Complex pore structure reservoir fluid identification method based on dynamic resistivity lower limit

Abstract

The invention relates to the technical field of physical logging, and provides a complex pore structure reservoir fluid identification method based on a dynamic resistivity lower limit, which comprises the following steps: obtaining experimental data of each core sample: irreducible water saturation and values of rock electrical parameters m and n; respectively establishing models of irreducible water saturation, m and n changing along with the pore structure; the formation water resistivity at the formation temperature T is calculated according to the formation water mineralization degree, and then the water saturation and the resistivity lower limit value dynamically changing along with the pore structure are obtained according to the formation water resistivity; obtaining a multi-dimensional fluid identification chart of the irreducible water saturation, the water saturation and the resistivity lower limit value dynamically changing along with the pore structure; the actual porosity, the actual permeability and the actual resistivity of the stratum are measured, measured data are projected to the multi-dimensional fluid identification chart, and the actual irreducible water saturation and the actual water saturation are obtained. The method solves the problems that the fluid property of the reservoir with the complex pore structure is difficult to quickly identify and the accuracy is low.

Description

Technical Field

[0001] The invention relates to the technical field of physical well logging, and in particular to a method for identifying fluid in a reservoir with a complex pore structure based on a dynamic resistivity lower limit. Background Art

[0002] When the exploration and development of offshore oil and gas fields enters the middle and late stages, the reservoir pore structure will become more and more complex, and the heterogeneity will become stronger and stronger. The fluid signal in the pores will no longer be sensitive in the logging response, especially the difference in neutron, density and acoustic time difference response is not obvious, and can only reflect the difference in physical properties. It is difficult to identify the fluid properties based on conventional logging curves. At present, there is no universal, fast and effective method to solve the problem of fluid identification in complex pore structure reservoirs.

[0003] Regarding reservoir fluid identification methods, after literature research, it was found that the intersection diagram method, overlap method, and multi-parameter comprehensive identification method are widely used. Related literature includes: Su Guoying et al. [1] (2006) used geochemical pyrolysis, chromatography and pyrolysis chromatography geochemical analysis and gas logging data to identify oil and water layers; Li Gan [2] (2012) optimized fluid identification sensitive parameters, reconstructed curves through multivariate regression method, and then used multiple reconstructed curves for intersection to identify fluids in oil and water layers; Ren Peigang et al. [3] (2013) used the fluid indication method based on dual porosity overlap to identify fluids by constructing a fluid identification factor-porosity intersection diagram; Han Yujiao et al. [4] (2022) used the Adaboost machine learning algorithm to optimize parameters based on conventional logging and oil and production test data, and finally integrated multiple parameters for fluid identification. Guang Youhui et al. [5] (2022) comprehensively analyzed the influence of fluid properties on measurement and logging parameters, constructed multi-factor sensitive parameters, and used Fisher function discriminant method to establish a gas-water interpretation model to identify reservoir fluids.

[0004] Through investigation, it is known that the existing reservoir fluid identification methods are all based on conventional logging curves, which amplify fluid signals and construct sensitive factors. However, this method is only applicable to reservoirs with simple pore structures and good reservoir homogeneity. As the reservoir pore structure becomes more and more complex and the heterogeneity becomes stronger, the fluid signals reflected by logging become weaker and weaker, and it is difficult to extract sensitive factors by combining and optimizing parameters. As a result, the fluid identification method based on sensitive factors has limitations in the fluid identification of reservoirs with complex pore structures. The main reason is that the pore structure characteristics reflected by the core experiment are not combined with the logging curve, which greatly reduces the accuracy and cannot effectively guide the exploration and development of oil and gas fields. Summary of the invention

[0005] The purpose of the present invention is to solve at least one technical problem in the background technology and to provide a method for identifying fluid in a reservoir with a complex pore structure based on a dynamic resistivity lower limit.

[0006] To achieve the above object, the present invention provides a method for identifying fluid in a reservoir with a complex pore structure based on a dynamic resistivity lower limit, comprising:

[0007] Obtain multiple core samples from reservoirs with complex pore structures;

[0008] Obtain the experimental data of each core sample: porosity, permeability, irreducible water saturation, and the values ​​of rock electrical parameters a, b, m, and n;

[0009] Models for the irreducible water saturation, m and n changing with pore structure were established respectively;

[0010] The formation water resistivity at the formation temperature T is calculated based on the formation water salinity, and then the water saturation and the lower limit of the resistivity that changes dynamically with the pore structure are obtained based on the formation water resistivity using the Archie formula.

