Method and device for obtaining three-phase saturation of natural gas hydrate, equipment and medium

Abstract

The present application relates to a kind of natural gas hydrate three-phase saturation acquisition method and device, equipment, medium, it is related to formation evaluation technical field, comprising: based on neutron logging data establishes the neutron porosity logging interpretation model of target well mixed section, and establishes the neutron porosity interpretation model of pure hydrate section similar to the lithology of target well mixed section and adjacent;Based on nuclear magnetic resonance logging data establishes the nuclear magnetic porosity logging interpretation model of target well mixed section;Establish the nuclear magnetic porosity interpretation model of pure hydrate section similar to the lithology of target well mixed section and adjacent;Based on each model, average formation porosity, average neutron porosity and average nuclear magnetic porosity, three-phase saturation is obtained by solving.This application provides the acquisition method, is based on nuclear magnetic resonance logging and neutron logging to establish nuclear magnetic-neutron interpretation model, accurately obtains the hydrate, free gas, water three-phase saturation of mixed section, provides accurate reservoir parameter for hydrate resource quantity evaluation.

Description

Technical Field

[0001] This invention relates to the field of formation evaluation technology, specifically to a method, apparatus, equipment, and medium for obtaining the three-phase saturation of natural gas hydrates. Background Technology

[0002] Currently, natural gas hydrates are a highly efficient and clean energy source with abundant resources, representing a strategic high ground for future global energy development. Research indicates that mixed layers of hydrates, free gas, and water coexisting within the stable zone of natural gas hydrates have been confirmed to exist in multiple regions. However, the key issue is how to accurately assess the saturation of hydrates, gaseous hydrocarbons, and water to provide a basis for hydrate deposit development.

[0003] Currently, methods for quantitatively evaluating the three-phase saturation of mixed layers include core analysis, sonic logging, and a combination of nuclear magnetic resonance and density.

[0004] Core analysis, which involves collecting the total amount of gas released by pressurized core samples and combining this with pore water desalination, can calculate the three-phase saturation. However, this method has the following drawbacks: First, obtaining core samples from the deep sea is expensive, and the data obtained is discrete, making it impossible to obtain continuous results for the mixed layer. Second, it is difficult to maintain core pressure, and it is hard to determine the formation water salinity and gas concentration in the in-situ state.

[0005] The acoustic logging method has several drawbacks. First, the presence of gas in the mixed layer leads to inaccurate extraction of P-wave and S-wave velocities, affecting the calculation results. Second, the rock physics model used in this method depends primarily on the microscopic occurrence of hydrates in the mixed layer, requiring acquisition through core CT scans and other methods, resulting in high uncertainty. Third, the formulas involve multiple unknowns, often using default values, which vary depending on the region and sediments, leading to significant errors in the calculation results.

[0006] The main problem with conventional NMR-density logging is that hydrate sediments have complex lithology, making it difficult to determine framework parameters. The porosity calculated by density logging is also low, resulting in large errors in the calculation results.

[0007] In summary, existing methods for obtaining saturation in mixed layers where hydrates, free gas, and water coexist within the stability zone of natural gas hydrates still suffer from significant calculation errors. Summary of the Invention

[0008] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method, apparatus, equipment and medium for obtaining the three-phase saturation of natural gas hydrate, so as to solve the defect that the calculation results of obtaining the saturation in the mixed layer where hydrate, free gas and water coexist in the stable zone of natural gas hydrate still have large errors.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a method for obtaining the three-phase saturation of natural gas hydrate, the method comprising:

[0011] A neutron porosity logging interpretation model for the mixed-layer section of the target well was established based on neutron logging data.

[0012] Based on the neutron porosity logging interpretation model, a neutron porosity interpretation model is established for a pure hydrate interval that is lithologically similar to and adjacent to the mixed interval of the target well.

[0013] A nuclear magnetic resonance (NMR) porosity logging interpretation model for the mixed-layer section of the target well was established based on NMR logging data.

