A method for testing the dynamic viscosity of a heavy oil emulsion reservoir

Abstract

The application discloses a method for testing dynamic viscosity of heavy oil emulsion reservoir. The method comprises the following steps: adding heavy oil and water / emulsified viscosity reducer solution into an intermediate container respectively; opening the injection end and the production end of a pretreated core or sand pipe, closing the injection end and the production end of a test core or sand pipe, and simultaneously injecting the heavy oil and the water / emulsified viscosity reducer solution into the pretreated core or sand pipe; after the pressure of the two ends of the pretreated core or sand pipe is stabilized, opening the injection end and the production end of the test core or sand pipe until the pressure of the two ends of the test core or sand pipe is stabilized, and recording the total injection speed of the heavy oil and the water / emulsified viscosity reducer solution, the pressure difference of the two ends of the test core or sand pipe and the oil-water volume ratio; and the dynamic viscosity of the heavy oil emulsion is obtained according to the percolation dynamics equation. The method solves the problem that the current indoor preparation method of the heavy oil emulsion is seriously out of line with the actual percolation condition of the reservoir, and can accurately reflect the dynamic viscosity of the heavy oil emulsion under the actual condition of the reservoir.

Description

Technical Field

[0001] This invention relates to a method for testing the dynamic viscosity of heavy oil emulsion reservoirs, belonging to the field of water / steam drive development and enhanced oil recovery of heavy oil reservoirs. Background Technology

[0002] Heavy oil reservoirs are rich in resources, but heavy oil is typically characterized by high content of gums and asphaltenes, and high viscosity. During heavy oil development, firstly, its viscosity is higher than that of injected water, leading to low waterflood recovery rates. Secondly, active substances such as gums and asphaltenes in heavy oil are easily adsorbed at the oil-water interface, forming water-in-oil emulsions, further increasing its viscosity and reducing its fluidity. Furthermore, chemical flooding to improve heavy oil recovery typically involves emulsifying crude oil into small-diameter droplets, dispersing them in an emulsion viscosity reducer solution, and then allowing them to flow to the production well, thus increasing the recovery rate. Regardless of whether it's reservoir formation, water / steam flooding, or emulsion viscosity reducer flooding, heavy oil and water phases will form heavy oil emulsions under the shearing action of the formation porous media. The emulsions formed during reservoir formation and water / steam flooding are water-in-oil emulsions, while those formed during chemical flooding to improve heavy oil recovery are oil-in-water emulsions.

[0003] Conventional methods for preparing heavy oil emulsions typically involve mixing an emulsifying displacement agent and crude oil in a specific ratio, followed by agitation, emulsification using an emulsifier, or ultrasonic emulsification to disperse water in the oil phase or crude oil in the emulsifying displacement agent solution. The shear viscosity of the emulsion under specific shear rates is measured using a rheometer to evaluate its dynamic viscosity in the formation. However, this method of preparing and testing heavy oil emulsions is completely divorced from actual reservoir conditions. This is because heavy oil emulsions form and flow within the porous reservoir medium. The size, tortuosity, and pore wall properties of this porous medium significantly influence the dynamic viscosity of the heavy oil emulsion. The current preparation and viscosity testing methods completely ignore these factors, making it impossible to accurately describe the dynamic viscosity of heavy oil emulsions in the formation porous medium. Therefore, a new method for testing the reservoir dynamic viscosity of heavy oil emulsions is needed to address these issues. Summary of the Invention

[0004] The purpose of this invention is to provide a method for evaluating the dynamic viscosity of heavy oil emulsions under simulated reservoir seepage conditions.

[0005] The reservoir dynamic viscosity test method for heavy oil emulsions provided by this invention utilizes a long-distance core or sand-filled pipe to simulate the reservoir seepage environment. First, heavy oil and water / emulsion viscosity reducer solution are simultaneously injected into the pretreated core or sand-filled pipe in a certain proportion. Then, after the pressure at both ends of the pretreated core or sand-filled pipe stabilizes, the outlet end of the pretreated core or sand-filled pipe is connected to the injection end of the test core or sand-filled pipe by a pipeline until the pressure on both sides of the test core or sand-filled pipe stabilizes. The seepage velocity, pressure difference, and volume ratio of the injected oil phase and water phase are recorded. The pressure when the pressure on both sides of the test core or sand-filled pipe stabilizes is taken as the seepage pressure difference.

