Oilfield three-phase separation process and separation system

Abstract

The present invention discloses an oilfield three-phase separation process and separation system, belonging to the field of oilfield technology. The process includes the following steps: 1. Density difference separation, inputting oilfield produced liquid or oilfield sewage into a three-phase separator, under the action of density difference, oil and natural gas in the oilfield produced liquid or oilfield sewage float up, and water flows downward; 2. Gas flotation, introducing natural gas into the three-phase separator, and the natural gas floats tiny bubbles, oil droplets, and mechanical impurities during the rising process; 3. Gas phase circulation, collecting the natural gas gas phase discharged from the three-phase separator and removing carbon dioxide and hydrogen sulfide, and then using it as the input gas of step 2 for recycling. The present invention does not need to heat the oil well produced liquid or oily sewage in advance, and can be treated at room temperature. Through the invented process, the oil content of the sewage reaches the recharge standard, the pH of the water body is stabilized, and new scale is avoided while descaling, which provides convenience for subsequent water treatment.

Description

Technical Field

[0001] The invention belongs to the technical field of oil fields, and more specifically, relates to an oil field three-phase separation process and a separation system. Background Art

[0002] Three-phase separators are widely used to separate oil, gas and water from the output fluid of oil wells in oil fields. The inlet pipe of the three-phase separator enters the inlet tank, the volume increases, the flow rate decreases, the pressure is reduced, and the gas naturally escapes and floats up as the pressure decreases. In the inlet tank, the oil, gas and water are initially separated by the difference in specific gravity. The separated water enters the sedimentation chamber from the bottom channel. When the separated liquid passes through the corrugated plate, the contact area increases. The stainless steel corrugated plate has the characteristics of hydrophilicity and oleophobicity, and the oil, gas and water are separated again. Then it enters the sedimentation chamber and is separated by the oil-water ratio. The liquid temperature is increased by heating, which increases the chance of collision between oil and water molecules and the specific gravity difference between oil and water. Small oil droplets, small water droplets and small bubbles collide to form large oil droplets, large water droplets and large bubbles, which accelerates the separation of oil, gas and water. Oil and gas float up and water sinks, achieving further separation of oil, gas and water, which are discharged through the outlet pipeline. The water in the three-phase separator is discharged into the buffer tank and is treated by gravity sedimentation, coarse filtration, fine filtration, flotation and a series of other treatments to make the oilfield wastewater meet the recharge standard.

[0003] The existing three-phase separation process is as follows: the water-containing crude oil from the well site is heated or enters the three-phase separator and then heated for three-phase separation. After separation, the gas goes to the gas-liquid separator to separate the oil and then is sent to the user for use. The water enters the sewage treatment system to separate mechanical impurities again. The separated purified oil enters the external transmission buffer tank for buffering and then is transmitted externally. The separated gas also goes to the associated gas separator.

[0004] The existing three-phase separation process has the following disadvantages: (1) High energy consumption. In order to obtain the ideal separation effect, the existing three-phase separator needs to increase the inlet temperature or increase the temperature in the three-phase separator. Only by increasing the liquid temperature can the specific gravity difference between oil, gas and water be increased, and the collision opportunities of oil, gas and water particles be increased, thereby improving the oil-water separation effect. However, as the oil field development reaches the middle and late stages, the incoming crude oil has a high water content, and increasing the liquid temperature will greatly increase energy consumption; (2) The separation effect is not good. When the inlet temperature is not too high, the oil content of the wastewater and the water content of the crude oil are both relatively high; (3) Wastewater treatment is difficult. After the three-phase separation of oilfield wastewater, buffering and gravity sedimentation are required. During a series of treatment processes such as coarse filtration, fine filtration, and flotation, the acidic gas in the sewage dissolves tiny bubbles that continuously gather, grow, float, and escape. These gases contain hydrogen sulfide and carbon dioxide. Therefore, the volatilization of the gas in the sewage will cause the pH value of the sewage to gradually increase during the treatment process. Calcium carbonate, magnesium carbonate and other scales are also continuously produced. While removing scale, new scale is generated, which makes it difficult to remove mechanical impurities mainly composed of scale. This makes the sewage treatment process long and complicated. (4) Severe corrosion. Due to the continuous escape of acidic gases, the oilfield storage and transportation facilities are severely corroded. For example, the top of crude oil and sewage storage tanks is a typical example of acid corrosion. Summary of the invention

