Tight sandstone reservoir fluid type identification method, system, equipment and medium

Abstract

The invention provides a tight sandstone reservoir fluid type identification method, system, equipment and medium, and the method comprises the following steps: obtaining a dynamic Young modulus based on the longitudinal wave, transverse wave and density logging information of a target well, and converting the dynamic Young modulus into a static Young modulus; establishing a pure water linear resistivity relational expression based on the static Young modulus, the deep resistivity and logging calculation porosity data, and obtaining saturated water resistivity based on the pure water linear resistivity relational expression; the stratum equivalent resistivity is obtained based on the relational expression of the static Young modulus and the logging resistivity; the reservoir fluid type is judged based on the stratum equivalent resistivity and the saturated water resistivity; the novel method for judging the fluid type of the tight sandstone reservoir is easy to operate, a chart is established through the specific value of the resistivity to the static Young modulus and the porosity, a calculation formula of a pure water line on a region is achieved, and the fluid type of the tight sandstone reservoir is judged by comparing the specific value of the resistivity to the static Young modulus of a single well.

Description

Technical Field

[0001] The present invention belongs to the technical field of well logging for oil and natural gas exploration, and specifically relates to a method, system, equipment and medium for identifying the type of fluid in a tight sandstone reservoir. Background Art

[0002] In the process of oil and gas exploration, the use of resistivity data to judge reservoir fluid is the most important means. However, when the tight sandstone reservoir is under strong compressive stress, the measured resistivity is affected by the horizontal stress difference, and the characteristics of high resistivity water layer often appear. Conventional porosity and resistivity charts cannot distinguish the difference between gas and water layers.

[0003] After searching, patent CN106285651B proposes a method for distinguishing the fluid properties of a tight sandstone formation, including: first determining the maximum horizontal principal stress and the minimum horizontal principal stress in the tight sandstone formation, and then determining the horizontal principal stress difference according to the maximum horizontal principal stress and the minimum horizontal principal stress, the horizontal principal stress difference being the difference between the maximum horizontal principal stress and the minimum horizontal principal stress; establishing a relationship between the apparent resistivity of the tight sandstone formation and the horizontal principal stress difference, and then determining the true resistivity of the tight sandstone formation according to the horizontal principal stress difference, the apparent resistivity of the tight sandstone formation and the relationship, and finally determining the fluid properties of the tight sandstone formation according to the true resistivity of the tight sandstone formation, which can effectively improve the accuracy of judging the fluid properties of the tight sandstone formation.

[0004] Patent CN106802433B proposes a rock formation resistivity correction method and device, including: measuring the resistance of the core under different pressure differences under simulated stress; wherein the simulated stress includes: simulated tensile stress or simulated compressive stress; further, according to the resistance of the core under different pressure differences, the resistivity of the core under different pressure differences is determined, and according to the resistivity of the core under different pressure differences, the resistivity correction coefficient under simulated stress is determined; further, according to the resistivity correction coefficient under simulated stress, the measured rock formation resistivity under the corresponding stress type is corrected. By correcting the measured rock formation resistivity under the corresponding stress type according to the resistivity correction coefficient under simulated stress, the corrected rock formation resistivity is more accurate, so that the physical properties of the actual tight sandstone reservoir can be accurately determined according to the corrected rock formation resistivity.

[0005] Literature such as "The influence of geostress in tight sandstone reservoirs on resistivity logging", "Correction method of well logging resistivity under strong compressive stress conditions in Kuqa foreland basin", "Experimental study on the influence of geostress on resistivity under high temperature and high pressure", "The influence mechanism of geostress on the resistivity of tight sandstone and the establishment of geostress correction resistivity model - taking the tight sandstone reservoir of Bashijiqik Formation in Keshen block as an example" etc., through resistivity measurement experiments and numerical simulation analysis under different stress conditions, believe that under the background of strong compressive stress, the resistivity increases with the increase of horizontal stress difference, and establish a corresponding correction method based on this.