[0014] Establish a nuclear magnetic resonance porosity interpretation model for a pure hydrate interval with similar lithology to the mixed interval of the target well and adjacent to it;

[0015] Based on the neutron porosity logging interpretation model, the neutron porosity interpretation model, the nuclear magnetic resonance (NMR) porosity interpretation model, and the NMR porosity logging interpretation model, the average formation porosity corresponding to the selected pure hydrate interval in the target well is used. Average neutron porosity and average NMR porosity The gas saturation of the mixing section is obtained by solving. , gas saturation The water saturation of the mixed-layer section was obtained by substituting the nuclear magnetic resonance porosity logging interpretation model into the solution. Based on the obtained gas saturation and water saturation The hydrate saturation of the mixed-layer section was obtained by reverse calculation. .

[0016] The acquisition method provided by this invention, based on field-measured nuclear magnetic resonance logging and neutron logging, establishes a nuclear magnetic resonance-neutron combined interpretation model, accurately and continuously evaluates the three-phase saturation of hydrates, free gas, and water in mixed layers, and provides accurate reservoir parameters for hydrate resource evaluation.

[0017] As a preferred technical solution of the present invention, the neutron porosity logging interpretation model of the mixed layer is as follows:

[0018] ;

[0019] In the formula, The measured neutron porosity logging values ​​at different depths in the mixed layer; This represents the porosity value of the mixed-layer formation. The water saturation at different depths in the mixed layer is shown. The hydrate saturation at different depths in the mixed layer. These represent the gas saturation at different depths in the mixing layer. ; The hydrogen content index of formation water. The hydrogen content index of hydrates. The hydrogen content index of the free gas. The hydrogen content index represents the stratigraphic framework.

[0020] As a preferred technical solution of the present invention, the neutron porosity interpretation model of the pure hydrate layer is as follows:

[0021] ;

[0022] In the formula, The measured neutron porosity value is for the pure hydrate layer. Porosity of the pure hydrate layer; This represents the water saturation value for this layer. This represents the hydrate saturation value for this layer, and .

[0023] As a preferred technical solution of the present invention, the nuclear magnetic resonance porosity logging interpretation model of the mixed layer is as follows:

[0024] ;

[0025] In the formula, Measured NMR porosity at different depths in the mixed layer; This represents the average formation porosity. The water saturation at different depths in the mixed layer is shown. The gas saturation at different depths in the mixing layer; is the polarization factor of the gas.

[0026] As a preferred technical solution of the present invention, the NMR porosity interpretation model of the pure hydrate layer is as follows:

[0027] .

[0028] As a preferred technical solution of the present invention, the selection criteria for the pure hydrate interval that is lithologically similar to and adjacent to the mixed interval of the target well simultaneously satisfy the following:

[0029] (1) The difference in average natural gamma value between the mixed layer and the pure hydrate layer in the target well is ≤5 API;

[0030] (2) The bottom depth of the selected layer is ≤2m and the top depth of the mixed layer of the target well is ≤2m.

[0031] As a preferred technical solution of the present invention, the gas saturation The system of equations was obtained by solving the system of equations, which includes:

[0032] ;

[0033] ;

[0034] ;

[0035] ;

[0036] ;

[0037] ;

[0038] ;

[0039] ;

[0040] ;

[0041] .

[0042] Secondly, the present invention provides an apparatus for obtaining the three-phase saturation of natural gas hydrates, the evaluation apparatus comprising:

[0043] The first model acquisition module is used to establish a neutron porosity logging interpretation model for the mixed-layer section of the target well based on neutron logging data.

[0044] The second model acquisition module is used to establish a neutron porosity interpretation model for a pure hydrate interval that is lithologically similar to and adjacent to the mixed interval of the target well, based on the neutron porosity logging interpretation model.

[0045] The third model acquisition module is used to establish a nuclear magnetic resonance porosity logging interpretation model for the mixed-layer section of the target well based on nuclear magnetic resonance logging data.

[0046] The fourth model acquisition module establishes a nuclear magnetic porosity interpretation model for pure hydrate intervals with similar lithology to the mixed intervals of the target well and adjacent to them.

