβ (2)

[0128] R Afβ =R Dfβ (3)

[0129] Where R in formula (1) Afβ express Figure 6 Module A contains a crack with a dip angle of β, and the resistivity of F Afβ Indicates that module A contains a formation factor with a fracture angle of β, R w represents the resistivity of formation water, R in (2) Dfβ express Figure 6 The resistivity of the D module contains a crack with a dip angle of β, F Dfβ It indicates that the D module contains a formation factor with a fracture dip angle of β.

[0130]

[0131] R 1.1 1.2 =R 1.1fγ +R 1.2fα (5)

[0132] R 1.3 1.4 =R 1.3fα +R 1.4fγ (6)

[0133] R 1.1fγ =R 1.4fγ ,R 1.2fα =R 1.3fα (7)

[0134] Where R in formula (4) B express Figure 6 The total resistivity of module B, R 1.11.2 express Figure 8 The resistivity of the series connection of module 1.1 and module 1.2 in (e), R 1.31.4 express Figure 8 The resistivity of the 1.3 module and the 1.4 module in series in (e). 1.1fγ and R 1.2fα Respectively Figure 8 The resistivity and Figure 8 Module 1.2 contains the resistivity of a crack with an inclination angle of α.

[0135]

[0136] Where R in formula (8) 1.1γ＝0 represents the resistivity when the inclination angle γ = 0, represents the fracture porosity with fracture dip angle γ, and R0 represents the resistivity of the saturated water matrix. 1.1γ＝90 represents the resistivity when the inclination angle γ = 90. F in equations (10) and (11) 1.1γ＝0 and F 1.1γ＝90 They represent the formation factors when the dip angle γ = 0 and the formation factors when the dip angle γ = 90, respectively. represents the matrix porosity of the rock, and mb represents the cementation index of the rock matrix. 1.1fγ Indicates the resistivity when the inclination angle γ is any degree.

[0137] R 1.1fγ =R w F 1.1fγ (13)

[0138] R 1.2fγ =R w F 1.2fα (14)

[0139] R 1.3fγ =R w F 1.3fα (15)

[0140] R 1.4fγ =R w F 1.4fγ (16)

[0141] The meanings of the symbols and letters here have been explained in the previous text and will not be repeated here.

[0142]

[0143] R C =R B,R A =R D (19)

[0144] Equations (17) and (18) can be used to calculate the resistivity of module B. Then, according to the centrosymmetric law, equation (19) can be obtained. At this point, the resistivity of each module has been solved.

[0145] Let F Afβ =F Dfβ =a,

[0146]

[0147] R AB =R A +R B =R w (a+b) (22)

[0148] R CD =R C +R D =R w (a+b) (23)

[0149]

[0150] in

[0151]

[0152] Equations (20) through (27) represent the final step in calculating the cementation index. For ease of calculation, variable substitution is performed in Equation (20). Equations (22) through (24) calculate the resistivity of the entire rock module, applying the series-parallel law of resistivity. This concludes the calculation of the cementation index for the two-dimensional rock module with three intersecting fractures. The following steps demonstrate the calculation of the cementation index for the two-dimensional rock module with four intersecting fractures:

[0153] R Afβ =R w F Afβ

[0154] R Dfβ =R w F Dfβ

[0155] R Afβ =R Dfβ

[0156]

[0157] R 1.1fα =R 1.4fα

[0158] R 2.12.2 = R 2.1fγ + R 2.2fθ

[0159] R 2.32.4 = R 2.3fθ + R 2.4fγ

[0160] R 2.1fγ = R 2.4fγ

[0161] R 2.2fθ = R 2.3fθ

[0162]

[0163] R 1.1fα = R w F 1.1fα

[0164] R​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​

[0176]

[0177] The above are the calculation steps of the cementation index of the two-dimensional rock model with four cross fractures. The meaning and content of each symbol and letter refer to the derivation process of the two-dimensional rock model with three cross fractures.

[0178] The above derivations of the cementation index of the two-dimensional rock model with three cross fractures and the two-dimensional rock model with four cross fractures can be extended to the cementation index of the two-dimensional rock model with multiple fractures. The calculation formula of the cementation index is:

[0179] in

[0180]

[0181]

[0182] This concludes the derivation of the cementation index formula for the two-dimensional rock model with cross-multiple fractures.

