Method and device for acquiring phase state of fluid in nano space and electronic equipment

Abstract

The invention relates to a method and a device for acquiring a fluid phase state in a nano space and electronic equipment, and relates to the technical field of oil reservoirs, the method comprises the following steps: acquiring an oil sample bubble point pressure P1 and an oil sample contact angle in a simulated shale pore structure; establishing a phase state model considering capillary force; inputting the characteristic parameters of the simulated shale pore structure, the characteristic parameters of the corresponding oil reservoir and the oil sample contact angle into a phase state model, and carrying out iterative calculation to obtain theoretical bubble point pressure P2; if yes, a phase state model meeting the requirement is obtained; and inputting a phase diagram temperature interval, carrying out iterative calculation by using a phase state model to obtain pressure, and drawing a phase diagram according to the temperature and the pressure. According to the acquisition method provided by the invention, the phase state model considering the capillary force effect is established, the bubble point pressure under the condition is obtained by combining the specific parameters and the oil sample contact angle, the bubble point pressure is compared with the experimental result, and the nanoscale phase state characteristics are obtained by combining the experimental data, so that a theoretical basis is provided for shale oil pressure control and stable production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil reservoirs, in particular to a method and device for obtaining fluid phase state in nanospace, and electronic equipment, and more particularly to a method and device for obtaining fluid phase state in nanospace of high-temperature and high-pressure shale oil reservoirs, and electronic equipment. BACKGROUND

[0002] At present, the phase state change in the nanoscale pores of shale oil is quite different from that of conventional reservoirs, the fluid critical parameters and the phase state ratio will deviate, affecting the phase transition and production of the entire reservoir. In nanoscale pores, the size difference between fluid molecules and pore size is small, and the pores will have a significant impact on the flow of fluid molecules, the nanoscale confinement space effect is obvious, and the fluid will be affected by the adsorption of the pore wall. At the same time, due to the nanoscale shale pores, a large capillary force will be generated, further affecting the phase state characteristics of the fluid, resulting in a large difference between the phase state characteristics of shale oil fluid and the test results in the PVT cylinder. Therefore, understanding and considering the complex interactions in these nanoscale pores are crucial for accurately assessing the phase transition behavior of shale oil reservoirs and optimizing production strategies.

[0003] Although many scholars have studied the fluid phase state in nanoscale pores through experimental or simulation methods, there are certain limitations.

[0004] This is because conventional experimental research cannot accurately simulate the structure of nanoscale pores and obtain the true details of the phase behavior of fluid in nanoscale pores under high temperature and high pressure; for example, PVT experiments usually measure the phase state characteristics of bulk fluid, and the phase state of nanoscale fluid cannot be accurately obtained through this method; for nanofluidic visualization experiments, the width is microns and the depth is nanometers, which is not a real nanoscale pore and also has limitations. Therefore, it is not possible to accurately and conveniently obtain the phase state characteristics and dynamic changes of shale pores under high temperature and high pressure through experimental methods alone. At the same time, simulation methods are difficult to fully match the real shale reservoir, and the simulation results will be affected by parameter uncertainty, which cannot guarantee the accuracy of the simulation results. SUMMARY

[0005] In view of the problems in the prior art, the present application aims to provide a method and device for obtaining fluid phase state in nanospace, to solve the problem of poor accuracy of the obtained fluid phase state in nanospace.

[0006] To achieve this goal, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a method for obtaining fluid phase state in nanospace, which comprises the following steps:

[0008] S1, obtaining oil sample bubble point pressure P1 and oil sample contact angle in the simulated shale pore structure;

[0009] S2, establishing a phase state model considering capillary force;

[0010] S3, according to the characteristic parameters of the simulated shale pore structure, the characteristic parameters of the corresponding reservoir and the oil sample contact angle, the theoretical bubble point pressure P2 is obtained by iterative calculation with the aid of the phase state model;

[0011] S4, comparing the oil sample bubble point pressure P1 and the theoretical bubble point pressure P2, if the phase state model meeting the requirements is obtained, otherwise the phase state model is modified until the phase state model meeting the requirements is obtained; then the temperature interval of the phase diagram is inputted and the pressure corresponding to the temperature is obtained by iterative calculation with the aid of the phase state model meeting the requirements, and the phase diagram is drawn according to the temperature and the pressure;

[0012] Wherein, S1 and S2 are not in sequence.

[0013] The obtaining method provided by the application obtains the wetting angle and bubble point pressure in the simulated shale pore structure through the simulation shale core pore structure experiment, establishes a phase state model considering the capillary force in the nanometer region, obtains the bubble point pressure under the condition in combination with the specific parameters and the obtained oil sample contact angle, and compares with the experimental results, and then obtains the more accurate nanoscale phase state characteristics in combination with the experimental data, which provides experimental support and theoretical basis for developing shale oil pressure control and stable production.

