Method and apparatus for mixing an emulsified oil displacement agent with crude oil

Abstract

The application discloses a method and device for mixing an emulsified oil displacement agent and crude oil, wherein the device comprises a pressure collection system, first and second constant-speed constant-pressure pumps, first and second intermediate containers, an injection end valve, a four-way valve, a container with porous medium, a three-way valve, a production end valve, a thermostat and a liquid collection system; the first and second constant-speed constant-pressure pumps are connected with the first and second intermediate containers respectively to provide pumping power; four interfaces of the four-way valve are connected with the first and second intermediate containers, the pressure collection system and the injection end valve respectively; an injection end of the container with porous medium is connected with the injection end valve; three interfaces of the three-way valve are connected with a production end of the container with porous medium, the production end valve and the pressure collection system respectively; the liquid collection system is connected with the production end valve; and the container with porous medium is arranged in the thermostat. The application enriches the preparation method of crude oil emulsion, and more truly simulates the seepage conditions of the emulsified oil displacement agent in emulsifying crude oil in a porous medium of an oil reservoir.

Description

Technical Field

[0001] This invention relates to the field of emulsified flooding technology in oilfield development, specifically to a method and apparatus for mixing an emulsified flooding agent and crude oil. Background Technology

[0002] Petroleum is crucial to national economic development and national security. How to efficiently develop petroleum is a key research focus for oilfields and scholars. Due to the strong adhesion of rock wettability and crude oil viscosity to reservoir pore surfaces, conventional waterflooding development results in low recovery rates. Emulsion flooding, due to its ability to significantly alter rock wettability and the properties of emulsified crude oil, has become an important method for enhancing oil recovery.

[0003] In laboratory evaluation of emulsified displacement agents, existing techniques typically involve mixing the emulsified displacement agent and crude oil in a specific ratio, followed by dispersion of the crude oil in the emulsified displacement agent through methods such as stirring, emulsification, or ultrasonic emulsification, thus preparing a crude oil emulsion. This emulsion is then used for subsequent evaluation. This preparation method obtains the crude oil emulsion under laboratory container conditions. However, this method is completely divorced from actual reservoir conditions. In actual reservoirs, the site where the emulsified displacement agent forms an emulsion with crude oil is the porous reservoir medium. Furthermore, the temperature, flow conditions, seepage dynamics, adhesion of crude oil to the porous medium surface, and the diffusion and adsorption losses of the emulsified displacement agent on the rock and mineral surfaces all significantly affect the state of the emulsion formed by the emulsified displacement agent and crude oil. Existing techniques for emulsion preparation completely ignore these factors, compromising the accuracy of subsequent emulsified displacement agent evaluations.

[0004] Therefore, it is necessary to develop a new method for mixing emulsified displacement agents and crude oil to solve the above problems. Summary of the Invention

[0005] To address the aforementioned technical problems in the existing technology, this invention provides a method and apparatus for mixing emulsified oil displacement agent and crude oil. This method solves the technical problem that the current indoor methods for preparing crude oil emulsions are severely out of sync with the actual seepage conditions of oil reservoirs, that is, it can accurately reflect the mixing state of emulsified oil displacement agent and crude oil under actual reservoir conditions.

[0006] To achieve the above objectives, the present invention provides a method for mixing an emulsified oil displacement agent and crude oil, wherein an emulsified oil displacement agent and crude oil are mixed and flowed in a porous medium under simulated reservoir seepage conditions to obtain a crude oil emulsion.

[0007] As a further preferred technical solution of the present invention, a crude oil emulsion is prepared by co-flushing an emulsifying oil displacement agent and crude oil in a porous medium, specifically including the following steps:

[0008] The emulsified oil displacement agent and crude oil are placed in the first intermediate container and the second intermediate container, respectively. A container with a porous medium is selected. Both the first intermediate container and the second intermediate container are connected to the injection end of the tubular container with the porous medium.

[0009] The tubular container with porous media is heated to a preset emulsification temperature. Then, the injection end and the extraction end of the tubular container with porous media are opened. The injection rates of the emulsified oil displacement agent and crude oil are set according to the preset ratio of emulsified oil displacement agent and crude oil. The emulsified oil displacement agent and crude oil are injected into the tubular container with porous media at the same time.

