A method for calculating the real-time particle size of a slow-release particle electrode

Abstract

The application provides a kind of sustained-release particle electrode real-time particle size calculation method, and the real-time average particle size of sustained-release particle electrode is calculated by fitting function and the mass fraction of sustained-release material in grid.The calculation method described in the application can accurately obtain the real-time particle size of sustained-release particle electrode gradually reduced due to hydrolysis in porous medium, so as to accurately describe the migration behavior of sustained-release particle electrode, and provide an important basis for accurate prediction of multiphase flow behavior and recovery factor in porous medium.

Description

Technical Field

[0001] This invention relates to the field of petroleum extraction technology, and in particular to a method for calculating the real-time particle size of a slow-release particle electrode. Background Technology

[0002] Due to the high water cut in oilfields in the mid-to-late stages of development, existing water injection technologies are no longer sufficient to meet the needs of the oilfields. Improving oil recovery is mainly achieved through two aspects: firstly, increasing the sweep efficiency of the injected fluid in the reservoir. This is primarily done by improving reservoir heterogeneity or reducing the mobility of the displacing phase, stabilizing the displacement front, and generally through profile modification or increasing the viscosity of the displacing fluid. Secondly, improving oil washing efficiency. This is mainly achieved by altering the wettability of the rock surface and reducing the adverse effects of capillary action, thereby lowering residual oil saturation. This is generally accomplished by using surfactants to reduce the interfacial tension between oil and water.

[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, and 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 reservoir, which can effectively improve the electrochemical reaction zone. Furthermore, 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, causing them to avoid the dominant water drive channels and act directionally on the remaining or residual oil-rich areas, thus forming an effective electrochemical displacement effect in the broad oil layer between the injection well and the production well, which can significantly improve the oil recovery rate.

[0004] CN117757455A discloses a particle electrode with sustained-release and electrophoretic functions, its preparation method, and its application. The method includes the following steps: mixing esters, alcohols, and a first catalyst to synthesize polyester oligomers via transesterification; adding a second catalyst and a stabilizer to the polyester oligomers to obtain polyester; uniformly mixing the polyester with nano-metal oxides in an organic solvent to obtain an organic solvent suspension containing polyester and nano-metal oxides; adding the organic solvent suspension to an aqueous solution containing a surfactant and uniformly dispersing it to obtain an oil-in-water emulsion; stirring and heating the oil-in-water emulsion until the organic solvent is completely evaporated, using inorganic salts to demulsify, 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, avoiding ineffective adsorption in the near-wellbore zone. During transport, the sustained-release membrane gradually hydrolyzes and releases the oil. Simultaneously, the migration path of the particle electrode is directionally controlled through electrophoresis, enabling the particle electrode to effectively act on the remaining / residual oil region, reducing the cost of three-dimensional electrochemical oil recovery.

[0005] Numerical simulation is an important tool for revealing multiphase flow behavior in porous media, laying a theoretical foundation for the development and optimization of enhanced oil recovery technologies. For three-dimensional electrochemical flooding processes employing slow-release particle electrodes, accurately simulating the migration behavior of these electrodes in porous media is crucial for accurately predicting oil displacement 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 the slow-release particle electrode does not remain constant but gradually decreases.

[0006] However, there is currently a lack of effective methods to calculate the particle size changes of slow-release particle electrodes, making it difficult to accurately describe the migration behavior of slow-release particle electrodes and thus impossible 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 calculates the real-time particle size of the slow-release particle electrode in a porous medium as it gradually decreases due to hydrolysis, 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 objective, the present invention adopts the following technical solution:

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

[0010] (1) The density of the sustained-release material was determined to be ρ. 缓 , will m 缓The slow-release material was added to simulated formation water, and a hydrolysis experiment was conducted at formation temperature. The time t required for complete hydrolysis was recorded, and the reaction rate r of the pure slow-release membrane material was calculated.

