Deep compact sandstone gas reservoir identification method and device, medium and equipment

Abstract

The invention discloses a deep compact sandstone gas reservoir identification method and device, a medium and equipment. The method comprises the following steps: sampling a rock core to obtain a plurality of rock core samples; obtaining the effective porosity of the plurality of rock core samples, the longitudinal wave velocity saturated with different fluids and the rock sample density saturated with different fluids through a plurality of groups of experiments; constructing an effective porosity-fluid impedance cross plot and analyzing the effective porosity-fluid impedance cross plot; constructing a rock physical volume model of the deep compact sandstone reservoir; constructing a rock longitudinal wave velocity and density relational expression under the condition of complete water saturation and constructing a rock longitudinal wave velocity and density relational expression under the condition of complete natural gas saturation; and constructing a fluid impedance ratio model to judge the fluid property of the deep compact sandstone reservoir. According to the method, the impedance ratio model formula of stratum saturated water and saturated fluid is obtained through the fluid impedance ratio model, so that the influence of oil-based mud invasion and underlying pressure on sandstone reservoir judgment is eliminated, the recognition result is accurate and reliable, and the precision is higher.

Description

Technical Field

[0001] This invention relates to the field of petroleum and natural gas geology and exploration and development technology, and in particular to a method, apparatus, medium and equipment for identifying deep tight sandstone gas layers. Background Technology

[0002] Tight sandstone reservoirs are the primary targets for oil and gas exploration in major oilfields. They are widely distributed in China, with an exploration area of ​​thousands of square kilometers. The oil and gas reservoirs are large in scale and rich in reserves. However, the sedimentary characteristics of tight sandstone reservoirs are mainly characterized by mixed sedimentation from multiple sources and rapid accumulation. Furthermore, tight sandstone reservoirs are characterized by complex and variable mineral composition, weak diagenesis, strong heterogeneity, and complex pore structure, making gas layer identification quite difficult.

[0003] In the prior art, a tight sandstone reservoir prediction method published under the publication number "CN113514884A" integrates existing seismic data, drilling and logging data, and uses post-stack seismic waveform joint inversion to predict tight sandstone reservoirs, thereby improving the prediction accuracy of sandstone reservoirs.

[0004] However, while this method improves the prediction accuracy of sandstone reservoirs to some extent, it still cannot eliminate the influence of oil-based mud intrusion and subsurface pressure on the identification of sandstone reservoirs. Summary of the Invention

[0005] The main objective of this invention is to provide a method, apparatus, medium, and equipment for identifying deep, tight sandstone gas reservoirs, aiming to solve the technical problem that oil-based mud intrusion and bottom pressure affect the identification of sandstone reservoirs.

[0006] To achieve the above objectives, this invention provides a method for identifying deep tight sandstone gas reservoirs. The method includes: sampling rock cores to obtain multiple core samples; obtaining the effective porosity, P-wave velocity saturated with different fluids, and rock sample density saturated with different fluids for each core sample through multiple sets of experiments; constructing and analyzing an effective porosity-fluid impedance cross-plot; constructing a rock physical volume model of deep tight sandstone reservoirs; constructing a relationship between P-wave velocity and density of rocks under fully saturated water conditions and a relationship between P-wave velocity and density of rocks under fully saturated natural gas conditions; and constructing a fluid impedance ratio model to determine the fluid properties of deep tight sandstone reservoirs.

[0007] Optionally, the step of sampling the rock core to obtain multiple core samples includes: selecting sandstone core samples from the reservoir section within the study area; and preparing rock samples to obtain multiple core samples.

[0008] Optionally, obtaining the effective porosity, P-wave velocity, and density of the core samples saturated with different fluids through multiple sets of experiments includes: conducting multiple sets of experiments to measure porosity, P-wave velocity, and density; obtaining the effective porosity of the core samples based on helium porosity experiments; measuring the density and P-wave velocity of the core samples after vacuuming and pressurizing them to saturate with natural gas; measuring the density and P-wave velocity of the core samples after vacuuming and pressurizing them to saturate with water; drying the core samples; and determining the P-wave velocity and density of the core samples saturated with different fluids based on the experiments.

