Experimental device for evaluating influence of oil well production pressure difference on stability of oil-water emulsion

Abstract

The utility model discloses an experimental device for evaluating the influence of oil well production pressure difference on the stability of oil-water emulsion, which is characterized in that an outlet of a produced water temperature-resistant and pressure-resistant container is connected with an inlet of a trace water injection pump, and an outlet of a produced oil temperature-resistant and pressure-resistant container is connected with an inlet of a trace oil injection pump; outlets of the micro water injection pump and the micro oil injection pump are respectively connected with two inlets of the three-way valve, an outlet of the three-way valve is connected with a liquid phase inlet of the high-pressure emulsification tank, and a liquid outlet of the high-pressure emulsification tank is connected with an inlet of the storage type temperature-resistant and pressure-resistant container; an outlet of the storage type temperature-resistant and pressure-resistant container is connected with an oil pipe inlet of the small-sized double-wing well head device through a one-way pressure regulating valve, an oil nozzle sleeve outlet of the small-sized double-wing well head device is connected with a short pipe, and an outlet of the short pipe is inserted into a center hole of a large-end end cover of the transparent receiving cover. The side wall of the transparent receiving cover is provided with a transparent observation window and a high-speed camera. The device can simulate various working conditions in actual production, provides an emulsion stability evaluation report, and is beneficial to optimization of an oil field production process.

Description

Technical Field

[0001] This utility model relates to an oil extraction evaluation device, and more particularly to an experimental device for evaluating the effect of oil well production pressure differential on the stability of oil-water emulsions, belonging to the technical field of oilfield experimental equipment. Background Technology

[0002] In oil extraction, changes in wellhead production pressure differential have a significant impact on the stability of oil-water emulsions. Oil-water emulsions are widely present in all stages of oilfield development, including reservoir extraction, surface gathering and transportation, and processing. Studying and evaluating the impact of wellhead production pressure differential on the stability of oil-water emulsions is of significant practical importance for optimizing oilfield production processes and improving oil recovery.

[0003] Oil-water emulsions are dispersion systems formed by the flow and mixing of oil and water phases. Based on the difference between the dispersed and continuous phases, emulsions can be classified into water-in-oil (W / O) and oil-in-water (O / W) types. The stability of emulsions is affected by various factors, including the type and concentration of emulsifiers, temperature, pressure, flow rate, and shear force. Changes in wellhead production pressure differentials not only affect the oil-water interfacial tension but also alter the fluid flow state, and may even lead to the dissolution or precipitation of gases in the oil-gas mixture. These factors directly influence the formation and stability of emulsions. Furthermore, the high-temperature and high-pressure underground environment also significantly impacts emulsion stability, necessitating experimental setups capable of simulating these extreme conditions. Existing research and experimental setups suffer from limitations such as single-function limitations, poor controllability of experimental conditions, and limited data acquisition and analysis methods, making it difficult to comprehensively assess the impact of wellhead production pressure differentials on the stability of oil-water emulsions.

[0004] Chinese invention patent application CN 107727533A discloses an "Experimental System for Identifying the Flow Pattern and Detecting the Composition of Oil-Water Emulsions with Variable Pipe Diameter," which enables the detection of components in oil-water mixtures and can determine the liquid state and rheological properties of the mixtures. However, it does not address the analysis of micro-droplet size, interfacial characteristics, or the study of unconventional crude oil emulsification mechanisms in emulsions, nor does it involve the analysis of the interfacial characteristics of micro-droplets in emulsions.

[0005] Chinese utility model patent CN 207457230U discloses a "Conductive Experimental System for Predicting the Viscosity and Composition of Non-Newtonian Oil-Water Emulsions," relating to the field of viscosity prediction and composition detection in crude oil extraction and transportation processes, specifically an conductive experimental system for predicting the viscosity and composition of non-Newtonian oil-water emulsions. This technical solution can predict the viscosity and composition of non-Newtonian fluids online through modal analysis, but it does not address the analysis of the causes of emulsion formation.

[0006] Given the limitations of current technology, namely the lack of research on the impact of wellhead production pressure differential on emulsion stability, it is necessary to design an experimental system capable of comprehensively evaluating the impact of wellhead production pressure differential on the stability of oil-water emulsions, thereby optimizing oilfield production processes and improving oil recovery. Utility Model Content

[0007] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, and such simplifications or omissions should not be construed as limiting the scope of the present invention.

[0008] In view of the problems existing in the above and / or prior art, this utility model is proposed.

[0009] The purpose of this invention is to overcome the problems existing in the prior art and provide an experimental device for evaluating the impact of oil well production pressure differential on the stability of oil-water emulsions. This device can simulate various working conditions in actual production, achieve precise control and real-time monitoring of experimental conditions, and collect and analyze experimental data in real time, providing a detailed emulsion stability evaluation report. This helps to optimize oilfield production processes and improve recovery rate and economic benefits.

