Annular shear rate instrument for oil-water two-phase flow and testing method

Abstract

The invention belongs to the technical field of shear rate instruments, and relates to an annulus shear rate instrument for oil-water two-phase flow and a testing method.The annulus shear rate instrument comprises an inner cylinder and an outer cylinder arranged on the inner cylinder in a sleeving mode, a detection gap exists between the inner cylinder and the outer cylinder, and the lower side of the outer cylinder extends to form a base; a liquid injection hole and an exhaust hole are formed in the upper side of the outer barrel, a liquid outlet hole is formed in the lower side of the outer barrel, rotating shafts extend from the two ends of the inner barrel, bearing support pieces are arranged on the rotating shafts, and the rotating shafts are coaxially connected with a driving device to drive the inner barrel to rotate. The device has the advantages that testing can be conducted through a simple instrument, and the testing structure is accurate.

Description

Technical Field

[0001] This invention relates to the technical field of shear rate instruments, and more particularly to an annular shear rate instrument and testing method for oil-water two-phase flow. Background Technology

[0002] Currently, as domestic oilfield development enters its mid-to-late stages, the water cut of produced fluids can reach as high as 80%–90%. At this point, the multiphase flow process in pipelines has changed significantly compared to the early stages of development. In the early stages of oilfield development, the water cut in produced fluids is low. Due to the presence of natural emulsifiers such as gums and asphaltenes, water-bearing crude oil easily forms stable water-in-oil emulsions during extraction and transportation. Numerous mature technologies and commercial instruments exist for measuring the rheological properties of such homogeneous fluids (including finely dispersed, stable oil-water emulsions). However, field surveys and experimental simulations have revealed that as oilfields enter the high water-cut stage, although the water cut in produced fluids is high, it does not directly transform from a relatively stable water-in-oil emulsion into a water-in-oil emulsion. Instead, it flows as an oil-water suspension system composed of free water and the water-in-oil emulsion. In engineering, this oil-water mixture is often treated as a homogeneous single-phase fluid when calculating pipeline flow friction and pressure drop. Therefore, mastering the testing method for the viscosity of high water-content oil-water mixtures is one of the key issues in calculating the friction of multiphase flow and even designing gathering and transportation pipelines.

[0003] Numerous researchers have experimentally determined the equivalent viscosity of oil-water mixtures, with the main methods including rotational viscometer method, loop method, and stirring method.

[0004] Traditional rotational viscometer methods are suitable for measuring the viscosity of homogeneous fluids, such as finely dispersed homogeneous liquids and stable oil-water emulsions. The main principle is to read the torque acting on the viscometer rotor, calculate the resistance of the fluid to the rotor based on its shape, and thus determine the fluid's viscosity.

[0005] Compared to the loop method, the main idea of ​​the loop method is to borrow from multiphase flow experiments, allowing an oil-water mixture to circulate in a simulated experimental loop to study the flow characteristics of multiphase fluids. Its main method involves calculating the equivalent viscosity of the mixture based on the pressure drop and flow rate of the mixture through the test pipe section, using Darcy's formula and the friction coefficient calculation formula. Clearly, the advantage of the loop method is that the flow conditions of the oil and water two phases under the test conditions most closely resemble actual pipe flow, and the obtained viscosity data can reflect the flow characteristics of the mixture in actual pipe flow with relatively high accuracy. Although the loop method can generate various flow patterns, the experimental setup is complex and difficult to operate, and the cost of a single experiment is high, requiring a large amount of oil. Therefore, it has not been widely used. Thus, its testing method should be improved to establish a simpler instrument for testing oil-water two-phase flow. Summary of the Invention

[0006] The purpose of this invention is to provide an annular shear rate meter and testing method for oil-water two-phase flow, so as to solve the technical problems of complex experimental equipment, difficult operation, high cost of a single experiment, and large oil consumption, and achieve the goal of conducting tests with simple instruments and accurate test structure.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: An annular shear rate meter for oil-water two-phase flow includes: An inner cylinder and an outer cylinder fitted on the inner cylinder, with a detection gap between the inner cylinder and the outer cylinder, and a base extending from the lower side of the outer cylinder; The outer cylinder has an injection hole and an exhaust hole on its upper side, and an outlet hole on its lower side. The inner cylinder has rotating shafts extending from both ends, and bearing supports are provided on the rotating shafts. A drive device is coaxially connected to the rotating shafts to drive the inner cylinder to rotate.