[0009] Optionally, the different fluids include oil-based mud, water, and natural gas.

[0010] Optionally, the deep tight sandstone reservoir rock physical volume model divides the rock into two parts, one part being the rock skeleton and the other part being the pores.

[0011] Optionally, after constructing and analyzing the effective porosity-fluid impedance cross-plot, the method further includes: when the rock sample is saturated with oil-based mud and water, the impedance value of the core sample is relatively large; when the rock sample is saturated with natural gas, the impedance value of the core sample is relatively small.

[0012] Optionally, the construction of the relationship between the P-wave velocity and density of rock under fully saturated conditions includes: constructing a physical volume model of rock under fully saturated conditions; and constructing the relationship between the P-wave velocity and density of rock under fully saturated conditions based on the physical volume model of rock under fully saturated conditions and the following formula:

[0013] V 水层 = (1-φ)*V 骨架 +φ*V 水 (1)

[0014] ρ 水层 =(1-φ)*ρ 骨架 +φ*ρ 水 (2)

[0015] In the formula: V 水层 V is the velocity of sound waves when the rock is saturated with water, in m / s. 骨架 The volume of the framework of dense sandstone, in cm. 3 V 水 The volume of water-saturated pores is expressed in cm³. 3 .

[0016] Optionally, the construction of the relationship between the P-wave velocity and density of rocks under fully saturated natural gas conditions includes: constructing a physical volume model of the rocks under fully saturated natural gas conditions; and constructing the relationship between the P-wave velocity and density of rocks under fully saturated natural gas conditions based on the physical volume model of the rocks under fully saturated natural gas conditions and the following formula:

[0017] V 气层 = (1-φ)*V 骨架 +φ*V 气 (3)

[0018] ρ 气层 =(1-φ)*ρ 骨架 +φ*ρ 气 (4)

[0019] In the formula: V 气 The volume of air-saturated pores is expressed in cm³. 3 φ represents the porosity of dense sandstone, in %; ρ 水 This is the density of water, expressed in g / cm³. 3 ;ρ 气 This is the density of natural gas, expressed in g / cm³. 3 .

[0020] Optionally, the method of constructing a fluid impedance ratio model to determine the fluid properties of deep tight sandstone reservoirs includes: constructing a fluid impedance ratio model based on the following formula:

[0021]

[0022] Z w =V w *ρ w (7)

[0023] Z f =V f *ρ f (8)

[0024]

[0025] In the formula: Z * Z is the fluid resistance ratio, dimensionless. w Formation water saturation resistance, unit: g / cm³·m / s; Z f Formation fluid impedance; V w V is the speed of sound in water, measured in m / s. f ρ represents the velocity of sound waves in formation fluids, in m / s. w The density of water, in g / cm³ 3 ;ρ f Density of the saturated fluid in the formation, in g / cm³ 3 ;T* ρ represents the time difference between formation saturated water and formation saturated fluid, with dimensionless units. * The density ratio of formation-saturated water to formation-saturated fluid is dimensionless. Porosity calculated for acoustic waves, in %; Porosity is calculated for density, in %; Porosity calculated using nuclear magnetic resonance logging for 3ms, in %; fluid properties of deep tight sandstone reservoirs determined based on the fluid impedance ratio model.

[0026] Optionally, after determining the fluid properties of the deep tight sandstone reservoir based on the fluid resistance ratio model, the method further includes: when the fluid resistance ratio is greater than 1, the reservoir is a gas layer; when the fluid resistance ratio is less than or equal to 1, the reservoir is a water layer.

[0027] Furthermore, to achieve the above objectives, this application embodiment also provides a deep tight sandstone gas reservoir identification device, the device comprising: a first acquisition module for sampling rock cores to obtain multiple rock core samples; a second acquisition module for obtaining the effective porosity, longitudinal wave velocity saturated with different fluids, and rock sample density saturated with different fluids of the multiple rock core samples through multiple sets of experiments; a first construction module for constructing and analyzing an effective porosity-fluid impedance cross-plot; a second construction module for constructing a rock physical volume model of a deep tight sandstone reservoir; a third construction module for constructing a relationship between the longitudinal wave velocity and density of the rock under fully saturated water conditions; a fourth construction module for constructing a relationship between the longitudinal wave velocity and density of the rock under fully saturated natural gas conditions; and a judgment module for constructing a fluid impedance ratio model to judge the fluid properties of the deep tight sandstone reservoir.