[0010] To address the above technical problems, this utility model provides an experimental apparatus for evaluating the impact of oil well production pressure differential on the stability of oil-water emulsions. The apparatus includes a produced water temperature- and pressure-resistant container and a produced oil temperature- and pressure-resistant container. The outlet of the produced water temperature- and pressure-resistant container is connected to the inlet of a micro-injection pump, and the outlet of the produced oil temperature- and pressure-resistant container is connected to the inlet of a micro-injection pump. The outlets of the micro-injection pump and the micro-injection pump are respectively connected to the two inlets of a three-way valve. The outlet of the three-way valve is connected to the liquid phase inlet of a high-pressure emulsification tank. The drain port of the high-pressure emulsification tank is connected to the inlet of a storage-type temperature- and pressure-resistant container. The outlet of the storage-type temperature- and pressure-resistant container is connected to the tubing inlet of a small double-wing wellhead device via a one-way pressure regulating valve. The outlet of the nozzle sleeve of the small double-wing wellhead device is connected to a short pipe, and the outlet of the short pipe is inserted into the center hole of the large end cap of a transparent receiving cover.

[0011] Furthermore, the side wall of the transparent receiving cover is provided with a transparent observation window that can be opened and closed, and a high-speed camera for capturing the state of the emulsion is provided at the transparent observation window.

[0012] Furthermore, the lower part of the transparent receiving cover is provided with a drain port, which is connected to the sample inlet at the top of the receiving tank through a sealed pipe, and the lower part of the side wall of the receiving tank is provided with a discharge port.

[0013] Furthermore, the high-pressure emulsifying tank is equipped with a stirring blade, and the top of the high-pressure emulsifying tank is equipped with a nitrogen inlet, which is connected to the outlet of the high-pressure gas cylinder through a high-pressure gas pipe and a pressure regulating valve.

[0014] Furthermore, the storage-type temperature and pressure resistant container includes an emulsification chamber and an S-shaped transparent ring channel. The drain port of the high-pressure emulsification tank is connected to the inlet of the emulsification chamber. The emulsification chamber is equipped with a stirrer and has an emulsification chamber air injection port at the top. The outlet of the emulsification chamber is connected to the inlet of the S-shaped transparent ring channel through a flow control valve.

[0015] Furthermore, the outlet of the sleeve gas cylinder is connected to the inlet of the gas storage tank, and the outlet of the gas storage tank is connected to the gas injection port of the emulsification chamber through a pressure regulating valve.

[0016] Furthermore, the produced water temperature and pressure resistant container, the produced oil temperature and pressure resistant container, and the high-pressure emulsification tank are each equipped with a heat insulation jacket. Each heat insulation jacket has a jacket water bath inlet at its bottom and a jacket water bath outlet at its top. The jacket water bath inlet is connected to the water supply port of the constant temperature water bath box, and the jacket water bath outlet is connected to the water return port of the constant temperature water bath box.

[0017] Furthermore, the produced water temperature and pressure resistant container, the produced oil temperature and pressure resistant container, and the high-pressure emulsification tank are respectively equipped with a temperature sensor, a pressure sensor, and a magnetic float level gauge;

[0018] A pressure sensor is installed on the top of the receiving tank, and a transparent observation window and a magnetic float level gauge are provided on the side of the receiving tank.

[0019] Furthermore, the high-pressure emulsifying tank is provided with a reagent addition port at the top and a sampling port at the bottom.

[0020] Furthermore, this experimental setup is also equipped with an electron microscope for observing the microstructure of oil-water emulsions, an interfacial tension-contact angle measuring instrument for measuring the interfacial tension and contact angle of oil-water emulsions, and a dual-drive membrane balance for measuring the interfacial membrane pressure of oil-water. The signal output terminals of the dual-drive membrane balance and the interfacial tension-contact angle measuring instrument are all connected to an information processing terminal.

[0021] Compared with the prior art, the present invention has achieved the following beneficial effects: 1. By evaluating the influence of the production pressure difference between the bottom of the oil well and the wellhead on the stability of the oil-water emulsion, the behavior of the oil-water emulsion under different pressure difference conditions can be understood more accurately, which helps to optimize the production process and improve the production efficiency and output of the oil field.

[0022] 2. In-depth research on the impact of oil well production pressure differential on the stability of oil-water emulsions can provide important references for the treatment and separation of oil-water emulsions. Optimizing production processes can reduce the stability of oil-water emulsions, improve separation efficiency, reduce pollution emissions, and protect the environment. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The drawings are provided for reference and illustration only and are not intended to limit this utility model. Wherein:

[0024] Figure 1 This is a schematic diagram of the experimental apparatus for evaluating the effect of oil well production pressure differential on the stability of oil-water emulsions according to this utility model.