[0010] After the pressure at the injection and extraction ends of the tubular container with porous media stabilizes, the extracted fluid is collected through a fluid receiving device. The collected extracted fluid is the prepared crude oil emulsion.

[0011] As a further preferred technical solution of the present invention, the tubular container with porous medium is a core holder or a sand-filling pipe.

[0012] As a further preferred embodiment of the present invention, the preset emulsification temperature is 25-100°C.

[0013] As a further preferred technical solution of the present invention, a constant temperature chamber is used to heat the tubular container with porous medium.

[0014] As a further preferred technical solution of the present invention, the preset ratio of the emulsified oil displacement agent to crude oil is 2-8:2-8.

[0015] As a further preferred embodiment of the present invention, the injection rate of the emulsified oil displacement agent and crude oil into the container with a porous medium is 0.1 to 10 ml / min.

[0016] As a further preferred embodiment of the present invention, the emulsified oil displacement agent is a surfactant, a polymeric surfactant, or an active nanofluid, and the crude oil is crude oil produced from the formation.

[0017] The present invention also provides an apparatus for a method of mixing an emulsified oil displacement agent and crude oil, comprising: a pressure acquisition system, a first constant-speed and constant-pressure pump, a second constant-speed and constant-pressure pump, a first intermediate container, a second intermediate container, an injection end valve, a four-way valve, a container with porous media, a three-way valve, a production end valve, a constant temperature chamber, and a liquid acquisition system. The first and second constant-speed and constant-pressure pumps are respectively connected to the first and second intermediate containers to provide pumping power. The four ports of the four-way valve are respectively connected to the first intermediate container, the second intermediate container, the pressure acquisition system, and the injection end valve. The injection end of the container with porous media is connected to the injection end valve. The three ports of the three-way valve are respectively connected to the production end of the container with porous media, the production end valve, and the pressure acquisition system. The liquid acquisition system is connected to the production end valve. The container with porous media is a core holder or a sand-filled pipe and is disposed within the constant temperature chamber.

[0018] The present invention provides a method and apparatus for mixing emulsified displacement agents and crude oil. By employing the above-mentioned technical solution, it overcomes the shortcomings of previous methods for preparing crude oil emulsions using mechanical stirring and ultrasonic methods, which require a static environment and separation from reservoir seepage conditions. The properties of crude oil emulsions obtained by conventional preparation methods are greatly affected by the emulsification method, stirring method, and stirring time, failing to accurately reflect the mixing state of the emulsified displacement agent and crude oil. The present invention, by simulating the pore environment and seepage state of the emulsified displacement agent and crude oil flowing in the reservoir, provides more realistic mixing conditions. The emulsion prepared by the method of the present invention is more uniform and has better stability. This invention not only enriches the methods for preparing crude oil emulsions but also more realistically simulates the seepage conditions of emulsified crude oil in the porous media of the reservoir.

[0019] In addition, this method solves the problem that current indoor methods for preparing crude oil emulsions are seriously out of sync with actual reservoir seepage conditions, meaning it can accurately reflect the mixing state of emulsified oil displacement agents and crude oil under actual reservoir conditions. Attached Figure Description

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0021] Figure 1 This is a schematic diagram of the apparatus for performing the mixing method of emulsified oil displacement agent and crude oil in Examples 1 and 2 of the present invention;

[0022] Figure 2 The bar chart shows the average particle size of crude oil emulsions obtained in Example 1 of this invention and by conventional stirring, and the relationship between the ratio of emulsifying displacement agent to crude oil at different proportions.

[0023] Figure 3 The images show the microstructure of crude oil emulsions obtained in Example 1 of this invention and by conventional stirring, with an oil-to-agent ratio of 5:5.

[0024] Figure 4 The graphs shown are the relationship between the dehydration rate and the standing time of crude oil emulsions obtained by conventional stirring in Example 1 of this invention, with an oil-to-agent ratio of 5:5.

[0025] Figure 5 The bar chart shows the average particle size of the crude oil emulsions obtained in Example 2 of this invention and the ratio of different proportions of emulsifying displacement agent to crude oil.

