Measuring device and method for measuring rheological property change of oil displacement foam system in oil reservoir

Abstract

The invention relates to a measuring device and method for measuring rheological property change of an oil displacement foam system in an oil reservoir, and the measuring device comprises a foam generator and a metal pipe; the foam outlet end of the foam generator is connected with the inlet end of the metal pipe in an on-off mode, and the metal pipe is formed by sequentially connecting at least two equal-diameter pipe bodies in series. The inner diameters of at least two sections of equal-diameter pipe bodies are different, each section of equal-diameter pipe body is a hollow pipe, or at least one section of equal-diameter pipe body is filled with equal-diameter particles; or the inner diameters of all the sections of equal-diameter pipe bodies are the same, and at least one section of equal-diameter pipe body is filled with equal-diameter particles. The device can be used for simulating the rheological property test of the oil displacement foam system in an oil reservoir in a long-distance migration environment from an injection well to a production well, the rheological property of the oil displacement foam system can be researched independently, the test efficiency is high, and the test error is small.

Description

Technical Field

[0001] The invention relates to the field of oil and gas development, and in particular to a measuring device and method for measuring rheological changes of an oil displacement foam system in an oil reservoir. Background Art

[0002] In the petroleum industry, foam flooding technology is widely used in oilfield exploitation. The oil flooding foam system is a composite system composed of gas, liquid and surfactant. The foam increases the displacement phase viscosity and flow resistance, increases the swept volume of the displacement fluid in the porous medium, and has good profile control capabilities. Combined with the advantages of surfactants in reducing oil / water interfacial tension and reducing the capillary resistance of oil droplets, the oil recovery rate can be significantly improved.

[0003] The oil displacement effect of the foam system is affected by its rheology. The rheology of the foam can affect its permeability and diffusivity in the reservoir, and thus affect the oil displacement effect. By testing the rheology of the foam system, we can guide the adjustment of the viscosity and stability of the foam system, improve its distribution uniformity in the reservoir, and thus improve the oil displacement effect.

[0004] Existing rheological measurement devices mainly focus on rheological measurement under normal temperature and pressure conditions, and there are few rheological test devices that can simulate the high temperature and high pressure conditions of oil reservoirs. In addition, due to the highly complex microstructure of porous media in oil reservoirs, the matrix, fracturing cracks, and natural cracks coexist in the oil reservoir. The flow of oil displacement foam system from injection wells to production wells in the oil reservoir involves foam migration, retention, aggregation, defoaming, regeneration and other processes. Existing high temperature and high pressure rheological test devices cannot simulate the actual flow state of foam in the oil reservoir, resulting in a large difference between the rheological test results and the field application effects. Summary of the invention

[0005] The purpose of the present invention is to provide a measuring device and method for determining the rheological changes of an oil recovery foam system in an oil reservoir, which can be used to simulate the rheological test of the oil recovery foam system in an environment of long-distance migration from an injection well to a production well in an oil reservoir, and is more conducive to the independent study of the rheological properties of the oil recovery foam system itself, with lower test efficiency and test error.

[0006] The purpose of the present invention can be achieved by adopting the following technical solutions:

[0007] The invention provides a measuring device for measuring rheological changes of an oil displacement foam system in an oil reservoir, comprising a foam generator and a metal tube; the foam outlet end of the foam generator can be connected to the inlet end of the metal tube in an on-off manner, and the metal tube is composed of at least two sections of equal-diameter tube bodies connected in series in sequence; the inner diameters of the at least two sections of the equal-diameter tube bodies are different, and each section of the equal-diameter tube body is a hollow tube, or at least one section of the equal-diameter tube body is filled with equal-diameter particles; or the inner diameters of the equal-diameter tube bodies are the same, and at least one section of the equal-diameter tube body is filled with equal-diameter particles.

[0008] In a preferred embodiment of the present invention, the measuring device further comprises a temperature-controlled base and a first foam collector; the outlet end of the metal tube is connected to the first foam collector via a corresponding pipeline, and the metal tube is arranged on the temperature-controlled base.

[0009] In a preferred embodiment of the present invention, the inner diameter of the equal-diameter tube body is 0.15-1.0 mm, and the length is 1.5-4 m; the metal tube is in a coiled shape, and the granular material is quartz sand.

[0010] In a preferred embodiment of the present invention, filter screens are provided at both ends of the equal-diameter tube filled with equal-diameter particles.

[0011] In a preferred embodiment of the present invention, pressure measuring points are provided at both ends of the metal tube and at the connection between two adjacent sections of equal-diameter tubes, and a corresponding pressure sensor is provided at each pressure measuring point; a flow sensor is connected to the outlet end of the metal tube; the measuring device also includes a data acquisition and processing system, which is electrically connected to the pressure sensor and the flow sensor.

[0012] In a preferred embodiment of the present invention, the foam outlet end can be connected to the inlet end of the metal pipe through a first pipeline, and can be connected to the second foam collector through a second pipeline; a visual observation cabin is connected in series to the second pipeline, and a camera is arranged outside the visual observation cabin, and the data acquisition and processing system is electrically connected to the camera.