[0028] In addition, to achieve the above objectives, embodiments of this application also provide a computer-readable storage medium including instructions that, when run on a computer, cause the computer to execute the deep tight sandstone gas layer identification method described in any embodiment of this application.

[0029] Furthermore, to achieve the above objectives, embodiments of this application also provide a computing device, which includes: at least one processor, a memory, and an input / output unit; wherein the memory is used to store a computer program, and the processor is used to call the computer program stored in the memory to execute the deep tight sandstone gas layer identification method described in any embodiment of this application.

[0030] This application provides a method for identifying deep tight sandstone gas reservoirs. Through multiple experiments, the P-wave velocity and density of tight sandstone under different saturated fluid conditions are obtained. Furthermore, by constructing a rock physical volume model of deep tight sandstone reservoirs, the differences in impedance under different fluid conditions can be studied. Finally, through a fluid impedance ratio model, the impedance ratio model formula for formation saturated water and saturated fluid can be obtained. This eliminates the influence of oil-based mud intrusion and subsurface pressure on sandstone reservoir identification, resulting in accurate and reliable identification results with higher precision. It also breaks through the limitations of traditional methods that rely on fixed elastic parameters for gas reservoir identification. Attached Figure Description

[0031] Figure 1 A flowchart illustrating the method for identifying deep tight sandstone gas layers provided in this application embodiment;

[0032] Figure 2 A structural block diagram of the deep tight sandstone gas layer identification device provided in the embodiments of this application;

[0033] Figure 3 A schematic diagram of the structure of a medium provided in an embodiment of this application;

[0034] Figure 4 This is a schematic diagram of the structure of a computing device provided in an embodiment of this application.

[0035] Explanation of reference numerals in the attached figures:

[0036] 300 - Deep tight sandstone gas layer identification device, 310 - First acquisition module, 320 - Second acquisition module, 330 - First construction module, 340 - Second construction module, 350 - Third construction module, 360 - Fourth construction module, 370 - Judgment module.

[0037] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0038] It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the application. Rather, these embodiments are provided to make the disclosure more thorough and complete, and to fully convey the scope of the disclosure to those skilled in the art.

[0039] In existing technologies, the analysis of key control factors for identifying gas-bearing layers in tight sandstone relies solely on measuring changes in rock physical properties after fluid displacement via rock physics experiments. However, this method has limitations, as it does not involve pressurizing the experimental process, thus neglecting the impact of high pore pressure on rock physical properties. Furthermore, gas layer identification still employs techniques such as the P-wave / S-wave velocity ratio, Poisson's ratio, and the three-porosity difference ratio method. While classical gas layer identification methods perform well in conventional reservoirs, oil-based mud intrusion and overpressure can alter the logging response.

[0040] To address the aforementioned technical problems, embodiments of this application provide a method for identifying deep, tight sandstone gas reservoirs, such as... Figure 1 As shown, the method may include the following steps:

[0041] S10, core samples are taken to obtain multiple core samples.

[0042] In an exemplary embodiment, step S10 may include:

[0043] S210, sandstone core samples from the reservoir section within the study area were selected;

[0044] S220, rock sample preparation was carried out to obtain multiple core samples.

[0045] Specifically, the core samples were prepared by selecting sandstone core samples from the reservoir section within the study area, and the core samples were standard plunger samples.

[0046] S20, the effective porosity, longitudinal wave velocity of saturated with different fluids (oil-based mud, water, natural gas) and density of rock samples saturated with different fluids were obtained through multiple sets of experiments.