[0008] As a preferred embodiment of the present invention, the inner cylinder is hollow; The inner cylinder is equipped with sealing caps at both ends.

[0009] As a preferred embodiment of the present invention, in the rotating flow of the inner and outer cylinders, the formulas for the linear velocity and angular velocity of the flow field in the annular space at different diameters are as follows: (1) ; In the formula, R1 and R2 are the outer diameter of the inner cylinder and the inner diameter of the outer cylinder, respectively.

[0011] In a preferred embodiment of the present invention, the shear rate is defined as: .

[0012] In a preferred embodiment of the present invention, the shear rate is defined as: .

[0013] As a preferred embodiment of the present invention, the Reynolds number of the flow in the rotating flow of the inner and outer cylinders is calculated using the following formula: ; The average velocity of the flow is: ; The final formula for the Reynolds number is: .

[0014] As a preferred embodiment of the present invention, the inner diameter of the outer cylinder is 112mm, the outer diameter of the inner cylinder is 100mm, the annular space distance is 6mm, and the length of the outer cylinder is 500mm.

[0015] As a preferred embodiment of the present invention, the two ends of the outer cylinder are detachable to facilitate equipment cleaning.

[0016] Another object of the present invention is to provide a testing method for annular shear rate meter for oil-water two-phase flow. Includes the following steps: Step 1: Set the inner cylinder to pass through the outer cylinder; Step 2: Pour the test liquid into the injection port; Step 3: First, close the drain port and open the vent port. Then, inject liquid into the annulus through the injection port until it is full. Finally, close the injection port. Step 4: Start the drive unit.

[0017] The beneficial effects of this invention are: 1. Fluids exhibit different properties under different shear conditions, especially in the mixed flow conditions of two-phase and multiphase flows. Therefore, accurate shear flow field conditions are required. Since axial flow in a circular pipe is difficult to achieve at high speeds and can be tested in the flow field, rotating flow can be used instead. Annular flow can achieve a more uniform shear flow field. This application uses an inner and outer cylinder to form a shearing device, which not only has a simple overall structure but also achieves the purpose of accurate testing.

[0018] 2. This application creates a well-defined, uniform, and controllable annular shear flow field: The core of this invention lies in utilizing the annular structure formed by inner and outer cylinders to generate a nearly uniform shear flow field through the rotation of the inner cylinder. The velocity and shear rate distributions of this flow field have clearly defined mathematical formulas, overcoming the shortcomings of traditional stirring methods or the instability and difficulty in quantification of flow fields in complex pipe flows. This provides a reliable and reproducible experimental environment for accurately studying the rheological behavior of fluids (especially oil-water two-phase flows) under specific shear conditions.

[0019] 3. Achieves precise quantification and wide-range adjustment of key rheological parameters: Based on a clear flow field theory, the instrument can directly convert simple operating parameters (inner cylinder rotation speed n, annular geometry R1, R2, L) into key rheological parameters such as shear rate and shear stress experienced by the fluid micro-element. Combined with a continuously variable speed motor, users can easily adjust the shear rate from hundreds to over 1000 s within a wide range (as shown in the example). - ¹) Precise control of shear conditions enables a comprehensive characterization of the fluid's rheological properties.

[0020] 4. Compact structure, simple operation, and flexible sample volume requirements: Compared with traditional large and complex annular experimental devices, the device of this invention has a high degree of integration and a small footprint. Modular design (such as a detachable outer cylinder end cap) makes cleaning and maintenance extremely convenient. Furthermore, by changing the annular size (e.g., the three embodiments correspond to capacities of 70.7 mL, 998 mL, and 2512 mL respectively), it can flexibly adapt to different sample volume testing needs, satisfying both preliminary screening of small laboratory samples and conducting medium-volume tests that more closely resemble actual working conditions, significantly reducing experimental costs and material consumption.

[0021] 5. Clear flow regime criteria and high reliability of experimental data: This invention provides a formula for calculating the Reynolds number (Re) based on the characteristic size of the annulus and the average flow velocity (Formula (7)). This allows researchers to quantitatively determine the flow state (laminar or turbulent) of the fluid in the annulus, ensuring that the experiment is conducted under the required flow regime, thereby guaranteeing the accuracy and validity of the measured rheological data, and providing direct and reliable theoretical basis and data support for the design and process optimization of oilfield gathering and transportation pipelines.