[0013] In a preferred embodiment of the present invention, the measuring device also includes: a first intermediate container, which can be connected to the first inlet end of the foam generator in an on-off manner, and is used to transport foaming liquid into the foam generator; a second intermediate container, which can be connected to the second inlet end of the foam generator in an on-off manner, and is used to transport gas into the foam generator.

[0014] In a preferred embodiment of the present invention, the first intermediate container includes a first cylinder with a first piston provided therein, the first piston divides the interior of the first cylinder into a first upper chamber for containing foaming liquid and a first lower chamber for containing liquid; the first upper chamber is connected to the first inlet end through a first pipeline in a disconnectable manner, and the first lower chamber is connected to the first constant speed and constant pressure pump through a corresponding pipeline; the second intermediate container includes a second cylinder with a second piston provided therein, the second piston divides the interior of the second cylinder into a second upper chamber for containing gas and a second lower chamber for containing liquid; the second upper chamber is connected to the second inlet end through a second pipeline in a disconnectable manner, and the second lower chamber is connected to the second constant speed and constant pressure pump through a corresponding pipeline; the data acquisition and processing system is electrically connected to both the first constant speed and constant pressure pump and the second constant speed and constant pressure pump.

[0015] In a preferred embodiment of the present invention, the foam generator includes a main cylinder having a movable piston inside, the movable piston divides the interior of the main cylinder into an upper auxiliary chamber for holding liquid and a lower mixing chamber, the upper auxiliary chamber is connected to a third constant speed and constant pressure pump through a third pipeline, the first inlet end, the second inlet end and the foam outlet end are all connected to the lower mixing chamber, and an agitator is provided in the lower mixing chamber.

[0016] The present invention also provides a method for measuring the rheological change of the oil displacement foam system in the oil reservoir, comprising:

[0017] A foam generator is used to stir the test gas and the test foaming liquid to generate an oil displacement foam system;

[0018] Injecting the oil displacement foam system into the metal pipe; wherein the metal pipe is composed of at least two sections of equal-diameter pipe bodies connected in series in sequence; the inner diameters of at least two sections of equal-diameter pipe bodies are different, and each section of the equal-diameter pipe body is a hollow pipe, or at least one section of the equal-diameter pipe body is filled with equal-diameter particles; or, the inner diameters of each section of the equal-diameter pipe body are the same, and at least one section of the equal-diameter pipe body is filled with equal-diameter particles;

[0019] Adjust the injection speed of the oil displacement foam system, and detect the pressure data at both ends of each section of the equal-diameter pipe body and the flow data at the outlet end of the metal pipe at different injection speeds;

[0020] The shear rate and viscosity of the oil displacement foam system in each section of the equal-diameter pipe at each moment are obtained according to the pressure data, flow data and injection speed corresponding to the two ends of each section of the equal-diameter pipe.

[0021] As described above, the testing device and method of the present invention can be used to simulate the rheological test of the oil displacement foam system in the long-distance migration environment from the injection well to the production well in the oil reservoir. Each section of the equal-diameter tube body can provide a consistent flow space. During the flow of the foam oil displacement system in the equal-diameter tube body, it can be ensured that the rheological property is only related to the properties of the oil displacement foam system itself, which is more conducive to the separate study of the rheological property of the oil displacement foam system itself. Moreover, the inner diameters of each equal-diameter tube body can be the same or different, and each equal-diameter tube body can be a hollow tube, or at least part of the equal-diameter tube body can be filled with equal-diameter particles, which can be used to simulate the matrix and cracks of the oil reservoir; and thus the real flow state of the foam oil displacement system in the oil reservoir can be more realistically simulated. Through the different designs of the metal tube, the rheological test of the oil displacement foam system in the flow conditions of the reservoir matrix, crack to matrix, crack to matrix and then to crack can be simulated, and the foam viscosity under multiple shear rates can be tested at one time, which improves the test efficiency and has a smaller test error. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The following drawings are only intended to illustrate and explain the present invention, and are not intended to limit the scope of the present invention.

[0023] in:

[0024] Figure 1 : A schematic diagram of the structure of a measuring device for measuring rheological changes of an oil displacement foam system in an oil reservoir provided by the present invention.

[0025] Figure 2 : A schematic structural diagram of the metal tube provided by the present invention.

[0026] Figure 3 : Another structural schematic diagram of the metal tube provided by the present invention.

[0027] Figure 4 : Another structural schematic diagram of the metal tube provided by the present invention.

[0028] Figure 5 : Another structural schematic diagram of the metal tube provided by the present invention.

[0029] Figure 6 : is a schematic diagram of the shear rate-viscosity rheological curve of the oil displacement foam system obtained in the present invention.