[0005] In order to solve at least one of the above technical problems, according to one aspect of the present invention, an oilfield three-phase separation process is provided, comprising the following steps:

[0006] 1. Density difference separation: the oilfield liquid or oilfield wastewater is input into the three-phase separator. Under the action of density difference, the oil and natural gas in the oilfield liquid or oilfield wastewater float up, and the water flows downward;

[0007] Second, flotation: natural gas is introduced into the three-phase separator, and the natural gas floats tiny bubbles, oil droplets, and mechanical impurities during the rising process;

[0008] 3. Gas phase circulation: collect the natural gas gas phase discharged from the three-phase separator, remove carbon dioxide and hydrogen sulfide, and then use it as the input gas for step 2 for recycling.

[0009] According to the oil field three-phase separation process of the embodiment of the present invention, optionally, in step three, the collected natural gas is recycled after being treated to remove oil, carbon dioxide and hydrogen sulfide.

[0010] According to the oil field three-phase separation process of the embodiment of the present invention, optionally, in step 2, the oil-water mixture in the three-phase separator contacts the natural gas after passing through the coarse-grained material layer.

[0011] According to another aspect of the present invention, there is provided a vertical oilfield three-phase separation system, comprising:

[0012] A vertical three-phase separator, the interior of which includes a sewage separation section, a coarse-grained material layer, an oil-water separation section and a gas phase section from bottom to top; the three-phase separator also includes an oil inlet, a crude oil area, an oil outlet 1, an air inlet 1, a water collector and an air outlet 1; the oil inlet is connected to the oil-water separation section from the outside of the three-phase separator; the crude oil area is arranged in the oil-water separation section to collect the crude oil overflowing from the top of the oil-water separation section; the oil outlet 1 of the self-supporting three-phase separator is connected to the bottom of the crude oil area to discharge the separated crude oil; the air inlet 1 of the self-supporting three-phase separator is connected to the sewage separation section to input natural gas; the water collector is arranged in the sewage separation section below the air inlet 1 to collect sewage; a sewage area is arranged outside the vertical three-phase separator, the sewage area is connected to the water collector to receive the sewage transmitted by the water collector, and the sewage area is provided with a water outlet to discharge the sewage; the top of the air outlet 1 of the self-supporting three-phase separator is connected to the gas phase section to output natural gas;

[0013] A gas deoiler, which is connected to the gas outlet 1 of the vertical three-phase separator through a pipeline, receives the natural gas transmitted by the gas outlet 1 and performs oil and gas separation, and outputs the purified natural gas;

[0014] A gas deacidifier, which is connected to the gas deoiler through a pipeline, receives the purified natural gas output by the gas deoiler, removes acid gases such as carbon dioxide and hydrogen sulfide from it, and then outputs it;

[0015] The natural gas pressure control unit has one end connected to the gas deacidifier and the other end connected to the gas inlet 1 of the vertical three-phase separator, and inputs the natural gas treated by the gas deacidifier into the gas inlet 1.

[0016] According to the vertical oilfield three-phase separation system of the embodiment of the present invention, optionally, in the vertical three-phase separator,

[0017] The oil inlet is connected to the cyclone in the oil-water separation section, and the top of the cyclone is connected to the oil-water separation section;

[0018] It also includes a liquid distribution pipe, the top of which is connected to the bottom of the cyclone. The liquid distribution pipe is arranged in the coarse-grained material layer, and the oil-water mixture retained from the bottom of the cyclone is distributed to various parts of the coarse-grained material layer through the liquid distribution pipe.

