An oilfield efficient oil-water-gas three-phase separation device

Abstract

This utility model relates to the field of oilfield surface engineering technology and relates to a high-efficiency oil-water-gas three-phase separation device for oilfields. It includes an oil-gas-water separation tank. An ultrasonic transmitting device and a liquid inlet II are located on the left end cap of the oil-gas-water separation tank, and a manhole is located on the right end cap. An air outlet II is located at the top of the oil-gas-water separation tank, and a sewage pipe, a water outlet I, and an oil outlet I are located at the bottom. A reflective deflector plate is located at the liquid inlet II inside the oil-gas-water separation tank, and a demister is located at the air outlet II inside the oil-gas-water separation tank. A coalescing plate and a defoamer are located at the top of the oil-gas-water separation tank, and an oil-water baffle is located at the bottom. Compared with traditional equipment, this device significantly shortens the separation time, greatly improves the quality of oil-water-gas separation, achieves a dissolved gas extraction rate of up to 98%, and increases reagent utilization by more than 40%. This utility model features high processing efficiency, strong adaptability, and stable operation. It is particularly suitable for treating produced fluids from oilfields with high water content, high gas content, and high viscosity, significantly improving the economy and reliability of oil-gas-water three-phase separation.

Description

Technical Field

[0001] This utility model relates to the field of oilfield surface engineering technology, and in particular to an efficient oil-water-gas three-phase separation device for oilfields. Background Technology

[0002] The three-phase separator in an oilfield is a key piece of equipment in the oil and gas gathering and transportation system. It is mainly used to treat water-containing crude oil or oily wastewater to achieve three-phase separation of oil, water, and natural gas. Oilfield oil-water-gas separation mainly relies on gravity settling three-phase separators, which work by utilizing the density differences of oil, water, and gas to achieve natural stratification. However, this technology still has the following problems:

[0003] 1. Low separation efficiency: For emulsified oil, high-viscosity crude oil or micron-sized water droplets, gravity sedimentation alone takes a long time and the sedimentation is insufficient, which seriously affects production efficiency and quality.

[0004] 2. Incomplete natural gas separation: Dissolved gases (such as methane and ethane) are slowly released under pressure. The separated microbubbles adhere to the surface of oil droplets or micron-sized water droplets, forming a gas-oil-water emulsion complex. This hinders the floating of oil droplets and the settling of wastewater, and intensifies the formation of the emulsion layer. If the residence time in the separator is insufficient or the temperature is too low, the gas cannot be completely separated. After entering the subsequent process, the pressure is suddenly released, causing a sudden pressure rise, which triggers the safety valve to open frequently, leading to the risk of system overpressure.

[0005] 3. Uneven mixing of reagents: Traditional dosing and injection mixing methods are difficult to disperse chemical reagents quickly, resulting in low reagent utilization, incomplete reaction, and increased costs;

[0006] 4. Poor adaptability: Changes in the influent flow rate or composition (such as intermittent gas production) will disrupt the steady state of the separator. Without an intelligent control system, it cannot adaptively optimize the separation parameters and requires frequent manual intervention.

[0007] 5. High cost: To compensate for insufficient separation efficiency, multiple separators are often connected in parallel or pretreatment equipment is added, which leads to increased investment and operation and maintenance costs, poor oil-water separation effect, increased power consumption of downstream electrostatic dehydrators, and unstable operation of electrostatic dehydrators caused by high water content or high salt wastewater.

[0008] In summary, existing three-phase separation systems suffer from low efficiency, poor stability, and high cost in oil-water separation and dissolved gas release. There is an urgent need for a highly efficient three-phase separation solution for oilfields that can simultaneously achieve rapid demulsification and stratification of oil and water and efficient release of dissolved gas, thereby improving system operational stability and processing efficiency. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this invention provides a high-efficiency three-phase separation device for oil, water, and gas in oilfields.

[0010] This utility model discloses a high-efficiency oil-water-gas three-phase separation device for oilfields, comprising an oil-gas-water separation tank. An ultrasonic transmitting device is installed at the center of the left end cap of the oil-gas-water separation tank, and an inlet II is provided at the upper end. A manhole is provided on the right end cap of the oil-gas-water separation tank, and an outlet II is provided on the upper right side of the oil-gas-water separation tank. A sewage pipe, a water outlet I, and an oil outlet I are arranged sequentially from left to right at the bottom of the oil-gas-water separation tank. A reflective deflector is provided at the inlet II inside the oil-gas-water separation tank, and a demister is provided at the outlet II inside the oil-gas-water separation tank. A coalescing plate and a defoamer are arranged sequentially from the inlet II to the outlet II at the top inside the oil-gas-water separation tank. An oil-water baffle is provided at the bottom of the oil-gas-water separation tank to the right of the defoamer. A safety valve and a solenoid valve are provided on the upper left side of the oil-gas-water separation tank.

