Method for calculating real-time particle size of slow-release particle electrode

Abstract

The invention provides a method for calculating the real-time particle size of a sustained-release particle electrode, and the real-time average particle size of the sustained-release particle electrode is calculated through a fitting function and the mass fraction of a sustained-release material in a grid. According to the calculation method, the real-time particle size, gradually reduced due to hydrolysis, of the slow-release particle electrode in the porous medium can be accurately obtained, so that the migration behavior of the slow-release particle electrode is accurately described, and an important basis is provided for accurate prediction of the multiphase flow behavior and the recovery ratio in the porous medium.

Description

Technical Field

[0001] The present invention relates to the technical field of oil extraction, and in particular to a method for calculating the real-time particle size of a slow-release particle electrode. Background Art

[0002] Due to the high water content in oil fields in the middle and late stages of development, existing water injection technologies are no longer able to meet the needs of these fields. Improving crude oil recovery is primarily achieved through two approaches: First, increasing the sweep coefficient of the injected fluid within the reservoir. This is primarily achieved by improving reservoir heterogeneity or reducing the mobility of the displacing phase, thereby stabilizing the displacement front. This is typically achieved through profile adjustment or increasing the viscosity of the displacing fluid. Second, improving oil washing efficiency is primarily achieved by changing the wettability of the rock surface, reducing the adverse effects of capillary phenomena, and lowering residual oil saturation. This is typically achieved by using surfactants to reduce the oil-water interfacial tension.

[0003] CN117345176A discloses a three-dimensional electrochemical oil recovery system and method based on particle electrodes. The system includes: an injection water container, a particle electrode container, a displacement fluid container, a drive pump, a power supply, a first electrode disposed in the injection well, and a second electrode disposed in the production well. The injection water container and the particle electrode container are respectively connected to the displacement fluid container, which is connected to the drive pump. The drive pump is connected to the wellbore of the injection well. The drive pump pumps the displacement fluid into the wellbore, and an electric field is applied between the injection well and the production well, thereby constructing a three-dimensional electrode system in the oil reservoir, which can effectively increase the electrochemical reaction area. Moreover, by adjusting the direction, magnitude, and application strategy of the electric field, the electrophoretic migration direction of the particle electrodes in the displacement fluid can be controlled, so that they avoid the dominant water drive channel and act in a directional manner on the remaining or residual oil-rich area, thereby forming an effective electrochemical displacement effect in the vast oil layer between the injection well and the production well, which can significantly improve the recovery rate.

[0004] CN117757455A discloses a particle electrode with sustained-release and electrophoretic functions, as well as its preparation method and application. The method comprises the following steps: mixing an ester, an alcohol, and a first catalyst to synthesize a polyester oligomer through an ester exchange reaction; adding a second catalyst and a stabilizer to the polyester oligomer to obtain a polyester; uniformly mixing the polyester with a nano-metal oxide in an organic solvent to obtain an organic solvent suspension containing the polyester and the nano-metal oxide; adding the organic solvent suspension to an aqueous solution containing a surfactant and uniformly dispersing the suspension to obtain an oil-in-water emulsion; stirring and heating the oil-in-water emulsion until the organic solvent is completely evaporated, breaking the emulsion with an inorganic salt, and washing and drying to obtain a particle electrode with sustained-release and electrophoretic functions. The prepared particle electrode has a sustained-release membrane that is sensitive to temperature and pH and carries a certain charge, preventing ineffective adsorption near the wellbore. The sustained-release membrane gradually hydrolyzes and releases the material during transport. Furthermore, electrophoresis is used to directionally control the migration path of the particle electrode, enabling the particle electrode to effectively target areas of residual oil, thereby reducing the cost of three-dimensional electrochemical oil recovery.

[0005] Numerical simulation is an important tool for revealing multiphase flow behavior in porous media and provides a theoretical foundation for the development and optimization of enhanced oil recovery technologies. For three-dimensional electrochemical flooding processes using slow-release particle electrodes, accurately simulating their migration behavior in porous media is crucial for accurately predicting recovery efficiency. The migration behavior of slow-release particle electrodes in fluids is closely related to their particle size. However, due to the gradual hydrolysis of the slow-release membrane, the particle size of slow-release particles decreases rather than remains constant.