[0047] In an exemplary embodiment, step S20 may include:

[0048] S210, conduct multiple sets of porosity, longitudinal wave velocity of saturated fluids with different saturations and multiple sets of density measurement experiments;

[0049] S220, based on helium porosity experiments, the effective porosity of multiple sets of core samples was obtained respectively;

[0050] S230, after vacuuming and pressurizing multiple sets of the core samples to saturate them with natural gas, their density and longitudinal wave velocity were measured.

[0051] S240, after vacuuming and pressurizing the core samples of multiple groups, their density and longitudinal wave velocity are measured.

[0052] S250, drying multiple sets of the core samples;

[0053] S260, based on the longitudinal wave velocity of different saturated fluids and the density of rock samples saturated with different fluids, determined the longitudinal wave velocity and density of rock samples saturated with different fluids through a series of density measurements.

[0054] In this exemplary embodiment, the effective porosity of the core sample is first measured by helium porosity test according to the "Core Analysis Method (SY / T5336-2006)". Then, referring to the "Laboratory Measurement Specification for Acoustic Parameters of Rock Samples (SY / T6490-2014)" standard, the rock sample is first vacuumed, pressurized and saturated with natural gas, and its density and P-wave velocity are measured. Then, the rock sample is vacuumed, pressurized and saturated with water, and its density and P-wave velocity are measured. Finally, the rock sample is dried, vacuumed, pressurized and saturated with oil-based mud, and its density and P-wave velocity are measured.

[0055] Furthermore, experimental joint measurements were conducted on 20 tight sandstone samples in the study area under different fluid replacement conditions. This ensured the accuracy and reliability of the experimental data while eliminating interference between different rock samples. It also maximized the restoration of the reservoir characteristics of deep tight sandstone reservoirs saturated with different fluids. Subsequently, an effective porosity-fluid impedance cross-plot was constructed using the core experimental data. Analysis of the plot showed that the rock sample impedance value was larger when the rock sample was saturated with oil-based mud and water, and smaller when the rock sample was saturated with natural gas. Moreover, there was a clear distinction between the liquid phase and the gas phase in the cross-plot.

[0056] S30, construct and analyze the cross plot of effective porosity-fluid impedance (rock sample longitudinal wave velocity × density).

[0057] In an exemplary embodiment, after step S30, the following steps may also be included:

[0058] S310, When the rock sample is saturated with oil-based mud and water, the impedance value of the core sample is too large;

[0059] S320, When the rock sample is saturated with natural gas, the impedance value of the core sample is relatively small.

[0060] S40, construct a petrophysical volume model of deep tight sandstone reservoirs.

[0061] The deep tight sandstone reservoir rock physical volume model divides the rock into two parts: a rock skeleton and pores.

[0062] S50, construct the relationship between the longitudinal wave velocity and density of rock under fully saturated conditions.

[0063] In an exemplary embodiment, step S50 may include the following steps:

[0064] S510, Construct a rock physical volume model under fully saturated conditions;

[0065] S520, Based on the physical volume model of rock under fully saturated conditions and the following formula, construct the relationship between the longitudinal wave velocity and density of rock under fully saturated conditions:

[0066] V 水层 = (1-φ)*V 骨架 +φ*V 水 (1)

[0067] ρ 水层 =(1-φ)*ρ 骨架 +φ*ρ 水 (2)

[0068] In the formula: V 水层 V is the velocity of sound waves when the rock is saturated with water, in m / s. 骨架 The volume of the framework of dense sandstone, in cm. 3 V 水 The volume of water-saturated pores is expressed in cm³. 3 .

[0069] S60, construct the relationship between the longitudinal wave velocity and density of rocks under fully saturated natural gas conditions.

[0070] In an exemplary embodiment, step S60 may include the following steps:

[0071] S610, constructing a rock physical volume model under fully saturated natural gas conditions;

[0072] S620, Based on the physical volume model of rocks under fully saturated natural gas conditions and the following formula, construct the relationship between the P-wave velocity and density of rocks under fully saturated natural gas conditions:

[0073] V 气层 = (1-φ)*V 骨架 +φ*V 气 (3)

[0074] ρ 气层 =(1-φ)*ρ 骨架 +φ*ρ 气 (4)

[0075] In the formula: V 气 The volume of air-saturated pores is expressed in cm³. 3 φ represents the porosity of dense sandstone, in %; ρ 水 The density of water, in g / cm³ 3 ;ρ 气 This is the density of natural gas, expressed in g / cm³. 3 .