[0014] As a preferred technical scheme of the application, the simulated shale pore structure comprises a molecular sieve.

[0015] As a preferred technical scheme of the application, the oil sample used in the obtaining of the oil sample bubble point pressure P1 and the oil sample contact angle in the simulated shale pore structure is the ground crude oil fluid obtained by sampling the corresponding actual wellhead, and the formation fluid composition components are obtained according to the well flow composition.

[0016] Preferably, the oil sample bubble point pressure P1 in the simulated shale pore structure is obtained by soaking the molecular sieve in a metering device containing high gas-containing oil sample, pressurizing to saturation, then pressurizing the metering device to only single oil phase in the device, then reducing the pressure, and when the first bubble appears on the surface of the molecular sieve, the pressure at this time is recorded as the oil sample bubble point pressure P1 in the simulated shale pore structure.

[0017] Preferably, when the metering device is pressurized to only single oil phase in the device, the temperature is controlled to be the formation temperature of the corresponding reservoir.

[0018] As a preferred technical scheme of the present application, the oil sample contact angle in the simulated shale pore structure is obtained by measuring the oil sample contact angle through the contact angle method after the simulated shale pore structure is made into a planar structure.

[0019] Preferably, the oil sample contact angle test is performed at least 5 times, and the average value of the obtained oil sample contact angle is taken.

[0020] As a preferred technical scheme of the present application, the characteristic parameters of the shale pore structure include the pore radius of the shale pore structure.

[0021] As a preferred technical scheme of the present application, the characteristic parameters of the oil reservoir include the oil sample components, the formation temperature and the formation pressure.

[0022] As a preferred technical scheme of the present application, the phase state model considering the capillary force is established by performing phase equilibrium calculation, capillary force calculation in the nano-pore, Peng-Robinson state equation calculation and component fugacity coefficient calculation in the nano-pore.

[0023] As a preferred technical scheme of the present application, the calculation formula of the phase equilibrium calculation is as follows:

[0024]

[0025] According to the definition of fugacity, the following is obtained:

[0026]

[0027] The calculation formula of the equilibrium coefficient is obtained as follows:

[0028]

[0029] In the formula, is the fugacity of component i in the liquid phase, is the fugacity of component i in the gas phase, K i is the gas-liquid equilibrium coefficient of component i, is the fugacity coefficient of component i in the liquid phase, is the fugacity coefficient of component i in the gas phase, T is the temperature of the pure component or the mixture, P L and P V are the pressures of the gas phase and the liquid phase, respectively, x i and y i are the mole fractions of component i in the liquid phase and the gas phase, respectively.

[0030] Preferably, the capillary force calculation formula in the nano-pore is as follows:

[0031] P V -P L =P cap

[0032]

[0033] where P cap is the capillary pressure, P L and P V are the gas and liquid phase pressures, respectively, θ is the contact angle, σ is the interfacial tension, R p is the pore radius.

[0034] Preferably, the Peng-Robinson equation of state calculation is obtained from the Peng-Robinson equation of state, which is given by:

[0035]

[0036]

[0037]

[0038]

[0039] where P is the pure component or mixture pressure, T is the pure component or mixture temperature, R is the molar gas constant, V m is the molar volume, γ is a dimensionless parameter, β is the difference in density between the adsorbed and free fluid, T c is the critical temperature, P c is the critical pressure, and δ is the adsorbed layer thickness.

[0040] Preferably, the fugacity coefficient of the components in the nanopores includes a fugacity coefficient of a pure component and a fugacity coefficient of a mixture.

[0041] Preferably, the fugacity coefficient of the pure component is calculated by:

[0042]

[0043] where f pure is the pure component fugacity, P is the pure component pressure in the system, Z is the gas or liquid phase compressibility factor,

[0044] Preferably, the fugacity coefficient of the mixture is calculated by:

[0045]

[0046]

[0047] where a n =∑ i ∑ j x i x j ai a j ; b n =∑ j x i b i ; a i is the parameter a of component i, a j is the parameter a of component j, b i is the parameter b of component i, a ij is obtained by consulting the Peng-Robinson state equation binary interaction parameter table; x j is the mole fraction of component j in the liquid phase; Z L is the compressibility factor of the liquid phase; Z V is the compressibility factor of the gas phase; is the fugacity coefficient of component i in the liquid phase; is the fugacity coefficient of component i in the gas phase.

[0048] Preferably, the calculation endpoint of the iterative operation when calculating the theoretical bubble point pressure P2 is∑y i =1.

[0049] Preferably, the input phase diagram temperature interval is iteratively calculated by a qualified phase state model to obtain the pressure corresponding to the temperature, including the bubble point pressure or the dew point pressure.

[0050] Preferably, when calculating the bubble point pressure, the calculation endpoint of the iterative operation is∑y i =1.