[0006] However, there is currently a lack of effective methods to calculate the changes in the particle size of slow-release particle electrodes, making it difficult to accurately describe the migration behavior of slow-release particle electrodes and, therefore, unable to accurately predict the recovery rate. Summary of the Invention

[0007] In view of the problems existing in the prior art, the present invention provides a method for calculating the real-time particle size of a slow-release particle electrode. The method accurately obtains the real-time particle size of the slow-release particle electrode as it gradually decreases due to hydrolysis in a porous medium through a calculation formula, thereby accurately describing the migration behavior of the slow-release particle electrode and providing an important basis for the accurate prediction of multiphase flow behavior and recovery rate in porous media.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] The present invention provides a method for calculating the real-time particle size of a sustained-release particle electrode, the method comprising the following steps:

[0010] (1) Determine the density of the sustained-release material as ρ 缓 , m 缓The slow-release material is added to the simulated formation water, and a hydrolysis experiment is carried out at the formation temperature. The time t required for complete hydrolysis is recorded, and the reaction rate r of the pure slow-release membrane material is calculated:

[0011] (2) Take m 初 The slow-release particle electrode was used as the test sample, and the average diameter of the test sample was measured as d 初 The test sample was added to the simulated formation water and hydrolysis experiment was carried out at the formation temperature. After the slow-release material was completely hydrolyzed, the particle electrode without slow-release membrane was separated and the mass was measured to be m 终 , record the time taken for complete hydrolysis as x 终 ; Determine the average diameter d of the particle electrode without sustained-release membrane 终 , calculate the number n of slow-release particle electrodes in the test sample:

[0012] (3) m 初 The slow-release particle electrode was added into the simulated formation water and the hydrolysis experiment was carried out at the formation temperature. i After a few seconds, the particle electrode with a certain thickness of sustained-release membrane was separated and the mass was measured to be m i ; the x i <x 终 ; Calculate the mass fraction y of the sustained-release material at this time i And the average diameter d of the slow-release particle electrode at this time i ;

[0013] (4) Repeat step (3) to obtain j groups of different x i Mass fraction y in seconds i and the average diameter d i ; With mass fraction y i is the horizontal axis, the average diameter d i As the vertical coordinate, the fitting function is used for fitting to obtain the correlation formula:

[0014] d=f(y)

[0015] (5) Divide the pore structure of the porous medium of the simulated formation into a grid, import it into the fluid mechanics calculation software, adopt the Euler-Euler multiphase flow model, set the three phases of water, oil, and particle electrode, and couple the fluid volume method to enhance the description of the water-oil interface; open the component transport model, and describe the consumption rate of the slow-release material in the hydrolysis experiment by adding the reaction rate r to the source term of the component transport equation, and calculate the mass fraction y of the slow-release material in the grid;

[0016] (6) The real-time average particle size d of the sustained-release particle electrode is calculated using the correlation formula f(y):

[0017] When d≥d 终 , d=d 实; when d≤d 终 , d=d 终 .

[0018] The method for calculating the real-time particle size of the slow-release particle electrode described in the present invention is simple to operate and rationally designed. First, the reaction rate of the pure slow-release membrane material and the number of slow-release particle electrodes in the test sample are calculated. By repeating the hydrolysis experiment multiple times, the mass fraction and average diameter of the slow-release particle electrodes obtained are fitted with a function to obtain a correlation equation. Finally, the real-time average particle size of the slow-release particle electrode is calculated based on the mass fraction of the slow-release material in the grid. The calculation method described in the present invention can accurately describe the gradual decrease in the particle size of the slow-release particle electrode in porous media due to hydrolysis, thereby accurately describing the migration behavior of the slow-release particle electrode, providing an important basis for the accurate prediction of multiphase flow behavior and recovery rate within porous media.