[0025] Figure 2 A photograph of the initial state of the emulsion prepared for Experiment 1;

[0026] Figure 3 Photographs showing the droplet size changes of the emulsion from Experiment 1 after it was sprayed through a 3mm nozzle under different pressures.

[0027] Figure 4 Photographs showing the droplet size changes of the emulsion in Experiment 2 after being sprayed through a 6mm nozzle under different pressures;

[0028] Figure 5 A photograph of the initial state of the emulsion prepared for Experiment 3;

[0029] Figure 6 Photographs showing the droplet size changes of the emulsion in Experiment 3 after it was sprayed through a 3mm nozzle under different pressures.

[0030] Figure 7 Photographs showing the droplet size changes of the emulsion in Experiment 3 after being sprayed through a 6mm nozzle under different pressures;

[0031] In the diagram: 1. Constant temperature water bath; 2. Produced water temperature and pressure resistant container; 3. Micro-injection pump; 4. Produced oil temperature and pressure resistant container; 5. Micro-injection pump; 6. Three-way valve; 7. High-pressure gas cylinder; 8. High-pressure emulsification tank; 9. Casing gas cylinder; 10. Gas storage tank; 11. Reserve type temperature and pressure resistant container; 12. One-way pressure regulating valve; 13. Small double-wing wellhead device; 14. Transparent receiving cover; 15. Receiving tank; 16. High-speed camera; 17. Electron microscope; 18. Interfacial tension-contact angle measuring instrument; 19. Dual-drive membrane balance; 20. Information processing terminal. Detailed Implementation

[0032] In the following description of this utility model, the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not mean that the device must have a specific orientation.

[0033] To make the technical means, creative features, achieved objectives and effects of this utility model easier to understand, the present utility model will be further described below with reference to specific illustrations. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0035] like Figure 1 As shown, the experimental apparatus of this utility model for evaluating the effect of oil well production pressure differential on the stability of oil-water emulsion includes a constant temperature water bath 1, a produced water temperature and pressure resistant container 2, a micro-injection pump 3, a produced oil temperature and pressure resistant container 4, a micro-injection pump 5, a three-way valve 6, a high-pressure gas cylinder 7, a high-pressure emulsification tank 8, a casing gas cylinder 9, a gas storage tank 10, a reserve type temperature and pressure resistant container 11, a one-way pressure regulating valve 12, a small double-wing wellhead device 13, a transparent receiving cover 14, a receiving tank 15, a high-speed camera 16, an electron microscope 17, an interfacial tension-contact angle measuring instrument 18, a dual-drive membrane balance 19, and an information processing terminal 20.

[0036] The adjustable temperature of the constant temperature water bath 1 is 0-120℃. The circulating water outlet is connected to an external tee, which is connected to the bottom water bath inlet of the produced water temperature and pressure resistant container 2 and the produced oil temperature and pressure resistant container 4. This is used to maintain the water bath at a constant temperature during the test and ensure a stable experimental environment.

[0037] The produced water temperature and pressure resistant container 2, the produced oil temperature and pressure resistant container 4, and the high-pressure emulsification tank 8 are each equipped with a heat insulation jacket. The bottom of each heat insulation jacket is provided with a jacket water bath inlet, and the top of each heat insulation jacket is provided with a jacket water bath outlet. The jacket water bath inlet is connected to the water supply port of the constant temperature water bath box 1, and the jacket water bath outlet is connected to the water return port of the constant temperature water bath box 1.

[0038] The outlet of the produced water temperature and pressure resistant container 2 is connected to the inlet of the micro-injection water pump 3, and the outlet of the produced oil temperature and pressure resistant container 4 is connected to the inlet of the micro-injection oil pump 5. The outlets of the micro-injection water pump 3 and the micro-injection oil pump 5 are respectively connected to the two inlets of the three-way valve 6. The outlet of the three-way valve 6 is connected to the liquid phase inlet of the high-pressure emulsification tank 8. The high-pressure emulsification tank 8 is equipped with a stirring blade, and the top of the high-pressure emulsification tank 8 is equipped with a nitrogen inlet. The nitrogen inlet is connected to the outlet of the high-pressure gas cylinder 7 through a high-pressure gas pipe and a pressure regulating valve, so that the high-pressure emulsification tank 8 can simulate the downhole pressure.

[0039] The drain port of the high-pressure emulsifying tank 8 is connected to the inlet of the storage-type temperature and pressure resistant container 11. The outlet of the storage-type temperature and pressure resistant container 11 is connected to the oil pipe inlet of the small double-wing wellhead device 13 through the one-way pressure regulating valve 12. The oil nozzle sleeve outlet of the small double-wing wellhead device 13 is connected to a short pipe. The outlet of the short pipe is inserted into the center hole of the large end cap of the transparent receiving cover 14.