[0076] From formulas (1) to (4), it can be seen that the sound wave velocity and density in the same stratum are not related to the rock skeleton but only to the properties of the fluid in the pores. At the same time, it can be seen that the acoustic impedance of the stratum is given by formula (5). Therefore, the impedance is different when the stratum is filled with different fluids.

[0077] Z=ρ*V (5)

[0078] In the formula: Z is the formation impedance, in g / cm3·m / s; ρ is the formation density, in g / cm3; V is the formation acoustic velocity, in m / s.

[0079] S70, construct a fluid impedance ratio model to determine the fluid properties of deep tight sandstone reservoirs.

[0080] In an exemplary embodiment, step S70 may include the following steps:

[0081] S710, based on the following formula, constructs a fluid resistance ratio model:

[0082]

[0083] Z w =V w *ρ w (7)

[0084] Z f =V f *ρ f (8)

[0085]

[0086] In the formula: Z * Z is the fluid resistance ratio, dimensionless. w Formation water saturation resistance, unit: g / cm³·m / s; Z f Formation fluid impedance; V w V is the speed of sound in water, measured in m / s. f ρ represents the velocity of sound waves in formation fluids, in m / s. w ρ is the density of water, expressed in g / cm³. f T represents the density of the saturated fluid in the formation, in g / cm³. * ρ represents the time difference between formation saturated water and formation saturated fluid, with dimensionless units. * The density ratio of formation-saturated water to formation-saturated fluid is dimensionless. Porosity calculated for acoustic waves, in %; Porosity is calculated for density, in %; Porosity calculated for 3ms NMR logging, in %;

[0087] S720, Based on the fluid impedance ratio model, determine the fluid properties of deep tight sandstone reservoirs.

[0088] Specifically, a fluid impedance ratio model is constructed using well logging data to determine the fluid properties of deep tight sandstone reservoirs. The ratio of the impedance when the formation is fully saturated with water to the impedance of the formation saturated with fluid is given by formula (6), where Z... w For formula (7), Z f Formula (8) can be derived into formula (9), where T * For formula

[0089] (10), ρ * Formula (11) is used where if the fluid resistance ratio is greater than 1, the reservoir is a gas layer, and if the fluid resistance ratio is less than or equal to 1, the reservoir is a water layer.

[0090] This application provides a method for identifying deep tight sandstone gas reservoirs. Through multiple experiments, the P-wave velocity and density of tight sandstone under different saturated fluid conditions are obtained. Furthermore, by constructing a rock physical volume model of deep tight sandstone reservoirs, the differences in impedance under different fluid conditions can be studied. Finally, through a fluid impedance ratio model, the impedance ratio model formula for formation saturated water and saturated fluid can be obtained. This eliminates the influence of oil-based mud intrusion and subsurface pressure on sandstone reservoir identification, resulting in accurate and reliable identification results with higher precision. It also breaks through the limitations of traditional methods that rely on fixed elastic parameters for gas reservoir identification.

[0091] Based on the above embodiments, refer to Figure 2 Another embodiment of this application also provides a deep tight sandstone gas layer identification device, which 300 may include the following modules:

[0092] The first acquisition module is used to sample the rock core and acquire multiple rock core samples;

[0093] The second acquisition module is used to obtain the effective porosity, longitudinal wave velocity saturated with different fluids, and rock sample density saturated with different fluids of multiple core samples through multiple sets of experiments.

[0094] The first construction module is used to construct and analyze the effective porosity-fluid resistance cross plot.

[0095] The second building module is used to build a petrophysical volume model of deep tight sandstone reservoirs;

[0096] The third building module is used to construct the relationship between the longitudinal wave velocity and density of rocks under fully saturated conditions.