[0019] The method for calculating the real-time particle size of the slow-release particle electrode of the present invention is applicable to various slow-release particle electrodes in the prior art, such as ferroferric oxide, ferric oxide or aluminum oxide coated with easily hydrolyzed polyester.

[0020] The simulated formation water of the present invention is prepared by a standard method. The standard brine prepared according to SY / T 5358-2010 is used according to the salinity data of the simulated formation water.

[0021] The formation temperature described in the present invention can be set according to the actual formation temperature that needs to be simulated.

[0022] Preferably, the reaction rate r of the pure sustained-release membrane material in step (1) is calculated as follows:

[0023]

[0024] Preferably, the sustained-release material in step (1) comprises a polyester with dimethyl terephthalate and ethylene glycol as monomers.

[0025] Preferably, the calculation formula for the number n of the slow-release particle electrodes in step (2) is:

[0026]

[0027] Among them, ρ 粒 is the density of the slow-release particle electrode.

[0028] Preferably, the mass fraction y of the sustained-release material in step (3) is i The calculation formula is:

[0029]

[0030] Preferably, the average diameter d of the slow-release particle electrode in step (3) isi The calculation formula is:

[0031]

[0032] Preferably, the j in step (4) is 5 to 10.

[0033] Preferably, the fitting function in step (4) includes any one of a polynomial fitting function, an exponential function or a linear fitting function.

[0034] Preferably, the porous medium in step (5) comprises any one of a glass etching model, a core slice or a digital core.

[0035] As a preferred technical solution of the present invention, the calculation method includes the following steps:

[0036] (1) Determine the density of the sustained-release material as ρ 缓 , m 缓 The slow-release material is added to the simulated formation water, and a hydrolysis experiment is carried out at the formation temperature. The time t required for complete hydrolysis is recorded, and the reaction rate r of the pure slow-release membrane material is calculated:

[0037]

[0038] The sustained-release material includes a polyester with dimethyl terephthalate and ethylene glycol as monomers;

[0039] (2) Take m 初 The slow-release particle electrode was used as the test sample, and the average diameter of the test sample was measured as d 初 The test sample was added to the simulated formation water and hydrolysis experiment was carried out at the formation temperature. After the slow-release material was completely hydrolyzed, the particle electrode without slow-release membrane was separated and the mass was measured to be m 终 , record the time taken for complete hydrolysis as x 终 ; Determine the average diameter d of the particle electrode without sustained-release membrane 终 , calculate the number n of slow-release particle electrodes in the test sample:

[0040]

[0041] Among them, ρ 粒 is the density of the slow-release particle electrode;

[0042] (3) m 初 The slow-release particle electrode was added into the simulated formation water and the hydrolysis experiment was carried out at the formation temperature. i After a few seconds, the particle electrode with a certain thickness of sustained-release membrane was separated and the mass was measured to be m i ; the x i <x 终; Calculate the mass fraction y of the sustained-release material at this time i And the average diameter d of the slow-release particle electrode at this time i ;

[0043] The mass fraction y of the sustained-release material i The calculation formula is:

[0044]

[0045] The average diameter d of the slow-release particle electrode i The calculation formula is:

[0046]

[0047] (4) Repeat step (3) to obtain j groups of different x i Mass fraction y in seconds i and the average diameter d i ; The j is 5 to 10; the mass fraction y i is the horizontal axis, the average diameter d i As the vertical coordinate, the fitting function is used for fitting to obtain the correlation formula:

[0048] d=f(y)

[0049] The fitting function includes any one of a polynomial fitting function, an exponential function or a linear fitting function;

[0050] (5) Divide the grid according to the pore structure of the porous medium of the simulated formation, import it into the fluid mechanics calculation software, adopt the Euler-Euler multiphase flow model, set the three phases of water, oil, and particle electrode, and couple the fluid volume method to enhance the description of the water-oil interface; open the component transport model, and describe the consumption rate of the slow-release material in the hydrolysis experiment by adding the reaction rate r to the source term of the component transport equation, and calculate the mass fraction y of the slow-release material in the grid;

[0051] The porous medium includes any one of a glass etching model, a core slice or a digital core;

[0052] (6) The real-time average particle size d of the sustained-release particle electrode is calculated using the correlation formula f(y):

[0053] When d≥d 终 , d=d 实 ; when d≤d 终 , d=d 终 .