[0006] The patents and literature mentioned in the search all show that resistivity cannot reflect formation fluid information under the background of strong compression stress, and corresponding corrections are required to accurately reflect formation fluid. The method mentioned in the above materials has solved the problem of fluid identification based on resistivity data in some wells under strong compression stress conditions during use. However, after being applied on an actual well scale, it was found that this method could not meet production needs. Analysis of this method found that there is a great relationship between the horizontal stress difference and the burial depth of the reservoir. When the burial depth of the reservoir in the same block is very different, or the burial depth of the reservoir in different blocks is very different, the magnitude of the horizontal stress difference is mainly affected by the depth. When the horizontal stress difference is used to correct the resistivity or to establish a fluid identification plate with the resistivity, the accuracy of fluid identification using this method is low and cannot meet the needs of fine reservoir evaluation. Summary of the invention

[0007] In view of the problems existing in the prior art, the present invention provides a method, system, equipment and medium for identifying the fluid type in a tight sandstone reservoir, which improves the accuracy of the fluid type in the tight sandstone reservoir.

[0008] The present invention is achieved through the following technical solutions:

[0009] A method for identifying fluid types in tight sandstone reservoirs comprises the following steps:

[0010] The dynamic Young's modulus is obtained based on the P-wave, S-wave and density logging data of the target well, and is converted into the static Young's modulus;

[0011] Based on the static Young's modulus, deep resistivity and logging porosity data, the pure water line resistivity relationship is established, and the water-saturated resistivity is obtained based on the pure water line resistivity relationship;

[0012] The equivalent resistivity of the formation is obtained based on the relationship between the static Young's modulus and the logging resistivity;

[0013] The reservoir fluid type is determined based on the equivalent resistivity of the formation and the resistivity of the saturated water.

[0014] Furthermore, the process of obtaining the dynamic Young's modulus based on the longitudinal wave, shear wave and density logging data of the target well and converting the dynamic Young's modulus into the static Young's modulus is as follows:

[0015] The dynamic Young's modulus E is calculated using the P-wave, S-wave and density logging data of this well. d :

[0016]

[0017] Among them, E d is the dynamic Young's modulus calculated by logging, ρ is the density, is the shear wave time difference, is the longitudinal wave time difference;

[0018] Collect the dynamic and static Young's modulus experimental data of the target well's study area and establish the dynamic and static Young's modulus conversion formula:

[0019] E s =A*E d +B (2)

[0020] Among them, E s is the static Young's modulus calculated from well logging, E d is the dynamic Young's modulus calculated by well logging, and A and B are empirical coefficients.

[0021] Furthermore, the process of establishing a pure water line resistivity relationship based on static Young's modulus, deep resistivity and logging calculated porosity data, and obtaining saturated water resistivity based on the pure water line resistivity relationship is as follows:

[0022] According to Archie's formula, there is a functional relationship between water-saturated resistivity, porosity and formation water mineralization.

[0023]

[0024] After the formation is subjected to compressive stress, the porosity remains basically unchanged because the fluid in the pores is incompressible, and the pore structure changes greatly. At this time, the water-saturated resistivity is expressed as:

[0025]

[0026] According to the ratio of formula (3) and formula (4),

[0027]

[0028] The logging data of the water-producing section in the target well area are selected to establish the relationship between the static Young's modulus and resistivity:

[0029] R 0c =f(E s )=A2*exp(A3*Es ) (6)

[0030] Combining equations (5) and (6), we can obtain the calculation formula for the equivalent resistivity of saturated water without stress:

[0031]

[0032] Among them, R0 is the resistivity of saturated water without extrusion, R 0c is the resistivity of saturated water under compression, R w is the formation water resistivity, is the porosity, m is the formation cementation index, which is determined based on the regional rock electrical experimental data, Δm is the change in pore structure after compression, and E s is the static Young's modulus, a is the rock electrical experimental coefficient, which is determined by rock electrical experiments, and A1, A2, A3, A4, and A5 are regional empirical coefficients.

[0033] Furthermore, by sorting out the collected high-temperature and high-pressure rock electrical experimental data, the water-saturated resistivity, analytical porosity and static Young's modulus calculated by logging at the corresponding depth point are obtained. The process of obtaining the parameters in formula (7) by performing nonlinear fitting of the ternary function using the least squares method is as follows:

[0034]

[0035] Among them, R0 is the resistivity of saturated water without compression.

[0036] Furthermore, the process of obtaining the equivalent resistivity of the formation based on the relationship between the static Young's modulus and the logging resistivity is:

[0037] According to the relationship between the static Young's modulus of the target well and the logging resistivity, the equivalent resistivity of the formation is calculated.

[0038] R tc =A5*exp(A6*E s ) (9)

[0039] Among them, E s is the static Young's modulus, R t is the true resistivity of the formation after correction, R tc is the equivalent apparent resistivity of the formation, and A5 and A6 are regional empirical coefficients.