[0022] 6. Highly targeted application, effectively addressing industry pain points: This invention is designed specifically to address the challenge of rheological measurement in oil-water two-phase flow (heterogeneous suspension system) during high water cut periods. It provides an efficient and compromise solution between a simple rotational viscometer (suitable for homogeneous fluids) and a complex loop device, filling a gap in existing technology for this specific application area and having significant practical implications for efficient oilfield development and the optimization of gathering and transportation processes. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the annular shear rate meter and testing method for oil-water two-phase flow according to the present invention; Figure 2 This is a schematic diagram of the Reynolds number values ​​in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the Reynolds number values ​​in Embodiment 2 of the present invention; Figure 4 This is a schematic diagram of the Reynolds number values ​​in Embodiment 3 of the present invention.

[0024] Legend: 1. Inner cylinder; 11. Rotating shaft; 12. Bearing support; 13. Drive unit; 14. Sealing cover; 2. Outer cylinder; 21. Injection port; 22. Vent port; 23. Outlet port; 3. Base. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1: like Figure 1 As shown, an annular shear rate meter for oil-water two-phase flow includes: an inner cylinder 1 and an outer cylinder 2 sleeved on the inner cylinder 1, with a detection gap between the inner cylinder 1 and the outer cylinder 2, and a base 3 extending from the lower side of the outer cylinder 2.

[0027] The outer cylinder 2 has an injection hole 21 and an exhaust hole 22 on its upper side, and an outlet hole 23 on its lower side. The inner cylinder 1 has a rotating shaft 11 extending from both ends. The rotating shaft 11 is equipped with a bearing support 12. The rotating shaft 11 is coaxially connected to a drive device 13 to drive the inner cylinder 1 to rotate.

[0028] In this embodiment, the inner cylinder 1 is hollow; sealing caps 14 are provided at both ends of the inner cylinder 1.

[0029] Among them, in the rotating flow of inner cylinder 1 and outer cylinder 2, the formulas for the linear velocity and angular velocity of the flow field in the annulus with different diameters are as follows: (1)

[0031] In the formula, R1 and R2 are the outer diameter of inner cylinder 1 and the inner diameter of outer cylinder 2, respectively.

[0032] The shear rate is defined as follows: .

[0033] In a preferred embodiment of the present invention, the shear rate is defined as: .

[0034] During circumferential cutting, the shear rate is 564-669S. -1 Average 614S -1 .

[0035] In the rotating flow within inner cylinder 1 and outer cylinder 2, the Reynolds number is calculated using the following formula: ; The average velocity of the flow is: ; The final formula for the Reynolds number is: .

[0036] In this embodiment, the inner diameter of the outer cylinder 2 is 112mm, the outer diameter of the inner cylinder 1 is 100mm, and the annular space distance is 6mm. The length of the outer cylinder 2 is 500mm. Both the inner cylinder 1 and the outer cylinder 2 are made of 316 stainless steel with a thickness of 5-15mm. The volume of the experimental annular cavity is 998ml. In this embodiment, both ends of the outer cylinder 2 are detachable for easy cleaning of the equipment.

[0037] The inner cylinder 1 passes through the outer cylinder 2 and is sealed at the end by an oil seal. The two ends of the inner cylinder 1 rotate on the bearing support 12 via the rotating shaft 11. At the same time, the rotating shaft 11 is driven to rotate by the driving device 13. In this embodiment, the driving device 13 is, but is not limited to, a 220V AC motor with a power of not less than 1KW and a maximum speed of 3000 rpm. During the experiment, the inner cylinder 1 rotates stably with the motor, and the speed of the motor can be infinitely adjusted by a frequency converter.

[0038] In this embodiment, the rotational speed of the drive device 13 is 1000 rpm. The shear rate distribution is calculated as follows: shear rate ranges from 823 to 1033, with an average of 922 s. -1 The shear rate and velocity distribution are shown in the figure below: The value of the Reynolds number is as follows: Figure 2 As shown: Example 2: In this example, a small volume test was completed: 1. The outer cylinder has an inner diameter of 50mm, the inner cylinder has an outer diameter of 40mm, and the annular space distance is 5mm; the length is 100mm; the inner and outer cylinders are made of 316 stainless steel, and the thickness (10mm) is determined according to the strength; both ends of the outer cylinder can be disassembled for easy cleaning of the equipment; the volume of the experimental annular cavity is 70.7ml. 2. The inner cylinder passes through the outer cylinder and the end face is sealed by an oil seal; 3. One end of the inner cylinder shaft is connected to the motor via a pin; 220V AC motor, power 0.5KW, maximum speed 2800 rpm; during the experiment, the inner cylinder rotates stably with the motor, and the motor speed can be infinitely adjusted by a frequency converter; 4. There is a "liquid injection port" and a "liquid discharge port" at the upper end of the outer cylinder, and a "liquid discharge port" at the lower end. All three ports are 10mm diameter internal threads and can be sealed with bolts. 5. When testing the liquid, first close the drain port and open the vent port. Then, inject the liquid into the annulus through the "injection port" until it is full. Finally, close the "injection port". 6. Performance Testing: Turn on the drive unit, adjust the motor to a certain speed, and test the liquid properties. Assuming the motor speed is 2000 rpm, calculate the shear rate distribution: the shear rate ranges from 745 to 1164, with an average of 932 s.-1 The shear rate and velocity distribution are shown in the figure below.