[0030] Description of Figure Numbers:

[0031] 1. Foam generator; 11. Three-way pipe; 12. First pipeline; 121. First switch valve; 13. Second pipeline; 131. Second switch valve; 132. Visual observation cabin; 14. Second foam collector; 15. Moving piston; 16. Third pipeline; 161. Third valve; 17. Third constant speed and constant pressure pump; 18. Agitator; 19. Motor;

[0032] 2. Metal tube; 21. Equal diameter tube body; 211. Hollow tube; 22. Equal diameter particles; 23. Pressure measuring point; 231. Pressure sensor; 24. Flow sensor; 25. First foam collector;

[0033] 3. Temperature control base;

[0034] 4. Data acquisition and processing system;

[0035] 5. Camera;

[0036] 6. first intermediate container; 61. first piston; 62. first pipeline; 621. first valve; 63. first constant speed and constant pressure pump;

[0037] 7. Second intermediate container; 71. Second piston; 72. Second pipeline; 721. Second valve; 73. Second constant speed and constant pressure pump. DETAILED DESCRIPTION

[0038] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described with reference to the accompanying drawings.

[0039] like Figures 1 to 6 As shown, the present application provides a measuring device for determining the rheological change of an oil displacement foam system in an oil reservoir, comprising a foam generator 1 and a metal tube 2; the foam outlet end of the foam generator 1 can be connected to the inlet end of the metal tube 2 in an on-off manner, and the metal tube 2 is composed of at least two sections of equal-diameter tube bodies 21 connected in series in sequence; the inner diameters of at least two sections of equal-diameter tube bodies 21 are different, and each section of the equal-diameter tube body 21 is a hollow tube 211, or at least one section of the equal-diameter tube body 21 is filled with equal-diameter particles 22; or, the inner diameters of each section of the equal-diameter tube body 21 are the same, and at least one section of the equal-diameter tube body 21 is filled with equal-diameter particles 22.

[0040] Among them, the metal pipe 2 is composed of at least two sections of equal-diameter tubes 21 connected in series in sequence, the inner diameter of each section of the equal-diameter tube 21 is uniform, and the equal-diameter tube 21 is a single tube extending in a long strip shape. The equal-diameter tube 21 itself is a single tube with a uniform inner diameter, and there are no other complex pipelines such as bifurcations; when the sections of the equal-diameter tubes 21 are connected, there are no bifurcations or other complex connection methods at the joints; for a single section of the equal-diameter tube 21, it is a hollow tube 211 (that is, the interior is hollow and not filled with particles), or it is filled with equal-diameter particles 22 (that is, particles with uniform particle size) to ensure that the internal medium of the single section of the equal-diameter tube 21 is uniform; in this way, when the oil-displacing foam system generated by the foam generator 1 flows into each section of the equal-diameter tube 21 of the metal pipe 2 and flows out, when the foam flooding system flows in each section of the equal-diameter tube 21, the equal-diameter tube 21 can provide a consistent flow space for the foam flooding system.

[0041] It can be understood that the particle sizes of the equal-diameter particles 22 filled in different sections of the equal-diameter tube body 21 can be the same or different; but the particle sizes of the equal-diameter particles 22 inside each section of the equal-diameter tube body 21 are uniform and the same.

[0042] When the oil-displacing foam system flows in an actual oil reservoir, its rheological properties are related to the properties of the oil-displacing foam system itself on the one hand, and to the complexity of the pores and fractures of the oil reservoir itself on the other hand; the design of the metal tube 2 in the present application can provide a consistent flow space in each section of the equal-diameter tube body 21. If there is a change in rheological properties during the flow of the foam oil-displacing system in the equal-diameter tube body 21, it is caused by the change in the properties of the fluid itself.

[0043] The above metal tube 2 can be actually designed in the following ways:

[0044] (1) At least two sections of the equal-diameter tube body 21 have different inner diameters, and each section of the equal-diameter tube body 21 is a hollow tube 211;

[0045] (2) at least two sections of the equal-diameter tube body 21 have different inner diameters, and at least one section of the equal-diameter tube body 21 is filled with equal-diameter particles 22;

[0046] (3) The inner diameters of the various sections of the equal-diameter tube body 21 are the same, and at least one section of the equal-diameter tube body 21 is filled with equal-diameter particles 22 .

[0047] For actual oil reservoirs, which have highly complex microstructures, the migration channels of fluids in the oil reservoirs include two major forms: matrix and fracture. The matrix can be divided into two forms: void and throat according to the size of the pores. For the equal-diameter tube body 21 that is a hollow tube 211, it can be used to simulate the fracture migration channel of the oil reservoir; for the equal-diameter tube body 21 filled with equal-diameter particles 22, it can be used to simulate the matrix migration channel of the oil reservoir (including pore migration channel and throat migration channel). The specific number of equal-diameter tube bodies 21 and the order of connection can be determined according to actual test needs.