[0011] Based on each established model, a multi-dimensional fluid identification chart is obtained in which the irreducible water saturation, the water saturation and the lower limit of the resistivity change dynamically with the pore structure;

[0012] The actual porosity, actual permeability and actual resistivity of each layer of the complex pore structure reservoir are measured, and the actual porosity, actual permeability and actual resistivity are projected onto the multi-dimensional fluid identification plate to obtain the actual irreducible water saturation and the actual water saturation.

[0013] According to one aspect of the present invention, a model for the variation of m and n with pore structure is established as follows:

[0014] m=p1lgPOR+q1;

[0015] lgn=p2-q2lgRw-ClgK;

[0016] Where p1, p2, q1, q2 and C are constants, Rw is the formation water resistivity, POR is the porosity of the core sample, and K is the permeability of the core sample.

[0017] According to one aspect of the present invention, a model for the change of irreducible water saturation with pore structure is established as follows:

[0018]

[0019] Where A and B are constants, and Swi is the irreducible water saturation.

[0020] According to one aspect of the present invention, the resistivity of the formation water at the formation temperature T is calculated according to the formation water salinity, and then the water saturation and the lower limit of the resistivity that changes dynamically with the pore structure are obtained according to the formation water resistivity using the Archie formula:

[0021]

[0022] Where Rt is resistivity, Sw is water saturation, and Ro is the lower limit of resistivity.

[0023] According to one aspect of the present invention, a multi-dimensional fluid identification chart for obtaining the irreducible water saturation, the water saturation and the resistivity lower limit value that dynamically changes with the pore structure is:

[0024] Using Python programming, the regular relationships among irreducible water saturation, water saturation, lower limit of resistivity, porosity and permeability are plotted into a multidimensional fluid identification chart; among them, the heat map of the relationship between irreducible water saturation and porosity and permeability is on the xy axis bottom of the multidimensional fluid identification chart, the heat map of the relationship between water saturation and porosity and resistivity is on the xz axis side of the multidimensional fluid identification chart, and the heat map of the relationship between the lower limit of resistivity and porosity and permeability is a three-dimensional surface in the multidimensional fluid identification chart.

[0025] According to one aspect of the present invention, the actual porosity, actual permeability and actual resistivity of each layer of the complex pore structure reservoir are measured, and the actual porosity, actual permeability and actual resistivity are projected onto the multi-dimensional fluid identification plate to obtain the actual bound water saturation and actual water saturation as follows:

[0026] The actual porosity, actual permeability and actual resistivity of the formation in the complex pore structure reservoir are obtained through logging, pressure measurement and core data, and the actual porosity, actual permeability and actual resistivity are projected onto the multi-dimensional fluid identification plate to obtain a three-dimensional data point. If the three-dimensional data point is located above the three-dimensional surface, the resistivity ≥ the lower limit of the resistivity, and the formation is determined to be a pure gas layer. If the three-dimensional data point is located below the three-dimensional surface, the resistivity < the lower limit of the resistivity, and the formation is determined to contain movable water. At the same time, the three-dimensional data point is projected onto the bottom surface of the xy axis and the side surface of the xz axis to obtain the actual bound water saturation and the actual water saturation of the formation.

[0027] To achieve the above object, the present invention also provides a complex pore structure reservoir fluid identification system based on the dynamic resistivity lower limit, comprising:

[0028] Core sample acquisition module, to obtain multiple core samples from reservoirs with complex pore structures;

[0029] The core experimental data acquisition module obtains the experimental data of each core sample: porosity, permeability, bound water saturation, and the values ​​of rock electrical parameters a, b, m, and n;

[0030] Model building module, which builds models of irreducible water saturation, m and n changing with pore structure;

[0031] The water saturation and resistivity lower limit calculation module calculates the formation water resistivity at the formation temperature T according to the formation water salinity, and then uses the Archie formula to obtain the water saturation and the resistivity lower limit that changes dynamically with the pore structure based on the formation water resistivity;

[0032] A multi-dimensional fluid identification chart acquisition module, based on each established model, acquires a multi-dimensional fluid identification chart showing the irreducible water saturation, the water saturation and the resistivity lower limit value dynamically changing with the pore structure;

[0033] The fluid identification module measures the actual porosity, actual permeability and actual resistivity of each layer of the complex pore structure reservoir, projects the actual porosity, actual permeability and actual resistivity onto the multi-dimensional fluid identification plate, and obtains the actual bound water saturation and the actual water saturation.