[0047] The solution module is used to interpret neutron porosity logging based on neutron porosity logging, nuclear magnetic resonance (NMR) porosity logging, and NMR porosity logging, utilizing the average formation porosity corresponding to the selected pure hydrate interval in the target well. Average neutron porosity and average NMR porosity The gas saturation of the mixing section is obtained by solving. , gas saturation The water saturation of the mixed-layer section was obtained by substituting the nuclear magnetic resonance porosity logging interpretation model into the solution. Based on the obtained gas saturation and water saturation The hydrate saturation of the mixed-layer section was obtained by reverse calculation. .

[0048] Thirdly, the present invention provides an electronic device comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores a computer program executable by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform the method for obtaining the three-phase saturation of natural gas hydrates as described in the first aspect.

[0049] Fourthly, the present invention provides a computer storage medium storing computer-executable instructions, which, when executed by a processor, implement the method for obtaining the three-phase saturation of natural gas hydrates as described in the first aspect.

[0050] Compared with existing technical solutions, the present invention has the following beneficial effects:

[0051] The acquisition method provided by this invention does not require the introduction of many rock electrical parameters or the construction of complex rock physics models. By jointly establishing an interpretation model of the changes in nuclear magnetic porosity and neutron porosity of mixed layers compared to pure hydrate layers, it provides an accurate method for obtaining the saturation of hydrates, gas and formation water in mixed layers, and has a wide range of applications. Attached Figure Description

[0052] Figure 1 This is a flowchart of a method for obtaining the three-phase saturation of natural gas hydrates according to an embodiment of the present invention;

[0053] Figure 2 This is a schematic diagram of the apparatus for obtaining the three-phase saturation of natural gas hydrates provided in an embodiment of the present invention;

[0054] Figure 3 This is a schematic diagram of an electronic device provided in an embodiment of the present invention;

[0055] Figure 4 This is a composite columnar section of the logging curves of well QDN-A in Embodiment 1 of the present invention;

[0056] Figure 5 This is the gas saturation map obtained at different depths of the mixing layer B in Embodiment 1 of the present invention;

[0057] Figure 6 This is a hydrate saturation map obtained at different depths of the mixed layer B in Embodiment 1 of the present invention;

[0058] Figure 7 This is a formation water saturation map obtained at different depths of the mixed layer B in Embodiment 1 of the present invention.

[0059] In the picture:

[0060] 100 - First model acquisition module, 200 - Second model acquisition module, 300 - Third model acquisition module, 400 - Fourth model acquisition module, 500 - Solving module;

[0061] 10-Electronic device, 11-Processor, 12-ROM, 13-RAM, 14-Bus, 15-I / O interface, 16-Input unit, 17-Output unit, 18-Storage unit, 19-Communication unit.

[0062] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims. Detailed Implementation

[0063] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0064] Currently, quantitative methods for the three-phase saturation of natural gas hydrate mixed layers include core analysis, sonic logging, and NMR-density combination methods. However, existing methods suffer from poor accuracy in obtaining three-phase saturation due to the difficulty in obtaining stable sample data and defects in the evaluation process. Therefore, this invention optimizes the acquisition method by utilizing NMR logging and neutron logging, and establishes an NMR-neutron combined interpretation model to accurately and continuously evaluate the three-phase saturation of hydrates, free gas, and water in the mixed layer, as detailed below:

[0065] I. This embodiment provides a method for obtaining the three-phase saturation of natural gas hydrates, the process of which is as follows: Figure 1 As shown, the acquisition method includes:

[0066] A neutron porosity logging interpretation model for the mixed-layer section of the target well was established based on neutron logging data.

[0067] Based on the neutron porosity logging interpretation model, a neutron porosity interpretation model is established for a pure hydrate interval that is lithologically similar to and adjacent to the mixed interval of the target well.

[0068] A nuclear magnetic resonance (NMR) porosity logging interpretation model for the mixed-layer section of the target well was established based on NMR logging data.