[0051] Preferably, when calculating the dew point pressure, the calculation endpoint of the iterative operation is∑x i =1.

[0052] In a second aspect, the present application provides a device for obtaining the phase state of a fluid in a nanospace, which uses the obtaining method as described in the first aspect, comprising:

[0053] a parameter obtaining module, configured to obtain the bubble point pressure P1 of an oil sample in a simulated shale pore structure, the contact angle of the oil sample, the characteristic parameters of the simulated shale pore structure, and the characteristic parameters of a corresponding oil reservoir;

[0054] a phase state model establishing module, configured to establish a phase state model considering capillary force;

[0055] a theoretical bubble point pressure calculating module, configured to obtain a theoretical bubble point pressure P2 by iterative calculation with the aid of the phase state model according to the characteristic parameters of the simulated shale pore structure, the characteristic parameters of the corresponding oil reservoir, and the contact angle of the oil sample;

[0056] The comparative output correction module is configured to compare the experimental bubble point pressure P1 with the theoretical bubble point pressure P2, and if <0.05, a required phase state model is obtained, otherwise the phase state model is corrected until a required phase state model is obtained;then, the phase diagram temperature range is inputted into the required phase state model for iterative calculation to obtain the pressure corresponding to the temperature, and the phase diagram is drawn according to the temperature and the pressure.

[0057] In a third aspect, the present application provides an electronic device, which comprises:

[0058] at least one processor;and

[0059] a memory connected in communication with the at least one processor;wherein,

[0060] the memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor to enable the at least one processor to execute the acquisition method of the first aspect.

[0061] Compared with the prior art, the present application has the following beneficial effects:

[0062] (1) The wetting angle and the bubble point pressure are obtained through the molecular sieve simulation shale core pore structure experiment, the experimental aperture and the experimental wetting angle are inputted into the phase state model, and the relatively accurate theoretical bubble point pressure under the condition can be obtained.

[0063] (2) By comparing the experimental bubble point pressure with the theoretical bubble point pressure, the theoretical model can be corrected, and the nanoscale phase state characteristics can be more accurately predicted. BRIEF DESCRIPTION OF DRAWINGS

[0064] Figure 1 is a flow chart of the acquisition method of the fluid phase state in the nanoscale space provided by the embodiment of the present application;

[0065] Figure 2 is a schematic diagram of the acquisition device of the fluid phase state in the nanoscale space provided by the embodiment of the present application;

[0066] Figure 3 is a schematic diagram of the electronic device provided by the embodiment of the present application;

[0067] Figure 4 is the phase diagram obtained by the embodiment of the present application.

[0068] In the figure: 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.

[0069] The application is further described in detail below. However, the examples described below are only simple examples of the application and do not represent or limit the protection scope of the application, and the protection scope of the application is subject to the claims. DETAILED DESCRIPTION

[0070] To better illustrate the application and facilitate understanding of the technical solutions of the application, the typical but non-limiting embodiments of the application are as follows:

[0071] The embodiment provides a method for acquiring a phase state of a fluid in a nanospace, as shown in the figure, the method comprises the following steps: Figure 1

[0072] S1, acquiring a bubble point pressure P1 of an oil sample in a simulated shale pore structure and an oil sample contact angle;

[0073] S2, establishing a phase state model considering capillary force;

[0074] S3, according to characteristic parameters of the simulated shale pore structure, characteristic parameters of a corresponding oil reservoir and the oil sample contact angle, the phase state model is used for iterative calculation to obtain a theoretical bubble point pressure P2;

[0075] S4, comparing the bubble point pressure P1 of the oil sample and the theoretical bubble point pressure P2, if a phase state model meeting the requirements is obtained, otherwise the phase state model is modified until a phase state model meeting the requirements is obtained; then a temperature interval of a phase diagram is inputted, and the phase state model meeting the requirements is used for iterative calculation to obtain a pressure corresponding to the temperature, and a phase diagram is drawn according to the temperature and the pressure;

[0076] The S1 and S2 are not arranged in sequence.

[0077] The simulated shale pore structure comprises a molecular sieve.

[0078] In the application, the molecular sieve used is a molecular sieve with controllable pore size to simulate the shale pore structure; and the pore structure in the molecular sieve is selected and designed according to the core pore size of a corresponding shale oil reservoir.

[0079] The oil sample used in the acquisition of the bubble point pressure P1 of the oil sample in the simulated shale pore structure and the oil sample contact angle is a ground crude oil fluid obtained by corresponding actual wellhead sampling, and the formation fluid composition components are obtained according to well flow composition.

[0080] In the application, the oil sample can also be configured according to the formation fluid composition components obtained according to the well flow composition.