[0040] The transparent receiving cover 14 has a transparent observation window on its side wall, and a high-speed camera 16 is installed at the transparent observation window to capture the state of the emulsion. The transparent observation window can be opened and closed, and can be cleaned independently after each experiment to make the viewing angle of the high-speed camera 16 clearer. The high-speed camera 16 is used to record the experimental process for subsequent analysis and review.

[0041] The lower part of the transparent receiving cover 14 is provided with a drain port, which is connected to the sample inlet at the top of the receiving tank 15 through a sealed pipe. The lower part of the side wall of the receiving tank 15 is provided with a discharge port.

[0042] The storage-type temperature and pressure resistant container 11 includes an emulsification chamber and an S-shaped transparent ring channel. The drain port of the high-pressure emulsification tank 8 is connected to the inlet of the emulsification chamber. The emulsification chamber is equipped with a stirrer and has an emulsification chamber air injection port on the top. The outlet of the emulsification chamber is connected to the inlet of the S-shaped transparent ring channel through a flow control valve.

[0043] The outlet of the sleeve gas cylinder 9 is connected to the inlet of the gas storage tank 10, and the outlet of the gas storage tank 10 is connected to the gas injection port of the emulsification chamber of the storage type temperature and pressure resistant container 11 through a pressure regulating valve.

[0044] Both the produced water temperature and pressure resistant vessel 2 and the produced oil temperature and pressure resistant vessel 4 are made of high-strength corrosion-resistant alloy material, with a volume of 25L. High-precision temperature and pressure sensors are installed inside the vessels. The temperature sensor measures from -200℃ to 500℃ with an accuracy of ±0.1℃. The pressure sensor measures from 0 to 50MPa with an accuracy of ±0.05%FS, enabling real-time monitoring and recording of temperature and pressure changes within the produced water temperature and pressure resistant vessel 2. The produced water temperature and pressure resistant vessel 2 is equipped with a two-way pressure regulating valve with an adjustment range of 2-6MPa and a maximum pressure of 60MPa. It is made of 316L stainless steel and has a response time of less than 0.5 seconds. The exterior of the vessel is coated with a 200-micron thick epoxy resin coating, and the interior is coated with a 100-micron thick polytetrafluoroethylene (PTFE) coating, providing additional corrosion protection. This device is designed to withstand temperatures up to 300℃ and pressures up to 50MPa.

[0045] Both the micro-volume water pump 3 and micro-volume oil pump 5 are made of high-strength stainless steel. The main components include a closed impeller made of 316L stainless steel, a cast iron pump casing, a shaft seal, and a drive motor. The closed impeller has a diameter of 150mm, five blades, and a maximum speed of 3600r / min. The cast iron pump casing is internally coated with a 200μm thick epoxy resin coating to enhance corrosion resistance. The shaft seal uses a silicon carbide mechanical seal. The drive motor has a power of 7.5kW, 380V, 50Hz, insulation class F, and protection class IP55. Performance parameters of the micro-volume water pump 3 and micro-volume oil pump 5: flow rate 10-200m³ / h. 3 The pump has a flow rate of 100 m / h, a head of 5-150 m, a maximum operating temperature of 120℃, and a maximum operating pressure of 16 bar. Both the micro-injection water pump 3 and the micro-injection oil pump 5 have an inlet and outlet diameter of 100 mm, are flange-connected, and are horizontally mounted on a reinforced steel base with shock-absorbing pads.

[0046] The three-way valve 6 is made of 304 high-strength stainless steel, offering excellent corrosion resistance and pressure resistance. It is used to control sample flow and pressure release. The valve body has a 10mm inner diameter, a maximum working pressure of 20MPa, and an operating temperature range of -40℃ to 200℃. The valve's operating handle features a non-slip design for precise control of fluid flow direction and pressure. The three-way valve 6 has three connection ports with internal PTFE seals to ensure excellent sealing performance and prevent leakage.

[0047] High-pressure gas cylinder 7 is made of high-strength alloy steel, possessing excellent pressure resistance. The adjustable pressure range is 0-300MPa, and the outlet is equipped with a one-way pressure regulating valve with an adjustment accuracy of ±0.1MPa, ensuring precise control of the output pressure. High-pressure gas cylinder 7 is mounted on a stable bracket made of corrosion-resistant stainless steel, increasing overall stability and durability. Safety protection devices include an overpressure protection valve and a pressure relief device, which automatically releases pressure to prevent the risk of explosion when the pressure inside the cylinder exceeds the set value. High-pressure gas cylinder 7 is mainly used to provide high-pressure gas in experiments, ensuring pressure stability within the high-pressure emulsification tank 8 through the pressure regulating valve.