[0006] Specifically, the displacement device used in this invention has the following structure:

[0007] The displacement device includes a pretreated core and a test core connected in sequence, or a pretreated sand-filled pipe and a test sand-filled pipe;

[0008] The injection end of the pretreated core or the pretreated sand-filled pipe is connected to intermediate container I and intermediate container II, and the extraction end of the test core or the test sand-filled pipe is connected to a liquid collection device.

[0009] Both ends of the pretreated core and the test core, or the pretreated sand-filled pipe and the test sand-filled pipe, are connected to a pressure acquisition system;

[0010] The pretreated core or the pretreated sand-filled pipe, the test core or the test sand-filled pipe, the intermediate container I and the intermediate container II are placed in a constant temperature chamber;

[0011] The pretreated core or the test core has a diameter of 2-5 cm, a length of 2.5-10 cm, and a permeability of 0.1-200 mD.

[0012] The pretreated sand-filled pipe or the test sand-filled pipe has a diameter of 2-5 cm, a length of 10-50 cm, and a permeability of 200-10000 mD.

[0013] Specifically, when the viscosity of the heavy oil is 50–200 mPa·s, the length of the pretreated core is 2.5–10 cm, and the permeability is 0.1–200 mD, wherein the permeability is selected according to the actual situation of the reservoir.

[0014] When the viscosity of the heavy oil is 200-400 mPa·s, the length of the pre-treated sand-filled pipe is 10-50 cm, and the permeability is 200-500 mD, wherein the permeability is selected according to the actual situation of the reservoir.

[0015] When the viscosity of the heavy oil is 400-1000 mPa·s, the length of the pre-treated sand-filled pipe is 10-50 cm, and the permeability is 500-1000 mD, wherein the permeability is selected according to the actual situation of the reservoir.

[0016] When the viscosity of the heavy oil is 1000-5000 mPa·s, the length of the pre-treated sand-filled pipe is 20-50 cm, and the permeability is 1000-5000 mD, wherein the permeability is selected according to the actual situation of the reservoir.

[0017] When the viscosity of the heavy oil is 5000-10000 mPa·s, the length of the pre-treated sand-filled pipe is 30-50 cm, and the permeability is 5000-10000 mD, wherein the permeability is selected according to the actual situation of the reservoir.

[0018] Specifically, the steps for testing using the displacement device are as follows:

[0019] S1. Add the heavy oil to the intermediate container I, add the water / emulsified viscosity reducer solution to the intermediate container II, and heat to the emulsification temperature;

[0020] S2. Open the injection end and production end of the pretreated core or the pretreated sand-filled pipe, close the injection end and production end of the test core or the test sand-filled pipe, and simultaneously inject the heavy oil and the water / emulsion viscosity reducer solution into the pretreated core or the pretreated sand-filled pipe.

[0021] S3. After the pressure at both ends of the pretreated core or the pretreated sand-filled pipe stabilizes, open the injection end and the production end of the test core or the test sand-filled pipe until the pressure at both ends of the test core or the test sand-filled pipe stabilizes. Record the total injection rate of the heavy oil and the water / emulsified viscosity reducer solution, the pressure difference at both ends of the test core or the test sand-filled pipe, and the oil-water volume ratio.

[0022] That is, firstly, the heavy oil emulsion is thoroughly mixed in the pretreated core or the pretreated sand-filled pipe to ensure that the heavy oil emulsion entering the test core or the test sand-filled pipe is completely homogeneous;

[0023] The reservoir dynamic viscosity of the heavy oil emulsion is obtained from the seepage dynamics equation shown below.

[0024]

[0025] In the formula, Q represents the total injection rate of heavy oil and water / emulsion viscosity reducer solution, ml / min; k represents the permeability of the test core or test sand-filled pipe, mD; L represents the length of the test core or test sand-filled pipe, cm; and A represents the seepage area, cm². 2; △P represents the pressure difference between the two ends of the test core or the test sand-filled pipe, MPa; μ represents the reservoir dynamic viscosity of the heavy oil emulsion, mPa·s.

[0026] In the above test method, in step S1, the temperature of the constant temperature chamber is controlled to be 25-100℃.

[0027] In the above test method, the viscosity of the heavy oil is 50 to 10000 mPa·s.

[0028] In the above test method, the injection rate of both the heavy oil and the water / emulsified viscosity reducer solution is 0.1 to 10 ml / min.

[0029] In the above test method, the volume ratio of the heavy oil to the water / emulsified viscosity reducer solution is 1-9:1-9.

[0030] The method of this invention is applicable to conventional emulsifying viscosity reducers in the art, such as surfactants, active nanoparticles, polymerizing agents, nanofluids, alkalis, etc.