[0048] For example, Figure 2 In the embodiment, the metal tube 2 includes three sections of equal-diameter tube bodies 21 sequentially connected from its inlet end to its outlet end. The inner diameters of the three sections of equal-diameter tube bodies 21 are different and the inner diameters increase from the inlet end to the outlet end of the metal tube 2, which can simulate the flow of the oil displacement foam system under different fractures in the reservoir; Figure 3 In an optional example, the entire metal tube 2 is filled with particles 22 of equal diameter, which can simulate the flow of the matrix of the oil displacement foam system in the reservoir; Figure 4In the figure, the metal tube 2 includes two sections of equal-diameter tube bodies 21 connected in series from the inlet end to the outlet end thereof, the equal-diameter tube body 21 near the inlet end is a hollow tube 211, and the other equal-diameter tube body 21 is filled with equal-diameter particles 22, which can simulate the flow of the oil displacement foam system from the fracture to the matrix in the reservoir; Figure 5 In the figure, the metal tube 2 includes three sections of equal-diameter tube bodies 21 connected in series from its inlet end to the outlet end. The inner diameters of the three sections of equal-diameter tube bodies 21 are the same. The equal-diameter tube body 21 in the middle is filled with equal-diameter particles 22, which can simulate the flow of the oil displacement foam system from the fracture to the matrix and then to the fracture in the reservoir.

[0049] Therefore, the measuring device in this embodiment can be used to simulate the rheological test of the oil displacement foam system in the long-distance migration environment from the injection well to the production well in the oil reservoir (corresponding to the flow process of the foam oil displacement system from the inlet end to the outlet end of the metal tube 2). Each section of the equal-diameter tube body 21 can provide a consistent flow space. During the flow of the foam oil displacement system in the equal-diameter tube body 21, it can be ensured that the rheological property is only related to the properties of the oil displacement foam system itself, which is more conducive to the separate study of the rheological property of the oil displacement foam system itself. Moreover, the inner diameters of the equal-diameter tube bodies 21 can be the same or different. Each equal-diameter tube body 21 can be a hollow tube 211, or at least part of the equal-diameter tube body 21 can be filled with equal-diameter particles 22, which can be used to simulate the matrix and cracks of the oil reservoir; and thus the real flow state of the foam oil displacement system in the oil reservoir can be more realistically simulated. Through different designs of the metal tube 2, the rheological test of the oil displacement foam system in flow conditions such as reservoir matrix, fracture to matrix, fracture to matrix and then to fracture can be simulated. The foam viscosity at multiple shear rates can also be tested at one time, which improves the test efficiency and reduces the test error.

[0050] In a specific implementation, the above-mentioned measuring device also includes a temperature control base 3 and a first foam collector 25 ; the outlet end of the metal tube 2 is connected to the first foam collector 25 through a corresponding pipeline, and the metal tube 2 is arranged on the temperature control base 3 .

[0051] The metal tube 2 is generally placed horizontally on the temperature control base 3. The temperature control base 3 can set the temperature according to the experimental needs, heat the metal tube 2, maintain a constant temperature state, and better simulate the temperature of the actual oil reservoir. The metal tube 2 is preferably in a coiled shape to save more space. The above-mentioned equal-diameter particles 22 can be made of quartz sand or copper powder, etc., and quartz sand is more preferably used, which is closer to the actual underground oil reservoir and has low cost; the specific filling quartz sand particle size can be selected according to the particle size distribution of the reservoir rock of the test oil reservoir. The material of the metal tube 2 needs to be a pressure-resistant material. For example, in this embodiment, the metal tube 2 is a stainless steel tube.

[0052] The inner diameter of each section of the equal-diameter tube body 21 is preferably 0.15-1.0 mm, and the length is preferably 1.5-4 m; so that each section of the equal-diameter tube body 21 is formed into a slender tube, which is thin and long, and can ensure that the pressure difference at both ends of each section of the equal-diameter tube body 21 is larger, which is more conducive to pressure measurement and ensures that the measurement error is smaller. The specific inner diameter and length of each section of the equal-diameter tube body 21 are determined according to the experimental needs, for example Figure 2 The three sections of equal-diameter tube bodies 21 in the metal tube 2 shown in the figure have inner diameters of 0.15-0.3 mm, 0.5-0.7 mm and 0.8 mm-1.0 mm from the inlet end to the outlet end, respectively, and lengths of 1.5-2.0 m, 2.0-3.0 m and 3.0-4.0 m, respectively.

[0053] In practical applications, a filter screen is provided at both ends of the equal-diameter tube body 21 filled with equal-diameter particles 22. The aperture of the filter screen should be smaller than the particle size of the equal-diameter particles 22 in the equal-diameter tube body 21 to prevent the equal-diameter particles 22 in the equal-diameter tube body 21 from entering the adjacent tube body.

[0054] Furthermore, pressure measuring points 23 are provided at both ends of the metal tube 2 and at the connection between two adjacent sections of the equal-diameter tube body 21, and a corresponding pressure sensor 231 is provided at each pressure measuring point 23; a flow sensor 24 is connected to the outlet end of the metal tube 2; the measuring device also includes a data acquisition and processing system 4, which is electrically connected to the pressure sensor 231 and the flow sensor 24 to facilitate recording of the pressure and flow at both ends of the equal-diameter tube body 21.