[0048] The high-pressure emulsifying tank 8 is made of high-strength stainless steel, with a tank diameter of 400mm, a wall thickness of 10mm, and a volume of 20L. An external water bath system is installed for temperature control and heating, with a temperature control range of 20℃ to 100℃. The high-pressure emulsifying tank 8 is equipped with a high-efficiency stirring paddle with a power of 2kW and an adjustable speed range of 0-1500r / min. A mixed gas inlet is located on the top of the tank, along with high-precision temperature and pressure sensors for real-time monitoring of the internal temperature and pressure.

[0049] The level gauge uses a magnetic float level gauge for accurate monitoring of the liquid level inside the tank. A reagent addition port is located on the top of the tank for easy addition of different reagents during mixing, and a sampling observation point is provided for convenient sampling and observation of the emulsification effect. The sealing ring is made of food-grade silicone to ensure high-pressure sealing performance and prevent leakage. Disassembly of the tank is simple; both the top cover and bottom drain port feature a quick-opening design with handles and latches for easy opening and closing. All connections use sanitary clamps to ensure quick and easy disassembly and cleaning.

[0050] The structure, material, and valves of the sleeve gas cylinder 9 are similar to those of the high-pressure gas cylinder 7. It is also made of high-strength alloy steel and has excellent pressure resistance. It provides sleeve gas to the emulsification chamber of the storage-type temperature and pressure resistant container 11 and can precisely adjust the pressure in the experiment.

[0051] The gas storage tank 10 is made of high-strength alloy steel, with a height of 600mm, a diameter of 300mm, a wall thickness of 8mm, and a volume of 20L. The pressurized air inlet has a diameter of 50mm and uses a standard flange connection to ensure airtightness and reliable connection. A high-precision pressure gauge is installed on the top of the tank, with a range of 0-30MPa and an accuracy of ±0.5%FS, displaying the internal pressure in real time. The gas storage tank 10 is also equipped with a two-way pressure regulating valve, with an adjustment range of 0-25MPa and a maximum pressure capacity of 30MPa. Made of 316L stainless steel, it ensures flexible adjustment and stable pressure under different experimental conditions.

[0052] The storage-type temperature and pressure resistant container 11 is made of high-strength stainless steel and has a volume of 25L. The container is designed with two chambers, left and right. The outlet of the left chamber is connected to the right chamber via a flow control valve. Pressure and temperature sensors are installed inside the storage-type temperature and pressure resistant container 11. The left chamber is an emulsification chamber equipped with a stirrer with a power of 1.5kW and an adjustable speed range of 0-1500r / min to ensure uniform sample mixing. The flow control valve is made of stainless steel for precise control of fluid flow. The temperature sensor has a measurement range of -50℃ to 300℃, and the pressure sensor has a pressure range of 0-30MPa with an accuracy of ±0.5%. A magnetic level gauge monitors the liquid level in real time. The reagent addition port has a diameter of 50mm and a sealing cap for convenient reagent addition. The sampling port is located at the bottom for easy sampling and analysis. The right chamber is an S-shaped transparent ring made of high-strength, pressure-resistant transparent polycarbonate (PC), allowing direct observation of the fluid state or imaging by a high-speed camera 16. A one-way pressure regulating valve 12 is installed at the outlet of the loop, with an adjustment range of 0-25MPa, to ensure stable pressure within the loop.

[0053] The small double-wing wellhead device 13 is used to simulate the structure of an oilfield wellhead, making the experiment closer to actual working conditions. This device is made of high-strength, corrosion-resistant alloy steel. The two wings of the lower casing cross-junction are each equipped with a casing valve, the inlet of which is connected to the annulus between the casing and tubing. The two wings of the upper tubing cross-junction are each equipped with a production valve, the inner port of which is connected to the tubing. An oil nozzle sleeve is installed at the outer port of the production gate valve, and each oil nozzle sleeve contains an oil nozzle with an orifice diameter of 3-8 mm to regulate the oil production rate.

[0054] The transparent receiving cover 14 is made of transparent high-strength polycarbonate (PC) material, possessing excellent chemical corrosion resistance and high-temperature resistance. It measures 500mm in diameter and 300mm in height. An internal food-grade silicone sealing ring ensures a tight seal, preventing gas or liquid leakage. A 100mm x 100mm transparent observation window is located on the side for real-time monitoring of the internal components. A 25mm diameter drain port with a quick-connect fitting at the bottom facilitates the collection and discharge of liquid samples. The transparent receiving cover 14 is used to collect gases or liquids generated during the experiment for subsequent analysis. Its transparent material and observation window design facilitate real-time monitoring of the experiment, ensuring the accuracy and reliability of experimental data.