[0011] As a further improvement of this utility model, the water outlet I and the oil outlet I are located on both sides of the oil-water baffle, respectively.

[0012] As a further improvement of this utility model, a pressure transmitter is provided at the upper end of the oil-gas-water separator, and a viscosity sensor is provided on the left side of the bottom of the oil-gas-water separator, an interface sensor is provided in the middle, and a conductivity sensor is provided on the right side of the oil-water baffle.

[0013] As a further improvement of this utility model, it also includes an explosion-proof junction box and an oil-gas-water three-phase separation controller. The oil-gas-water three-phase separation controller is connected to the explosion-proof junction box via signal and control cable I. The explosion-proof junction box is connected to the ultrasonic transmitting device, viscosity sensor, interface sensor, conductivity sensor and pressure transmitter via signal and control cable II, respectively.

[0014] Compared with existing technologies, this utility model has the following advantages:

[0015] 1. In terms of production quality and efficiency: Ultrasonic demulsification technology has completely changed the situation of low efficiency of traditional gravity sedimentation. Ultrasonic action only takes 3-15 minutes to achieve more thorough separation. The oil content of the effluent can be controlled below 50mg / L, and the separation speed is increased by 30-50 times. This high-efficiency separation directly brings about a leap in the equipment's processing capacity.

[0016] 2. Economic and environmental benefits: The cavitation effect generated by ultrasound creates strong turbulence in the liquid, which allows added demulsifiers and other chemical agents to be uniformly dispersed throughout the fluid system within milliseconds. This increases the agent utilization rate by more than 40%, reduces the amount of agents added, and avoids the waste of unreacted agents. Especially for heavy oil processing, traditional chemical demulsifiers have limited effectiveness for crude oil with a viscosity exceeding 500 mPa·s, while ultrasound can achieve a wider range of adaptability by adjusting the frequency.

[0017] 3. Dissolved gas treatment: Ultrasonic technology can work efficiently under mild conditions of 50℃, reducing fuel consumption by 40%. More importantly, the cavitation nuclei of ultrasound serve as the preferred nucleation points for gas separation, significantly reducing the free energy barrier required for gas evolution. This allows dissolved gases such as methane to rapidly form microbubbles under the action of the sound field, which then aggregate and grow. The gas evolution rate is 2-3 times higher than that of traditional gravity separation, with a separation rate of up to 98%. While increasing the efficiency of recovered gas, the low-temperature and low-pressure operating environment also significantly reduces equipment corrosion and enhances equipment safety.

[0018] 4. Operational Flexibility: The independently developed oil-gas-water three-phase separator controller has unique integrated advantages. The system has the ability to adjust the frequency in real time and can automatically adapt to flow fluctuations of ±30% to maintain stable separation results. The new generation of equipment integrates real-time acoustic impedance monitoring, real-time incoming liquid viscosity detection, real-time outgoing oil conductivity detection, and real-time outgoing oil water content monitoring functions. It can automatically adjust parameters according to data changes, with a response time of less than 50ms. At the same time, the entire system and the same equipment can process both light crude oil with a viscosity of 5mPa·s and heavy oil with a viscosity of up to 850mPa·s through parameter adjustments.

[0019] 5. In terms of stability: The properties of the produced fluid and the entire separation process are monitored in real time by automated instruments, ensuring the quality of exported oil, water and gas, and monitoring the stability of system operating parameters.

[0020] 6. Systemic aspects: The implementation of the high-efficiency oil-water-gas three-phase separation device in the oilfield has significantly improved the efficiency of dissolved gas precipitation, effectively avoiding the phenomenon of "secondary gas precipitation" caused by the sudden release of incompletely precipitated dissolved gas due to pressure or temperature changes after entering the downstream system with the liquid phase. This fundamentally ensures the operational stability of the subsequent processing system. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of this utility model. Detailed Implementation