[0055] The data acquisition and processing system 4 can collect the pressure data detected by each pressure sensor 231 and the flow data detected by the flow sensor 24, and can obtain the shear rate and viscosity of the oil displacement foam system in each section of the equal-diameter pipe body 21 at each moment according to the corresponding pressure data and flow data at both ends of each section of the equal-diameter pipe body 21 and the injection speed of the foam generator 1 into the metal pipe 2, so as to facilitate the experimenters to conduct relevant research on the properties of the oil displacement foam system.

[0056] Generally, for the convenience of processing and installation, a three-way joint is connected between two adjacent equal-diameter tubes 21, and both ends of the three-way joint are connected to the equal-diameter tubes 21 on both sides, and the other end of the three-way joint is used as a pressure measuring point 23 to connect the corresponding pressure sensor 231. By setting the pressure measuring points 23 at both ends of each equal-diameter tube 21, it is convenient to measure the foam viscosity at multiple shear rates at one time.

[0057] The above-mentioned foam generator 1 is mainly used to generate an oil-displacing foam system. In order to ensure that the foam generated by the foam generator 1 is stable before being injected into the metal tube 2, the foam outlet end can be connected to the inlet end of the metal tube 2 through the first pipeline 12, and can be connected to the second foam collector 14 through the second pipeline 13; a visual observation cabin 132 is connected in series on the second pipeline 13, and a camera 5 is arranged outside the visual observation cabin 132, and the data acquisition and processing system 4 is electrically connected to the camera 5 to facilitate real-time observation of the foam state.

[0058] Generally, for the convenience of connection, the foam outlet is connected to a three-way pipe 11 through a corresponding pipeline, and the other two interfaces of the three-way pipe 11 are respectively connected to the first pipeline 12 and the second pipeline 13. A first switch valve 121 is provided on the first pipeline 12; a second switch valve 131 and a visual observation cabin 132 are provided on the second pipeline 13, and the visual observation cabin 132 is provided near the second foam collector 14. The first foam collector 25 and the second foam collector 14 can be liquid collection bottles, for example, and the camera 5 can be a high-definition camera. The visual observation cabin 132 includes a cabin body, and an opening is provided on the middle side wall of the cabin body, and is sealed by aluminosilicate glass, and the internal image of the visual observation cabin 132 can be observed through the camera 5.

[0059] When in use, the oil displacement foam system generated by the foam generator 1 is introduced into the visual observation cabin 132 to observe the foaming state of the foam in real time. After the foam generation is stable, the oil displacement foam system is introduced into the metal pipe 2.

[0060] In order to facilitate the preparation of oil displacement foam system, the measuring device also includes:

[0061] A first intermediate container 6 is connected to the first inlet end of the foam generator 1 in an on-off manner and is used to transport the foaming liquid into the foam generator 1;

[0062] The second intermediate container 7 is connected to the second inlet end of the foam generator 1 in an on-off manner and is used for conveying gas into the foam generator 1 .

[0063] The oil displacement foam system is a composite system composed of gas, liquid and surfactant, and the foaming liquid here refers to a mixture of liquid and surfactant.

[0064] Specifically, the first intermediate container 6 includes a first cylinder with a first piston 61 inside, and the first piston 61 divides the interior of the first cylinder into a first upper chamber for containing foaming liquid and a first lower chamber for containing liquid; the first upper chamber is connected to the first inlet end through a first pipeline 62 in a disconnectable manner, and the first lower chamber is connected to the first constant speed and constant pressure pump 63 through a corresponding pipeline; the second intermediate container 7 includes a second cylinder with a second piston 71 inside, and the second piston 71 divides the interior of the second cylinder into a second upper chamber for containing gas and a second lower chamber for containing liquid; the second upper chamber is connected to the second inlet end through a second pipeline 72 in a disconnectable manner, and the second lower chamber is connected to the second constant speed and constant pressure pump 73 through a corresponding pipeline; the data acquisition and processing system 4 is electrically connected to the first constant speed and constant pressure pump 63 and the second constant speed and constant pressure pump 73.

[0065] The foam generator 1 includes a main cylinder with a movable piston 15 inside. The movable piston 15 divides the interior of the main cylinder into an upper auxiliary chamber for containing liquid and a lower mixing chamber. The upper auxiliary chamber is connected to a third constant speed and constant pressure pump 17 through a third pipeline 16. The first inlet end, the second inlet end and the foam outlet end are all connected to the lower mixing chamber, and an agitator 18 (such as a stirring paddle) is provided in the lower mixing chamber.

[0066] Reference Figure 1 , a first valve 621 is provided on the first pipeline 62, a second valve 721 is provided on the second pipeline 72, and a third valve 161 is provided on the third pipeline 16. The above-mentioned data acquisition and processing system 4 is electrically connected to the first switch valve 121, the second switch valve 131, the first valve 621, the second valve 721 and the third valve 161 to control the on and off of each place. The first intermediate container 6 and the second intermediate container 7 are both equipped with a piston in the middle, the upper part is the fluid to be injected, the lower part is liquid (such as distilled water) and connected to the pump, and the piston is squeezed by the distilled water by a constant speed and constant pressure pump to make the piston move upward, thereby transporting the fluid to be injected, and the metering injection amount can be more accurately controlled.