[0055] The receiving container 15 is made of high-strength 304 stainless steel, possessing excellent corrosion resistance and pressure resistance. It has a volume of 20L, a diameter of 300mm, and a height of 500mm. A 50mm diameter sample inlet is located at the top of the container, connected to the transparent receiving cover 14 via a sealed pipe, ensuring leak-free sample transfer. A 25mm diameter discharge port with a high-precision valve is located on the side of the container for easy sample discharge and dispensing. Food-grade silicone sealing rings are fitted to the top and bottom of the receiving container 15 to ensure airtightness and prevent sample leakage. A transparent observation window on the side of the container allows for real-time monitoring of the sample storage status, and a magnetic level gauge is installed to display the sample level in real time. A pressure sensor is installed at the top to monitor the internal pressure, ensuring the safety of sample storage. The receiving container 15 is primarily used to store samples collected from the transparent receiving cover 14, ensuring that the samples are not contaminated or leaked during storage. Its high-strength stainless steel material and precise sealing design guarantee the safe storage of samples. The transparent observation window and level gauge design allow operators to monitor sample storage in real time, ensuring the accuracy and reliability of experimental data.

[0056] An electron microscope 17 is used to observe the microstructure and characteristics of the sample to aid in understanding the experimental results. An interfacial tension-contact angle meter 18 is used to measure the interfacial tension and contact angle of the oil-water emulsion to study the emulsification process and behavior of the sample. A dual-drive membrane balance 19 is used to measure the interfacial membrane pressure of the oil-water emulsion to evaluate its stability. The signal output terminals of both the dual-drive membrane balance 19 and the interfacial tension-contact angle meter 18 are connected to an information processing terminal 20, which is used to collect, process, and analyze experimental data.

[0057] This experimental setup targets unconventional produced fluids from oilfields. Through high-pressure experimental conditions, it reveals the emulsification mechanism of these fluids by measuring the formation of emulsions at the wellhead and the droplet size and interfacial characteristics after oil injection. Specific working steps include:

[0058] Step 1: The aqueous solution naturally settled from the wellhead of the oilfield is stored as the experimental water phase in the produced water temperature and pressure resistant container 2. The crude oil produced from the actual reservoir is dehydrated and stored as the experimental oil phase in the produced oil temperature and pressure resistant container 4. Both the produced water temperature and pressure resistant container 2 and the produced oil temperature and pressure resistant container 4 are externally connected to a constant temperature water bath 1 for temperature control. Temperature sensors and pressure sensors are installed inside the produced water temperature and pressure resistant container 2 and the produced oil temperature and pressure resistant container 4. The injection flow rates of the water phase and the oil phase are adjusted by the micro-injection water pump 3 and the micro-injection oil pump 5.

[0059] Step 2: Adjust and balance the pressure of the experimental system; calculate the required oil-water ratio for the experiment; set the rotation speed of the micro-injection water pump 3 and the micro-injection oil pump 5; set the water bath temperature of the constant temperature water bath 1; calculate the oil-gas-water ratio; replace the oil nozzle in the oil nozzle sleeve to make its orifice diameter meet the experimental requirements; and prepare for the experiment.

[0060] Step 3: Pump the oil phase and water phase into the high-pressure emulsifying tank 8 in the emulsion generation system. The high-pressure emulsifying tank 8 is externally connected to the circulating water bath of the constant temperature water bath box 1 for temperature control. The high-pressure emulsifying tank 8 is equipped with temperature and pressure sensors. The high-pressure environment of the oilfield downhole is simulated by the high-pressure gas cylinder 7 and the pressure regulating valve. Under the stirring of the emulsifier at a certain speed, an oil-water emulsion is formed. After passing through the flow control valve, it enters the storage type temperature and pressure resistant container 11.

[0061] Step 4: The emulsion, along with the high-pressure gas, enters the left chamber and emulsification chamber of the storage-type temperature and pressure resistant container 11. Under stirring, it is further mixed to form a three-phase fluid of oil, gas, and water with a certain gas-liquid ratio. The three-phase fluid enters the S-shaped transparent channel of the right chamber through the flow control valve for direct observation and is photographed by a high-speed camera.

[0062] Step 5: After the emulsion flows out from the S-shaped transparent annulus, it enters the tubing of the small double-wing wellhead device 13, flows out from the production gate on one side, enters the nozzle sleeve, and finally is sprayed out from the nozzle orifice into the transparent receiving cover 14.

[0063] In the phase determination experiment, the emulsion is collected by the transparent receiving hood 14 after being sprayed. The state of the oil and gas is observed by the high-speed camera 16, and the change or breakage of the droplet shape is observed when the emulsion droplets hit the wall of the transparent receiving hood 14.

[0064] In the droplet size analysis experiment, droplets attached to the nozzle edge and the transparent receiving cover 14 were collected respectively. The oil emulsion droplets were observed using an electron microscope 17 and a high-speed camera 16, and photos were taken continuously for recording. The droplet size changes were analyzed using image processing software.