[0054] Compared with the prior art, the present invention has at least the following beneficial effects:

[0055] The method for calculating the real-time particle size of the slow-release particle electrode provided by the present invention is rationally designed and simple to operate. The real-time particle size of the slow-release particle electrode is calculated through a formula, and the migration behavior of the slow-release particle electrode can be accurately described during the simulation process. The relative error of the predicted recovery rate is small, which has good guiding significance for oil production. DETAILED DESCRIPTION

[0056] For the convenience of understanding the present invention, the present invention is given below with examples. It should be understood by those skilled in the art that the examples are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0057] The present invention is further described in detail below. However, the following examples 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 shall be subject to the claims.

[0058] As a specific embodiment of the present invention, a method for calculating the real-time particle size of a sustained-release particle electrode is provided.

[0059] The slow-release particle electrode used in this specific embodiment is ferrosoferric oxide coated with polyethylene terephthalate, and the simulated formation water is standard brine with a mineralization of 80 g / L prepared according to SY / T 5358-2010; the material to be slow-released is easily hydrolyzed polyester polyethylene terephthalate; and the porous medium includes a glass etching model.

[0060] The calculation method comprises the following steps:

[0061] (1) Determine the density of the sustained-release material as ρ 缓 =1230000 g / m3, m 缓 = 5 g of the sustained-release material was added to simulated formation water, and a hydrolysis experiment was carried out at a formation temperature of 82°C. The time required for complete hydrolysis was recorded as t = 63 seconds, and the reaction rate r of the pure sustained-release membrane material was calculated as:

[0062]

[0063] The sustained-release material is a polyester with dimethyl terephthalate and ethylene glycol as monomers;

[0064] (2) Take m 初 = 5 g of slow-release particle electrode as the test sample, and the average diameter of the test sample is measured as d 初 =7.98×10 -7 The test sample was added to the simulated formation water and hydrolysis experiment was carried out at the formation temperature. After the slow-release material was completely hydrolyzed, the particle electrode without slow-release membrane was separated and the mass was measured to be m 终 = 3.1 g, record the time taken for complete hydrolysis as x 终; Determine the average diameter d of the particle electrode without sustained-release membrane 终 =5.2×10 -7 , calculate the number n of slow-release particle electrodes in the test sample:

[0065]

[0066] Among them, ρ 粒 is the density of the slow-release particle electrode, which is 5170000g / m 3 ;

[0067] (3) m 初 The slow-release particle electrode was added into the simulated formation water and the hydrolysis experiment was carried out at the formation temperature. i After a few seconds, the particle electrode with a certain thickness of sustained-release membrane was separated and the mass was measured to be m i ; the x i <x 终 ; Calculate the mass fraction y of the sustained-release material at this time i And the average diameter d of the slow-release particle electrode at this time i ;

[0068] The mass fraction y of the sustained-release material i The calculation formula is:

[0069]

[0070] The average diameter d of the slow-release particle electrode i The calculation formula is:

[0071]

[0072] In this specific embodiment, the hydrolysis time x i Seconds, mass m i and the average diameter d of the slow-release particle electrode i The results are shown in Table 1.

[0073] Table 1

[0074]

[0075]

[0076] (4) Repeat step (3) to obtain j groups of different x i Mass fraction y in seconds i and the average diameter d i ; The j is 10; with a mass fraction y i is the horizontal axis, the average diameter d i As the vertical coordinate, the fitting function is used for fitting to obtain the correlation formula:

[0077] d=f(y)=721.28y+534.09

[0078] (5) The glass etching model of the porous medium pore structure simulating the formation was meshed and imported into the fluid mechanics calculation software. The Euler-Euler multiphase flow model was used to set three phases of water, oil, and particle electrode. The fluid volume method was coupled to enhance the description of the water-oil interface. The component transport model was enabled. The consumption rate of the slow-release material in the hydrolysis experiment was described by adding the reaction rate r to the source term of the component transport equation. The mass fraction y of the slow-release material in the grid was calculated.