[0031] This invention is applicable to the testing of the dynamic viscosity of different types of heavy oil emulsions during seepage in porous reservoir media, such as water-in-oil emulsions, oil-in-water emulsions, and multiple emulsions.

[0032] The method of the present invention has the following advantages:

[0033] This invention overcomes the shortcomings of previous methods for preparing crude oil emulsions using mechanical stirring and ultrasound, which require a static environment and are detached from reservoir seepage conditions. It not only enriches the technology for evaluating the fluidity of heavy oil emulsions but also more realistically simulates the seepage conditions of emulsified crude oil in porous reservoir media using emulsifying agents. This invention solves the problem of a severe disconnect between current laboratory methods for preparing crude oil emulsions and actual reservoir seepage conditions, accurately reflecting the dynamic viscosity of heavy oil emulsions under actual reservoir conditions. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the displacement device used in the method of the present invention.

[0035] Figure 2 This is a flowchart of the dynamic viscosity evaluation method for heavy oil emulsions according to the present invention.

[0036] Figure 3 The dynamic viscosity of the heavy oil-in-water emulsion with an oil-water ratio of 7:3 obtained in Example 1 and Comparative Example 1 of this invention is given.

[0037] Figure 4 The dynamic viscosity of the heavy oil-in-water emulsion with a water-to-oil ratio of 5:5, obtained in Example 2 and Comparative Example 2 of this invention. Detailed Implementation

[0038] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0039] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0040] A schematic diagram of the displacement device used in this invention is shown below. Figure 1 As shown, the pretreatment sand-filling pipe 7 and the test sand-filling pipe 8 are connected. The injection end of the pretreatment sand-filling pipe 7 is connected to intermediate containers 4 and 5 and the pressure acquisition system 1 via a four-way valve 6. The outlet end of the test sand-filling pipe 8 is connected to the liquid acquisition device 12 and the pressure acquisition system 1 via a three-way valve 9. The pipeline connecting the pretreatment sand-filling pipe 7 and the test sand-filling pipe 8 is also connected to the pressure acquisition system 1 to monitor the pressure. One end of the intermediate containers 4 and 5 is connected to constant speed and constant pressure pumps 2 and 3 for driving. The intermediate containers 4 and 5, the pretreatment sand-filling pipe 7 and the test sand-filling pipe 8, and the corresponding pipelines are housed in a constant temperature chamber 11.

[0041] Example 1

[0042] according to Figure 2 The process shown uses the aforementioned displacement device to test the dynamic viscosity of heavy oil emulsions. The pretreatment sand-filled tube has a diameter of 2.5 cm, a length of 15 cm, and a permeability of 600 mD; the test sand-filled tube has a diameter of 2.5 cm, a length of 50 cm, and a permeability of 600 mD.

[0043] (1) Prepare 100ml of dehydrated crude oil with a viscosity of 505mPa·s (60℃) and place it in the intermediate container 4;

[0044] (2) Prepare 100ml of water and place it in the middle container 5;

[0045] (3) Open the constant temperature chamber 11 and set the temperature to 60℃;

[0046] (4) Open the pressure acquisition system 1 and open the injection end and extraction end valves of the pretreatment sand filling pipe 7;

[0047] (5) Inject heavy oil and water simultaneously into the pretreated sand-filled pipe 7. The injection rate of heavy oil is 0.35 ml / min, and the injection rate of water is 0.15 ml / min.

[0048] (6) After the pressure stabilizes, connect the outlet of the pre-treatment sand filling pipe 7 and the inlet of the test sand filling pipe 8;

[0049] (7) Once the pressure difference across the sand-filled pipe 8 is stable, record the seepage rate Q and the pressure difference ΔP across the sand-filled pipe.

[0050] (8) Using Darcy's law, establish the seepage dynamics equation in the porous medium of heavy oil emulsion reservoirs:

[0051]

[0052] In the formula, Q—total injection rate of oil and water phases, ml / min; k—permeability of the sand-filled tube, mD; L—length of the sand-filled tube, cm; A—seepage area, cm² 2 ; △P—Pressure difference between the two ends of the test sand-filled pipe, MPa. μ—Dynamic viscosity of the heavy oil emulsion reservoir, mPa·s.

[0053] (9) Using the above seepage kinetic equation, the dynamic viscosity of the heavy oil-in-water emulsion was calculated, and the results are as follows: Figure 3 As shown.

[0054] Figure 3 Comparative Example 1 represents the produced fluid collected at the outlet of the test sand-filled pipe 8, and the viscosity was obtained by traditionally using a rheometer.