[0069] Establish a nuclear magnetic resonance porosity interpretation model for a pure hydrate interval with similar lithology to the mixed interval of the target well and adjacent to it;

[0070] Based on the neutron porosity logging interpretation model, the neutron porosity interpretation model, the nuclear magnetic resonance (NMR) porosity interpretation model, and the NMR porosity logging interpretation model, the average formation porosity corresponding to the selected pure hydrate interval in the target well is used. Average neutron porosity and average NMR porosity The gas saturation of the mixing section is obtained by solving. , gas saturation The water saturation of the mixed-layer section was obtained by substituting the nuclear magnetic resonance porosity logging interpretation model into the solution. Based on the obtained gas saturation and water saturation The hydrate saturation of the mixed-layer section was obtained by reverse calculation. .

[0071] Specifically, a neutron porosity logging interpretation model was established for the mixed-phase formation of the target well. Based on the traditional volumetric model, the neutron porosity logging interpretation model for the mixed-phase formation (hydrate, free gas, and water) of the target well is as follows:

[0072] (1);

[0073] In the formula, The measured neutron porosity logging values ​​at different depths in the mixed layer; This represents the porosity value of the mixed-layer formation. , and These represent the water saturation, hydrate saturation, and gas saturation at different depths in the mixed layer. ; , , and These are the hydrogen content indices for formation water, hydrates, free gas, and the formation framework, respectively; for example, , , , It is related to the lithology of the strata.

[0074] Specifically, a pure hydrate layer with similar lithology to and adjacent to the mixed layer of the target well was selected, and a neutron porosity logging interpretation model for the pure hydrate layer was established. Since it is a pure hydrate layer, the gas saturation at this time... According to equation (1), the neutron porosity logging interpretation model for pure hydrate zones is as follows:

[0075] (2);

[0076] In the formula, The values ​​represent the measured neutron porosity of the pure hydrate layer. For the porosity of the pure hydrate layer, and These are the water saturation value and hydrate saturation value of this layer, respectively. .

[0077] In this invention, the selection criteria for pure hydrate intervals that are lithologically similar to and adjacent to the mixed intervals of the target well simultaneously satisfy the following:

[0078] (1) The difference in average natural gamma value between the mixed layer and the pure hydrate layer in the target well is ≤5 API;

[0079] (2) The bottom depth of the selected layer is ≤2m and the top depth of the mixed layer of the target well is ≤2m.

[0080] Combining formulas (1) and (2), since the lithology of the pure hydrate section and the mixed section is similar, the hydrogen content index of the stratigraphic framework of the two sections can be considered to be equal, i.e. Furthermore, since the lithology of the two strata did not change significantly and they are adjacent, the porosity change caused by formation compaction is negligible. Therefore, the formation porosity of the two strata can be considered equal, and both can be taken as the average formation porosity. ,Right now

[0081] Equations (1)-(2):

[0082] (3);

[0083] Pure hydrate layer: different fluid saturation is 1.

[0084] (4);

[0085] Mixed-layer segment: different fluid saturation levels are 1.

[0086] (5);

[0087] Equations (5) to (4):

[0088] (6);

[0089] make Then equation (6) can be written as:

[0090] (7);

[0091] Combine equations (3) and (7), and exemplarily, to , , ,have to,

[0092] (8);

[0093] A nuclear magnetic resonance (NMR) porosity interpretation model for the mixed-layer section of the target well was established. NMR logging measures the vertical or lateral relaxation characteristics of hydrogen nuclei in the formation. While hydrates contain abundant hydrogen atoms in both water and gas molecules, NMR logging is not sensitive to hydrogen nuclei in solids; therefore, its logging signal primarily reflects fluid information within the formation. For the mixed-layer section of the target well, based on the traditional volumetric model, the NMR porosity interpretation model is as follows:

[0094] (9);

[0095] In the formula, Measured NMR porosity at different depths in the mixed layer; and These represent the water saturation and gas saturation at different depths in the mixed layer; , These are the hydrogen content indices for formation water and free gas, respectively. The polarization factor of the gas; for example, , , .