[0040] Furthermore, the determination process of the reservoir fluid type based on the formation equivalent resistivity and the water-saturated resistivity is as follows:

[0041] According to the static Young's modulus and the equivalent resistivity of the formation, the true resistivity of the formation is obtained;

[0042] If the true resistivity of the formation is greater than the water-saturated resistivity, the reservoir fluid type is an oil and gas layer, otherwise the reservoir fluid type is a water layer.

[0043] Furthermore, the process of obtaining the true resistivity of the formation according to the static Young's modulus and the equivalent resistivity of the formation is:

[0044]

[0045] Among them, E s is the static Young's modulus, R t is the true resistivity of the formation after correction, R tc is the formation equivalent apparent resistivity, R t ′ is the logging resistivity, A5 and A6 are the regional empirical coefficients.

[0046] A tight sandstone reservoir fluid type identification system, comprising:

[0047] The first processing module is used to obtain the dynamic Young's modulus based on the longitudinal wave, shear wave and density logging data of the target well, and convert the dynamic Young's modulus into a static Young's modulus;

[0048] The second processing module is used to establish a pure water line resistivity relationship based on static Young's modulus, deep resistivity and logging porosity data, and obtain saturated water resistivity based on the pure water line resistivity relationship;

[0049] The third processing module is used to obtain the equivalent resistivity of the formation based on the relationship between the static Young's modulus and the logging resistivity;

[0050] The judgment module is used to judge the reservoir fluid type based on the size of the formation equivalent resistivity and the saturated water resistivity.

[0051] A computer device 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 steps of a method for identifying fluid types in a tight sandstone reservoir are implemented.

[0052] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of a method for identifying fluid types in a tight sandstone reservoir.

[0053] Compared with the prior art, the present invention has the following beneficial technical effects:

[0054] The present invention provides a method, system, equipment and medium for identifying the type of fluid in a tight sandstone reservoir, comprising the following steps: obtaining a dynamic Young's modulus based on longitudinal wave, shear wave and density logging data of a target well, and converting the dynamic Young's modulus into a static Young's modulus; establishing a pure water line resistivity relationship based on the static Young's modulus, deep resistivity and logging calculated porosity data, and obtaining the water-saturated resistivity based on the pure water line resistivity relationship; obtaining the formation equivalent resistivity based on the static Young's modulus and logging resistivity relationship; judging the reservoir fluid type based on the size of the formation equivalent resistivity and the water-saturated resistivity; the new method for judging the type of fluid in a tight sandstone reservoir proposed by the present invention is simple to operate, and a chart is established by using the ratio of resistivity to static Young's modulus and porosity to realize the calculation formula of the pure water line in the region, and the tight sandstone reservoir fluid type is judged by comparing the difference in the ratio of resistivity to static Young's modulus of a single well. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is a flow chart of a method for identifying fluid types in tight sandstone reservoirs according to an embodiment of the present invention;

[0056] Figure 2 This is a conversion relationship diagram of the dynamic and static Young's modulus in an embodiment of the present invention;

[0057] Figure 3 This is a graph showing the relationship between the static Young's modulus and resistivity of a water well tested in an embodiment of the present invention;

[0058] Figure 4 This is a relationship diagram for calculating the resistivity of a pure water layer based on rock electrical experiments in an embodiment of the present invention;

[0059] Figure 5 This is a diagram showing the results of identifying the reservoir fluid type of the XX well in an embodiment of the present invention. DETAILED DESCRIPTION

[0060] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0061] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0062] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0063] The present invention provides a method for identifying the fluid type in a tight sandstone reservoir. Figure 1 As shown, the following steps are included:

[0064] The dynamic Young's modulus is obtained based on the P-wave, S-wave and density logging data of the target well, and is converted into the static Young's modulus;

[0065] Based on the static Young's modulus, deep resistivity and logging porosity data, the pure water line resistivity relationship is established, and the water-saturated resistivity is obtained based on the pure water line resistivity relationship;

[0066] The equivalent resistivity of the formation is obtained based on the relationship between the static Young's modulus and the logging resistivity;

[0067] The reservoir fluid type is determined based on the equivalent resistivity of the formation and the resistivity of the saturated water.