[0081] ​The oil sample bubble point pressure P1 in the simulated shale pore structure is obtained by soaking a molecular sieve corresponding to the core pore size of the shale oil reservoir in a metering device containing a high gas-containing oil sample, pressurizing to saturation, then pressurizing the metering device to only a single oil phase in the device, then reducing the pressure, and recording the pressure when the first bubble appears on the surface of the molecular sieve as the oil sample bubble point pressure P1 in the simulated shale pore structure.

[0082] The temperature is controlled to be the formation temperature corresponding to the oil reservoir when the metering device is pressurized to only a single oil phase in the device.

[0083] The oil sample contact angle is obtained by preparing a planar structure of the simulated shale pore structure and measuring the oil sample contact angle by the contact angle method.

[0084] The oil sample contact angle is tested at least 5 times, and the average value of the obtained oil sample contact angles is taken as the oil sample contact angle.

[0085] In the present application, the exemplary oil sample contact angle test process is: using a contact angle tester to measure the static contact angle of the oil sample; when multiple measurements are performed, the average value of the test values is taken as the oil sample contact angle.

[0086] The characteristic parameters of the simulated shale pore structure include the pore radius of the simulated shale pore structure.

[0087] The characteristic parameters of the oil reservoir include the oil sample components, the formation temperature and the formation pressure.

[0088] In the present application, the characteristic parameters of the oil reservoir are the relevant characteristic parameters of the target shale oil reservoir for which the fluid phase state is to be obtained.

[0089] The phase state model considering capillary force is established by performing phase equilibrium calculation, capillary force calculation in nanometer pores, Peng-Robinson state equation calculation and component fugacity coefficient calculation in nanometer pores.

[0090] In the present application, the theoretical bubble point pressure P2 is obtained by iterative calculation of phase equilibrium calculation, capillary force calculation in nanometer pores, Peng-Robinson state equation calculation and component fugacity coefficient calculation in nanometer pores, and the target phase state model is obtained after the calculation meets the requirements, the required temperature interval is input into the phase diagram, then the pressure corresponding to each temperature is calculated using the phase state model, and then the phase diagram is drawn according to the temperature and pressure.

[0091] The calculation formula of the phase equilibrium calculation is as follows:

[0092]

[0093] According to the definition of fugacity, it is obtained:

[0094]

[0095] The calculation formula of the equilibrium coefficient is:

[0096]

[0097] In the formula, is the fugacity of component i in the liquid phase, is the fugacity of component i in the gas phase, K i is the gas-liquid equilibrium coefficient of component i, is the fugacity coefficient of component i in the liquid phase, is the fugacity coefficient of component i in the gas phase, T is the temperature of the pure component or the mixture, P L and P V are the pressures of the gas phase and the liquid phase respectively, x i and y i are the mole fractions of component i in the liquid phase and the gas phase respectively.

[0098] Wherein, the calculated P L is the theoretical bubble point pressure P2 or the bubble point pressure of the present application, and the calculated P v is the dew point pressure of the present application.

[0099] Wherein, the calculation formula of the capillary force in the nanopore is as follows:

[0100] P V -P L =P cap

[0101]

[0102] In the formula, P cap is the capillary force, P L and P V are the pressures of the gas phase and the liquid phase respectively, θ is the contact angle, σ is the interfacial tension, and R p is the pore radius.

[0103] In the present application, the calculated P L is the theoretical bubble point pressure P2 of the present application under the constraint of the calculation formula of the capillary force in the nanopore.

[0104] Wherein, the Peng-Robinson equation of state calculation is obtained from the Peng-Robinson equation of state, and the formula is as follows:

[0105]

[0106]

[0107]

[0108]

[0109] where P is the pure component or mixture pressure, T is the pure component or mixture temperature, R is the molar gas constant, V m is the molar volume, β is the density difference between the adsorbed fluid and the free fluid, T c is the critical temperature, P c is the critical pressure, and δ is the adsorbed layer thickness.

[0110] where the fugacity coefficient of the component in the nanopore includes the fugacity coefficient of the pure component and the fugacity coefficient of the mixture;

[0111] where the fugacity coefficient of the pure component is calculated by:

[0112]

[0113] where f pure is the pure component fugacity, P is the pure component pressure in the system, Z is the compressibility factor of the gas or liquid phase,

[0114] where the fugacity coefficient of the mixture is calculated by:

[0115]

[0116]

[0117] a n =∑ i ∑ j x i x j a i a j ; b n =∑ j x i b i ; a i is the parameter a of component i, a j is the parameter a of component j, b i is the parameter b of component i, a ij is obtained by consulting the Peng-Robinson equation of state binary interaction parameter table; x j is the mole fraction of component j in the liquid phase; Z L is the compressibility factor of the liquid phase; Z V is the compressibility factor of the gas phase; is the fugacity coefficient of component i in the liquid phase; is the fugacity coefficient of component i in the gas phase.