[0097] The fourth construction module is used to construct the relationship between the longitudinal wave velocity and density of rocks under fully saturated natural gas conditions;

[0098] The judgment module is used to construct a fluid impedance ratio model to determine the fluid properties of deep tight sandstone reservoirs.

[0099] Based on the above embodiments, this application also provides a computer-readable storage medium, see reference. Figure 3 The computer-readable storage medium shown is an optical disc 50, on which a computer program (i.e., a program product) is stored. When the computer program is run by a processor, it will implement the steps described in the above-described method implementation, such as: sampling the rock core to obtain multiple core samples; obtaining the effective porosity, P-wave velocity saturated with different fluids, and rock sample density saturated with different fluids for multiple core samples through multiple sets of experiments; constructing and analyzing the effective porosity-fluid impedance cross-plot; constructing a rock physical volume model of deep tight sandstone reservoirs; constructing the relationship between P-wave velocity and density of rocks under fully saturated water conditions; constructing the relationship between P-wave velocity and density of rocks under fully saturated natural gas conditions; and constructing a fluid impedance ratio model to determine the fluid properties of deep tight sandstone reservoirs. The specific implementation methods of each step will not be repeated here.

[0100] It should be noted that examples of the computer-readable storage medium may also include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other optical and magnetic storage media, which will not be elaborated here.

[0101] Furthermore, based on the above embodiments, this application also provides a computing device. Figure 4 A block diagram is shown of an exemplary computing device 60 suitable for implementing embodiments of the present application. The computing device 60 may be a computer system or a server. Figure 4 The computing device 60 shown is merely an example and should not impose any limitation on the functionality and scope of use of the embodiments of this application.

[0102] like Figure 4 As shown, the components of computing device 60 may include, but are not limited to: one or more processors or processing units 601, system memory 602, and bus 603 connecting different system components (including system memory 602 and processing unit 601).

[0103] The computing device 60 typically includes a variety of computer system readable media. These media can be any available media that can be accessed by the computing device 60, including volatile and non-volatile media, removable and non-removable media.

[0104] System memory 602 may include computer system readable media in the form of volatile memory, such as random access memory (RAM) 6021 and / or cache memory 6022. Computing device 60 may further include other removable / non-removable, volatile / non-volatile computer system storage media. By way of example only, ROM 6023 may be used to read and write non-removable, non-volatile magnetic media (…). Figure 4 Not shown in the image (usually referred to as a "hard drive"). Although not shown in Figure 4 The diagram illustrates that disk drives for reading and writing to removable non-volatile disks (e.g., "floppy disks") and optical disc drives for reading and writing to removable non-volatile optical discs (e.g., CD-ROMs, DVD-ROMs, or other optical media) can be provided. In these cases, each drive can be connected to a bus 603 that connects different system components via one or more data media interfaces. The system memory 602 may include at least one program product having a set (e.g., at least one) of program modules configured to perform the functions of the embodiments of this application.

[0105] A program / utility 6025 having a set (at least one) of program modules 6024 may be stored, for example, in system memory 602, and such program modules 6024 include, but are not limited to, an operating system, one or more application programs, other program modules, and program data, each or some combination of these examples may include an implementation of a network environment. Program modules 6024 typically perform the functions and / or methods described in the embodiments of this application.

[0106] The computing device 60 can also communicate with one or more external devices 604 (such as a keyboard, pointing device, display, etc.). This communication can be performed via the input / output (I / O) interface 605. Furthermore, the computing device 60 can also communicate with one or more networks (e.g., local area networks (LANs), wide area networks (WANs), and / or public networks, such as the Internet) via a network adapter 606. Figure 4 As shown, network adapter 606 communicates with other modules of computing device 60 (such as processing unit 601, etc.) via bus 603, which connects different system components. It should be understood that, although... Figure 4 Other hardware and / or software modules may be used in conjunction with computing device 60, as not shown in the diagram.