[0068] It should be noted that before determining the reservoir fluid type, this application needs to collect and organize the logging data and rock physical data that need to be studied, where the logging data include P-wave time difference curves, S-wave time difference curves, lithology density curves, deep resistivity curves, and logging-calculated porosity curves; the rock physical data include dynamic and static Young's modulus experimental data and high-temperature and high-pressure rock electrical data of the area.

[0069] It should be further explained that the static Young's modulus can characterize the stress-strain relationship of the material along the load direction. Under the background of strong compressive stress, the static Young's modulus can reflect the formation stress and deformation, has a good relationship with the horizontal stress difference, and the calculation of the static Young's modulus does not need to consider the influence of depth.

[0070] Therefore, in order to address the problem of low accuracy of the fluid identification method based on horizontal stress difference and resistivity in tight sandstone reservoirs under strong compressive stress, the present invention proposes, on the basis of accurate calculation of static Young's modulus and porosity, establishing a fluid identification method based on the comparison of resistivity after static Young's modulus correction and pure water line resistivity under stress background conditions, thereby improving the accuracy of fluid types in tight sandstone reservoirs.

[0071] Preferably, the process of obtaining the dynamic Young's modulus based on the longitudinal wave, shear wave and density logging data of the target well and converting the dynamic Young's modulus into the static Young's modulus is:

[0072] The dynamic Young's modulus E is calculated using the P-wave, S-wave and density logging data of this well. d :

[0073]

[0074] Among them, E d is the dynamic Young's modulus calculated by logging, ρ is the density, is the shear wave time difference, is the longitudinal wave time difference;

[0075] like Figure 2 As shown in the figure, the dynamic and static Young's modulus experimental data of the target well's study area are collected, and the dynamic and static Young's modulus conversion formula is established:

[0076] E s =A*E d +B (2)

[0077] Among them, E s is the static Young's modulus calculated from well logging, E d is the dynamic Young's modulus calculated by well logging, and A and B are empirical coefficients.

[0078] Preferably, the process of establishing a pure water line resistivity relationship based on static Young's modulus, deep resistivity and logging-calculated porosity data, and obtaining saturated water resistivity based on the pure water line resistivity relationship is:

[0079] According to Archie's formula, there is a functional relationship between water-saturated resistivity, porosity and formation water mineralization.

[0080]

[0081] After the formation is subjected to compressive stress, the porosity remains basically unchanged because the fluid in the pores is incompressible, and the pore structure changes greatly. At this time, the water-saturated resistivity is expressed as:

[0082]

[0083] According to the ratio of formula (3) and formula (4),

[0084]

[0085] The logging data of the water-producing section in the target well area are selected to establish the relationship between the static Young's modulus and resistivity:

[0086] R 0c =f(E s )=A2*exp(A3*E s ) (6)

[0087] Combining equations (5) and (6), we can obtain the calculation formula for the equivalent resistivity of saturated water without stress:

[0088]

[0089] Among them, R0 is the resistivity of saturated water without extrusion, R 0c is the resistivity of saturated water under compression, R w is the formation water resistivity, is the porosity, m is the formation cementation index, which is determined based on the regional rock electrical experimental data, Δm is the change in pore structure after compression, and E s is the static Young's modulus, a is the rock electrical experimental coefficient, which is determined by rock electrical experiments, and A1, A2, A3, A4, and A5 are regional empirical coefficients.

[0090] Preferably, according to Figure 3 The obtained relationship between the resistivity of the water layer and the static Young's modulus, combined with the rock electrical experimental data, can be used to obtain the relationship between the static Young's modulus, porosity, resistivity and the equivalent resistivity of the pure water line based on multivariate fitting, as shown in Figure 4 As shown in the figure, by sorting out the collected high-temperature and high-pressure rock electrical experimental data, the water-saturated resistivity, analytical porosity and static Young's modulus calculated by logging at the corresponding depth point are obtained, and the process of using the least squares method to perform nonlinear fitting of the ternary function to obtain the parameters in formula (7) is as follows:

[0091]

[0092] Among them, R0 is the resistivity of saturated water without extrusion,

[0093] Preferably, the process of obtaining the equivalent resistivity of the formation based on the relationship between the static Young's modulus and the logging resistivity is:

[0094] According to the relationship between the static Young's modulus of the target well and the logging resistivity, the equivalent resistivity of the formation is calculated.