[0055] from Figure 2 It can be seen that for the same oil-to-water ratio of 7:3, the viscosity obtained by the method of this invention is greater than that obtained by traditional methods. This is mainly due to two factors: the strong adhesion of heavy oil to the porous surface, resulting in a high dynamic viscosity; and the additional resistance caused by the Jamin effect when the heavy oil emulsion passes through small pores. The combined effect of these two factors reduces the accuracy of traditional testing methods.

[0056] Example 2

[0057] according to Figure 2 The process shown uses the aforementioned displacement device to test the dynamic viscosity of heavy oil emulsion. The pretreatment sand-filled tube has a diameter of 2.5 cm, a length of 15 cm, and a permeability of 600 mD. The test sand-filled tube has a diameter of 2.5 cm, a length of 50 cm, and a permeability of 600 mD.

[0058] (1) Prepare 100ml of dehydrated crude oil with a viscosity of 505mPa·s (60℃) and place it in an intermediate container;

[0059] (2) Prepare 100 ml of a 0.5% aqueous solution of commercially available emulsified viscosity reducer octylphenol polyoxyethylene ether (OP-10) and place it in an intermediate container;

[0060] (3) Turn on the incubator and set the temperature to 60℃;

[0061] (4) Turn on the pressure acquisition system and open the injection and extraction valves of the pretreatment sand filling pipe;

[0062] (5) Inject heavy oil and emulsified viscosity reducer solution into the pretreated sand-filled pipe at the same time. The injection rate of heavy oil is 0.25 ml / min and the injection rate of water is 0.25 ml / min.

[0063] (6) After the pressure stabilizes, connect the outlet of the pre-treated sand-filling pipe and the inlet of the test sand-filling pipe;

[0064] (7) Once the pressure difference across the sand-filled pipe stabilizes, record the seepage rate Q and the pressure difference ΔP across the sand-filled pipe.

[0065] (8) Using Darcy's law, establish the seepage dynamics equation in the porous medium of heavy oil emulsion reservoirs:

[0066]

[0067] In the formula, Q—total injection rate of oil and water phases, ml / min; k—permeability of the sand-filled tube, mD; L—length of the sand-filled tube, cm; A—seepage area, cm² 2 ; △P—Pressure difference between the two ends of the test sand-filled pipe, MPa. μ—Dynamic viscosity of the heavy oil emulsion reservoir, mPa·s.

[0068] (9) Using the above seepage kinetic equation, the dynamic viscosity of the heavy oil-in-water emulsion was calculated, and the results are as follows: Figure 4 As shown.

[0069] Figure 4 Comparative Example 2 represents the produced fluid collected at the outlet of the test sand-filled pipe 8, and the viscosity was obtained by traditionally using a rheometer.

[0070] from Figure 4 It can be seen that for the same heavy oil and emulsifying viscosity reducer solution prepared at a ratio of 5:5, the viscosity obtained by the method of this invention is greater than that obtained by traditional methods. This is mainly because the role of the emulsifying viscosity reducer is to emulsify the heavy oil into droplets that enter the emulsifying viscosity reducer solution and flow with it. However, during the process of heavy oil droplets passing through porous media, a severe Jamin effect occurs, which greatly reduces their flow capacity in the porous media of the formation.

[0071] Example 3

[0072] according to Figure 2 The process shown employs the aforementioned displacement device to test the dynamic viscosity of heavy oil emulsions. The pretreated core sample has a diameter of 2.5 cm, a length of 2.5 cm, and a permeability of 100 mD; the test core sample has a diameter of 2.5 cm, a length of 10 cm, and a permeability of 100 mD.

[0073] (1) Prepare 100ml of dehydrated crude oil with a viscosity of 102mPa·s (25℃) and place it in an intermediate container;

[0074] (2) Prepare 100 ml of a 0.5% aqueous solution of commercially available emulsified viscosity reducer octylphenol polyoxyethylene ether (OP-10) and place it in an intermediate container;

[0075] (3) Turn on the incubator and set the temperature to 25℃;

[0076] (4) Turn on the pressure acquisition system and open the injection and extraction valves of the pretreated core.

[0077] (5) Heavy oil and emulsified viscosity reducer solution were injected into the pretreated core at the same time. The injection rate of heavy oil was 0.25 ml / min and the injection rate of water was 0.25 ml / min.

[0078] (6) After the pressure stabilizes, connect the outlet of the pretreated core and the inlet of the test core;

[0079] (7) After the pressure difference between the two sides of the test core stabilizes, record the seepage rate Q and the pressure difference ΔP between the two sides of the test core.