[0067] The foam generator 1 also includes a base connected to the bottom of the main cylinder, and a motor 19 is provided in the base. The motor 19 is connected to the agitator 18 and is used to drive the agitator 18 to rotate. The data acquisition and processing system 4 is connected to the motor 19 to control the action of the motor 19. The foam generator 1 also uses a piston in the middle, and the upper part of the piston is liquid (such as distilled water) and is connected to a constant speed and constant pressure pump, which can more accurately control the metering injection amount.

[0068] Furthermore, the present application also provides a method for measuring the rheological changes of an oil displacement foam system in an oil reservoir, comprising:

[0069] The test gas and the test foaming liquid are stirred by the foam generator 1 to generate an oil displacement foam system;

[0070] Inject the oil displacement foam system into the metal pipe 2; wherein the metal pipe 2 is composed of at least two sections of equal-diameter pipe bodies 21 connected in series in sequence; at least the two sections of equal-diameter pipe bodies 21 have different inner diameters, and each section of the equal-diameter pipe body 21 is a hollow pipe 211, or at least one section of the equal-diameter pipe body 21 is filled with equal-diameter particles 22; or, the inner diameters of the sections of the equal-diameter pipe body 21 are the same, and at least one section of the equal-diameter pipe body 21 is filled with equal-diameter particles 22;

[0071] Adjust the injection speed of the oil displacement foam system, and detect the pressure data at both ends of each section of the equal-diameter pipe body 21 and the flow data at the outlet end of the metal pipe 2 at different injection speeds;

[0072] According to the corresponding pressure data, flow data and injection speed at both ends of each section of the equal-diameter pipe body 21, the shear rate and viscosity of the oil displacement foam system in each section of the equal-diameter pipe body 21 at each moment can be obtained, and the rheological curve of the shear rate and viscosity can also be obtained.

[0073] The measurement method can specifically be measured using the above-mentioned measurement device, and has the same advantages as the measurement device, which will not be described in detail here.

[0074] Further, stirring the test gas and the test foaming liquid by using the foam generator 1 specifically includes:

[0075] The test gas and the test foaming liquid are injected into the foam generator 1 at the same time, and the injection speed of the test gas and the test foaming liquid is adjusted according to the test requirements so as to adjust the gas-liquid ratio.

[0076] Before the oil displacement foam system is injected into the metal pipe 2, the following steps are also included:

[0077] The oil displacement foam system is injected into the visual observation cabin 132, and the image in the visual observation cabin 132 is collected by the camera 5. The foaming state of the foam is observed in real time through the data acquisition and processing system 4. After the foam generation is stable, the foam is introduced into the metal pipe 2.

[0078] Furthermore, the viscosity and shear rate of the oil displacement foam system in the equal-diameter pipe body 21 at each time can be calculated by the following formula:

[0079] For the equal-diameter tube 21 filled with equal-diameter particles 22, the viscosity μ of the foam can be calculated by the following Darcy formula (1-1), and the shear rate γ of the foam can be calculated by the following formula (1-2):

[0080]

[0081] γ=d(Q / ΦA) / dr p (1-2)

[0082] Wherein, μ represents the viscosity of the foam; k represents the permeability of the corresponding equal-diameter tube 21, D; A represents the cross-sectional area of ​​the corresponding equal-diameter tube 21, cm 2 ; L represents the length of the corresponding equal-diameter tube 21, cm; Q represents the flow rate of the corresponding equal-diameter tube 21, cm 3 / s; △P represents the pressure difference between the two ends of the corresponding equal-diameter tube 21, MPa;

[0083] γ represents the shear rate of the foam; φ represents the porosity of the equal-diameter particles 22 filled in the corresponding equal-diameter tube 21, %; r p It represents the average pore radius of the equal-diameter particles 22 filled in the corresponding equal-diameter tube 21, cm.

[0084] For the equal-diameter tube body 21 which is a hollow tube 211, the viscosity μ of the foam can be calculated by the following formula (2-1), and the shear rate γ of the foam can be calculated by the following formula (2-2):

[0085] μ=Kγ n-1 (2-1)

[0086]

[0087] n=dlg(DΔP / 4L) / dlg(8u / D) (3-1)

[0088] u=4Q / πD 2 (3-2)

[0089]

[0090] Wherein, μ represents the viscosity of the foam; γ represents the shear rate of the foam; n represents the rheological index, which can be calculated by the above formula (3-1); u represents the flow rate, which can be calculated by the above formula (3-2); K represents the consistency coefficient, which can be calculated by the above formula (3-3); Q represents the flow rate of the corresponding equal-diameter pipe 21, cm 3 / s; r represents the radius of the corresponding equal-diameter tube 21; D represents the diameter of the corresponding equal-diameter tube 21; ΔP represents the pressure difference between the two ends of the corresponding equal-diameter tube 21, MPa; L represents the length of the corresponding equal-diameter tube 21, cm; K' represents the intercept of the relationship curve between DΔP / 4L and 8u / D on the ordinate axis in the double logarithmic coordinate system.