[0107] The processing unit 601 executes various functional applications and data processing by running programs stored in the system memory 602. For example, it samples the rock core to obtain multiple core samples; obtains the effective porosity, P-wave velocity saturated with different fluids, and rock sample density saturated with different fluids for each core sample through multiple sets of experiments; constructs and analyzes an effective porosity-fluid impedance cross-plot; constructs a rock physical volume model of a deep tight sandstone reservoir; constructs a relationship between P-wave velocity and density under fully saturated water conditions; constructs a relationship between P-wave velocity and density under fully saturated natural gas conditions; and constructs a fluid impedance ratio model to determine the fluid properties of the deep tight sandstone reservoir. The specific implementation methods of each step will not be repeated here. It should be noted that although several units / modules or sub-units / sub-modules of the deep tight sandstone gas layer identification device are mentioned in the detailed description above, this division is merely exemplary and not mandatory. In fact, according to the embodiments of this application, the features and functions of two or more units / modules described above can be embodied in one unit / module. Conversely, the features and functions of a unit / module described above can be further divided into multiple units / modules for specificity.

[0108] In the description of this application, it should be noted that the terms "first", "second", and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0109] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0110] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the shown or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0111] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0112] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0113] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0114] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The protection scope of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the technical scope disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

[0115] Furthermore, although the operations of the method of this application are described in a specific order in the accompanying drawings, this does not require or imply that these operations must be performed in that specific order, or that all the operations shown must be performed to achieve the desired result. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps.

Claims

1. A method for identifying deep, tight sandstone gas layers, characterized in that, The method for identifying deep, tight sandstone gas layers includes: Core samples were taken to obtain multiple core specimens; The effective porosity, longitudinal wave velocity saturated with different fluids, and rock sample density saturated with different fluids were obtained through multiple sets of experiments. Construct and analyze the effective porosity-fluid resistance cross plot; Constructing a petrological volumetric model of deep tight sandstone reservoirs; Construct the relationship between the longitudinal wave velocity and density of rocks under fully saturated conditions; Construct the relationship between longitudinal wave velocity and density of rocks under fully saturated natural gas conditions; A fluid impedance ratio model was constructed to determine the fluid properties of deep tight sandstone reservoirs.

2. The method for identifying deep tight sandstone gas layers according to claim 1, characterized in that, The process of sampling the rock core to obtain multiple core samples includes: Sandstone core samples from reservoir sections within the study area were selected; Rock samples were prepared to obtain multiple core samples.

3. The method for identifying deep tight sandstone gas layers according to claim 1, characterized in that, The process of obtaining the effective porosity, longitudinal wave velocity saturated with different fluids, and rock sample density saturated with different fluids from multiple core samples through multiple sets of experiments includes: Multiple sets of experiments were conducted to measure porosity, longitudinal wave velocity of saturated fluids with different saturations, and density. The effective porosity of multiple sets of core samples was obtained based on helium porosity experiments. After vacuuming and pressurizing the core samples to saturate them with natural gas, their density and P-wave velocity were measured. The density and longitudinal wave velocity of multiple sets of core samples were measured after vacuuming and pressurizing to saturate with water. The core samples from multiple groups were dried. The longitudinal wave velocity and rock sample density of different saturated fluids were determined based on experiments involving combined measurements of longitudinal wave velocity and multiple density sets.

4. The method for identifying deep tight sandstone gas layers according to claim 1, characterized in that, The different fluids include oil-based mud, water, and natural gas.

5. The method for identifying deep tight sandstone gas layers according to claim 1, characterized in that, The rock physical volume model of the deep tight sandstone reservoir divides the rock into two parts: the rock skeleton and the pores.

6. The method for identifying deep tight sandstone gas layers according to claim 1, characterized in that, After constructing and analyzing the effective porosity-fluid resistance cross-plot, the method further includes: When the rock sample is saturated with oil-based mud and water, the impedance value of the core sample is relatively large. When the rock sample is saturated with natural gas, the impedance value of the core sample is relatively small.