[0026] In the diagram: 1. Pressure acquisition system; 2. First constant speed and constant pressure pump; 3. Second constant speed and constant pressure pump; 4. First intermediate container; 5. Second intermediate container; 6. Four-way valve; 7. Injection end valve; 10. Outlet end valve; 8. Container with porous media; 9. Three-way valve; 11. Thermostatic chamber; 12. Liquid acquisition system.

[0027] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0028] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0029] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0030] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0031] The water used in the following examples is simulated formation water with a mineralization of 5000 mg / L.

[0032] Example 1

[0033] The method for mixing emulsified displacement agent and crude oil proposed in this invention employs, as follows: Figure 1The apparatus shown is for a method of mixing emulsified oil displacement agent and crude oil. The preparation equipment includes: a pressure acquisition system 1, a first constant-speed and constant-pressure pump 2, a second constant-speed and constant-pressure pump 33, a first intermediate container 4, a second intermediate container 5, an injection valve 7, a four-way valve 6, a container 8 with porous media, a three-way valve 9, a production valve 10, a constant temperature chamber 11, and a liquid acquisition system 12. The first constant-speed and constant-pressure pump 2 and the second constant-speed and constant-pressure pump 33 are respectively connected to the first intermediate container 4 and the second intermediate container 5 to provide pumping power. The four ports of the four-way valve 6 are respectively connected to the first intermediate container 4, the second intermediate container 5, the pressure acquisition system 1, and the injection valve 7. The injection end of the container 8 with porous media is connected to the injection valve 7. The three ports of the three-way valve 9 are respectively connected to the production end of the container 8 with porous media, the production valve 10, and the pressure acquisition system 1. The liquid acquisition system 12 is connected to the production valve 10. The container 8 with porous media is a sand-filled pipe and is placed inside the constant temperature chamber 11.

[0034] The method for mixing emulsifying displacement agent and crude oil using the crude oil emulsion preparation equipment described above specifically includes the following steps:

[0035] (1) Prepare 100ml of dehydrated crude oil (60℃) with a viscosity of 765.3mPa·s and place it in the first intermediate container 4;

[0036] (2) Prepare 100 ml of commercially available 0.5% emulsified oil displacement agent sodium dodecyl sulfate (SDS) aqueous solution and place it in the second intermediate container 5.

[0037] (3) Open the constant temperature chamber 11 and set the temperature to 60℃;

[0038] (4) Open the pressure acquisition system 1, and open the injection end valve 7 and the extraction end valve 10 of the sand filling pipe (permeability of 1000mD and length of 50cm);

[0039] (5) With the total injection rate of emulsified oil displacement agent and crude oil at 0.5 ml / min, the injection rates of emulsified oil displacement agent and crude oil are set according to the preset oil-to-oil ratio (volume ratio of emulsified oil displacement agent and crude oil).

[0040] (6) After the pressure stabilizes, the extracted fluid is collected using the liquid collection system 12, which is the prepared crude oil emulsion.

[0041] In the above steps of Example 1, according to the preset oil-to-liquid ratios in step (5) of 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, and 8:2, different crude oil emulsions were collected in step (6), and their average particle size was tested using a laser particle size analyzer. Figure 2 As shown; the microscopic state during observation was observed using an electron microscope, such as Figure 3As shown; the relationship curve between the dehydration rate of crude oil emulsion and the settling time was tested using the stratification method, as shown in the figure. Figure 4 As shown.

[0042] Comparative Example 1

[0043] The existing method for mixing emulsified displacement agent and crude oil is as follows: Using a total volume of 20 ml of emulsified displacement agent (SDS) solution and crude oil, the emulsified displacement agent and crude oil are measured and placed in a 50 ml beaker according to oil-to-agent ratios (volume ratio of emulsified displacement agent to crude oil) of 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, and 8:2. The mixture is stirred at 400 rpm for 20 minutes in a water bath at 60°C. The resulting emulsion is the crude oil emulsion prepared under conventional stirring conditions (each oil-to-agent ratio corresponds to one type of crude oil emulsion).