[0034] To achieve the above-mentioned purpose, the present invention also provides an electronic device, including a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the complex pore structure reservoir fluid identification method based on the dynamic resistivity lower limit as described above.

[0035] To achieve the above-mentioned purpose, the present invention also provides a computer-readable storage medium, characterized in that a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the complex pore structure reservoir fluid identification method based on the dynamic resistivity lower limit as described above is implemented.

[0036] According to the scheme of the present invention, the present invention establishes a complex pore structure reservoir fluid identification plate based on the dynamic resistivity lower limit. The present invention aims at the complex pore structure reservoir fluid problem, refines and summarizes the core experimental data, and combines it with the logging signal, which not only solves the problem that the complex pore structure reservoir fluid properties are difficult to quickly identify and the accuracy is low, but also can further quantitatively obtain the formation bound water saturation and water saturation, reduce unnecessary pressure measurement sampling costs, and effectively guide subsequent exploration and development. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A flow chart schematically showing a method for identifying fluid in a reservoir with a complex pore structure based on a lower limit of dynamic resistivity according to an embodiment of the present invention;

[0038] Figure 2 A schematic diagram of a multi-dimensional fluid identification map according to an embodiment of the present invention is shown.

[0039] Figure 3 Schematic representation of an example comparison of fluid identification in a newly drilled well in the target area. DETAILED DESCRIPTION

[0040] The present invention will now be discussed with reference to exemplary embodiments. It should be understood that the embodiments discussed are only to enable those skilled in the art to better understand and thus implement the present invention, rather than implying any limitation on the scope of the present invention.

[0041] As used herein, the term “including” and variations thereof are to be interpreted as open-ended terms meaning “including, but not limited to.” The term “based on” is to be interpreted as “based, at least in part, on.” The terms “one embodiment” and “an embodiment” are to be interpreted as “at least one embodiment.”

[0042] Figure 1 The flowchart schematically shows a method for identifying fluid in a complex pore structure reservoir based on a dynamic resistivity lower limit according to an embodiment of the present invention. Figure 1 As shown, in this embodiment, the method for identifying fluid in a complex pore structure reservoir based on the lower limit of dynamic resistivity includes:

[0043] Obtain multiple core samples from reservoirs with complex pore structures;

[0044] Obtain the experimental data of each core sample: porosity, permeability, irreducible water saturation, and the values ​​of rock electrical parameters a, b, m, and n;

[0045] Models for the irreducible water saturation, m and n changing with pore structure were established respectively;

[0046] The formation water resistivity at the formation temperature T is calculated based on the formation water mineralization (obtained through chemical analysis), and then the water saturation and the lower limit of the resistivity that changes dynamically with the pore structure are obtained based on the formation water resistivity using the Archie formula;

[0047] Obtain a multi-dimensional fluid identification chart showing dynamic changes of the irreducible water saturation, the water saturation and the lower limit of the resistivity with the pore structure;

[0048] The actual porosity, actual permeability and actual resistivity of each layer of the complex pore structure reservoir are measured, and the actual porosity, actual permeability and actual resistivity are projected onto the multi-dimensional fluid identification plate to obtain the actual irreducible water saturation and the actual water saturation.

[0049] In this embodiment, a and m are cementation indices, and b and n are saturation indices.

[0050] Further, according to one embodiment of the present invention, the porosity POR, permeability K, irreducible water saturation Swi, and rock electrical parameters a, b, m, and n of each core sample are obtained through core experiments such as conventional physical properties, mercury injection, semi-permeability, nuclear magnetic resonance, and rock resistivity;

[0051] Further, according to one embodiment of the present invention, a model for the variation of m and n with pore structure is established as follows:

[0052] m=p1lgPOR+q1;

[0053] lgn=p2-q2lgRw-ClgK;

[0054] Where p1, p2, q1, q2 and C are constants, Rw is the formation water resistivity, POR is the porosity of the core sample, and K is the permeability of the core sample.