[0079] (6) The real-time average particle size d of the sustained-release particle electrode is calculated using the correlation formula f(y):

[0080] When d≥d 终 , d=d 实 ; when d≤d 终 , d=d 终 .

[0081] The average particle size obtained in this embodiment can be used to obtain oil recovery rate data, and the specific steps include:

[0082] The real-time average particle size of the sustained-release particle electrode obtained in this embodiment is used to correct the diameter of the particle electrode. In the hydrolysis experiment, in the area where the sustained-release material is completely hydrolyzed, that is, in the area where the mass fraction y of the sustained-release material is less than 0.001, the initial viscosity μ of the oil phase is adjusted according to the volume fraction of the particle electrode in the oil-containing grid. 初 =0.0024 kg m -1 s -1 The correction formula for oil phase viscosity μ is:

[0083] μ=wαμ 初

[0084] Where α is the volume fraction of the particle electrode, and w is the correction coefficient, which is 0.9.

[0085] After the simulation is completed, the remaining oil volume V = 5.4 μL, which is equal to the initial oil volume V 初 =12.8μL, the recovery factor η is calculated as:

[0086]

[0087] If the method for calculating the real-time particle size of the sustained-release particle electrode provided in this specific embodiment is not used to obtain the real-time average particle size of the sustained-release particle electrode to correct the diameter of the particle electrode, the relative error of the oil recovery rate data calculated using the above method is large, and the error comparison results are shown in Table 2.

[0088] Table 2

[0089]

[0090] The relative error of the recovery rate obtained by the calculation method of the real-time particle size of the slow-release particle electrode in this specific implementation method is reduced by more than 15%, which has a good guiding significance for oil production.

[0091] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for calculating the real-time particle size of a sustained-release particle electrode, characterized in that: The calculation method comprises the following steps: (1) Determine the density of the sustained-release material as ρ 缓 , m 缓 The slow-release material is added to the simulated formation water, and a hydrolysis experiment is carried out at the formation temperature. The time t required for complete hydrolysis is recorded, and the reaction rate r of the pure slow-release membrane material is calculated: (2) Take m 初 The slow-release particle electrode was used as the test sample, and the average diameter of the test sample was measured as d 初 The test sample was added to the simulated formation water and hydrolysis experiment was carried out at the formation temperature. After the slow-release material was completely hydrolyzed, the particle electrode without slow-release membrane was separated and the mass was measured to be m 终 , record the time taken for complete hydrolysis as x 终 ; Determine the average diameter d of the particle electrode without sustained-release membrane 终 , calculate the number n of slow-release particle electrodes in the test sample: (3) m 初 The slow-release particle electrode was added into the simulated formation water and the hydrolysis experiment was carried out at the formation temperature. i After a few seconds, the particle electrode with a certain thickness of sustained-release membrane was separated and the mass was measured to be m i ; the x i <x 终 ; Calculate the mass fraction y of the sustained-release material at this time i And the average diameter d of the slow-release particle electrode at this time i ; (4) Repeat step (3) to obtain j groups of different x i Mass fraction y in seconds i and the average diameter d i ; With mass fraction y i is the horizontal axis, the average diameter d i As the vertical coordinate, the fitting function is used for fitting to obtain the correlation formula: d=f(y) (5) Divide the pore structure of the porous medium of the simulated formation into a grid, import it into the fluid mechanics calculation software, adopt the Euler-Euler multiphase flow model, set the three phases of water, oil, and particle electrode, and couple the fluid volume method to enhance the description of the water-oil interface; open the component transport model, and describe the consumption rate of the slow-release material in the hydrolysis experiment by adding the reaction rate r to the source term of the component transport equation, and calculate the mass fraction y of the slow-release material in the grid; (6) The real-time average particle size d of the sustained-release particle electrode is calculated using the correlation formula f(y): When d≥d 终 , d=d 实 ; when d≤d 终 , d=d 终 .