[0095] R tc =A5*exp(A6*Es ) (9)

[0096] Among them, E s is the static Young's modulus, R t is the true resistivity of the formation after correction, R tc is the equivalent apparent resistivity of the formation, and A5 and A6 are regional empirical coefficients.

[0097] Preferably, the process of determining the reservoir fluid type based on the formation equivalent resistivity and the water-saturated resistivity is as follows:

[0098] According to the static Young's modulus and the equivalent resistivity of the formation, the true resistivity of the formation is obtained;

[0099] If the true resistivity of the formation is greater than the water-saturated resistivity, the reservoir fluid type is an oil and gas layer, otherwise the reservoir fluid type is a water layer.

[0100] Furthermore, the process of obtaining the true resistivity of the formation according to the static Young's modulus and the equivalent resistivity of the formation is:

[0101]

[0102] Among them, E s is the static Young's modulus, R t is the true resistivity of the formation after correction, R tc is the formation equivalent apparent resistivity, R t ′ is the logging resistivity, A5 and A6 are the regional empirical coefficients.

[0103] It should be noted that if Figure 5 As shown in the figure, the 8th track is a comparison between the pure water line resistivity calculated by this method and the true resistivity obtained by correction. When the corrected resistivity is greater than the pure water line resistivity, it is filled with light color, indicating air layer. When the corrected resistivity is less than the pure water line resistivity, it is filled with light color, indicating water. Figure 5 It can be seen that this section is filled with dark color as a whole, indicating that the reservoir type of this section is mainly water. The test confirms that the reservoir fluid type of this section is a gas-bearing water layer. The fluid type determined by this method is consistent with the test results, indicating the reliability of the method described in this application.

[0104] The present invention provides a tight sandstone reservoir fluid type identification system, comprising:

[0105] The first processing module is used to obtain the dynamic Young's modulus based on the longitudinal wave, shear wave and density logging data of the target well, and convert the dynamic Young's modulus into a static Young's modulus;

[0106] The second processing module is used to establish a pure water line resistivity relationship based on static Young's modulus, deep resistivity and logging porosity data, and obtain saturated water resistivity based on the pure water line resistivity relationship;

[0107] The third processing module is used to obtain the equivalent resistivity of the formation based on the relationship between the static Young's modulus and the logging resistivity;

[0108] The judgment module is used to judge the reservoir fluid type based on the size of the formation equivalent resistivity and the saturated water resistivity.

[0109] In another embodiment of the present invention, a computer device is provided, the computer device comprising a processor and a memory, the memory being used to store a computer program, the computer program comprising program instructions, and the processor being used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, and is specifically suitable for loading and executing one or more instructions in a computer storage medium to implement a corresponding method flow or corresponding function; the processor described in the embodiment of the present invention can be used for the operation of a method for identifying the type of fluid in a tight sandstone reservoir.

[0110] In another embodiment of the present invention, the present invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device for storing programs and data. It is understandable that the computer-readable storage medium here can include both the built-in storage medium in the computer device and the extended storage medium supported by the computer device. The computer-readable storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space, and these instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the corresponding steps of the method for identifying the type of fluid in a tight sandstone reservoir in the above embodiment.

[0111] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0112] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0113] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0114] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for identifying fluid types in tight sandstone reservoirs, characterized in that: The following steps are involved: The dynamic Young's modulus is obtained based on the P-wave, S-wave and density logging data of the target well, and is converted into the static Young's modulus; Based on the static Young's modulus, deep resistivity and logging porosity data, the pure water line resistivity relationship is established, and the water-saturated resistivity is obtained based on the pure water line resistivity relationship; The equivalent resistivity of the formation is obtained based on the relationship between the static Young's modulus and the logging resistivity; The reservoir fluid type is determined based on the equivalent resistivity of the formation and the resistivity of the saturated water.

2. A method for identifying fluid types in tight sandstone reservoirs according to claim 1, characterized in that: The process of obtaining the dynamic Young's modulus based on the longitudinal wave, shear wave and density logging data of the target well and converting the dynamic Young's modulus into the static Young's modulus is as follows: The dynamic Young's modulus E is calculated using the P-wave, S-wave and density logging data of this well. d : Among them, E d is the dynamic Young's modulus calculated by logging, ρ is the density, is the shear wave time difference, is the longitudinal wave time difference; Collect the dynamic and static Young's modulus experimental data of the target well's study area and establish the dynamic and static Young's modulus conversion formula: E s =A*E d +B (2) Among them, E s is the static Young's modulus calculated from well logging, E d is the dynamic Young's modulus calculated by well logging, and A and B are empirical coefficients.