[0055] Further, according to one embodiment of the present invention, a model for the change of irreducible water saturation with pore structure is established as follows:

[0056]

[0057] Where A and B are constants, and Swi is the irreducible water saturation.

[0058] Further, according to one embodiment of the present invention, the values ​​of the above constants p1, p2, q1, q2, A, B and C are obtained by a nonlinear optimization fitting method.

[0059] Further, according to an embodiment of the present invention, the formation water resistivity at the formation temperature T is calculated according to the formation water salinity, and then the water saturation and the lower limit of the resistivity that changes dynamically with the pore structure are obtained according to the formation water resistivity using the Archie formula:

[0060]

[0061] Where Rt is resistivity, Sw is water saturation, and Ro is the lower limit of resistivity.

[0062] Further, according to an embodiment of the present invention, a multi-dimensional fluid identification chart for obtaining irreducible water saturation, water saturation and resistivity lower limit values ​​that change dynamically with pore structure is:

[0063] Using Python programming, the regular relationships among irreducible water saturation, water saturation, lower limit of resistivity, porosity and permeability are plotted into a multidimensional fluid identification chart; among them, the heat map of the relationship between irreducible water saturation and porosity and permeability is on the xy axis bottom of the multidimensional fluid identification chart, the heat map of the relationship between water saturation and porosity and resistivity is on the xz axis side of the multidimensional fluid identification chart, and the heat map of the relationship between the lower limit of resistivity and porosity and permeability is a three-dimensional surface in the multidimensional fluid identification chart.

[0064] In this embodiment, the multi-dimensional fluid identification chart is as follows: Figure 2 As shown, the x-axis in the multidimensional fluid identification chart is porosity POR, the y-axis is permeability K, and the z-axis is resistivity Rt. Red scattered points represent gas layers, light blue scattered points represent gas-water layers, and dark blue scattered points represent water layers. The heat map of the relationship between irreducible water saturation Swi and porosity and permeability is on the bottom of the xy axis, and the heat map of the relationship between water saturation Sw and porosity and resistivity is on the side of the xz axis. The values ​​of irreducible water saturation Swi and water saturation Sw are both represented by the color depth of the color bar. The relationship between the lower limit value of resistivity Rt and porosity and permeability is a three-dimensional surface in the multidimensional fluid identification chart. In this way, the multidimensional fluid identification chart can intuitively show how the irreducible water saturation Swi, water saturation Sw and the lower limit value of resistivity Rt change with porosity and permeability.

[0065] Further, according to an embodiment of the present invention, the actual porosity, actual permeability and actual resistivity of each layer of the complex pore structure reservoir are measured, and the actual porosity, actual permeability and actual resistivity are projected onto a multi-dimensional fluid identification plate to obtain the actual irreducible water saturation and actual water saturation as follows:

[0066] The actual porosity, actual permeability and actual resistivity of the formation in the complex pore structure reservoir are obtained through logging, pressure measurement and core data, and the actual porosity, actual permeability and actual resistivity are projected onto the multi-dimensional fluid identification plate to obtain a three-dimensional data point. If the three-dimensional data point is located above the three-dimensional surface, the resistivity ≥ the lower limit of the resistivity, and the formation is determined to be a pure gas layer. If the three-dimensional data point is located below the three-dimensional surface, the resistivity < the lower limit of the resistivity, and the formation is determined to contain movable water. At the same time, the three-dimensional data point is projected onto the bottom surface of the xy axis and the side surface of the xz axis to obtain the actual bound water saturation and the actual water saturation of the formation.

[0067] In this embodiment, the actual porosity, actual permeability and actual resistivity of the formation are obtained through corresponding well logging, pressure measurement and core data, and then projected onto Figure 2In the case where the projected three-dimensional data points are located above the three-dimensional surface, indicating that Rt≥Ro, it means that the formation is a pure gas layer. If the projected points are located below the three-dimensional surface, indicating that Rt<Ro, it means that the layer contains movable water. In this way, the fluid properties of the reservoir can be quickly identified. At the same time, by projecting the data onto the x-y axis bottom surface and the x-z axis side surface, the irreducible water saturation Swi and the water saturation Sw of this layer can be quickly obtained, and further the movable water saturation Swm and the oil saturation So can be quantitatively obtained. Among them, the movable water saturation Swm = Sw - Swi, and the oil saturation So = 1 - Sw, which can be used for reserve calculation and evaluation of the later development effect.