[0039] 7. The numerical value of the Reynolds number is as follows: Figure 3 As shown:

[0040] Example 3: Large Liquid Volume Test 1. The outer cylinder has an inner diameter of 170mm, the inner cylinder has an outer diameter of 150mm, and the annular space distance is 10mm; the length is 500mm; the inner and outer cylinders are made of 316 stainless steel, and the thickness (10mm) is determined according to the strength; both ends of the outer cylinder can be disassembled for easy cleaning of the equipment; the volume of the experimental annular cavity is 2512ml. 2. The inner cylinder passes through the outer cylinder and its end face is sealed by an oil seal; the shafts at both ends of the inner cylinder are horizontally fixed to the fixed bracket of the base by bearings; 3. One end of the inner cylinder shaft is connected to the motor via a pin; 220V AC motor, power 1.5KW, maximum speed 2800 rpm; during the experiment, the inner cylinder rotates stably with the motor, and the motor speed can be infinitely adjusted by a frequency converter; 4. There is an injection port and a drain port at the upper end of the outer cylinder, and a drain port at the lower end. All three ports are 10mm diameter internal threads and can be sealed with bolts. 5. When testing the liquid, first close the drain port, open the vent port, then inject the liquid into the annulus through the injection port until it is full, and finally close the injection port. 6. Performance Testing: Turn on the motor and adjust it to a certain speed to test the liquid's properties. Assuming the motor speed is 1000 rpm, calculate the shear rate distribution: the shear rate ranges from 736 to 946, with an average of 834 s. -1 The shear rate and velocity distribution are shown in the figure below.

[0041] 7. The numerical value of the Reynolds number is as follows: Figure 4 As shown:

[0042] In summary, fluids exhibit different properties under different shear conditions, especially in the mixed flow conditions of two-phase and multiphase flows. Therefore, accurate shear flow field conditions are required. Since axial flow in a circular pipe is difficult to achieve at high speeds and cannot be experimentally tested in the flow field, rotating flow can be used instead. Annular flow can achieve a more uniform shear flow field. This application uses an inner cylinder 1 and an outer cylinder 2 to form a shearing device, which not only has a simple overall structure but also achieves the purpose of accurate testing.

[0043] Example 4: A test method for annular shear rate meter for oil-water two-phase flow, comprising the following steps: Step 1: Set the inner cylinder 1 to pass through the outer cylinder 2; Step 2: Pour the test liquid into the injection port; Step 3: First, close the drain port and open the vent port. Then, inject liquid into the annulus through the injection port until it is full. Finally, close the injection port. Step 4: Start the drive unit 13.

[0044] In summary, this application creates a well-defined, uniform, and controllable annular shear flow field. The core of this invention lies in utilizing the annular structure formed by inner and outer cylinders to generate a nearly uniform shear flow field through the rotation of the inner cylinder. The velocity and shear rate distributions of this flow field have clearly defined mathematical formulas, overcoming the shortcomings of traditional stirring methods or the instability and difficulty in quantifying flow fields in complex pipe flows. This provides a reliable and reproducible experimental environment for accurately studying the rheological behavior of fluids (especially oil-water two-phase flows) under specific shear conditions.

[0045] Simultaneously, it achieves precise quantification and wide-range adjustment of key rheological parameters: based on a clear flow field theory, the instrument can directly convert simple operating parameters (inner cylinder rotation speed n, annular geometry R1, R2, L) into key rheological parameters such as shear rate and shear stress experienced by the fluid micro-element. Combined with a continuously variable speed motor, users can easily adjust the shear rate from hundreds to over 1000 s within a wide range (as shown in the example). - ¹) Precise control of shear conditions enables a comprehensive characterization of the fluid's rheological properties.