[0011] (2) Take m 初 The sustained-release particle electrode was used as the test sample, and the average diameter of the test sample was measured to be d. 初 The test sample was added to simulated formation water and hydrolyzed at formation temperature. After the slow-release material was completely hydrolyzed, a particle electrode without a slow-release membrane was obtained and its 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 a sustained-release membrane. 终 Calculate the number n of sustained-release particle electrodes in the test sample:

[0012] (3) m 初 Slow-release particle electrodes were added to simulated formation water, and hydrolysis experiments were conducted at formation temperature. Hydrolysis x i After a few seconds, a particle electrode with a sustained-release film of a certain thickness was obtained, and the mass measured was 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 sustained-release particle electrode at this time i ;

[0013] (4) Repeat step (3) to obtain j different x groups. i Mass fraction y per second i and average diameter d i ; with mass fraction y i The x-axis represents the average diameter d. i Using the ordinate as the vertical axis, a fitting function is used to fit the data, yielding the correlation equation:

[0014] d = f(y)

[0015] (5) Mesh the porous structure of the simulated formation and import it into the fluid dynamics calculation software. Use the Euler-Euler multiphase flow model and set three phases: water, oil, and particle electrodes. Couple the fluid volume method to enhance the description of the water-oil interface. Enable 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. Calculate the mass fraction y of the slow-release material in the mesh.

[0016] (6) The real-time average particle size d of the sustained-release particle electrode is calculated using the correlation 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 sustained-release particle electrode described in this invention is simple to operate and rationally designed. First, the reaction rate of the pure sustained-release membrane material and the number of sustained-release particle electrodes in the test sample are calculated. Through repeated hydrolysis experiments, the mass fraction and average diameter of the sustained-release particle electrodes are fitted using a function to obtain a correlation. Finally, combined with the mass fraction of the sustained-release material in the grid, the real-time average particle size of the sustained-release particle electrode is calculated. The calculation method described in this invention can accurately describe the gradual decrease in particle size of the sustained-release particle electrode in porous media due to hydrolysis, thereby accurately describing the migration behavior of the sustained-release particle electrode and providing an important foundation for the accurate prediction of multiphase flow behavior and recovery rate in porous media.

[0019] The method for calculating the real-time particle size of the slow-release particle electrode described in this invention is applicable to various slow-release particle electrodes in the prior art, such as easily hydrolyzable polyester-coated iron(III) oxide, iron(II) oxide, or aluminum(II) oxide.

[0020] The simulated formation water described in this invention is prepared using standard methods. The required salinity data for the simulated formation water are obtained using standard brine prepared according to SY / T 5358-2010.

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

[0022] Preferably, the formula for calculating the reaction rate r of the pure sustained-release membrane material in step (1) is:

[0023]

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

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

[0026]

[0027] Where, ρ 粒 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 sustained-release particle electrode in step (3) is...i The calculation formula is:

[0031]

[0032] Preferably, 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) includes any one of glass etching model, core sheet or digital core.

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

[0036] (1) The density of the sustained-release material was determined to be ρ. 缓 , will m 缓 The slow-release material was added to simulated formation water, and a hydrolysis experiment was conducted at formation temperature. The time t required for complete hydrolysis was recorded, and the reaction rate r of the pure slow-release membrane material was calculated.

[0037]

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

[0039] (2) Take m 初 The sustained-release particle electrode was used as the test sample, and the average diameter of the test sample was measured to be d. 初 The test sample was added to simulated formation water and hydrolyzed at formation temperature. After the slow-release material was completely hydrolyzed, a particle electrode without a slow-release membrane was obtained and its 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 a sustained-release membrane. 终 Calculate the number n of sustained-release particle electrodes in the test sample:

[0040]

[0041] Where, ρ 粒 The density of the slow-release particle electrode;