[0068] Furthermore, Figure 3 It is an example diagram for fluid identification of a new well drilled in the research target area. As Figure 3 shown, the first trace in the figure is the spontaneous potential SP, the natural gamma ray GR, and the borehole diameter curve HD1, the second trace is the measured depth curve, the third trace is the resistivity curves while drilling A40H, P40H, P28H, and P16H, the fourth trace curves are the shear wave slowness curve DTSM, the compressional wave slowness curve DTCO, the neutron curve TNPH, and the density curve RHOB, the fifth and sixth traces are gas logging and cuttings logging respectively, and the seventh trace is the fluid identification conclusion interpreted by the multi-dimensional fluid identification chart of the present invention and the pressure measurement and sampling results. It can be clearly seen from Figure 3 this that the characteristics of the logging curves reflected by different fluid properties are not sensitive, especially for the neutron, density, and acoustic curves that are most sensitive to gas-bearing properties, and there are basically no differences vertically. And it is confirmed by pressure measurement and sampling that: 3179.6 - 3190.1m is a gas layer, 3190.1 - 3213.0m is a gas-water zone, and 3213.0 - 3215.0m is a water layer, which is consistent with the fluid identification conclusion interpreted based on the multi-dimensional fluid identification chart of the present invention, further verifying the accuracy of the multi-dimensional fluid identification chart of the present invention.

[0069] According to the above solution of the present invention, the present invention establishes a fluid identification chart for complex pore structure reservoirs based on the lower limit of dynamic resistivity. For the fluid problem of complex pore structure reservoirs, the present invention refines and summarizes the core experimental data and combines it with the logging signals, which not only solves the problems of difficult and inaccurate rapid identification of fluid properties in complex pore structure reservoirs, but also can further quantitatively obtain the irreducible water saturation and water saturation of the formation, reduce unnecessary pressure measurement and sampling costs, and effectively guide the subsequent exploration and development.

[0070] Furthermore, to achieve the above object, the present invention also provides a fluid identification system for complex pore structure reservoirs based on the lower limit of dynamic resistivity, including:

[0071] A core sample acquisition module for acquiring multiple core samples in the complex pore structure reservoir;

[0072] The core experimental data acquisition module obtains the experimental data of each core sample: porosity, permeability, bound water saturation, and the values ​​of rock electrical parameters a, b, m, and n;

[0073] Model building module, which builds models of irreducible water saturation, m and n changing with pore structure;

[0074] The water saturation and resistivity lower limit calculation module calculates the formation water resistivity at the formation temperature T according to the formation water salinity, and then uses the Archie formula to obtain the water saturation and the resistivity lower limit that changes dynamically with the pore structure based on the formation water resistivity;

[0075] A multi-dimensional fluid identification chart acquisition module is used to acquire a multi-dimensional fluid identification chart showing that the irreducible water saturation, the water saturation and the lower limit of the resistivity change dynamically with the pore structure;

[0076] The fluid identification module measures the actual porosity, actual permeability and actual resistivity of each layer of the complex pore structure reservoir, projects the actual porosity, actual permeability and actual resistivity onto the multi-dimensional fluid identification plate, and obtains the actual bound water saturation and the actual water saturation.

[0077] Further, according to one embodiment of the present invention, the porosity POR, permeability K, irreducible water saturation Swi, and rock electrical parameters a, b, m, and n of each core sample are obtained through core experiments such as conventional physical properties, mercury injection, semi-permeability, nuclear magnetic resonance, and rock resistivity;

[0078] Further, according to one embodiment of the present invention, a model for the variation of m and n with pore structure is established as follows:

[0079] m=p1lgPOR+q1;

[0080] lgn=p2-q2lgRw-ClgK;

[0081] Where p1, p2, q1, q2 and C are constants, Rw is the formation water resistivity, POR is the porosity of the core sample, and K is the permeability of the core sample.

[0082] Further, according to one embodiment of the present invention, a model for the change of irreducible water saturation with pore structure is established as follows:

[0083]

[0084] Where A and B are constants, and Swi is the irreducible water saturation.