[0096] Based on the selected pure hydrate zone, a nuclear magnetic resonance (NMR) porosity logging interpretation model was established: Since the porosity fluids in the pure hydrate zone consist only of hydrates and formation water, and NMR porosity is not sensitive to hydrogen nuclei in solid hydrates, the NMR porosity interpretation model is as follows:

[0097] (10);

[0098] Equations (9)-(10):

[0099] (11);

[0100] Specifically, to determine the fluid saturation of the mixed layer, the average formation porosity corresponding to the selected pure hydrate layer in the target well is read. Average neutron porosity Average NMR porosity Solve the system of equations by combining equations (8) and (11). and Based on the calculated gas saturation Substitute into equation (9) to obtain the water saturation at each depth point in the mixed layer. By using the fact that the sum of the saturations of the three factors is 1, the hydrate saturation can finally be calculated. .

[0101] II. This embodiment provides a device for obtaining the three-phase saturation of natural gas hydrates, such as... Figure 2 As shown, the evaluation device includes:

[0102] The first model acquisition module 100 is used to establish a neutron porosity logging interpretation model for the mixed layer of the target well based on neutron logging data.

[0103] The second model acquisition module 200 is used to establish a neutron porosity interpretation model for a pure hydrate interval that is lithologically similar to and adjacent to the mixed interval of the target well, based on the neutron porosity logging interpretation model.

[0104] The third model acquisition module 300 is used to establish a nuclear magnetic resonance porosity logging interpretation model for the mixed-layer section of the target well based on nuclear magnetic resonance logging data.

[0105] The fourth model acquisition module 400 is used to establish a nuclear magnetic porosity interpretation model for pure hydrate intervals that are similar in lithology to and adjacent to the mixed intervals of the target well.

[0106] Solution module 500 is used to interpret neutron porosity logging based on neutron porosity logging, nuclear magnetic resonance (NMR) porosity logging, and NMR porosity logging, utilizing the average formation porosity corresponding to the selected pure hydrate interval in the target well. Average neutron porosity and average NMR porosity The gas saturation of the mixing section is obtained by solving. , gas saturation The water saturation of the mixed-layer section was obtained by substituting the nuclear magnetic resonance porosity logging interpretation model into the solution. Based on the obtained gas saturation and water saturation The hydrate saturation of the mixed-layer section was obtained by reverse calculation. .

[0107] Regarding the apparatus in the above embodiments, the specific manner in which each module performs its operation has been described in detail in the embodiments related to the method, and will not be elaborated upon here.

[0108] III. This embodiment provides an electronic device intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device may also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices (e.g., helmets, glasses, watches, etc.), and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the invention described and / or claimed herein.

[0109] like Figure 3 As shown, the electronic device 10 includes at least one processor 11 and a memory, such as a read-only memory (ROM) 12 or a random access memory (RAM) 13, communicatively connected to the at least one processor 11. The memory stores computer programs executable by the at least one processor. The processor 11 can perform various appropriate actions and processes based on the computer program stored in the ROM 12 or loaded into the RAM 13 from storage unit 18. The RAM 13 can also store various programs and data required for the operation of the electronic device 10. The processor 11, ROM 12, and RAM 13 are interconnected via a bus 14. An I / O interface 15 is also connected to the bus 14.

[0110] Multiple components in electronic device 10 are connected to I / O interface 15, including: input unit 16, such as keyboard, mouse, etc.; output unit 17, such as various types of displays, speakers, etc.; storage unit 18, such as disk, optical disk, etc.; and communication unit 19, such as network card, modem, wireless transceiver, etc. Communication unit 19 allows electronic device 10 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0111] Processor 11 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. Processor 11 performs the various methods and processes described above, such as the method for obtaining the three-phase saturation of natural gas hydrates.