[0118] In the present application, according to the characteristic parameters of the simulated shale pore structure, the characteristic parameters of the corresponding reservoir and the contact angle of the oil sample, the calculation process of the theoretical bubble point pressure P2 is as follows by means of iterative calculation of the phase state model:

[0119] input the temperature and the mole fraction x of component i in the liquid phase composition i , provide the initial bubble point pressure, calculate the fugacity coefficient and the bubble point pressure, if ∑y i ≠ 1, adjust the pressure P for iteration until ∑y i = 1, stop calculation, and output the theoretical bubble point pressure P2.

[0120] wherein, according to the phase diagram temperature interval, the pressure obtained by the phase state model is the saturation pressure, including the bubble point pressure and the dew point pressure.

[0121] wherein, the process of calculating the bubble point pressure according to the phase diagram temperature interval is as follows: input the temperature and the mole fraction x of component i in the liquid phase composition i , provide the initial bubble point pressure, calculate the fugacity coefficient and the bubble point pressure, if ∑y i ≠ 1, adjust the pressure P for iteration until ∑y i = 1, stop calculation, and output the theoretical bubble point pressure.

[0122] wherein, the process of calculating the dew point pressure according to the phase diagram temperature interval is as follows: input the temperature and the mole fraction y of component i in the gas phase composition i , provide the initial dew point pressure, calculate the fugacity coefficient and the dew point pressure, if ∑x i ≠ 1, adjust the pressure P for iteration until ∑x i = 1, stop calculation, and output the theoretical dew point pressure.

[0123] that is, in the present application, when calculating the pressure in the temperature interval of the phase diagram, the verification of is not performed, and when ∑y i = 1 or ∑x i = 1 is reached by iteration, the pressure corresponding to the temperature is output.

[0124] In the present application, the temperature interval of the phase diagram can be designed according to the actual required temperature interval, and the corresponding step size in the temperature interval or the temperature point value sequence can be directly designed, and each temperature point value will correspond to an output pressure after iterative operation by the phase state model.

[0125] In the present application, the initial bubble point pressure can be selected as the oil sample bubble point pressure P1, or the bubble point pressure without capillary force condition limitation, and other conditions being the same, and the commercial numerical model software commonly used in the field is also used to calculate.

[0126] In the present application, the specific process of the correction is as follows:

[0127] The non-experimentally obtained parameters V m , γ and β in the Peng-Robinson state equation are adjusted.

[0128]

[0129]

[0130]

[0131] In the formula, V p is the pore volume ratio, n t is the total number of fluid molecules, N A is the Avogadro constant, R p is the pore radius, δ is the adsorption layer thickness, ε a is the effective molecular volume coefficient of the adsorption area, ε t is the effective molecular volume coefficient in the bulk phase.

[0132] Since n t , δ, ε a , ε t cannot be directly obtained from experiments, the model accuracy can be improved by adjusting the parameters.

[0133] When the oil sample bubble point pressure P1 is greater than the theoretical bubble point pressure P2, the parameter ε a is adjusted to be smaller, and the parameter ε t is adjusted to be larger.

[0134] When the oil sample bubble point pressure P1 is less than the theoretical bubble point pressure P2, the parameter ε t is adjusted to be smaller, and the parameter ε a is adjusted to be larger.

[0135] After adjusting the parameters ε a and ε t , the iterative calculation of the phase state model considering the capillary force is performed again, and the cycle is continued until the phase state model meeting the requirements is obtained.

[0136] Further, the embodiment provides a fluid phase state acquisition device in a nanospace based on the foregoing acquisition method, as shown in Figure 2 , the acquisition device is acquired by using the foregoing acquisition method, and comprises:

[0137] A parameter acquisition module is used to obtain the oil sample bubble point pressure P1, oil sample contact angle, characteristic parameters of the simulated shale pore structure, and characteristic parameters of the corresponding reservoir in the simulated shale pore structure;

[0138] Phase model building module, used to build a phase model taking capillary force into account;

[0139] The theoretical bubble point pressure calculation module is used to iteratively calculate the theoretical bubble point pressure P2 based on the characteristic parameters of the simulated shale pore structure, the characteristic parameters of the corresponding oil reservoir, and the contact angle of the oil sample with the help of the phase model;

[0140] Comparison output correction module is used to compare the oil sample bubble point pressure P1 and the theoretical bubble point pressure P2. <0.05, then the phase model that meets the requirements is obtained, otherwise the phase model is modified until Obtain a phase model that meets the requirements; then input the phase diagram temperature range and use the phase model that meets the requirements to perform iterative calculations to obtain the pressure corresponding to the temperature, and draw a phase diagram based on the temperature and pressure.

[0141] Figure 3 1 is a block diagram of an electronic device 10 in which an embodiment of the present invention may be implemented. The electronic device is 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 assistants, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.) and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or claimed herein.