[0080] (8) Using Darcy's law, establish the seepage dynamics equation in the porous medium of heavy oil emulsion reservoir (same as Example 2).

[0081] (9) Using the above seepage dynamics equation, the dynamic viscosity of the heavy oil-in-water emulsion was calculated, and the results are shown in Table 1.

[0082] Follow the steps above to perform comparative examples 3-1 to 3-3: replace the length of the pretreated core with 1cm, 2cm and 5cm, and leave the rest unchanged.

[0083] Table 1 shows the dynamic viscosity of heavy oil-in-water emulsions measured when the length of the pretreated core was 1 cm, 2 cm, and 5 cm, respectively.

[0084] Table 1. Statistics of dynamic viscosity of the heavy oil-in-water emulsions tested in Example 3 and the comparative example.

[0085] Group Example 3 Comparative Example 3-1 Comparative Example 3-2 Comparative Example 3-3 Pretreated core length (cm) 2.5 1 2 5 Dynamic viscosity (mPa·s) 7.92 18.14 12.25 7.91

[0086] It can be seen that the length of the pretreated core has a significant impact on the test results. This is mainly because when the pretreated core is too short, the heavy oil and the emulsion viscosity reducer solution do not reach a complete emulsification state when flowing out of the pretreated core. The emulsion particle size is relatively large, and the additional resistance caused by the Jamin effect is large when flowing into the test core, resulting in increased pressure at both ends of the test core. Only when the length of the pretreated core is greater than 2.5 cm can the emulsion be completely emulsified after flowing through the pretreated core.

[0087] Example 4

[0088] according to Figure 2 The process shown employs the aforementioned displacement device to test the dynamic viscosity of heavy oil emulsions. The pretreatment sand-filled tube has a diameter of 2.5 cm, a length of 10 cm, and a permeability of 300 mD; the test sand-filled tube has a diameter of 2.5 cm, a length of 50 cm, and a permeability of 300 mD.

[0089] (1) Prepare 100ml of dehydrated crude oil with a viscosity of 324mPa·s (25℃) and place it in an intermediate container;

[0090] (2) Prepare 100 ml of a 0.5% aqueous solution of commercially available emulsified viscosity reducer octylphenol polyoxyethylene ether (OP-10) and place it in an intermediate container;

[0091] (3) Turn on the incubator and set the temperature to 25℃;

[0092] (4) Turn on the pressure acquisition system and open the injection and extraction valves of the pretreatment sand filling pipe;

[0093] (5) Inject heavy oil and emulsified viscosity reducer solution into the pretreated sand-filled pipe at the same time. The injection rate of heavy oil is 0.25 ml / min and the injection rate of water is 0.25 ml / min.

[0094] (6) After the pressure stabilizes, connect the outlet of the pre-treated sand-filling pipe and the inlet of the test sand-filling pipe;

[0095] (7) Once the pressure difference across the sand-filled pipe stabilizes, record the seepage rate Q and the pressure difference ΔP across the sand-filled pipe.

[0096] (8) Using Darcy's law, establish the seepage dynamics equation in the porous medium of heavy oil emulsion reservoir (same as Example 2).

[0097] (9) Using the above seepage dynamics equation, the dynamic viscosity of the heavy oil-in-water emulsion was calculated, and the results are shown in Table 1.

[0098] Follow the steps above to perform comparative examples 4-1 to 4-3: replace the length of the pre-treated sand-filled pipe with 5cm, 8cm and 15cm, and keep the rest unchanged.

[0099] Table 2 shows the dynamic viscosity of heavy oil-in-water emulsions measured when the length of the pretreated core was 5 cm, 8 cm, and 15 cm, respectively.

[0100] Table 2. Dynamic viscosity statistics of the heavy oil-in-water emulsions tested in Example 4 and the comparative example.

[0101] Group Example 4 Comparative Example 4-1 Comparative Example 4-2 Comparative Example 4-3 Length of pre-treated sand-filled pipe (cm) 10 5 8 15 Dynamic viscosity (mPa·s) 24.7 35.8 31.6 24.8

[0102] It can be seen that the length of the pretreatment sand-filled tube has a significant impact on the test results. This is mainly because when the length of the pretreatment sand-filled tube is too short, the heavy oil and the emulsion viscosity reducer solution do not reach a complete emulsified state when flowing out of the pretreatment sand-filled tube. The emulsion particles are relatively large, and the additional resistance caused by the Jamin effect is large when flowing into the test sand-filled tube, resulting in increased pressure at both ends of the test sand-filled tube. Only when the length of the pretreatment sand-filled tube is greater than 10 cm can the emulsion be completely emulsified after flowing through the pretreatment sand-filled tube.