[0085] Further, according to one embodiment of the present invention, the values ​​of the above constants p1, p2, q1, q2, A, B and C are obtained by a nonlinear optimization fitting method.

[0086] Further, according to an embodiment of the present invention, the formation water resistivity at the formation temperature T is calculated according to the formation water salinity, and then the water saturation and the lower limit of the resistivity that changes dynamically with the pore structure are obtained according to the formation water resistivity using the Archie formula:

[0087]

[0088] Where Rt is resistivity, Sw is water saturation, and Ro is the lower limit of resistivity.

[0089] Further, according to an embodiment of the present invention, a multi-dimensional fluid identification chart for obtaining irreducible water saturation, water saturation and resistivity lower limit values ​​that change dynamically with pore structure is:

[0090] Using Python programming, the regular relationships among irreducible water saturation, water saturation, lower limit of resistivity, porosity and permeability are plotted into a multidimensional fluid identification chart; among them, the heat map of the relationship between irreducible water saturation and porosity and permeability is on the xy axis bottom of the multidimensional fluid identification chart, the heat map of the relationship between water saturation and porosity and resistivity is on the xz axis side of the multidimensional fluid identification chart, and the heat map of the relationship between the lower limit of resistivity and porosity and permeability is a three-dimensional surface in the multidimensional fluid identification chart.

[0091] In this embodiment, the multi-dimensional fluid identification chart is as follows: Figure 2 As shown, the x-axis in the multidimensional fluid identification chart is porosity POR, the y-axis is permeability K, and the z-axis is resistivity Ro. Red scattered points represent gas layers, light blue scattered points represent gas-water layers, and dark blue scattered points represent water layers. The heat map of the relationship between irreducible water saturation Swi and porosity and permeability is on the bottom of the xy axis, and the heat map of the relationship between water saturation Sw and porosity and resistivity is on the side of the xz axis. The values ​​of irreducible water saturation Swi and water saturation Sw are both represented by the color depth of the color bar. The relationship between the lower limit value of resistivity Ro and porosity and permeability is a three-dimensional surface in the multidimensional fluid identification chart. In this way, the multidimensional fluid identification chart can intuitively show how the irreducible water saturation Swi, water saturation Sw and the lower limit value of resistivity Ro change with porosity and permeability.

[0092] Further, according to an embodiment of the present invention, the actual porosity, actual permeability, and actual resistivity of each layer of a reservoir with a complex pore structure are measured, and the actual porosity, actual permeability, and actual resistivity are projected onto a multi-dimensional fluid identification chart to obtain the actual irreducible water saturation and actual water saturation as follows:

[0093] The actual porosity, actual permeability, and actual resistivity of the formation in the reservoir with a complex pore structure are obtained through well logging, pressure measurement, and core data. The actual porosity, actual permeability, and actual resistivity are projected into the multi-dimensional fluid identification chart to obtain three-dimensional data points. If the three-dimensional data point is above the three-dimensional surface, i.e., the resistivity ≥ the lower resistivity limit value, then the formation is determined to be a pure gas layer. If the three-dimensional data point is below the three-dimensional surface, i.e., the resistivity < the lower resistivity limit value, then it is determined that the formation contains movable water. At the same time, the actual irreducible water saturation and actual water saturation of the formation are obtained by projecting the three-dimensional data point onto the bottom surface of the x-y axis and the side surface of the x-z axis.

[0094] In this embodiment, the actual porosity, actual permeability, and actual resistivity of the formation are obtained through corresponding well logging, pressure measurement, and core data, and then they are projected onto Figure 2 If the projected three-dimensional data point is above the three-dimensional surface, indicating that Rt ≥ Ro, it means that the formation is a pure gas layer. If the projected point is below the three-dimensional surface, indicating that Rt < Ro, it means that the layer contains movable water. In this way, the fluid properties of the reservoir can be quickly discriminated. At the same time, by projecting the data onto the bottom surface of the x-y axis and the side surface of the x-z axis, the irreducible water saturation Swi and water saturation Sw of the layer can be quickly obtained, and the movable water saturation Swm and oil saturation So can be further quantitatively obtained, where the movable water saturation Swm = Sw - Swi, and the oil saturation So = 1 - Sw, which can be used for reserve calculation and evaluation of the later development effect.