[0065] After each experiment, the oil nozzle of the oil nozzle sleeve is replaced, the ratio of the three-phase fluid (oil, gas, and water) is reset, the pressure on the high-pressure side of the oil nozzle sleeve is reset, and the next round of experiments is conducted. Through multiple rounds of simulation, the optimal working conditions in actual production are found to improve the recovery rate and economic benefits.

[0066] like Figure 2 As shown, the emulsion prepared in Experiment 1 was sampled in its initial state, and the droplet size was observed and photographed using an electron microscope. The initial particle size of the emulsion prepared in Experiment 1 was 46 μm.

[0067] Replace the nozzle in the nozzle sleeve with a 3mm diameter nozzle, and spray the emulsion with an initial particle size of 46μm through the nozzle. Adjust the outlet pressure of the gas storage tank 10 to 1.0MPa, 1.2MPa, and 1.5MPa respectively. After spraying, immediately collect droplets on the sampling plate, observe the droplet size under a microscope, and take pictures as shown. Figure 3 As shown.

[0068] The droplet size data obtained in Experiment 1 are shown in Table 1 below:

[0069] Table 1

[0070] mean Harmonic Mean Minimum median initial 46.76μm 32.88μm 12.56μm 35.17μm 1.0MPa 18.99μm 14.20μm 6.71μm 16.09μm 1.2MPa 16.05μm 11.96μm 5.91μm 11.48μm 1.5MPa 6.49μm 5.54μm 1.98μm 6.15μm

[0071] Replace the nozzle in the nozzle sleeve with a 6mm diameter nozzle, and spray the emulsion with an initial particle size of 46μm through the nozzle. Adjust the outlet pressure of the gas storage tank 10 to 1.0MPa, 1.2MPa, and 1.5MPa respectively. After spraying, immediately collect droplets on the sampling plate, observe the droplet size under a microscope, and take pictures as shown. Figure 4 As shown.

[0072] The droplet size data obtained in Experiment 2 are shown in Table 2 below:

[0073] Table 2

[0074] mean Harmonic Mean Minimum median initial 46.76μm 32.88μm 12.56μm 35.17μm 1.0MPa 30.38μm 24.31μm 9.53μm 25.24μm 1.2MPa 20.67μm 17.99μm 6.99μm 19.75μm 1.5MPa 14.28μm 10.48μm 5.38μm 9.85μm

[0075] like Figure 5 As shown, the emulsion prepared in Experiment 3 was sampled in its initial state, and the droplet size was observed and photographed using an electron microscope. The initial particle size of the emulsion prepared in Experiment 3 was 28.76 μm.

[0076] Replace the nozzle in the nozzle sleeve with a 3mm diameter nozzle, and spray the emulsion with an initial particle size of 28.76μm through the nozzle. Adjust the outlet pressure of the gas storage tank 10 to 1.0MPa and 1.5MPa respectively. After spraying, immediately collect the droplets on the sampling plate, observe the droplet size under a microscope and take pictures as shown. Figure 6 As shown.

[0077] The droplet size data obtained in Experiment 3 are shown in Table 3 below:

[0078] Table 3

[0079]

[0080] Replace the nozzle in the nozzle sleeve with a 6mm diameter nozzle, and spray the emulsion with an initial particle size of 28.76μm through the nozzle. Adjust the outlet pressure of the gas storage tank 10 to 1.0MPa and 1.5MPa respectively. After spraying, immediately collect the droplets on the sampling plate, observe the droplet size under a microscope and take pictures as shown. Figure 7 As shown.

[0081] The droplet size data obtained in Experiment 3 are shown in Table 4 below:

[0082] Table 4

[0083]

[0084] The above experiments show that when the initial droplet size of the oil sample is 28.76 μm, the droplet size becomes 24.38 μm under spraying at 1.5 MPa and a 6 mm nozzle, which is a decrease of 4.28 μm, and the decrease is relatively small. This indicates that when the initial droplet size of the oil-water emulsion is small, the change in droplet size is less affected.

[0085] The above description is merely a preferred embodiment of the present utility model, showing and describing the basic principles, main features, and advantages of the present utility model. It is not intended to limit the scope of patent protection of the present utility model. Those skilled in the art should understand that the present utility model is not limited to the above embodiments. In addition to the above embodiments, the present utility model may have other implementations without departing from the spirit and scope of the present utility model. Various changes and improvements to the present utility model are also possible. All technical solutions formed by equivalent substitutions or equivalent transformations fall within the scope of protection claimed by the present utility model. The scope of protection claimed by the present utility model is defined by the appended claims and their equivalents. Technical features not described in the present utility model can be implemented by or using existing technology, and will not be elaborated here.