[0112] In some embodiments, the method for obtaining the three-phase saturation of natural gas hydrates can be implemented as a computer program tangibly contained in a computer-readable storage medium, such as storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed on electronic device 10 via ROM 12 and / or communication unit 19. When the computer program is loaded into RAM 13 and executed by processor 11, one or more steps of the method for obtaining the three-phase saturation of natural gas hydrates described above can be performed. Alternatively, in other embodiments, processor 11 can be configured to perform the method for obtaining the three-phase saturation of natural gas hydrates by any other suitable means (e.g., by means of firmware).

[0113] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), payload-programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transmitting data and instructions to the storage system, the at least one input device, and the at least one output device.

[0114] Computer programs used to implement the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when executed by the processor, the computer programs cause the functions / operations specified in the flowcharts and / or block diagrams to be performed. The computer programs may be executed entirely on a machine, partially on a machine, or as a standalone software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0115] In the context of this invention, a computer-readable storage medium can be a tangible medium that may contain or store a computer program for use by or in conjunction with an instruction execution system, apparatus, or device. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination thereof. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0116] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user provides input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including sound input, voice input, or tactile input).

[0117] The systems and technologies described herein can be implemented in computing systems that include backend components (e.g., as data servers), or middleware components (e.g., application servers), or frontend components (e.g., user computers with graphical user interfaces or web browsers through which users can interact with implementations of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium (e.g., communication networks). Examples of communication networks include local area networks (LANs), wide area networks (WANs), blockchain networks, and the Internet.

[0118] A computing system can include clients and servers. Clients and servers are generally located far apart and typically interact through communication networks. The client-server relationship is created by computer programs running on the respective computers and having a client-server relationship with each other. The server can be a cloud server, also known as a cloud computing server or cloud host, which is a hosting product within the cloud computing service system to address the shortcomings of traditional physical hosts and VPS services, such as high management difficulty and weak business scalability.

[0119] The server provided in this embodiment includes: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements a method for obtaining the three-phase saturation of natural gas hydrates.

[0120] Unless otherwise specifically stated, terms such as processing, calculation, operation, determination, display, etc., may refer to the actions and / or processes of one or more processing or computing systems or similar devices that represent the manipulation and conversion of data representing physical (e.g., electronic) quantities within the registers or memory of the processing system into other data similarly representing physical quantities within the memory, registers, or other such information storage, transmission, or display devices of the processing system. Information and signals can be represented using any of a variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the above description can be represented by voltage, current, electromagnetic waves, magnetic fields or particles, light fields or particles, or any combination thereof.

[0121] Those skilled in the art will also understand that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with embodiments of the present invention can all be implemented as electronic hardware, computer software, or a combination thereof. To clearly illustrate the interchangeability between hardware and software, the various illustrative components, blocks, modules, circuits, and steps described above are generally described in terms of their functionality. Whether this functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Those skilled in the art can implement the described functionality in alternative ways for each specific application; however, such implementation decisions should not be construed as departing from the scope of protection of the present invention.

[0122] The steps of the methods or algorithms described in conjunction with the embodiments herein can be directly embodied in hardware, software modules executed by a processor, or a combination thereof. The software modules can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium well known in the art. An exemplary storage medium is connected to the processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and storage medium can reside in an ASIC. The ASIC can reside in a user terminal. Alternatively, the processor and storage medium can exist as discrete components in the user terminal.

[0123] For software implementation, the techniques described in this invention can be implemented using modules (e.g., procedures, functions, etc.) that perform the functions described in this application. This software code can be stored in memory units and executed by a processor. The memory units can be implemented within the processor or externally; in the latter case, they are communicatively coupled to the processor via various means, as is well known in the art.

[0124] IV. To illustrate the evaluation effect achievable by the method for obtaining the three-phase saturation of natural gas hydrates provided by this invention, a practical example is used for explanation, as follows:

[0125] Example 1

[0126] This embodiment provides a method for obtaining the three-phase saturation of natural gas hydrates, as detailed below:

[0127] Take a well drilled in the southeastern sea area of ​​Qiongdong in 2021 as an example (QDN-A). Figure 4 This is a composite histogram of logging curves for well QDN-A. Based on the logging response characteristics of the mixed-layer section, the mixed-layer section of well QDN-A is 138-141 mbsf, which is section B in the figure.