[0103] Example 5

[0104] according to Figure 2 The process shown employs the aforementioned displacement device to test the dynamic viscosity of heavy oil emulsions. The pretreatment sand-filled tube has a diameter of 2.5 cm, a length of 10 cm, and a permeability of 800 mD; the test sand-filled tube has a diameter of 2.5 cm, a length of 50 cm, and a permeability of 800 mD.

[0105] (1) Prepare 100ml of dehydrated crude oil with a viscosity of 866mPa·s (25℃) and place it in an intermediate container;

[0106] (2) Prepare 100 ml of a 0.5% aqueous solution of commercially available emulsified viscosity reducer octylphenol polyoxyethylene ether (OP-10) and place it in an intermediate container;

[0107] (3) Turn on the incubator and set the temperature to 25℃;

[0108] (4) Turn on the pressure acquisition system and open the injection and extraction valves of the pretreatment sand filling pipe;

[0109] (5) Inject heavy oil and emulsified viscosity reducer solution into the pretreated sand-filled pipe at the same time. The injection rate of heavy oil is 0.25 ml / min and the injection rate of water is 0.25 ml / min.

[0110] (6) After the pressure stabilizes, connect the outlet of the pre-treated sand-filling pipe and the inlet of the test sand-filling pipe;

[0111] (7) Once the pressure difference across the sand-filled pipe stabilizes, record the seepage rate Q and the pressure difference ΔP across the sand-filled pipe.

[0112] (8) Using Darcy's law, establish the seepage dynamics equation in the porous medium of heavy oil emulsion reservoir (same as Example 2).

[0113] (9) Using the above seepage dynamics equation, the dynamic viscosity of the heavy oil-in-water emulsion was calculated, and the results are shown in Table 1.

[0114] Follow the steps above to perform comparative examples 5-1 to 5-3: replace the length of the pre-treated sand-filled pipe with 5cm, 8cm and 20cm, and keep the rest unchanged.

[0115] Table 3 shows the dynamic viscosity of heavy oil-in-water emulsions measured when the length of the pretreated core was 5 cm, 8 cm, and 20 cm, respectively.

[0116] Table 3. Dynamic viscosity statistics of the heavy oil-in-water emulsions tested in Example 5 and the comparative example.

[0117] Group Example 5 Comparative Example 5-1 Comparative Example 5-2 Comparative Example 5-3 Length of pre-treated sand-filled pipe (cm) 10 5 8 20 Dynamic viscosity (mPa·s) 28.6 42.1 36.5 28.5

[0118] It can be seen that the length of the pretreatment sand-filled tube has a significant impact on the test results. This is mainly because when the length of the pretreatment sand-filled tube is too short, the heavy oil and the emulsion viscosity reducer solution do not reach a complete emulsified state when flowing out of the pretreatment sand-filled tube. The emulsion particles are relatively large, and the additional resistance caused by the Jamin effect is large when flowing into the test sand-filled tube, resulting in increased pressure at both ends of the test sand-filled tube. Only when the length of the pretreatment sand-filled tube is greater than 10 cm can the emulsion be completely emulsified after flowing through the pretreatment sand-filled tube.

[0119] Example 6

[0120] according to Figure 2 The process shown employs the aforementioned displacement device to test the dynamic viscosity of heavy oil emulsions. The pretreatment sand-filled tube has a diameter of 2.5 cm, a length of 20 cm, and a permeability of 3000 mD; the test sand-filled tube has a diameter of 2.5 cm, a length of 50 cm, and a permeability of 3000 mD.

[0121] (1) Prepare 100ml of dehydrated crude oil with a viscosity of 2865mPa·s (25℃) and place it in an intermediate container;

[0122] (2) Prepare 100 ml of a 0.5% aqueous solution of commercially available emulsified viscosity reducer octylphenol polyoxyethylene ether (OP-10) and place it in an intermediate container;

[0123] (3) Turn on the incubator and set the temperature to 25℃;

[0124] (4) Turn on the pressure acquisition system and open the injection and extraction valves of the pretreatment sand filling pipe;

[0125] (5) Inject heavy oil and emulsified viscosity reducer solution into the pretreated sand-filled pipe at the same time. The injection rate of heavy oil is 0.25 ml / min and the injection rate of water is 0.25 ml / min.

[0126] (6) After the pressure stabilizes, connect the outlet of the pre-treated sand-filling pipe and the inlet of the test sand-filling pipe;

[0127] (7) Once the pressure difference across the sand-filled pipe stabilizes, record the seepage rate Q and the pressure difference ΔP across the sand-filled pipe.