[0019] According to the vertical oilfield three-phase separation system of the embodiment of the present invention, optionally, in the vertical three-phase separator, air inlet one is connected to aerator one in the sewage separation section.

[0020] According to the vertical oilfield three-phase separation system of an embodiment of the present invention, optionally, the sewage area is vertically arranged beside the vertical three-phase separator, and the height position of the water outlet is lower than the height position of the lowest point of the oil-water separation section; the top of the sewage area is connected to the gas phase section of the vertical three-phase separator through a gas phase balance pipe.

[0021] According to another aspect of the present invention, there is provided a horizontal oilfield three-phase separation system, comprising:

[0022] A horizontal three-phase separator, wherein the interior thereof includes an oil-water separation section, an oil-water separation section 2 and an oil outlet section in sequence from one end to the other end in the horizontal direction; the horizontal three-phase separator also includes an oil inlet 2, a cyclone 2, a liquid distribution pipe 2, an air inlet 4, a partition 1, an air inlet 5 and an air outlet 4; the oil inlet 2 is connected to the oil-water separation section from the outside of the horizontal three-phase separator; the outlet of the oil inlet 2 is connected to the cyclone 2; the top end of the liquid distribution pipe 2 is connected to the bottom of the cyclone 2, and the oil-water mixture left at the bottom of the cyclone 2 is distributed to the oil-water separation section through the liquid distribution pipe 2 The separation section is arranged at various places in the horizontal direction; the air inlet 4 is connected from the outside of the horizontal three-phase separator to the bottom of the oil-water separation section to input natural gas; the partition 1 separates the oil-water separation section and the oil-water separation section 2, and a gap is left from the top of the partition 1 to the top of the inner wall of the horizontal three-phase separator for the overflow of the oil-water mixture; the air inlet 5 is connected from the outside of the horizontal three-phase separator to the bottom of the oil-water separation section 2 to input natural gas; the tops of the oil-water separation section and the oil-water separation section 2 are both connected with an air outlet 4 to output the natural gas from the tops of the oil-water separation section and the oil-water separation section 2;

[0023] A gas deoiler, which is connected to the gas outlet 4 of the horizontal three-phase separator through a pipeline, receives the natural gas transmitted by the gas outlet 4 and performs oil and gas separation, and outputs the purified natural gas;

[0024] A gas deacidifier, which is connected to the gas deoiler through a pipeline, receives the purified natural gas output by the gas deoiler, removes acid gases such as carbon dioxide and hydrogen sulfide from it, and then outputs it;

[0025] The natural gas pressure control unit has one end connected to the gas deacidifier and the other end connected to the air inlet four and air inlet five of the horizontal three-phase separator, and inputs the natural gas treated by the gas deacidifier into the air inlet four and air inlet five.

[0026] According to the horizontal oilfield three-phase separation system of an embodiment of the present invention, optionally, it also includes a coarse-grained material layer 2, which is formed at one end of the oil-water separation section 2 close to the partition 1; the air inlet 5 is located between the coarse-grained material layer 2 and the oil outlet section.

[0027] According to the horizontal oilfield three-phase separation system of the embodiment of the present invention, optionally, in the horizontal three-phase separator, air inlet four is connected to aerator three, and air inlet five is connected to aerator four.

[0028] Beneficial Effects

[0029] Compared with the prior art, the oilfield three-phase separation process and separation system of the present invention have at least the following beneficial effects:

[0030] (1) The oilfield three-phase separation process of the present invention can simultaneously perform three different separation mechanisms on the oilfield produced liquid or oilfield wastewater entering therein. Through the cooperation of the three separation mechanisms of "density difference separation + air flotation + seed coarsening", it can achieve room-temperature dehydration of oil well produced liquid or room-temperature oil removal of oilfield wastewater. The oil content of wastewater meets the recharge standard, and the pH of the water body is stabilized, thereby avoiding the generation of new scale while removing scale, and causing mechanical impurities such as scale to form large particles, which provides convenience for subsequent water treatment;