[0142] like Figure 3 As shown, electronic device 10 includes at least one processor 11 and a memory, such as a read-only memory (ROM) 12 and a random access memory (RAM) 13, communicatively connected to at least one processor 11. The memory stores a computer program executable by the at least one processor. Processor 11 can perform various appropriate actions and processes based on the computer program stored in ROM 12 or loaded from storage unit 18 into RAM 13. RAM 13 can also store various programs and data required for the operation of electronic device 10. Processor 11, ROM 12, and RAM 13 are interconnected via bus 14. An input / output (I / O) interface 15 is also connected to bus 14.

[0143] A plurality of components in the electronic device 10 are connected to the I / O interface 15, including: an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a magnetic disk, an optical disk, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the electronic device 10 to exchange information / data with other devices through a computer network, such as the Internet, and / or various telecommunication networks.

[0144] The processor 11 can be various general and / or special purpose processing components with processing and computing capabilities. Some examples of the 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 appropriate processor, controller, microcontroller, etc. The processor 11 performs various methods and processes described above, such as the acquisition method of fluid phase state in nanospace.

[0145] In some embodiments, the acquisition method of fluid phase state in nanospace can be implemented as a computer program tangibly embodied in a computer readable storage medium, such as the storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed onto the electronic device 10 via the ROM 12 and / or the communication unit 19. When the computer program is loaded onto the RAM 13 and executed by the processor 11, one or more steps of the acquisition method of fluid phase state in nanospace described above can be performed. Alternatively, in other embodiments, the processor 11 can be configured to perform the acquisition method of fluid phase state in nanospace by any other appropriate means, such as by means of firmware.

[0146] Various implementations of the systems and techniques described above in this embodiment can be realized in digital electronic circuitry, integrated circuitry, a field programmable gate array (FPGA), an application-specific integrated circuit (ASIC), a system on a chip (SOC), a programmable logic device (CPLD), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include implementation in one or more computer programs that are executable and / or interpretable on a programmable system including at least one programmable processor, which can be special or general purpose, coupled to receive data and instructions from, and to transmit data and instructions to, a storage system, at least one input device, and at least one output device.

[0147] Computer programs for implementing the methods of the present application can be written in any combination of one or more programming languages. These computer programs can be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the computer program, when executed, enables the functions / acts specified in the flowcharts and / or block diagrams to be implemented. The computer program can be executed entirely on a machine, partially on a machine, partially on a machine as a standalone software package and partially on a remote machine or entirely on a remote machine or server.

[0148] In the context of the present application, a computer-readable storage medium can be a tangible medium that can contain or store a computer program for use by or in connection with an instruction execution system, apparatus, or device. A computer-readable storage medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium can be a machine-readable signal medium. More specific examples of a machine-readable storage medium will include one or more lines of a program of instructions in a transitory signal, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0149] To provide for interaction with a user, the systems and techniques described here 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 a pointing device (e.g., a mouse, a trackball, or a cursor direction key) by which the user can provide input to the electronic device. Other kinds of devices can be used to provide for interaction with a user as well; 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 acoustic, speech, or tactile input.

[0150] The systems and techniques described herein can be implemented in a computing system that includes a back end component, e.g., as a data server, or that includes a middleware component, e.g., an application server, or that includes a front end component, e.g., a user computer having a graphical user interface or a Web browser through which a user can interact with an implementation of the systems and techniques described herein, or any combination of such back end, middleware, or front end components. The components of the system can be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0151] The computing system can include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other. A server can be a cloud server, also known as a cloud computing server or cloud host, which is a host product in the cloud computing service system, to solve the defects of large management difficulty and weak business scalability in traditional physical host and VPS service.

[0152] Further, in order to illustrate that the method for obtaining the phase state of fluid in nanospace provided by the present application can achieve good results, actual examples are used for illustration, as follows:

[0153] Embodiment

[0154] This embodiment implements the method for obtaining according to a real core and oil sample of a shale oil block, as follows:

[0155] 1. Select a nanoscale molecular sieve according to the pore size of a real core of a shale oil block;

[0156] 2. Obtain formation fluid composition components according to the composition of well flow and configure an oil sample;

[0157] 3. Soak the molecular sieve in a metering device containing a high-gas oil sample to perform pressurized saturation, and observe the liquid level. When the liquid level no longer drops, it indicates that the saturation is complete;

[0158] 4. Pressurize the metering device until only a single oil phase is present in the device. During the pressurization process, set the temperature to the formation temperature;

[0159] 5. Gradually reduce the pressure, continuously observe the changes on the surface of the molecular sieve through a visual imaging system, and record the pressure P1 at the moment when the first gas bubble appears on the surface of the molecular sieve as the bubble point pressure of the oil sample in the pore size. The specific obtained bubble point pressure P1 of the oil sample is 15.26 MPa;

[0160] 6. Molecular sieves of the same material were used to make a planar structure. The static contact angle of the oil sample was measured using a contact angle tester. Five parallel tests were performed and the average value was taken as the contact angle value. The specific contact angles obtained were 82.1°, 81.8°, 82.7°, 82.0°, and 81.4°, respectively. The calculated average value was 82.0°, which was the contact angle of the oil sample.