[0044] The sample of Comparative Example 1 was tested using the same test method as in Example 1, and the test results are as follows: Figure 2-4 As shown in the comparison, although the particle size of the crude oil emulsions formed in Example 1 and Comparative Example 1 both increased with the increase of the oil-to-liquid ratio, the magnitude of the increase differed. When the oil-to-liquid ratio was below 6:4, the average particle size of the crude oil emulsion prepared by the conventional method was larger than that of the emulsion prepared by the present invention. However, when the oil-to-liquid ratio was above 6:4, the average particle size of the crude oil emulsion prepared by the conventional method was smaller than that of the emulsion prepared by the present invention. This is mainly due to the diffusion and adsorption losses of the emulsifying oil displacement agent in the rock pores. Under low oil-to-liquid ratio conditions, the diffusion, adsorption, and wetting ratio of the emulsifying oil displacement agent during flow is low, while the proportion used for emulsifying crude oil is high. Coupled with the strong shearing effect of the porous medium, this results in a smaller average particle size of the emulsion and a more uniform emulsion state (see [reference]). Figure 3 The emulsion prepared in Example 1 has a uniform particle size, resulting in higher stability and a more uniform dehydration rate. In contrast, the emulsion prepared in Comparative Example 1 has a more dispersed particle size distribution, leading to rapid oil droplet aggregation under static conditions and thus poor stability. The emulsion dehydrates rapidly (see...). Figure 4 ).

[0045] Example 2

[0046] The method for mixing emulsified displacement agent and crude oil proposed in this invention employs, as follows: Figure 1The apparatus shown is for a method of mixing emulsified oil displacement agent and crude oil. The preparation equipment includes: a pressure acquisition system 1, a first constant speed and constant pressure pump 2, a second constant speed and constant pressure pump 33, a first intermediate container 4, a second intermediate container 5, an injection end valve 7, a four-way valve 6, a container 8 with porous media, a three-way valve 9, a production end valve 10, a constant temperature chamber 11, and a liquid acquisition system 12. The first constant speed and constant pressure pump 2 and the second constant speed and constant pressure pump 33 are respectively connected to the first intermediate container 4 and the second intermediate container 5 to provide pumping power. The four ports of the four-way valve 6 are respectively connected to the first intermediate container 4, the second intermediate container 5, the pressure acquisition system 1, and the injection end valve 7. The injection end of the container 8 with porous media is connected to the injection end valve 7. The three ports of the three-way valve 9 are respectively connected to the production end of the container 8 with porous media, the production end valve 10, and the pressure acquisition system 1. The liquid acquisition system 12 is connected to the production end valve 10. The container 8 with porous media is a core holder and is placed inside the constant temperature chamber 11.

[0047] The method for mixing emulsifying displacement agent and crude oil using the crude oil emulsion preparation equipment described above specifically includes the following steps:

[0048] (1) Prepare 100ml of dehydrated crude oil (60℃) with a viscosity of 765.3mPa·s and place it in the first intermediate container 4;

[0049] (2) Prepare 100 ml of commercially available 0.5% emulsified oil displacement agent octylphenol polyoxyethylene ether (OP-10) aqueous solution and place it in the second intermediate container 5.

[0050] (3) Open the constant temperature chamber 11 and set the temperature to 60℃;

[0051] (4) Open the pressure acquisition system 1, and open the injection end valve 7 and the extraction end valve 10 of the core holder (permeability of 1000mD and length of 50cm);

[0052] (5) With the total injection rate of emulsified oil displacement agent and crude oil at 0.5 ml / min, the injection rates of emulsified oil displacement agent and crude oil are set according to the preset oil-to-oil ratio (volume ratio of emulsified oil displacement agent and crude oil).

[0053] (6) After the pressure stabilizes, the extracted fluid is collected using the liquid collection system 12, which is the prepared crude oil emulsion.

[0054] In the above steps of Example 2, according to the preset oil-to-liquid ratios in step (5) of 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, and 8:2, different crude oil emulsions were collected in step (6), and their average particle size was tested using a laser particle size analyzer. Figure 5 As shown.