[0031] (2) The oilfield three-phase separation process of the present invention can remove the acidic gases carbon dioxide and hydrogen sulfide in crude oil and sewage, and basically contains no acidic gases, which can reduce the corrosion of crude oil and sewage storage tanks;

[0032] (3) The oilfield three-phase separation system of the present invention has a three-phase separator based on the process design of the present invention, which has two structures, vertical and horizontal, and can effectively implement each step of the process of the present invention when performing three-phase separation;

[0033] (4) In the oilfield three-phase separation system of the present invention, a coarse-grained material layer is added to the three-phase separator to prevent excessive accumulation of bubbles, increase the collision opportunities of oil droplets, small bubbles and mechanical impurities, and thus enhance the flotation effect;

[0034] (5) The oilfield three-phase separation system of the present invention uses a gas deacidifier to deacidify the oilfield associated gas generated by separation, and the deacidified natural gas is then circulated in the three-phase separator to increase the pH value of the oil well production liquid or oily wastewater, thereby achieving the purpose of removing acidic gases from oilfield crude oil and wastewater, simplifying the subsequent wastewater treatment process, and delaying the corrosion of acidic gases to equipment, thereby increasing the effective service life of the system;

[0035] (6) In the oilfield three-phase separation system of the present invention, the liquid distribution pipe in the three-phase separator can evenly distribute the oil-water mixture to all parts of the coarse-grained material layer, thereby further increasing the chance of contact between the oil-water mixture and the floating natural gas bubbles and enhancing the flotation effect;

[0036] (7) In the oilfield three-phase separation system of the present invention, an aerator is arranged in the three-phase separator to make the natural gas form fine bubbles and float up, which are fully contacted with the descending oil-water mixture, thereby assisting in strengthening the separation effect of the oil, gas and water three phases and enhancing the flotation effect;

[0037] (8) In the oil field three-phase separation system of the present invention, the natural gas pressure control unit can quantitatively transmit the deacidified natural gas to the gas inlet 1. When the natural gas output is excessive, the excess natural gas can be supplied to users through the gas pipeline. When the natural gas is insufficient, the natural gas can be replenished in time through the gas replenishment pipeline. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present invention, but are not intended to limit the present invention.

[0039] Figure 1 A schematic diagram of a vertical oilfield three-phase separation system of the present invention is shown;

[0040] Figure 2 A schematic diagram of a vertical three-phase separator of the present invention is shown;

[0041] Figure 3 A schematic diagram of a gas deoiler of the present invention is shown;

[0042] Figure 4 A schematic diagram of a gas deacidification device according to the present invention is shown;

[0043] Figure 5 A schematic diagram of a natural gas pressure control unit of the present invention is shown;

[0044] Figure 6 A schematic diagram of a horizontal three-phase separator of the present invention is shown;

[0045] Reference numerals:

[0046] 1. Vertical three-phase separator;

[0047] 10. Oil inlet; 100. Cyclone; 11. Crude oil area; 12. Oil outlet 1; 13. Air inlet 1; 130. Aerator 1; 14. Water collector; 140. Sewage interface; 15. Sewage area; 150. Sand outlet 2; 151. Gas phase balance pipe; 16. Water outlet; 17. Air outlet 1; 170. Mist capture area; 18. Liquid distribution pipe; 19. Sand outlet 1;

[0048] 1000, sewage separation section; 1100, coarse granulation material layer; 1200, oil-water separation section; 1300, gas phase section;

[0049] 2. Gas degreaser;

[0050] 20. Air inlet 2; 21. Oil outlet 2; 22. Air outlet 2; 23. Sewage outlet 1;

[0051] 2000, oil pollution section; 2100, gas purification section;

[0052] 3. Gas deacidifier;

[0053] 30. Air inlet three; 300. Aerator two; 31. Air outlet three; 32. Sewage outlet two; 33. Alkali solution sampling tube; 34. Alkali solution mist collector;

[0054] 3000, alkali liquid section; 3100, natural gas section;

[0055] 4. Natural gas pressure control unit;