[0128] (8) Using Darcy's law, establish the seepage dynamics equation in the porous medium of heavy oil emulsion reservoir (same as Example 2).

[0129] (9) Using the above seepage dynamics equation, the dynamic viscosity of the heavy oil-in-water emulsion was calculated, and the results are shown in Table 1.

[0130] Follow the steps above to perform comparative examples 6-1 to 6-3: replace the length of the pre-treated sand-filled pipe with 10cm, 15cm and 30cm, and leave the rest unchanged.

[0131] Table 4 shows the dynamic viscosity of heavy oil-in-water emulsions measured when the length of the pretreated core was 10 cm, 15 cm, and 30 cm, respectively.

[0132] Table 4. Dynamic viscosity statistics of the heavy oil-in-water emulsions tested in Example 6 and the comparative example.

[0133] Group Example 6 Comparative Example 6-1 Comparative Example 6-2 Comparative Example 6-3 Length of pre-treated sand-filled pipe (cm) 20 10 15 30 Dynamic viscosity (mPa·s) 45.2 86.8 65.4 45.5

[0134] It can be seen that the length of the pretreatment sand-filled tube has a significant impact on the test results. This is mainly because when the length of the pretreatment sand-filled tube is too short, the heavy oil and the emulsion viscosity reducer solution do not reach a complete emulsified state when flowing out of the pretreatment sand-filled tube. The emulsion particles are relatively large, and the additional resistance caused by the Jamin effect is large when flowing into the test sand-filled tube, resulting in increased pressure at both ends of the test sand-filled tube. Only when the length of the pretreatment sand-filled tube is greater than 20 cm can the emulsion be completely emulsified after flowing through the pretreatment sand-filled tube.

[0135] Example 7

[0136] according to Figure 2 The process shown employs the aforementioned displacement device to test the dynamic viscosity of heavy oil emulsions. The pretreatment sand-filled tube has a diameter of 2.5 cm, a length of 30 cm, and a permeability of 8000 mD; the test sand-filled tube has a diameter of 2.5 cm, a length of 50 cm, and a permeability of 8000 mD.

[0137] (1) Prepare 100ml of dehydrated crude oil with a viscosity of 7243mPa·s (25℃) and place it in an intermediate container;

[0138] (2) Prepare 100 ml of a 0.5% aqueous solution of commercially available emulsified viscosity reducer octylphenol polyoxyethylene ether (OP-10) and place it in an intermediate container;

[0139] (3) Turn on the incubator and set the temperature to 25℃;

[0140] (4) Turn on the pressure acquisition system and open the injection and extraction valves of the pretreatment sand filling pipe;

[0141] (5) Inject heavy oil and emulsified viscosity reducer solution into the pretreated sand-filled pipe at the same time. The injection rate of heavy oil is 0.25 ml / min and the injection rate of water is 0.25 ml / min.

[0142] (6) After the pressure stabilizes, connect the outlet of the pre-treated sand-filling pipe and the inlet of the test sand-filling pipe;

[0143] (7) Once the pressure difference across the sand-filled pipe stabilizes, record the seepage rate Q and the pressure difference ΔP across the sand-filled pipe.

[0144] (8) Using Darcy's law, establish the seepage dynamics equation in the porous medium of heavy oil emulsion reservoir (same as Example 2).

[0145] (9) Using the above seepage dynamics equation, the dynamic viscosity of the heavy oil-in-water emulsion was calculated, and the results are shown in Table 1.

[0146] Follow the steps above to make comparative examples 7-1 to 7-3: replace the length of the pre-treated sand-filled pipe with 10cm, 20cm and 40cm, and keep the rest unchanged.

[0147] Table 5 shows the dynamic viscosity of heavy oil-in-water emulsions measured when the length of the pretreated core was 10 cm, 20 cm, and 40 cm, respectively.

[0148] Table 5. Dynamic viscosity statistics of the heavy oil-in-water emulsions tested in Example 7 and the comparative example.

[0149] Group Example 7 Comparative Example 7-1 Comparative Example 7-2 Comparative Example 7-3 Length of pre-treated sand-filled pipe (cm) 30 10 20 40 Dynamic viscosity (mPa·s) 64.9 124.8 98.7 65.3

[0150] It can be seen that the length of the pretreatment sand-filled tube has a significant impact on the test results. This is mainly because when the length of the pretreatment sand-filled tube is too short, the heavy oil and the emulsified viscosity reducer solution do not reach a complete emulsified state when flowing out of the pretreatment sand-filled tube. The emulsion particle size is relatively large, and the additional resistance caused by the Jamin effect is large when flowing into the test sand-filled tube, resulting in increased pressure at both ends of the test sand-filled tube. Only when the length of the pretreatment sand-filled tube is greater than 30 cm can the emulsion be completely emulsified after flowing through the pretreatment sand-filled tube.