[0161] 7. Establish a phase model and perform phase equilibrium calculations. By satisfying the equal fugacity constraint and calculating the equilibrium coefficient formula, the Peng-Robinson state equation is improved to consider the influence of capillary forces.

[0162] 8. The experimental oil sample was divided into batches, as shown in Table 1. The batched components, formation temperature, formation pressure, experimental pore size, and experimentally measured contact angle were input into the phase behavior model, as shown in Table 2. The theoretical bubble point pressure P2 was calculated to be 15.248 MPa.

[0163] 9. Comparing P1 and P2, it can be seen that the phase model meets the requirements. Then input the temperature value in Table 3, and then output the pressure corresponding to the temperature. See Table 3 for details. Then draw the phase diagram based on Table 3. The obtained phase diagram is as follows Figure 4 shown.

[0164] Table 1

[0165] Component CO2 [CAT] [C2-C4] [C6-C8] [C 10+ ]]> Molar mass / % 6.03 63.25 18.01 9.56 3.15

[0166] Table 2

[0167] Formation temperature / °C Formation pressure / MPa Experimental pore size / nm Contact angle / ° 106 35.9 MPa 5 82.0

[0168] Table 3

[0169]

[0170]

[0171] From the results of the above embodiments, it can be seen that the acquisition method provided by the present invention obtains the wetting angle and bubble point pressure by simulating the pore structure experiment of the shale core, establishes a phase model that takes into account the action of capillary forces in the nano region, combines specific parameters and the obtained oil sample contact angle to obtain the bubble point pressure under these conditions, and compares them with the experimental results, and then combines the experimental data to obtain more accurate nanoscale phase characteristics, providing experimental support and theoretical basis for carrying out pressure control and stable production of shale oil.

[0172] It is to be understood that the application is not limited to the details of the above-described embodiments but covers any modifications within the scope and the spirit of the application.

[0173] The preferred embodiments of the application have been described in detail above, but the application is not limited to the specific details described above. Any modifications to the application, equivalent substitutions for the components used in the application, and the addition of auxiliary components, the selection of specific methods, etc. all fall within the scope of protection and disclosure of the application.

[0174] In addition, it should be noted that each of the specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the application will not further describe various possible combinations.

[0175] Furthermore, any combination of the various embodiments of the application can also be made, as long as it does not deviate from the idea of the application, it should also be considered as disclosed by the application.

Claims

1. A method for acquiring a phase state of a fluid in a nanospace, characterized by, The acquisition method comprises the following steps: S1, acquiring the oil sample bubble point pressure P1 in the simulated shale pore structure and the oil sample contact angle; S2, establishing a phase state model considering capillary force; S3, according to the characteristic parameters of the simulated shale pore structure, the characteristic parameters of the corresponding reservoir and the oil sample contact angle, the theoretical bubble point pressure P2 is obtained by iterative calculation with the aid of the phase state model; S4, comparing the bubble point pressure P1 of the oil sample with the theoretical bubble point pressure P2, if a required phase model is obtained, otherwise the phase model is modified until a required phase model is obtained; then the temperature interval of the phase diagram is inputted to obtain the pressure corresponding to the temperature by iterative calculation using the required phase model, and the phase diagram is plotted according to the temperature and the pressure; Wherein, S1 and S2 are not in sequence.

2. The acquisition method of claim 1, wherein, The simulated shale pore structure comprises a molecular sieve.

3. The acquisition method of claim 1 or 2, wherein, The oil sample used in the acquisition of the oil sample bubble point pressure P1 in the simulated shale pore structure and the oil sample contact angle is the ground crude oil fluid obtained by sampling at the corresponding actual wellhead, and the formation fluid composition components are obtained according to the well flow composition; Preferably, the oil sample bubble point pressure P1 in the simulated shale pore structure is obtained by soaking the molecular sieve with the core pore size corresponding to the shale reservoir in a metering device containing high gas-containing oil sample, pressurizing to saturation, then pressurizing the metering device to have only a single oil phase in the device, then reducing the pressure, and when the first bubble appears on the surface of the molecular sieve, the pressure at this time is recorded as the oil sample bubble point pressure P1 in the simulated shale pore structure; Preferably, when the metering device is pressurized to have only a single oil phase in the device, the temperature is controlled to be the formation temperature corresponding to the reservoir.

4. The acquisition method according to any one of claims 1 to 3, characterized in that, The oil sample contact angle in the simulated shale pore structure is obtained by measuring the oil sample contact angle with the simulated shale pore structure made into a planar structure by the contact angle method; Preferably, the oil sample contact angle test is carried out at least 5 times, and the average value of the obtained oil sample contact angles is taken.