[0095] Further, as Figure 3 shown, the first track in the figure is the spontaneous potential SP, natural gamma GR, and borehole diameter curve HD1, the second track is the measured depth curve, the third track is the resistivity curves while drilling A40H, P40H, P28H, and P16H, the fourth track curves are the shear wave slowness curve DTSM, compressional wave slowness curve DTCO, neutron curve TNPH, and density curve RHOB, the fifth and sixth tracks are gas logging and cuttings logging respectively, and the seventh track is the fluid identification conclusion interpreted by using the multi-dimensional fluid identification chart of the present invention and the pressure measurement sampling result. From Figure 3It can be clearly seen that the logging curve characteristics reflected by different fluid properties are insensitive, especially the neutron, density and acoustic wave curves that are most sensitive to gas content, which have basically no difference in the vertical direction. And after pressure measurement and sampling, it was confirmed that 3179.6-3190.1m is a gas layer, 3190.1-3213.0m is a gas-water layer, and 3213.0-3215.0m is a water layer, which is consistent with the fluid identification conclusion interpreted based on the multi-dimensional fluid identification chart of the present invention, further verifying the accuracy of the multi-dimensional fluid identification chart of the present invention.

[0096] According to the above scheme of the present invention, the present invention establishes a complex pore structure reservoir fluid identification plate based on the dynamic resistivity lower limit. The present invention aims at the complex pore structure reservoir fluid problem, refines and summarizes the core experimental data, and combines it with the logging signal, which not only solves the problem that the complex pore structure reservoir fluid properties are difficult to quickly identify and the accuracy is low, but also can further quantitatively obtain the formation bound water saturation and water saturation, reduce unnecessary pressure measurement sampling costs, and effectively guide subsequent exploration and development.

[0097] Furthermore, to achieve the above-mentioned purpose, the present invention also provides an electronic device, comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein when the computer program is executed by the processor, the method for identifying fluids in complex pore structure reservoirs based on the lower limit of dynamic resistivity as described above is implemented.

[0098] Furthermore, to achieve the above-mentioned purpose, the present invention also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the method for identifying fluids in complex pore structure reservoirs based on the lower limit of dynamic resistivity as described above is implemented.

[0099] Those skilled in the art will appreciate that the modules and algorithm steps described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0100] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and equipment can refer to the corresponding processes in the aforementioned method implementation methods, and will not be repeated here.

[0101] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the modules is only a logical function division. There may be other division methods in actual implementation, such as multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0102] The modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical modules, that is, they may be located in one place or distributed on multiple network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the embodiments of the present invention.

[0103] In addition, each functional module in the embodiment of the present invention may be integrated into one processing module, or each module may exist physically separately, or two or more modules may be integrated into one module.

[0104] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the energy-saving signal sending / receiving method of each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, ROM, RAM, magnetic disks, or optical disks.

[0105] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other.

[0106] It should be understood that the size of the serial numbers of each step in the content of the invention and the implementation methods of the present invention does not absolutely mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the implementation methods of the present invention.

Claims

1. A method for identifying fluid in complex pore structure reservoirs based on the lower limit of dynamic resistivity, characterized in that: include: Obtain multiple core samples from reservoirs with complex pore structures; Obtain the experimental data of each core sample: porosity, permeability, irreducible water saturation, and the values ​​of rock electrical parameters a, b, m, and n; Models for the irreducible water saturation, m and n changing with pore structure were established respectively; The formation water resistivity at the formation temperature T is calculated based on the formation water salinity, and then the water saturation and the lower limit of the resistivity that changes dynamically with the pore structure are obtained based on the formation water resistivity using the Archie formula. Based on each established model, a multi-dimensional fluid identification chart is obtained in which the irreducible water saturation, the water saturation and the lower limit of the resistivity change dynamically with the pore structure; The actual porosity, actual permeability and actual resistivity of each layer of the complex pore structure reservoir are measured, and the actual porosity, actual permeability and actual resistivity are projected onto the multi-dimensional fluid identification plate to obtain the actual irreducible water saturation and the actual water saturation.

2. The method for identifying fluid in complex pore structure reservoirs based on the lower limit of dynamic resistivity according to claim 1, characterized in that: The model of m and n changing with pore structure is established as: m=p1lgPOR+q1; lgn=p2―q2lgRw―ClgK; Where p1, p2, q1, q2 and C are constants, Rw is the formation water resistivity, POR is the porosity of the core sample, and K is the permeability of the core sample.