Claims

1. An experimental apparatus for evaluating the effect of production pressure differential in oil wells on the stability of oil-water emulsions, comprising a temperature- and pressure-resistant vessel for produced water and a temperature- and pressure-resistant vessel for produced oil, characterized in that, The outlet of the produced water temperature and pressure resistant container is connected to the inlet of the micro-injection water pump, and the outlet of the produced oil temperature and pressure resistant container is connected to the inlet of the micro-injection oil pump. The outlets of the micro-injection water pump and the micro-injection oil pump are respectively connected to the two inlets of a three-way valve. The outlet of the three-way valve is connected to the liquid phase inlet of the high-pressure emulsification tank. The drain port of the high-pressure emulsification tank is connected to the inlet of the storage type temperature and pressure resistant container. The outlet of the storage type temperature and pressure resistant container is connected to the tubing inlet of the small double-wing wellhead device through a one-way pressure regulating valve. The outlet of the nozzle sleeve of the small double-wing wellhead device is connected to a short pipe, and the outlet of the short pipe is inserted into the center hole of the large end cap of the transparent receiving cover.

2. The experimental apparatus for evaluating the effect of oil well production pressure differential on the stability of oil-water emulsions according to claim 1, characterized in that: The side wall of the transparent receiving cover is provided with a transparent observation window that can be opened and closed, and a high-speed camera for capturing the state of the emulsion is provided at the transparent observation window.

3. The experimental apparatus for evaluating the effect of oil well production pressure differential on the stability of oil-water emulsions according to claim 1, characterized in that: The lower part of the transparent receiving cover is provided with a drain port, which is connected to the sample inlet at the top of the receiving tank through a sealed pipe. The lower part of the side wall of the receiving tank is provided with a discharge port.

4. The experimental apparatus for evaluating the effect of oil well production pressure differential on the stability of oil-water emulsions according to claim 1, characterized in that: The high-pressure emulsifying tank is equipped with a stirring blade, and a nitrogen inlet is provided at the top of the high-pressure emulsifying tank. The nitrogen inlet is connected to the outlet of the high-pressure gas cylinder through a high-pressure gas pipe and a pressure regulating valve.

5. The experimental apparatus for evaluating the effect of oil well production pressure differential on the stability of oil-water emulsions according to claim 1, characterized in that: The storage-type temperature and pressure resistant container includes an emulsification chamber and an S-shaped transparent ring channel. The drain port of the high-pressure emulsification tank is connected to the inlet of the emulsification chamber. The emulsification chamber is equipped with a stirrer and has an emulsification chamber air injection port at the top. The outlet of the emulsification chamber is connected to the inlet of the S-shaped transparent ring channel through a flow control valve.

6. The experimental apparatus for evaluating the effect of oil well production pressure differential on the stability of oil-water emulsions according to claim 1, characterized in that: The outlet of the sleeve gas cylinder is connected to the inlet of the gas storage tank, and the outlet of the gas storage tank is connected to the gas injection port of the emulsification chamber through a pressure regulating valve.

7. The experimental apparatus for evaluating the effect of oil well production pressure differential on the stability of oil-water emulsions according to claim 1, characterized in that: The produced water temperature and pressure resistant container, the produced oil temperature and pressure resistant container, and the high-pressure emulsification tank are each equipped with a heat insulation jacket. Each heat insulation jacket has a jacket water bath inlet at the bottom and a jacket water bath outlet at the top. The jacket water bath inlet is connected to the water supply port of the constant temperature water bath box, and the jacket water bath outlet is connected to the water return port of the constant temperature water bath box.

8. The experimental apparatus for evaluating the effect of oil well production pressure differential on the stability of oil-water emulsions according to claim 1, characterized in that: The produced water temperature and pressure resistant container, the produced oil temperature and pressure resistant container, and the high-pressure emulsification tank are respectively equipped with temperature sensors, pressure sensors, and magnetic float level gauges; A pressure sensor is installed on the top of the receiving tank, and a transparent observation window and a magnetic float level gauge are provided on the side of the receiving tank.

9. The experimental apparatus for evaluating the effect of oil well production pressure differential on the stability of oil-water emulsions according to claim 1, characterized in that: The high-pressure emulsifying tank is provided with a reagent addition port at the top and a sampling port at the bottom.

10. The experimental apparatus for evaluating the effect of oil well production pressure differential on the stability of oil-water emulsions according to claim 1, characterized in that: This experimental setup is also equipped with an electron microscope for observing the microstructure of oil-water emulsions, an interfacial tension-contact angle measuring instrument for measuring the interfacial tension and contact angle of oil-water emulsions, and a dual-drive membrane balance for measuring the interfacial membrane pressure of oil-water. The signal output terminals of the dual-drive membrane balance and the interfacial tension-contact angle measuring instrument are all connected to an information processing terminal.

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