[0042] (3) m 初 Slow-release particle electrodes were added to simulated formation water, and hydrolysis experiments were conducted at formation temperature. Hydrolysis x i After a few seconds, a particle electrode with a sustained-release film of a certain thickness was obtained, and the mass measured was 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 sustained-release particle electrode at this time i ;

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

[0044]

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

[0046]

[0047] (4) Repeat step (3) to obtain j different x groups. i Mass fraction y per second i and average diameter d i The value of j is 5 to 10; with a mass fraction y i The x-axis represents the average diameter d. i Using the ordinate as the vertical axis, a fitting function is used to fit the data, yielding the correlation equation:

[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) Mesh the porous structure of the simulated formation and import it into the fluid dynamics calculation software. Use the Euler-Euler multiphase flow model and set three phases: water, oil, and particle electrodes. Couple the fluid volume method to enhance the description of the water-oil interface. Enable 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. Calculate the mass fraction y of the slow-release material in the mesh.

[0051] The porous medium includes any one of glass etched models, core sections, or digital cores;

[0052] (6) The real-time average particle size d of the sustained-release particle electrode is calculated using the correlation 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 this invention is reasonably designed and simple to operate. The real-time particle size of the slow-release particle electrode is calculated by formula, which can accurately describe the migration behavior of the slow-release particle electrode in the simulation process. The relative error of the predicted recovery rate is small, which has good guiding significance for oil extraction. Detailed Implementation

[0056] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0057] 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.

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

[0059] In this specific embodiment, the slow-release particle electrode is polyethylene terephthalate coated iron(III) oxide, and the simulated formation water is a standard brine with a salinity 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 includes the following steps:

[0061] (1) The density of the sustained-release material was determined to be ρ. 缓 =1230000 grams per cubic meter, m 缓 =5 grams of slow-release material was added to simulated formation water, and a hydrolysis experiment was conducted at a formation temperature of 82°C. The time required for complete hydrolysis was recorded as t = 63 seconds. The reaction rate r of the pure slow-release membrane material was calculated:

[0062]

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

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

[0065]

[0066] Where, ρ 粒 The density of the slow-release particle electrode is 5,170,000 g / m³. 3 ;

[0067] (3) m 初 Slow-release particle electrodes were added to simulated formation water, and hydrolysis experiments were conducted at formation temperature. Hydrolysis x i After a few seconds, a particle electrode with a sustained-release film of a certain thickness was obtained, and the mass measured was 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 sustained-release particle electrode at this time i ;

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

[0069]

[0070] The average diameter d of the sustained-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 sustained-release particle electrode i The results are shown in Table 1.

[0073] Table 1

[0074]

[0075]

[0076] (4) Repeat step (3) to obtain j different x groups. i Mass fraction y per second i and average diameter d i The j is 10; with mass fraction y i The x-axis represents the average diameter d. i Using the ordinate as the vertical axis, a fitting function is used to fit the data, yielding the correlation equation:

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

[0078] (5) Mesh the porous medium pore structure glass etching model of the simulated formation, import it into the fluid dynamics calculation software, adopt the Euler-Euler multiphase flow model, set three phases: water, oil and particle electrode, and couple the fluid volume method to enhance the description of the water-oil interface; enable 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 mesh;

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

[0080] When d≥d 终 d=d 实 When d≤d 终 d=d 终 .

[0081] Oil recovery rate data can be obtained using the average grain size obtained in this specific embodiment. The specific steps include:

[0082] The diameter of the sustained-release particle electrode is corrected using the real-time average particle size obtained in this specific embodiment. In the hydrolysis experiment, in the region where the sustained-release material is completely hydrolyzed, i.e., the region where the mass fraction y of the sustained-release material is less than 0.001, the initial viscosity μ of the oil phase is determined based on the volume fraction of the particle electrode in the oil-containing grid. 初 =0.0024kg m -1 s -1 A correction is made to describe the enhanced oil displacement effect brought about by the particle electrode. The correction formula for the 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 factor, which is 0.9.