[0022] This utility model discloses a high-efficiency oil-water-gas three-phase separation device for oilfields, comprising an oil-gas-water separation tank 301, an explosion-proof junction box 319, and a three-phase separation controller 320. The oil-gas-water three-phase separation controller 320 employs a PID-Fuzzy composite control algorithm with a sampling period ≤50ms and a response time ≤300ms. An ultrasonic transmitter 312 is installed at the center of the left end cap of the oil-gas-water separation tank 301, and a liquid inlet II 31 is provided at the upper end. The ultrasonic transmitter 312 has an adjustable operating frequency of 20–100kHz and an adjustable power of 5–20kW. The liquid inlet II 31 is connected to the produced fluid inlet pipeline 1. A reflective deflector plate 303 is provided at the liquid inlet II 31 inside the oil-gas-water separator 301. The reflective deflector plate 303 adopts a corrugated plate structure with a 30° tilt angle and the surface is polished, which can effectively disperse the fluid kinetic energy and make the incoming liquid evenly distributed. An outlet II 34 is provided on the upper right side of the oil-gas-water separator 301. The outlet II 34 is connected to the natural gas transmission pipeline 2. A demister 305 is provided at the outlet II 34 inside the oil-gas-water separator 301. A manhole 304 is provided on the right end cap of the oil-gas-water separator 301. The design of the manhole 304 facilitates the inspection and maintenance of the equipment inside the oil-gas-water separator 301 by the staff.

[0023] Inside the oil-gas-water separator 301, from the liquid inlet II 31 to the gas outlet II 34, a coalescing plate 306 and a defoamer 307 are sequentially arranged at the top. The coalescing plate 306 is made of 316L stainless steel, with a hydrophobic surface treatment, a contact angle ≥110°, a plate spacing of 50±2mm, and is arranged at an inclination of 45°. The defoamer 307 can effectively suppress the formation of foam layers and maintain interface stability. An oil-water baffle 308 is provided at the bottom of the oil-gas-water separator 301 to the right of the defoamer 307. At the bottom of the oil-gas-water separator 301, from left to right, a drain pipe 30, a water outlet I 32, and an oil outlet I 33 are sequentially arranged. The water outlet I 32 and the oil outlet I 33 are located on both sides of the oil-water baffle 308, and vortex defoamers are provided at both the water outlet I 32 and the oil outlet I 33 inside the oil-gas-water separator 301. The separator 302 is connected to the sewage pipe 30 and the sewage pipeline 4, and a shut-off valve 3 is provided on the sewage pipeline 4. The oil outlet I 33 is connected to the external transmission pipeline 5, and an automatic crude oil water content monitoring sensor 318 is provided on the external transmission pipeline 5. The automatic crude oil water content monitoring sensor 318 can monitor the water content of the externally transmitted oil in real time. A viscosity sensor 315 is provided on the left side of the bottom of the oil-gas-water separator 301, an interface sensor 316 is provided in the middle, and a conductivity sensor 317 is provided on the right side of the oil-water baffle 308. The interface sensor 316 is a radio frequency admittance interface sensor with a measurement accuracy of ±1mm. It is equipped with a hydrostatic level gauge for redundant measurement and can detect whether the oil layer interface is stable to ensure smooth crude oil overflow. The conductivity sensor 317 can monitor the quality of the overflow crude oil in real time.

[0024] A safety valve 309 and a solenoid valve 313 are provided on the upper left side of the oil-gas-water separator 301. The safety valve 309 adopts a spring-piloted structure, and the opening pressure is set to 1.1 times the working pressure. The action error is controlled within ±1%. A pressure transmitter 310 is provided in the middle of the upper part of the oil-gas-water separator 301.

[0025] The oil-gas-water three-phase separation controller 320 is connected to the explosion-proof junction box 319 via signal and control cable I 322. The explosion-proof junction box 319 is connected to the ultrasonic transmitting device 312, viscosity sensor 315, interface sensor 316, conductivity sensor 317 and pressure transmitter 310 via signal and control cable II 321.