5. The acquisition method according to any one of claims 1 to 4, characterized in that, The characteristic parameters of the simulated shale pore structure include the pore radius of the simulated shale pore structure.

6. The acquisition method according to any one of claims 1 to 5, wherein, The characteristic parameters of the reservoir include the oil sample components, the formation temperature and the formation pressure.

7. The method according to any one of claims 1 to 6, wherein the method comprises the step of: The phase state model considering capillary force is calculated by performing phase equilibrium calculation, capillary force calculation in nanometer pores, Peng-Robinson state equation calculation and component fugacity coefficient calculation in nanometer pores. ​ 8. The method according to any one of claims 1 to 7, wherein the method comprises the step of: The calculation formula of the phase equilibrium calculation is as follows: According to the definition of fugacity, the following is obtained: The calculation formula of the equilibrium coefficient is as follows: where f i L is the fugacity of component i in the liquid phase, f i V is the fugacity of component i in the gas phase, K i is the gas-liquid equilibrium coefficient for component i, is the fugacity coefficient of component i in the liquid phase, is the fugacity coefficient of component i in the gas phase, T is the temperature of the pure component or mixture, P L and P V are the pressures of the gas and liquid phases, respectively, x i and y i are the mole fractions of component i in the liquid and gas phases, respectively; Preferably, the capillary force calculation formula in nanometer pores is as follows: P V -P L = P cap where P cap is the capillary pressure, P L and P V are the gas and liquid phase pressures, respectively, θ is the contact angle, σ is the interfacial tension, and R p is the pore radius. Preferably, the Peng-Robinson state equation calculation is obtained from the Peng-Robinson state equation, and the formula is as follows: where P is the pure component or mixture pressure, T is the pure component or mixture temperature, R is the molar gas constant, V m is the molar volume, γ is a dimensionless parameter, β is the density difference between the adsorbed fluid and the free fluid, T c is the critical temperature, P c is the critical pressure, δ is the adsorbed layer thickness; Preferably, the component fugacity coefficient in nanometer pores includes the fugacity coefficient of a pure component and the fugacity coefficient of a mixture; Preferably, the calculation formula of the fugacity coefficient of a pure component is as follows: where f is the fugacity of the pure component, P is the pressure of the pure component in the system, and Z is the compressibility factor of the gas or liquid phase, pure where f is the fugacity of the pure component, P is the pressure of the pure component in the system, and Z is the compressibility factor of the gas or liquid phase, Preferably, the calculation formula of the fugacity coefficient of a mixture is as follows: where a n =∑ i x j x i a j a i a j ; b n =∑ j x i b i ; a i is the parameter a of component i, a j is the parameter a of component j, b i is the parameter b of component i, a ij is obtained by consulting the Peng-Robinson equation of state binary interaction parameter table; x j is the mole fraction of component j in the liquid phase; Z L is the compressibility of the liquid phase; Z V compressibility factor for the gas phase; fugacity coefficient of component i in the liquid phase; fugacity coefficient of component i in the gas phase; Preferably, the end of calculation of the iterative calculation when calculating the theoretical bubble point pressure P2 is ∑y i = 1. Preferably, the corresponding temperature pressure including bubble point pressure or dew point pressure is obtained by iterative calculation with the required phase state model in the input phase diagram temperature interval; Preferably, the calculation end point of the iterative calculation when calculating the bubble point pressure is ∑y i = 1; Preferably, the calculation end point of the iterative calculation when calculating the dew point pressure is ∑x i = 1.

9. A device for obtaining the phase state of a fluid in a nanospace, characterized in that: The acquisition device adopts the acquisition method according to any one of claims 1-8, comprising: A parameter acquisition module for acquiring the oil sample bubble point pressure P1 in the simulated shale pore structure, the oil sample contact angle, the characteristic parameters of the simulated shale pore structure and the characteristic parameters of the corresponding reservoir; A phase state model establishment module for establishing a phase state model considering capillary force; A theoretical bubble point pressure calculation module is configured to calculate the theoretical bubble point pressure P2 by means of a phase state model according to the characteristic parameters of the simulated shale pore structure, the characteristic parameters of the corresponding reservoir and the oil sample contact angle. A contrast output correction module is used to compare the bubble point pressure P1 of the oil sample with the theoretical bubble point pressure P2, and if <0.05, the phase model is qualified, otherwise the phase model is corrected until After inputting the temperature interval of the phase diagram, the pressure corresponding to the temperature is calculated by using the qualified phase model, and the phase diagram is drawn according to the temperature and the pressure.

10. An electronic device, comprising: The electronic device includes: at least one processor; and a memory connected with the at least one processor in communication; wherein The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor to enable the at least one processor to execute the acquisition method of any one of claims 1-8.

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