2. The calculation method according to claim 1, characterized in that The calculation formula for the reaction rate r of the pure sustained-release membrane material in step (1) is:

3. The calculation method according to claim 1 or 2, characterized in that: The sustained-release material in step (1) comprises polyester with dimethyl terephthalate and ethylene glycol as monomers.

4. The calculation method according to any one of claims 1 to 3, characterized in that: The calculation formula for the number n of the slow-release particle electrodes in step (2) is: Among them, ρ 粒 is the density of the slow-release particle electrode.

5. The calculation method according to any one of claims 1 to 4, characterized in that: The mass fraction y of the sustained-release material in step (3) i The calculation formula is:

6. The calculation method according to any one of claims 1 to 5, characterized in that: The average diameter d of the slow-release particle electrode in step (3) i The calculation formula is:

7. The calculation method according to any one of claims 1 to 6, characterized in that: In step (4), j is 5 to 10.

8. The calculation method according to any one of claims 1 to 7, characterized in that: The fitting function in step (4) includes any one of a polynomial fitting function, an exponential function or a linear fitting function.

9. The calculation method according to any one of claims 1 to 8, characterized in that: The porous medium in step (5) includes any one of a glass etching model, a core slice or a digital core.

10. The calculation method according to any one of claims 1 to 9, characterized in that: The calculation method comprises the following steps: (1) Determine the density of the sustained-release material as ρ 缓 , m 缓 The slow-release material is added to the simulated formation water, and a hydrolysis experiment is carried out at the formation temperature. The time t required for complete hydrolysis is recorded, and the reaction rate r of the pure slow-release membrane material is calculated: The sustained-release material includes a polyester with dimethyl terephthalate and ethylene glycol as monomers; (2) Take m 初 The slow-release particle electrode was used as the test sample, and the average diameter of the test sample was measured as d 初 The test sample was added to the simulated formation water and hydrolysis experiment was carried out at the formation temperature. After the slow-release material was completely hydrolyzed, the particle electrode without slow-release membrane was separated and the mass was measured to be m 终 , record the time taken for complete hydrolysis as x 终 ; Determine the average diameter d of the particle electrode without sustained-release membrane 终 , calculate the number n of slow-release particle electrodes in the test sample: Among them, ρ 粒 is the density of the slow-release particle electrode; (3) m 初 The slow-release particle electrode was added into the simulated formation water and the hydrolysis experiment was carried out at the formation temperature. i After a few seconds, the particle electrode with a certain thickness of sustained-release membrane was separated and the mass was measured to be m i ; the x i <x 终 ; Calculate the mass fraction y of the sustained-release material at this time i And the average diameter d of the slow-release particle electrode at this time i ; The mass fraction y of the sustained-release material i The calculation formula is: The average diameter d of the slow-release particle electrode i The calculation formula is: (4) Repeat step (3) to obtain j groups of different x i Mass fraction y in seconds i and the average diameter d i ; The j is 5 to 10; the mass fraction y i is the horizontal axis, the average diameter d i As the vertical coordinate, the fitting function is used for fitting to obtain the correlation formula: d=f(y) The fitting function includes any one of a polynomial fitting function, an exponential function or a linear fitting function; (5) Divide the grid according to the pore structure of the porous medium of the simulated formation, import it into the fluid mechanics calculation software, adopt the Euler-Euler multiphase flow model, set the three phases of water, oil, and particle electrode, and couple the fluid volume method to enhance the description of the water-oil interface; open the component transport model, and describe the consumption rate of the slow-release material in the hydrolysis experiment by adding the reaction rate r to the source term of the component transport equation, and calculate the mass fraction y of the slow-release material in the grid; The porous medium includes any one of a glass etching model, a core slice or a digital core; (6) The real-time average particle size d of the sustained-release particle electrode is calculated using the correlation formula f(y): When d≥d 终 , d=d 实 ; when d≤d 终 , d=d 终 .

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