Claims

1. A method for testing the dynamic viscosity of a heavy oil emulsion reservoir, comprising the following steps performed in a displacement device: The displacement device is any one of the following: (1) The displacement device includes a pretreated core and a test core connected in sequence; the injection end of the pretreated core is connected to intermediate container I and intermediate container II, and the extraction end of the test core is connected to a liquid collection device. Both ends of the pretreated core and the test core are connected to a pressure acquisition system; (2) The displacement device includes a pretreatment sand filling pipe and a test sand filling pipe connected in sequence; the injection end of the pretreatment sand filling pipe is connected to intermediate container I and intermediate container II, and the extraction end of the test sand filling pipe is connected to a liquid collection device. Both ends of the pre-treated sand-filling pipe and the test sand-filling pipe are connected to a pressure acquisition system; The testing method includes the following steps: S1. Add the heavy oil to the intermediate container I, add the water / emulsified viscosity reducer solution to the intermediate container II, and heat to the emulsification temperature; S2. Open the injection end and production end of the pretreated core or the pretreated sand-filled pipe, close the injection end and production end of the test core or the test sand-filled pipe, and simultaneously inject the heavy oil and the water / emulsion viscosity reducer solution into the pretreated core or the pretreated sand-filled pipe. S3. After the pressure at both ends of the pretreated core or the pretreated sand-filled pipe stabilizes, open the injection end and the production end of the test core or the test sand-filled pipe until the pressure at both ends of the test core or the test sand-filled pipe stabilizes. Record the total injection rate of the heavy oil and the water / emulsified viscosity reducer solution, the pressure difference at both ends of the test core or the test sand-filled pipe, and the oil-water volume ratio. The reservoir dynamic viscosity of the heavy oil emulsion is obtained from the seepage dynamics equation shown below. In the formula, Q represents the total injection rate of heavy oil and water / emulsion viscosity reducer solution, ml / min; k represents the permeability of the test core or test sand-filled pipe, mD; L represents the length of the test core or test sand-filled pipe, cm; and A represents the seepage area, cm². 2 ; △P represents the pressure difference between the two ends of the test core or the test sand-filled pipe, MPa; μ represents the reservoir dynamic viscosity of the heavy oil emulsion, mPa·s.

2. The test method according to claim 1, characterized in that: The pretreated core or the pretreated sand-filled pipe, the test core or the test sand-filled pipe, the intermediate container I and the intermediate container II are placed in a constant temperature chamber.

3. The test method according to claim 2, characterized in that: In step S1, the temperature of the constant temperature chamber is controlled to be 25~100℃.

4. The test method according to any one of claims 1-3, characterized in that: The pretreated core or the test core has a diameter of 2-5 cm, a length of 2.5-10 cm, and a permeability of 0.1-200 mD. The pretreated sand-filled pipe or the test sand-filled pipe has a diameter of 2-5 cm, a length of 10-50 cm, and a permeability of 200-10000 mD.

5. The test method according to claim 4, characterized in that: When the viscosity of the heavy oil is 50~200 mPa·s, the length of the pretreated core is 2.5~10 cm and the permeability is 0.1~200 mD; When the viscosity of the heavy oil is 200~400 mPa·s, the length of the pre-treated sand-filled pipe is 10~50 cm, and the permeability is 200~500 mD; When the viscosity of the heavy oil is 400~1000 mPa·s, the length of the pre-treated sand-filled pipe is 10~50 cm and the permeability is 500~1000 mD; When the viscosity of the heavy oil is 1000~5000 mPa·s, the length of the pre-treated sand-filled pipe is 20~50 cm, and the permeability is 1000~5000 mD; When the viscosity of the heavy oil is 5000~10000 mPa·s, the length of the pre-treated sand-filled pipe is 30~50 cm and the permeability is 5000~10000 mD.

6. The test method according to any one of claims 1-3, characterized in that: The injection rate of both the heavy oil and the water / emulsified viscosity reducer solution is 0.1~10 ml / min.

7. The test method according to any one of claims 1-3, characterized in that: The volume ratio of the heavy oil to the water / emulsified viscosity reducer solution is 1~9:1~9.

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