[0183] Step D includes: This part will explore the effects of matrix porosity and fracture porosity on the cementation index of the cross-three-fracture 2D rock model and the cross-four-fracture 2D rock model, and generate images to obtain the effects of matrix porosity and fracture porosity on the cementation index of the cross-multiple-fracture 2D rock model. Figures 10(a), 10(b), 10(c), and 10(d) show the effects of matrix porosity on the cementation index of the cross-three-fracture 2D rock model; Figures 11(a), 11(b), 11(c), and 11(d) show the effects of fracture porosity on the cementation index of the cross-three-fracture 2D rock model; and Figures 12(a), 12(b), 12(c), and 12(d) show the effects of matrix porosity on the cementation index of the cross-four-fracture 2D rock model. In the figures, ɑ represents the fracture inclination (the angle between the fracture and the horizontal plane), and Δ represents the fracture azimuth (the angle between the fracture projection on the horizontal plane and the north direction).

[0184] The present invention has the following beneficial effects: its novel computational model accurately assesses the cementation index of intersecting multiple fractures in dual-porosity reservoirs, thereby improving the accuracy of reservoir fluid saturation assessments. This model considers the influence of factors such as matrix porosity and fracture porosity, making the assessment results more consistent with actual reservoir conditions. Applications in actual reservoirs have demonstrated that the model provides more reliable assessment results than traditional methods.

[0185] In addition, the model of the present invention also has the following beneficial effects:

[0186] Improved assessment accuracy: By considering the geometric characteristics and physical properties of fractures, the model of the present invention can provide a more accurate assessment of the cementation index than traditional methods.

[0187] Strong adaptability: This model is applicable to dual-porosity reservoirs with various fracture morphologies, including intersecting multiple fractures, and has wide applicability.

[0188] Easy to operate: The model's calculation process is based on existing geological and logging data and is easy to operate and implement.

[0189] Significant economic benefits: Accurate assessment of the cementation index helps optimize oil and gas field development strategies, increase oil and gas recovery rates, and reduce development costs.

[0190] On the other hand, an embodiment of the present invention also provides an Archie cementation index evaluation device for two-dimensional multi-fracture rocks, including a memory, a processor, and a computer program stored in the memory and runnable on the processor. When the processor executes the computer program, it implements the Archie cementation index evaluation method for two-dimensional multi-fracture rocks as described above.

[0191] The processor and the memory can be connected via a bus or other means. The memory, as a non-transient computer-readable storage medium, can be used to store non-transient software programs and non-transient computer executable programs. In addition, the memory may include a high-speed random access memory and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some embodiments, the memory may optionally include a memory remotely arranged relative to the processor, and these remote memories may be connected to the processor via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0192] On the other hand, an embodiment of the present invention further provides a computer-readable storage medium storing computer-executable instructions for enabling a computer to execute the aforementioned Archie cementation index evaluation method for two-dimensional multi-fracture rock.

[0193] Those skilled in the art will appreciate that all or some of the steps and systems in the method disclosed above can be implemented as software, firmware, hardware, and appropriate combinations thereof. Some physical components or all physical components can be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or implemented as hardware, or implemented as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, and the computer-readable medium can include computer storage media (or non-transitory media) and communication media (or temporary media). As known to those skilled in the art, the term computer storage media is included in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data) and is volatile and non-volatile, removable, and non-removable. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory, or other memory technology, CD-ROM, digital versatile disks (DVD), or other optical disk storage, magnetic cassettes, magnetic tapes, disk storage, or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, as is well known to those skilled in the art, communication media typically embodies computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0194] The preferred embodiments of the present invention are described above with reference to the accompanying drawings, but are not intended to limit the scope of the present invention. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and essence of the present invention should be within the scope of the present invention.

Claims

1. A method for evaluating the Archie cementation index of two-dimensional multi-fracture rock, characterized in that: The method for evaluating the Archie cementation index of two-dimensional multi-fracture rock comprises the following steps: Obtain crack data; constructing a two-dimensional rock model of a dual-porosity medium containing multiple fractures based on the fracture data; Obtaining the resistivity of the segmentation module according to the two-dimensional rock model of the dual-porosity medium containing multiple fractures; Obtaining the resistivity of the entire rock module according to the resistivity of the segmentation module; Based on the resistivity of the entire rock module, the Archie cementation index is obtained.

2. The Archie cementation index evaluation method for two-dimensional multi-fracture rock according to claim 1, characterized in that: The method of obtaining crack data comprises the following steps: Get the location of the crack intersection; Get the angle between the crack and the horizontal line; Crack data are obtained according to the positions of the crack intersections and the angles between the cracks and the horizontal line.