[0085] After the simulation, the volume of the remaining oil was calculated to be V = 5.4 μL, which is different from the initial oil volume V. 初 =12.8μL, the recovery rate η is calculated as follows:

[0086]

[0087] If the real-time average particle size of the slow-release particle electrode is not calculated using the method provided in this specific embodiment to correct the diameter of the particle electrode, the oil recovery data obtained by the above method will have a relatively large error. The error comparison results are shown in Table 2.

[0088] Table 2

[0089]

[0090] The method for calculating the real-time particle size of the slow-release particle electrode in this specific implementation reduces the relative error of the recovery rate by more than 15%, which has great guiding significance for oil extraction.

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

Claims

1. A method for calculating the real-time particle size of a slow-release particle electrode, characterized in that, The calculation method includes the following steps: (1) The density of the sustained-release material was determined to be... ρ 缓 , to make quality m 缓 The slow-release material was added to simulated formation water, and a hydrolysis experiment was conducted at formation temperature. The time required for complete hydrolysis was recorded. t The reaction rate of the pure sustained-release membrane material was calculated. r : (2) Take the mass as m 初 The sustained-release particle electrode was used as the test sample, and the average diameter of the test sample was measured to be... d 初 The test sample was added to simulated formation water and hydrolyzed at formation temperature. After the slow-release material was completely hydrolyzed, a particle electrode without a slow-release membrane was obtained and its mass was measured. m 终 Record the time taken for complete hydrolysis as follows x 终 ; Determine the average diameter of the particle electrode without a sustained-release membrane. d 终 Calculate the number of sustained-release particle electrodes in the test sample. n : (3) The mass is m 初 The slow-release particle electrode was added to simulated formation water, and a hydrolysis experiment was conducted at formation temperature. x i After seconds, a particle electrode with a sustained-release film of a certain thickness was obtained through separation, and the measured mass was [missing information]. m i The x i < x 终 ; Calculate the mass fraction of the sustained-release material at this time. y i and the average diameter of the sustained-release particle electrode at this time d i ; (4) Repeat step (3) to obtain j Different groups x i Quality score per second y i and average diameter d i ; by mass fraction y i The x-axis represents the average diameter. d i Using the ordinate as the vertical axis, a fitting function is used to fit the data, yielding the correlation equation: (5) Mesh the porous structure of the simulated formation's porous medium and import it into the fluid dynamics calculation software. Use the Euler-Euler multiphase flow model and set three phases: water, oil, and particle electrodes. Couple the fluid volume method to enhance the description of the water-oil interface. Enable the component transport model and measure the reaction rate. r The consumption rate of the sustained-release material in the hydrolysis experiment is described by adding it to the source term of the component transport equation, and the mass fraction of the sustained-release material in the grid is calculated. y ; (6) Through the aforementioned correlation f ( y The real-time average particle size of the sustained-release particle electrode was calculated. d : when , ;when , .

2. The calculation method according to claim 1, characterized in that, The reaction rate of the pure sustained-release membrane material in step (1) r The calculation formula is: 。 3. The calculation method according to claim 1, characterized in that, The sustained-release material in step (1) includes polyester with dimethyl terephthalate and ethylene glycol as monomers.

4. The calculation method according to claim 1, characterized in that, The number of sustained-release particle electrodes in step (2) n The calculation formula is: in, ρ 粒 The density of the slow-release particle electrode.

5. The calculation method according to claim 1, characterized in that, The mass fraction of the sustained-release material in step (3) y i The calculation formula is: 。 6. The calculation method according to claim 4, characterized in that, The average diameter of the sustained-release particle electrode in step (3) d i The calculation formula is:

7. The calculation method according to claim 1, characterized in that, Step (4) j The range is 5 to 10.

8. The calculation method according to claim 1, 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 claim 1, characterized in that, The porous medium in step (5) includes any one of glass etching models, core sections, or digital cores.

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