[0056] 40. Compressor; 41. Air supply pipeline; 410. Control valve 1; 42. Air supply pipeline; 420. Control valve 2;

[0057] 5. Horizontal three-phase separator;

[0058] 50. Oil inlet 2; 51. Cyclone 2; 52. Liquid distribution pipe 2; 53. Air inlet 4; 530. Aerator 3; 54. Baffle 1; 55. Coarse-grained material layer 2; 56. Air inlet 5; 560. Aerator 4; 57. Air outlet 4; 570. Mist capture area 2; 580. Sewage outlet 3; 581. Sewage outlet 4; 582. Sewage outlet 5; 59. Crude oil heater;

[0059] 5000, oil-waste separation section; 5100, oil-water separation section 2; 5200, oil outlet section. DETAILED DESCRIPTION

[0060] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the embodiments of the present invention will be described clearly and completely in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them.

[0061] Unless otherwise defined, the technical terms or scientific terms used herein shall have the common meanings understood by persons with ordinary skills in the field to which the present invention belongs. The words "one", "two" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components.

[0062] Example 1

[0063] The oil field three-phase separation process of this embodiment includes the following steps:

[0064] 1. Density difference separation: the oilfield liquid or oilfield wastewater is input into the three-phase separator. Under the action of density difference, the oil and natural gas in the oilfield liquid or oilfield wastewater float up, and the water flows downward;

[0065] Second, flotation: natural gas is introduced into the three-phase separator, and the natural gas floats tiny bubbles, oil droplets, and mechanical impurities during the rising process;

[0066] 3. Gas phase circulation: collecting the natural gas phase discharged from the three-phase separator, removing carbon dioxide and hydrogen sulfide, and recycling it as the input gas for step 2;

[0067] Furthermore, in step three, the collected natural gas is recycled after being treated to remove oil, carbon dioxide and hydrogen sulfide;

[0068] Furthermore, in step 2, the oil-water mixture in the three-phase separator contacts the natural gas after passing through the coarse-grained material layer.

[0069] The three-phase separation process of the present embodiment can simultaneously perform three different separation mechanisms on the oilfield produced liquid or oilfield sewage entering therein. The first is gravity separation. Through the inherent structure of the three-phase separator, the oilfield produced liquid or oilfield sewage utilizes the density difference of different phases, and the oil and gas float up, while the impurities such as water and sewage sink. The second is the flotation principle. The process of the present embodiment circulates the natural gas passed into the three-phase separator. During the flotation process, the mechanical impurities, small oil droplets, and small bubbles in the water will adhere to the natural gas, and the oil-water mixture will be disturbed to increase the collision chance, thereby forming the flotation of tiny bubbles, small diameter oil droplets, and mechanical impurities. The third is the seed principle. In the process of the present embodiment, the natural gas is passed into the three-phase separator after being deacidified. The concentrations of hydrogen sulfide and carbon dioxide contained in the sewage and crude oil are relatively high. The hydrogen sulfide and carbon dioxide are removed from the crude oil and the three-phase separator. Sewage diffuses into the natural gas bubbles and is carried away by the bubbles. The pH value of the water body rises rapidly near the stable state. Due to the rapid change of pH, a large number of tiny mechanical impurities are quickly formed in the three-phase separator in a short time. These bubbles, mechanical impurities, oil droplets and other tiny particles in the water act as crystal seeds, providing crystal cores for the growth and aggregation of particles, thereby quickly forming scale sedimentation; at the same time, the presence of the coarse-grained material layer can prevent the bubbles from aggregating too large, increase the collision opportunities of oil droplets, small bubbles and mechanical impurities, and thus enhance the flotation effect; through the three-phase separation process of this embodiment, the three separation mechanisms can interact with each other, thereby effectively reducing the water content of the exported crude oil and the oil content of the sewage, and making the pH value of the sewage basically stable, creating conditions for sedimentation separation, and greatly simplifying the process of subsequent sewage treatment.