[0026] In use, the produced fluid first enters the oil-gas-water separator 301 through the inlet pipe 1, impacting the reflective deflector 303. The reflective deflector 303 has a 30-degree inclined corrugated structure, which effectively disperses the fluid's kinetic energy, ensuring uniform distribution of the incoming fluid. When the liquid reaches the bottom of the oil-gas-water separator 301, the viscosity sensor 315 monitors the viscosity of the feed liquid in real time and transmits the data to the oil-gas-water three-phase separation controller 320. Then, after analysis by the oil-gas-water three-phase separation controller 320, different ultrasonic modes are applied according to different viscosities to perform demulsification-degassing synergistic operation on the produced fluid. The ultrasonic transmitter 312 emits an axial sound field to generate cavitation bubbles, which continuously act inside the oil-gas-water separator 301, destroying the W / O emulsion interface film, inducing dissolved gas nucleation, and forming a stable standing wave field inside. The oil droplet coalescence rate increases to 1.2 mm / s, and the bubble rising speed reaches 15 mm / s. Then, the oil-gas-water three-phase separation controller 320 adaptive module is activated to provide real-time feedback control of the production situation. Through real-time monitoring of acoustic impedance and real-time detection by viscosity sensor 315, when a sudden change in incoming fluid is detected, the pulse mode is automatically switched and the power is dynamically adjusted. Interface sensor 316 detects whether the oil layer interface is stable to ensure smooth overflow of crude oil. At the same time, defoamer 307 starts to operate to effectively suppress the formation of foam layer and maintain interface stability. The produced fluid is quickly separated under the action of ultrasonic emission device 312. The separated crude oil enters the overflow stage. When the oil layer thickness reaches the set value, the crude oil overflows smoothly from oil-water baffle 308. During the overflow process, conductivity sensor 317 monitors the quality of overflow crude oil in real time, and crude oil water content automatic monitoring sensor 318 monitors the water content of the exported oil in real time. The entire separation process is fully automated and requires no manual intervention, which not only ensures the quality of exported crude oil but also improves processing efficiency.

[0027] The ultrasonic transmitting device 312 operates continuously, and dissolved gas is continuously released from the liquid in the system, forming a gas top. As the gas in the tank increases, the gas pressure in the oil-gas-water separator 301 continuously increases. When the gas pressure in the tank is greater than the pressure of the natural gas external network, the gas in the tank is transported to the natural gas external network through the natural gas external transmission pipeline 2. The pressure transmitter 310 monitors the system pressure in real time to ensure the stable operation of the system.

[0028] With the continuous operation of the high-efficiency oil-water-gas three-phase separation device in the oilfield, impurities such as mud and sand in the produced fluid accumulate at the bottom of the device. According to the detection of the interface sensor 316, after the sewage discharge thickness is reached, the shut-off valve 3 is manually opened to manually discharge the sewage.

Claims

1. A high-efficiency oil-water-gas three-phase separation device for oilfields, comprising an oil-gas-water separator (301), characterized in that... An ultrasonic transmitting device (312) is installed at the center of the left end cap of the oil-gas-water separator (301), and a liquid inlet II (31) is provided at the upper end. A manhole (304) is provided on the right end cap of the oil-gas-water separator (301), and an air outlet II (34) is provided on the upper right side of the oil-gas-water separator (301). A sewage pipe (30), a water outlet I (32), and an oil outlet I (33) are provided sequentially from left to right at the bottom of the oil-gas-water separator (301). The liquid inlet II (31) is located inside the oil-gas-water separator (301). A reflective deflector plate (303) is provided at the oil-gas-water separator (301). A demister (305) is provided at the outlet II (34) inside the oil-gas-water separator (301). A coalescing plate (306) and a defoamer (307) are provided in sequence from the liquid inlet II (31) to the outlet II (34) inside the oil-gas-water separator (301). An oil-water baffle (308) is provided at the bottom of the oil-gas-water separator (301) to the right of the defoamer (307). A safety valve (309) and a solenoid valve (313) are provided on the upper left side of the oil-gas-water separator (301).

2. The high-efficiency oil-water-gas three-phase separation device for oilfields according to claim 1, characterized in that... The water outlet I (32) and oil outlet I (33) are located on both sides of the oil-water baffle (308).

3. The high-efficiency oil-water-gas three-phase separation device for oilfields according to claim 1, characterized in that... The oil-gas-water separator (301) is equipped with a pressure transmitter (310) at the upper end, a viscosity sensor (315) is provided on the left side of the bottom of the oil-gas-water separator (301), an interface sensor (316) is provided in the middle, and a conductivity sensor (317) is provided on the right side of the oil-water baffle (308).

4. The high-efficiency oil-water-gas three-phase separation device for oilfields according to claim 1, characterized in that... It also includes an explosion-proof junction box (319) and an oil-gas-water three-phase separation controller (320). The oil-gas-water three-phase separation controller (320) is connected to the explosion-proof junction box (319) via signal and control cable I (322). The explosion-proof junction box (319) is connected to the ultrasonic transmitter (312), viscosity sensor (315), interface sensor (316), conductivity sensor (317) and pressure transmitter (310) via signal and control cable II (321).

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