[0128] Step 1: Establish the neutron porosity logging interpretation model corresponding to the mixed section B of the QDN-A well.

[0129] (1);

[0130] Step 2: Select a pure hydrate layer with similar lithology to the mixed section of well QDN-A and adjacent to it, and establish a neutron porosity logging interpretation model for the pure hydrate layer.

[0131] from Figure 4The second natural gamma curve shows that the hydrated section A (135-138 mbsf) in well QDN-A has similar lithology to the mixed section B and is directly overlying the mixed section B. The penultimate curve also shows that the formation porosity of the two sections is essentially a straight line with no significant variation; the density neutron curves are basically overlapping, showing no gas response characteristics. Therefore, the conditions for the selected pure hydrated section are met.

[0132] The neutron porosity logging interpretation model for the pure hydrate zone A is as follows:

[0133] (2);

[0134] Step 3: Establish a nuclear magnetic resonance porosity logging interpretation model for the mixed-layer section B of well QDNB-A.

[0135] Based on the traditional volumetric model, the nuclear magnetic resonance porosity interpretation model is as follows:

[0136] (9);

[0137] Step 4: Based on the pure hydrate layer A selected in Step 2, establish its nuclear magnetic resonance porosity logging interpretation model.

[0138] Since the porosity fluids in the pure hydrate layer are only hydrates and formation water, and nuclear magnetic resonance porosity is not sensitive to hydrogen nuclei in solid hydrates, the nuclear magnetic resonance porosity interpretation model is as follows:

[0139] (10);

[0140] Step 5: Determine the saturation of different fluids in the mixed layer B.

[0141] Read the average formation porosity corresponding to the selected pure hydrate section A in QDN-A. Average neutron porosity Average NMR porosity , Figure 5 , Figure 6 , Figure 7 The diagram shows the three-phase saturation at different depths of the mixed layer B, where... Figure 5 To determine the gas saturation at different depths in the mixing layer B, Figure 6 For hydrate saturation diagram, Figure 7 This is a formation water saturation map. From... Figure 5 It can be seen that the gas saturation of the mixing layer B is ( Figure 5 The blue line represents 0-30%, with an average of 19%; the hydrate saturation of the mixed layer B ( Figure 6The blue line indicates a water saturation level between 30% and 80%, with an average of 56%; the water saturation level in the mixed section B formation ranges from 3% to 70%, with an average of 25%; and the predicted gas saturation level (…) Figure 5 (blue line) and hydrate saturation ( Figure 6 The blue lines are all lower than the total saturation calculated from resistivity logging. Figure 5 and Figure 6 The red line indicates that the calculation is reasonable.

[0142] The present invention is described in detail through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0143] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0144] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0145] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for obtaining the three-phase saturation of natural gas hydrate, characterized in that, The acquisition method includes: A neutron porosity logging interpretation model for the mixed-layer section of the target well was established based on neutron logging data. Based on the neutron porosity logging interpretation model, a neutron porosity interpretation model is established for a pure hydrate interval that is lithologically similar to and adjacent to the mixed interval of the target well. A nuclear magnetic resonance (NMR) porosity logging interpretation model for the mixed-layer section of the target well was established based on NMR logging data. Establish a nuclear magnetic resonance porosity interpretation model for a pure hydrate interval with similar lithology to the mixed interval of the target well and adjacent to it; Based on the neutron porosity logging interpretation model, the neutron porosity interpretation model, the nuclear magnetic resonance (NMR) porosity interpretation model, and the NMR porosity logging interpretation model, the average formation porosity corresponding to the selected pure hydrate interval in the target well is used. Average neutron porosity and average NMR porosity The gas saturation of the mixing section is obtained by solving. , gas saturation The water saturation of the mixed-layer section was obtained by substituting the nuclear magnetic resonance porosity logging interpretation model into the solution. Based on the obtained gas saturation and water saturation The hydrate saturation of the mixed-layer section was obtained by reverse calculation. .