[0046] This invention features a compact overall structure, simple operation, and flexible sample volume requirements: compared to traditional large and complex annular experimental devices, the device structure of this invention has a high degree of integration and a small footprint. Modular design (such as a detachable outer cylinder end cap) makes cleaning and maintenance extremely convenient. Furthermore, by changing the annular size (e.g., the three embodiments correspond to capacities of 70.7 mL, 998 mL, and 2512 mL respectively), it can flexibly adapt to different sample volume testing needs, satisfying both preliminary screening of small laboratory samples and conducting medium-volume tests that more closely resemble actual working conditions, significantly reducing experimental costs and material consumption.

[0047] This application provides clear flow regime criteria and highly reliable experimental data: This invention provides a formula for calculating the Reynolds number (Re) based on the characteristic size of the annulus and the average flow velocity (Formula (7)). This allows researchers to quantitatively determine the flow state (laminar or turbulent) of the fluid in the annulus, ensuring that the experiment is conducted under the required flow regime, thereby guaranteeing the accuracy and validity of the measured rheological data, and providing direct and reliable theoretical basis and data support for the design and process optimization of oilfield gathering and transportation pipelines.

[0048] This application is highly targeted and effectively addresses industry pain points: This invention is designed specifically to solve the challenge of rheological measurement in oil-water two-phase flow (heterogeneous suspension system) during high water cut periods. It provides an efficient and compromise solution between a simple rotational viscometer (suitable for homogeneous fluids) and a complex loop device, filling the gap in existing technology in this specific application area and having significant practical implications for efficient oilfield development and the optimization of gathering and transportation processes.

[0049] All the devices selected in this application are general standard parts or components known to those skilled in the art. Their structures and principles can be learned by those skilled in the art through technical manuals or conventional experimental methods.

[0050] In the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.

[0051] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0052] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. An annular shear rate meter for oil-water two-phase flow, characterized by, include: An inner cylinder and an outer cylinder fitted on the inner cylinder, with a detection gap between the inner cylinder and the outer cylinder, and a base extending from the lower side of the outer cylinder; The outer cylinder has an injection hole and an exhaust hole on its upper side, and an outlet hole on its lower side. The inner cylinder has rotating shafts extending from both ends, and bearing supports are provided on the rotating shafts. A drive device is coaxially connected to the rotating shafts to drive the inner cylinder to rotate.

2. The annular shear rate meter for oil-water two-phase flow as described in claim 1, characterized in that, The inner cylinder is hollow. The inner cylinder is equipped with sealing caps at both ends.

3. The annular shear rate meter for oil-water two-phase flow as described in claim 2, characterized in that, In the rotating flow within the inner and outer cylinders, the formulas for the linear velocity and angular velocity at different diameters in the annular flow field are as follows: ； In the formula, R1 and R2 are the outer diameter of the inner cylinder and the inner diameter of the outer cylinder, respectively.

4. The annular shear rate meter for oil-water two-phase flow as described in claim 3, characterized in that, wherein The shear rate is defined as: 。 5. The annular shear rate meter for oil-water two-phase flow as described in claim 3, characterized in that, wherein The shear rate is defined as: 。 6. The annular shear rate meter for oil-water two-phase flow as described in claim 5, characterized in that, In the rotating flow within the inner and outer cylinders, the Reynolds number is calculated using the following formula: ； The average velocity of the flow is: ； The final formula for the Reynolds number is: 。 7. The annular shear rate meter for oil-water two-phase flow as described in claim 6, characterized in that, The outer cylinder has an inner diameter of 112mm, the inner cylinder has an outer diameter of 100mm, and the annular space distance is 6mm; the length of the outer cylinder is 500mm.

8. The annular shear rate meter for oil-water two-phase flow as described in claim 7, characterized in that, The outer cylinder has detachable ends for easy cleaning of the equipment.

9. A method of testing an annular shear rate meter for oil-water two-phase flow, characterized by, Including the annular shear rate meter as described in any one of claims 1-8, and simultaneously: Includes the following steps: Step 1: Set the inner cylinder to pass through the outer cylinder; Step 2: Pour the test liquid into the injection port; Step 3: First, close the drain port and open the vent port. Then, inject liquid into the annulus through the injection port until it is full. Finally, close the injection port. Step 4: Start the drive unit.

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