3. The method for identifying fluid in complex pore structure reservoirs based on the lower limit of dynamic resistivity according to claim 2, characterized in that: The model of irreducible water saturation changing with pore structure is established as: Where A and B are constants, and Swi is the irreducible water saturation.

4. The method for identifying fluid in complex pore structure reservoirs based on the lower limit of dynamic resistivity according to claim 3, characterized in that: The resistivity of the formation water at the formation temperature T is calculated according to the formation water salinity, and then the water saturation and the lower limit of the resistivity that changes dynamically with the pore structure are obtained according to the formation water resistivity using the Archie formula: Where Rt is the true resistivity of rock, P is the mineralization, Sw is the water saturation, and Ro is the lower limit of the rock saturated with water resistivity.

5. The method for identifying fluid in complex pore structure reservoirs based on the lower limit of dynamic resistivity according to claim 4, characterized in that: The multi-dimensional fluid identification chart for obtaining the irreducible water saturation, the water saturation and the resistivity lower limit value dynamically changing with the pore structure is: Using Python programming, the regular relationships among irreducible water saturation, water saturation, lower limit of resistivity, porosity and permeability are plotted into a multidimensional fluid identification chart; among them, the heat map of the relationship between irreducible water saturation and porosity and permeability is on the xy axis bottom of the multidimensional fluid identification chart, the heat map of the relationship between water saturation and porosity and resistivity is on the xz axis side of the multidimensional fluid identification chart, and the heat map of the relationship between the lower limit of resistivity and porosity and permeability is a three-dimensional surface in the multidimensional fluid identification chart.

6. The method for identifying fluid in complex pore structure reservoirs based on the lower limit of dynamic resistivity according to claim 5, characterized in that: The actual porosity, actual permeability and actual resistivity of each layer of the complex pore structure reservoir are measured, and the actual porosity, actual permeability and actual resistivity are projected onto the multi-dimensional fluid identification plate to obtain the actual bound water saturation and actual water saturation as follows: The actual porosity, actual permeability and actual resistivity of the formation in the complex pore structure reservoir are obtained through logging, pressure measurement and core data, and the actual porosity, actual permeability and actual resistivity are projected onto the multi-dimensional fluid identification plate to obtain a three-dimensional data point. If the three-dimensional data point is located above the three-dimensional surface, the resistivity ≥ the lower limit of the resistivity, and the formation is determined to be a pure gas layer. If the three-dimensional data point is located below the three-dimensional surface, the resistivity < the lower limit of the resistivity, and the formation is determined to contain movable water. At the same time, the three-dimensional data point is projected onto the bottom surface of the xy axis and the side surface of the xz axis to obtain the actual bound water saturation and the actual water saturation of the formation.

7. A complex pore structure reservoir fluid identification system based on the dynamic resistivity lower limit, characterized in that: include: Core sample acquisition module, to obtain multiple core samples from reservoirs with complex pore structures; The core experimental data acquisition module obtains the experimental data of each core sample: porosity, permeability, bound water saturation, and the values ​​of rock electrical parameters a, b, m, and n; Model building module, which builds models of irreducible water saturation, m and n changing with pore structure; The water saturation and resistivity lower limit calculation module calculates the formation water resistivity at the formation temperature T according to the formation water salinity, and then uses the Archie formula to obtain the water saturation and the resistivity lower limit that changes dynamically with the pore structure based on the formation water resistivity; A multi-dimensional fluid identification chart acquisition module, based on each established model, acquires a multi-dimensional fluid identification chart showing the irreducible water saturation, the water saturation and the resistivity lower limit value dynamically changing with the pore structure; The fluid identification module measures the actual porosity, actual permeability and actual resistivity of each layer of the complex pore structure reservoir, projects the actual porosity, actual permeability and actual resistivity onto the multi-dimensional fluid identification plate, and obtains the actual bound water saturation and the actual water saturation.

8. An electronic device, characterized in that The method comprises a processor, a memory and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements a complex pore structure reservoir fluid identification method based on a dynamic resistivity lower limit as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for identifying fluid in a complex pore structure reservoir based on a dynamic resistivity lower limit according to any one of claims 1 to 6 is implemented.

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