[0055] Comparative Example 2

[0056] The existing method for mixing emulsified displacement agent and crude oil is as follows: Using a total volume of 20 ml of emulsified displacement agent (OP-10) solution and crude oil, the emulsified displacement agent and crude oil are measured and placed in a 50 ml beaker according to oil-to-agent ratios (volume ratios) of 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, and 8:2. The mixture is stirred at 400 rpm for 20 minutes in a water bath at 60°C. The resulting emulsion is the crude oil emulsion prepared under conventional stirring conditions (each oil-to-agent ratio corresponds to one type of crude oil emulsion). The average particle size is measured using a laser particle size analyzer. Figure 5 As shown.

[0057] It can be seen that as the oil-to-agent ratio changes, Figure 5 The variation trends of average particle size of the emulsions prepared in Example 2 and Comparative Example 2 are similar to those in the following examples. Figure 2 Similar to those in the text.

[0058] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and various changes or modifications can be made to these embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is defined only by the appended claims.

Claims

1. A method for mixing an emulsified oil displacement agent and crude oil, characterized in that, Under simulated seepage conditions in porous media of an oil reservoir, an emulsified oil displacement agent and crude oil were mixed and flowed in a porous medium to prepare a crude oil emulsion. A crude oil emulsion is prepared by co-flushing an emulsifying agent and crude oil in a porous medium, specifically including the following steps: The emulsified oil displacement agent and crude oil are placed in the first intermediate container and the second intermediate container, respectively. A tubular container with a porous medium and a permeability of 1000mD is selected. Both the first intermediate container and the second intermediate container are connected to the injection end of the tubular container with the porous medium. The tubular container with porous media is heated to a preset emulsification temperature. Then, the injection end and the extraction end of the tubular container with porous media are opened. The injection rates of the emulsified oil displacement agent and crude oil are set according to the preset ratio of emulsified oil displacement agent and crude oil. The emulsified oil displacement agent and crude oil are injected into the tubular container with porous media at the same time. After the pressure at the injection and extraction ends of the tubular container with porous media stabilizes, the extracted fluid is collected through a fluid receiving device. The collected extracted fluid is the prepared crude oil emulsion.

2. The method for mixing emulsified displacement agent and crude oil according to claim 1, characterized in that, The tubular container with porous media is a core holder or a sand-filled pipe.

3. The method for mixing the emulsified displacement agent and crude oil according to claim 1, characterized in that, The preset emulsification temperature is 25~100℃.

4. The method for mixing the emulsified displacement agent and crude oil according to claim 1, characterized in that, The tubular container with porous media was heated using a constant temperature chamber.

5. The method for mixing the emulsified displacement agent and crude oil according to claim 1, characterized in that, The preset ratio of emulsified oil displacement agent to crude oil is 2~8:8~2.

6. The method for mixing the emulsified displacement agent and crude oil according to claim 1, characterized in that, The injection rate of the emulsified oil displacement agent and crude oil into the tubular container with porous media is 0.1~10 ml / min.

7. The method for mixing the emulsified displacement agent and crude oil according to any one of claims 1-6, characterized in that, The emulsifying oil displacement agent is a surfactant, polymeric surfactant, or active nanofluid, and the crude oil is crude oil produced from the formation.

8. An apparatus for performing the method of mixing the emulsified displacement agent and crude oil according to any one of claims 1 to 7, characterized in that, include: The system comprises a pressure acquisition system, a first constant-speed and constant-pressure pump, a second constant-speed and constant-pressure pump, a first intermediate container, a second intermediate container, an injection valve, a four-way valve, a tubular container with porous media, a three-way valve, a production valve, a constant-temperature chamber, and a liquid acquisition system. The first and second constant-speed and constant-pressure pumps are connected to the first and second intermediate containers respectively to provide pumping power. The four-way valve's four ports are connected to the first intermediate container, the second intermediate container, the pressure acquisition system, and the injection valve respectively. The injection end of the tubular container with porous media is connected to the injection valve. The three-way valve's three ports are connected to the production end of the tubular container with porous media, the production valve, and the pressure acquisition system respectively. The liquid acquisition system is connected to the production valve. The tubular container with porous media is a core holder or a sand-filled pipe and is housed within the constant-temperature chamber.

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