3. The method for evaluating the Archie cementation index of two-dimensional multi-fracture rock according to claim 1, characterized in that: The method of constructing a two-dimensional rock model of a dual-porosity medium containing multiple fractures based on the fracture data comprises the following steps: According to the fracture data, if there are double intersecting fractures, a two-dimensional rock model of double fractures and double porosity media is established with the intersection of the double fractures as the model center; According to the crack data, if the number of cracks is greater than two, the cracks are translated until all the cracks intersect at the same point, thereby obtaining a multi-crack intersection point; Taking the intersection of the multiple fractures as the model center, a two-dimensional rock model of the multiple fractures and dual-porosity medium is established; A two-dimensional rock model of a dual-porosity medium containing multiple fractures is obtained according to the two-dimensional rock model of the dual-fracture dual-porosity medium and the two-dimensional rock model of the multi-fracture dual-porosity medium.

4. The method for evaluating the Archie cementation index of two-dimensional multi-fracture rock according to claim 1, wherein: The method of obtaining the resistivity of the segmentation module according to the two-dimensional rock model of the dual-porosity medium containing multiple fractures comprises the following steps: Based on the two-dimensional rock model of the dual-porosity medium with multiple fractures, multiple rounds of segmentation processing are performed. In the first round of segmentation processing, the following steps are performed: Establishing a first vertical dividing line and a first horizontal dividing line to obtain a first dividing module group, wherein the first dividing module group includes four different first dividing modules; an intersection of the first vertical dividing line and the first horizontal dividing line coincides with a center of the two-dimensional rock model of the dual-porosity medium containing multiple fractures; If there is only one crack in the first segmentation module, the resistivity of the first segmentation module is calculated using the equivalent medium theory to obtain a first resistivity; If two different first segmentation modules are centrosymmetric, their first resistivities are the same; In the nth round of segmentation processing, it includes: If the number of cracks in the n-1th segmentation module is greater than one, an nth vertical segmentation line and an nth horizontal segmentation line are established for the n-1th segmentation module to obtain an nth segmentation module group, wherein the nth segmentation module group includes four different nth segmentation modules; the intersection of the nth vertical segmentation line and the nth horizontal segmentation line coincides with the center of the n-1th segmentation module; The cracks in the n-1th segmentation module are translated or symmetrically moved along the nth vertical segmentation line until all the cracks in the n-1th segmentation module intersect at the center of the n-1th segmentation module and a certain nth segmentation module has only one crack; Calculating the resistivity of the nth segmented module having only one crack to obtain an nth resistivity; Wherein n is an integer greater than or equal to two; The resistivity of each segmentation module is obtained according to the first resistivity and the nth resistivity.

5. The method for evaluating the Archie cementation index of two-dimensional multi-fracture rock according to claim 4, characterized in that: If there is only one crack in the first segmentation module, the resistivity of the first segmentation module is calculated using the equivalent medium theory to obtain a first resistivity. The formula used includes: R Afβ =R w F Afβ ; R Dfβ =R w F Dfβ ; R Afβ =R Dfβ ; Among them, R Afβ Represents the first resistivity of module A; R Dfβ represents the first resistivity of the D module; the A module and the D module are different first segmentation modules; the A module and the D module are centrally symmetrical and both contain a crack with an inclination angle of β; F Afβ Represents the formation factor of the A module; R w Indicates the resistivity of formation water; F Dfβ Represents the formation factor of the D module.

6. The method for evaluating the Archie cementation index of two-dimensional multi-fracture rock according to claim 1, characterized in that: The step of obtaining the resistivity of the entire rock module according to the resistivity of the segmentation module comprises the following steps: According to the resistivity of each segmented module, the resistivity of the entire rock module is calculated using the series and parallel connection rule of resistors.

7. The method for evaluating the Archie cementation index of two-dimensional multi-fracture rock according to claim 1, characterized in that: Obtaining the Archie cementation index according to the resistivity of the entire rock module comprises the following steps: The Archie cementation index is calculated based on the resistivity of the entire rock module and combined with the Archie formula.

8. The method for evaluating the Archie cementation index of two-dimensional multi-fracture rock according to claim 1, wherein: The method for evaluating the Archie cementation index of two-dimensional multi-fracture rock further includes the following steps: Obtain matrix porosity data; Obtain fracture porosity data; The changes of the matrix porosity data and the fracture porosity data in response to the Archie cementation index are analyzed to obtain cementation index change analysis data.

9. An Archie cementation index evaluation device for two-dimensional multi-fracture rock, characterized in that: The method comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the method for evaluating the Archie cementation index of two-dimensional multi-fracture rock according to any one of claims 1 to 8 is implemented.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are used to enable a computer to execute the Archie cementation index evaluation method for two-dimensional multi-fracture rock according to any one of claims 1 to 8.

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