7. The method for identifying deep tight sandstone gas layers according to claim 1, characterized in that, The formula for the relationship between the longitudinal wave velocity and density of rock under fully saturated conditions includes: Construct a physical volume model of rocks under fully saturated conditions; Based on the physical volume model of rock under fully saturated conditions and the following formula, the relationship between the longitudinal wave velocity and density of rock under fully saturated conditions is constructed: V 水层 =(1-φ)*V 骨架 +φ*V 水 (1) r 水层 =(1-φ)*ρ 骨架 +f*r 水 (2) In the formula: V 水层 V is the velocity of sound waves when the rock is saturated with water, in m / s. 骨架 The volume of the framework of dense sandstone, in cm. 3 V 水 The volume of water-saturated pores, in cm³. 3 .

8. The method for identifying deep tight sandstone gas layers according to claim 1, characterized in that, The formula for the relationship between the longitudinal wave velocity and density of rocks under fully saturated natural gas conditions includes: Constructing a rock physical volume model under fully saturated natural gas conditions; Based on the physical volume model of rocks under fully saturated natural gas conditions and the following formula, the relationship between the P-wave velocity and density of rocks under fully saturated natural gas conditions is constructed: V 气层 =(1-φ)*V 骨架 +φ*V 气 (3) r 气层 =(1-φ)*ρ 骨架 +f*r 气 (4) In the formula: V 气 The volume of air-saturated pores is expressed in cm³. 3 φ represents the porosity of dense sandstone, in %; ρ 水 The density of water, in g / cm³ 3 ;ρ 气 This is the density of natural gas, expressed in g / cm³. 3 .

9. The method for identifying deep tight sandstone gas layers according to claim 1, characterized in that, The construction of the fluid impedance ratio model to determine the fluid properties of deep tight sandstone reservoirs includes: The fluid impedance ratio model is constructed based on the following formula: Z w =V w *ρ w (7) Z f =V f *ρ f (8) In the formula: Z * Z is the fluid resistance ratio, dimensionless. w Formation water saturation resistance, unit: g / cm³·m / s; Z f Formation fluid impedance; V w V is the speed of sound in water, measured in m / s. f ρ represents the velocity of sound waves in formation fluids, in m / s. w The density of water, in g / cm³ 3 ;ρ f Density of the saturated fluid in the formation, in g / cm³ 3 ;T * ρ represents the time difference between formation saturated water and formation saturated fluid, with dimensionless units. * The density ratio of formation-saturated water to formation-saturated fluid is dimensionless. Porosity calculated for acoustic waves, in %; Porosity is calculated for density, in %; Porosity calculated for 3ms NMR logging, in %; The fluid properties of deep tight sandstone reservoirs are determined based on the fluid impedance ratio model.

10. The method for identifying deep tight sandstone gas layers according to claim 1, characterized in that, After determining the fluid properties of deep tight sandstone reservoirs based on the fluid impedance ratio model, the method further includes: When the fluid resistance ratio is greater than 1, the reservoir is a gas layer; When the fluid resistance ratio is less than or equal to 1, the reservoir is a water layer.

11. A device for identifying deep, tight sandstone gas layers, characterized in that, include: The first acquisition module is used to sample the rock core and obtain multiple rock core samples; The second acquisition module is used to obtain the effective porosity, longitudinal wave velocity saturated with different fluids, and rock sample density saturated with different fluids of multiple core samples through multiple sets of experiments. The first construction module is used to construct and analyze the effective porosity-fluid resistance cross plot. The second building module is used to build a petrophysical volume model of deep tight sandstone reservoirs; The third construction module is used to construct the relationship between the longitudinal wave velocity and density of rocks under fully saturated conditions. The fourth construction module is used to construct the relationship between the longitudinal wave velocity and density of rocks under fully saturated natural gas conditions; The judgment module is used to construct a fluid impedance ratio model to determine the fluid properties of deep tight sandstone reservoirs.

12. A computer-readable storage medium, characterized in that, It includes instructions that, when run on a computer, cause the computer to perform the method for identifying deep tight sandstone gas layers as described in any one of claims 1 to 9.

13. A computing device, characterized in that, The computing device includes: At least one processor, memory, and input / output unit; The memory is used to store computer programs, and the processor is used to call the computer programs stored in the memory to execute the deep tight sandstone gas layer identification method according to any one of claims 1 to 9.

Images