[0091] It should be noted that the flow rate Q of the above-mentioned corresponding equal-diameter pipe body 21 is generally based on the flow rate data detected by the flow sensor 24 connected to the outlet end of the metal pipe 2. Since there are both gas and liquid level in the oil displacement foam system, for liquid, the flow rate at various locations in the pipe is the same, but for gas, due to the compressibility of gas, when the pressure at various locations in the pipe is different, the flow rate will also vary slightly. Therefore, during actual calculation, Boyle's law can also be used to correct the flow rate data detected by the flow sensor 24, and the corrected value obtained is used as the flow rate Q of the corresponding equal-diameter pipe body 21.

[0092] In order to better understand the measurement method of this embodiment, a specific embodiment is used as an example below. The measurement method includes:

[0093] Step 1: Connect the measuring device and check the sealing of the measuring device, open the temperature control base 3 and the data acquisition and processing system 4, and perform debugging and calibration. Set the temperature of the temperature control base 3 to the test temperature and keep the temperature constant for more than 30 minutes.

[0094] Step 2: Inject the foaming liquid into the first intermediate container 6 and the gas into the second intermediate container 7. Start the agitator 18 in the foam generator 1, and after the speed stabilizes, start the first constant speed and constant pressure pump 63 and the second constant speed and constant pressure pump 73, open the first valve 621 and the second valve 721 to inject the gas and the foaming liquid into the foam generator 1 at the same time, and according to the test needs, control the injection speed of the gas and the foaming liquid by adjusting the pump speed of the first constant speed and constant pressure pump 63 and the second constant speed and constant pressure pump 73, and then adjust the gas-liquid ratio.

[0095] Step 3: Start the third constant speed constant pressure pump 17, open the third valve 161 and the second switch valve 131, close the first switch valve 121, and introduce the foam liquid into the visual observation cabin 132 by controlling the height of the piston in the foam generator 1. Through the data acquisition and processing system 4, observe the foaming state of the foam in real time. After the foam generation is stable, close the second switch valve 131, open the first switch valve 121, and introduce the foam into the metal pipe 2;

[0096] Step 4: by adjusting the pump speed of the third constant speed and constant pressure pump 17, the foam injection speed is adjusted, and the pressure at both ends of each section of the equal diameter tube body 21 in the metal tube 2 and the flow rate at the outlet end of the metal tube 2 are measured at different foam injection speeds;

[0097] Step 5: According to the injection speed, flow data and the corresponding pressure data at both ends of each section of the equal-diameter tube body 21, the shear rate γ and viscosity μ of the oil displacement foam system in each section of the equal-diameter tube body 21 at each time are calculated, and the shear rate-viscosity rheological curve of the oil displacement foam system in each section of the equal-diameter tube body 21 is drawn.

[0098] For example, the above-mentioned measuring device was used to measure the rheological properties of the oil displacement foam system YFG812 used in an oil field. The gas was nitrogen, the gas-liquid ratio was 2:1, and the test temperature simulated the reservoir temperature of 45°C. Figure 4 The metal tube 2 simulating crack-to-matrix flow is subjected to rheological test, and the rheological curve obtained by the test is shown in FIG. Figure 6 shown.

[0099] In summary, the testing device and method in this embodiment is a measurement method and device that can simulate the rheological changes of the oil recovery foam system during migration from the injection well to the recovery well in the oil reservoir. By adjusting the diameter of the equal-diameter tube body 21 in different sections in the metal tube 2 and the change of the sand filling particle size, the changes of pores, throats and cracks in the reservoir can be simulated; the foam properties under multiple shear rates can be tested at one time (by adjusting the inner diameter of the metal tube 2); the rheological test of the oil recovery foam system under different reservoir temperatures and pressures can be simulated; the rheological test of foam generated by different gases and foaming liquids can be simulated; the foam viscosity under multiple shear rates can be tested at one time to improve the test efficiency; the rheological test of the oil recovery foam system under the long-distance migration environment from the injection well to the recovery well can be simulated; the rheological test of the oil recovery foam system under the flow conditions of reservoir matrix, crack to matrix, crack to matrix and then to crack can be simulated.

[0100] It should be noted that the testing device and method in this embodiment can be applied to any oil displacement foam system, such as a carbon dioxide foam system, a nitrogen foam system or an air foam system.

[0101] The above are only exemplary embodiments of the present invention and are not intended to limit the scope of the present invention. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A measuring device for determining rheological changes of an oil displacement foam system in an oil reservoir, characterized in that: Includes a foam generator and a metal tube; The foam outlet end of the foam generator is connected to the inlet end of the metal pipe in an on-off manner, and the metal pipe is composed of at least two sections of equal-diameter pipes connected in series in sequence; At least two sections of the equal-diameter tube body have different inner diameters, and each section of the equal-diameter tube body is a hollow tube, or at least one section of the equal-diameter tube body is filled with equal-diameter particles; or, the inner diameters of each section of the equal-diameter tube body are the same, and at least one section of the equal-diameter tube body is filled with equal-diameter particles.