2. The acquisition method as described in claim 1, characterized in that, The neutron porosity logging interpretation model for the mixed layer is as follows: ； In the formula, The measured neutron porosity logging values ​​at different depths in the mixed layer; This represents the porosity value of the mixed-layer formation. The water saturation at different depths in the mixed layer is shown. The hydrate saturation at different depths in the mixed layer. The gas saturation at different depths in the mixing layer. ; The hydrogen content index of formation water. The hydrogen content index of hydrates. The hydrogen content index of the free gas. The hydrogen content index represents the stratigraphic framework.

3. The acquisition method as described in claim 2, characterized in that, The neutron porosity interpretation model for the pure hydrate layer is as follows: ； In the formula, The measured neutron porosity value is for the pure hydrate layer. Porosity of the pure hydrate layer; This represents the water saturation value for this layer. This represents the hydrate saturation value for this layer, and ; This represents the hydrogen content index of the stratigraphic framework of this section.

4. The acquisition method as described in claim 3, characterized in that, The nuclear magnetic resonance porosity logging interpretation model for the mixed-layer section is as follows: ； In the formula, Measured NMR porosity at different depths in the mixed layer; This represents the average formation porosity. The water saturation at different depths in the mixed layer is shown. The gas saturation at different depths in the mixing layer; is the polarization factor of the gas.

5. The acquisition method as described in claim 4, characterized in that, The NMR porosity interpretation model for the pure hydrate layer is as follows: 。 6. The acquisition method as described in claim 1, characterized in that, The selection criteria for the pure hydrate intervals that are lithologically similar to and adjacent to the mixed intervals of the target well simultaneously satisfy the following: (1) The difference in average natural gamma value between the mixed layer and the pure hydrate layer in the target well is ≤5 API; (2) The bottom depth of the selected section is ≤2m of the top depth of the mixed layer of the target well or the top depth is ≤2m of the bottom depth of the mixed layer of the target well.

7. The acquisition method as described in claim 5, characterized in that, gas saturation The system of equations was obtained by solving the system of equations, which includes: ； ； ； ； ； ； ； ； ； 。 8. A device for obtaining the three-phase saturation of natural gas hydrate, characterized in that, The acquisition device includes: The first model acquisition module is used to establish a neutron porosity logging interpretation model for the mixed-layer section of the target well based on neutron logging data. The second model acquisition module is used to establish a neutron porosity interpretation model for a pure hydrate interval that is lithologically similar to and adjacent to the mixed interval of the target well, based on the neutron porosity logging interpretation model. The third model acquisition module is used to establish a nuclear magnetic resonance porosity logging interpretation model for the mixed-layer section of the target well based on nuclear magnetic resonance logging data. The fourth model acquisition module establishes a nuclear magnetic porosity interpretation model for pure hydrate intervals with similar lithology to the mixed intervals of the target well and adjacent to them. The solution module is used to interpret neutron porosity logging based on neutron porosity logging, nuclear magnetic resonance (NMR) porosity logging, and NMR porosity logging, utilizing the average formation porosity corresponding to the selected pure hydrate interval in the target well. Average neutron porosity and average NMR porosity The gas saturation of the mixing section is obtained by solving. , gas saturation The water saturation of the mixed-layer section was obtained by substituting the nuclear magnetic resonance porosity logging interpretation model into the solution. Based on the obtained gas saturation and water saturation The hydrate saturation of the mixed-layer section was obtained by reverse calculation. .

9. An electronic device, characterized in that, The electronic device includes: At least one processor; and a memory communicatively connected to said at least one processor; The memory stores a computer program that can be executed by the at least one processor, which is then executed by the at least one processor to enable the at least one processor to perform the method for obtaining the three-phase saturation of natural gas hydrate as described in any one of claims 1-7.

10. A computer storage medium, characterized in that, The computer storage medium stores computer-executable instructions, which, when executed by a processor, implement the method for obtaining the three-phase saturation of natural gas hydrates as described in any one of claims 1-7.

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