3. A method for identifying fluid types in tight sandstone reservoirs according to claim 1, characterized in that: The process of establishing the pure water line resistivity relationship based on the static Young's modulus, deep resistivity and logging calculated porosity data, and obtaining the saturated water resistivity based on the pure water line resistivity relationship is as follows: According to Archie's formula, there is a functional relationship between water-saturated resistivity, porosity and formation water mineralization. After the formation is subjected to compressive stress, the porosity remains basically unchanged because the fluid in the pores is incompressible, and the pore structure changes greatly. At this time, the water-saturated resistivity is expressed as: According to the ratio of formula (3) and formula (4), The logging data of the water-producing section in the target well area are selected to establish the relationship between the static Young's modulus and resistivity: R 0c =f(E s )=A2*exp(A3*E s ) (6) Combining equations (5) and (6), we can obtain the calculation formula for the equivalent resistivity of saturated water without stress: Among them, R0 is the resistivity of saturated water without extrusion, R 0c is the resistivity of saturated water under compression, R w is the formation water resistivity, is the porosity, m is the formation cementation index, which is determined based on the regional rock electrical experimental data, Δm is the change in pore structure after compression, and E s is the static Young's modulus, a is the rock electrical experimental coefficient, which is determined by rock electrical experiments, and A1, A2, A3, A4, and A5 are regional empirical coefficients.

4. A method for identifying fluid types in tight sandstone reservoirs according to claim 3, characterized in that: By sorting out the collected high-temperature and high-pressure rock electrical experimental data, the water-saturated resistivity, analytical porosity and static Young's modulus calculated by logging at the corresponding depth point are obtained. The process of using the least squares method to perform nonlinear fitting of the ternary function to obtain the parameters in formula (7) is as follows: Among them, R0 is the resistivity of saturated water without compression.

5. A method for identifying fluid types in tight sandstone reservoirs according to claim 1, characterized in that: The process of obtaining the equivalent resistivity of the formation based on the relationship between the static Young's modulus and the logging resistivity is: According to the relationship between the static Young's modulus of the target well and the logging resistivity, the equivalent resistivity of the formation is calculated. R tc =A5*exp(A6*E s ) (9) Among them, E s is the static Young's modulus, R t is the true resistivity of the formation after correction, R tc is the equivalent apparent resistivity of the formation, and A5 and A6 are regional empirical coefficients.

6. A method for identifying fluid types in tight sandstone reservoirs according to claim 1, characterized in that: The judgment process of judging the reservoir fluid type based on the equivalent resistivity of the formation and the resistivity of saturated water is as follows: According to the static Young's modulus and the equivalent resistivity of the formation, the true resistivity of the formation is obtained; If the true resistivity of the formation is greater than the water-saturated resistivity, the reservoir fluid type is an oil and gas layer, otherwise the reservoir fluid type is a water layer.

7. A method for identifying fluid types in tight sandstone reservoirs according to claim 6, characterized in that: The process of obtaining the true resistivity of the formation according to the static Young's modulus and the equivalent resistivity of the formation is: Among them, E s is the static Young's modulus, R t is the true resistivity of the formation after correction, R tc is the formation equivalent apparent resistivity, R t ' is the logging resistivity, A5 and A6 are the regional empirical coefficients.

8. A tight sandstone reservoir fluid type identification system, characterized in that: A method for identifying fluid types in a tight sandstone reservoir according to any one of claims 1 to 7, comprising: The first processing module is used to obtain the dynamic Young's modulus based on the longitudinal wave, shear wave and density logging data of the target well, and convert the dynamic Young's modulus into a static Young's modulus; The second processing module is used to establish a pure water line resistivity relationship based on static Young's modulus, deep resistivity and logging porosity data, and obtain saturated water resistivity based on the pure water line resistivity relationship; The third processing module is used to obtain the equivalent resistivity of the formation based on the relationship between the static Young's modulus and the logging resistivity; The judgment module is used to judge the reservoir fluid type based on the size of the formation equivalent resistivity and the saturated water resistivity.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method for identifying the fluid type of a tight sandstone reservoir as described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of a method for identifying fluid types in a tight sandstone reservoir as described in any one of claims 1 to 7 are implemented.

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