2. The measuring device for measuring the rheological change of the oil displacement foam system in the oil reservoir as claimed in claim 1, characterized in that: The measuring device also includes a temperature control base and a first foam collector; The outlet end of the metal tube is connected to the first foam collector through a corresponding pipeline, and the metal tube is arranged on the temperature control base.

3. The measuring device for measuring the rheological change of the oil displacement foam system in the oil reservoir as claimed in claim 1, characterized in that: The inner diameter of the equal-diameter tube body is 0.15-1.0 mm, and the length is 1.5-4 m; the metal tube is in a coiled shape, and the granular material is quartz sand.

4. The measuring device for measuring the rheological change of the oil displacement foam system in the oil reservoir as claimed in claim 1, characterized in that: Filter screens are arranged at both ends of the equal-diameter tube body filled with the equal-diameter particles.

5. The measuring device for measuring rheological changes of oil displacement foam system in oil reservoir as claimed in claim 1, characterized in that: Pressure measuring points are provided at both ends of the metal tube and at the connection between two adjacent equal-diameter tubes, and corresponding pressure sensors are provided at each of the pressure measuring points; a flow sensor is connected to the outlet end of the metal tube; The measuring device further comprises a data acquisition and processing system, and the data acquisition and processing system is electrically connected to both the pressure sensor and the flow sensor.

6. The measuring device for measuring the rheological change of the oil displacement foam system in the oil reservoir as claimed in claim 5, characterized in that: The foam outlet end is connected to the inlet end of the metal pipe through a first pipeline in an on-off manner, and is connected to the second foam collector through a second pipeline in an on-off manner; a visual observation cabin is connected in series to the second pipeline, and a camera is arranged outside the visual observation cabin, and the data acquisition and processing system is electrically connected to the camera.

7. The measuring device for measuring the rheological change of the oil displacement foam system in the oil reservoir as claimed in claim 6, characterized in that: The measuring device also includes: a first intermediate container, connected to the first inlet end of the foam generator in an on-off manner and used for conveying foaming liquid into the foam generator; The second intermediate container is connected to the second inlet end of the foam generator in an on-off manner and is used to transport gas into the foam generator.

8. The measuring device for measuring the rheological change of the oil displacement foam system in the oil reservoir as claimed in claim 7, characterized in that: The first intermediate container comprises a first cylinder with a first piston disposed therein, the first piston divides the interior of the first cylinder into a first upper chamber for containing foaming liquid and a first lower chamber for containing liquid; the first upper chamber is connected to the first inlet end through a first pipeline in an on-off manner, and the first lower chamber is connected to a first constant speed and constant pressure pump through a corresponding pipeline; The second intermediate container comprises a second cylinder with a second piston inside, the second piston divides the inside of the second cylinder into a second upper chamber for containing gas and a second lower chamber for containing liquid; the second upper chamber is connected to the second inlet end through a second pipeline in an on-off manner, and the second lower chamber is connected to a second constant speed and constant pressure pump through a corresponding pipeline; The data acquisition and processing system is electrically connected to both the first constant speed and constant pressure pump and the second constant speed and constant pressure pump.

9. The measuring device for measuring the rheological change of the oil displacement foam system in the oil reservoir as claimed in claim 7, characterized in that: The foam generator includes a main cylinder with a movable piston inside, the movable piston divides the interior of the main cylinder into an upper auxiliary chamber for containing liquid and a lower mixing chamber, the upper auxiliary chamber is connected to a third constant speed and constant pressure pump through a third pipeline, the first inlet end, the second inlet end and the foam outlet end are all connected to the lower mixing chamber, and an agitator is provided in the lower mixing chamber.

10. A method for measuring the rheological changes of an oil displacement foam system in an oil reservoir, characterized in that: include: A foam generator is used to stir the test gas and the test foaming liquid to generate an oil displacement foam system; Injecting the oil displacement foam system into a metal pipe; wherein the metal pipe is composed of at least two sections of equal-diameter pipes connected in series in sequence; at least two sections of the equal-diameter pipes have different inner diameters, and each section of the equal-diameter pipes is a hollow pipe, or at least one section of the equal-diameter pipe is filled with equal-diameter particles; or, each section of the equal-diameter pipe has the same inner diameter, and at least one section of the equal-diameter pipe is filled with equal-diameter particles; Adjusting the injection speed of the oil displacement foam system, detecting the pressure data at both ends of each section of the equal-diameter pipe body and the flow data at the outlet end of the metal pipe at different injection speeds; The shear rate and viscosity of the oil displacement foam system in each section of the equal-diameter pipe body at each moment are obtained according to the pressure data corresponding to the two ends of each section of the equal-diameter pipe body, the flow data and the injection speed.

Images