[0070] Example 2

[0071] The vertical oilfield three-phase separation system of this embodiment includes:

[0072] The vertical three-phase separator 1 is a vertical structure, and includes a sewage separation section 1000, a coarse-grained material layer 1100, an oil-water separation section 1200 and a gas phase section 1300 from bottom to top; the vertical three-phase separator 1 also includes an oil inlet 10, a crude oil zone 11, an oil outlet 12, an air inlet 13, a water collector 14 and an air outlet 17; the oil inlet 10 is connected to the oil-water separation section 1200 from the outside of the vertical three-phase separator 1 to input crude oil; the crude oil zone 11 is arranged in the oil-water separation section 1200 to collect the crude oil overflowing from the top of the oil-water separation section 1200; the oil outlet 12 ... oil-water separation section 1200 is connected to the oil-water separation section 1200 from the outside of the vertical three-phase separator 1 to input crude oil; the oil-water separation section 11 is connected to the oil-water separation section 1200 from the outside of the vertical three-phase separator 1 to input crude oil; the oil-water separation section 11 is connected to the oil-water separation section 1200 from the outside of the vertical three-phase separator 1 to input crude oil; the oil-water separation section 11 is connected to the oil-water separation section 1200 from the outside of the vertical three-phase separator 1 to input crude oil; the oil-water separation section 11 is connected to the oil-water separation section 1200 from the outside of The phase separator 1 is externally connected to the bottom of the crude oil zone 11 to discharge the separated crude oil; the air inlet 13 of the self-supporting three-phase separator 1 is externally connected to the sewage separation section 1000 to input natural gas; the water collector 14 is arranged in the sewage separation section 1000 below the air inlet 13 to collect sewage; a sewage zone 15 is arranged outside the vertical three-phase separator 1, the sewage zone 15 is connected to the water collector 14 to receive the sewage transmitted by the water collector 14, and the sewage zone 15 is provided with a water outlet 16 to discharge sewage; the air outlet 17 of the self-supporting three-phase separator 1 is externally connected to the gas phase section 1300 at the top to output natural gas;

[0073] The gas deoiler 2 is connected to the gas outlet 17 of the vertical three-phase separator 1 through a pipeline, receives the natural gas transmitted by the gas outlet 17 and performs oil and gas separation, and outputs the purified natural gas;

[0074] The gas deacidifier 3 is connected to the gas deoiler 2 through a pipeline, receives the purified natural gas output by the gas deoiler 2, removes acid gases such as carbon dioxide and hydrogen sulfide from it, and then outputs it;

[0075] The natural gas pressure control unit 4 has one end connected to the gas deacidifier 3 and the other end connected to the gas inlet 13 of the vertical three-phase separator 1 , so that the natural gas treated by the gas deacidifier 3 is input into the gas inlet 13 .

[0076] The vertical three-phase separation system of this embodiment is composed of four parts, namely, a vertical three-phase separator 1, a gas deoiler 2, a gas deacidifier 3 and a natural gas pressure control unit 4. Figure 1 shown.

[0077] Among them, the vertical three-phase separator 1 is as follows Figure 2As shown, the vertical three-phase separator 1 of this embodiment is different from the traditional vertical three-phase separation equipment in that a coarse-grained material layer 1100 is added between the sewage separation section 1000 and the oil-water separation section 1200 in this embodiment. More specifically, the coarse-grained material layer 1100 of this embodiment is filled with commonly used water treatment three-dimensional fillers, and an air inlet 13 is set at the sewage separation section 1000 in this embodiment to introduce natural gas. It should be noted that the natural gas introduced into the air inlet 13 of this embodiment is mainly oilfield associated gas, that is, the gas phase gas separated when the oil well production liquid is separated into three phases, and the associated natural gas is deacidified by the gas deacidifier 3 before being circulated into the vertical three-phase separator 1.

[0078] In the vertical three-phase separator 1 of this embodiment, when the oil well production liquid or oilfield sewage enters the oil-water separation section 1200 through the oil inlet 10, the oil and water are initially separated, the main oil stays in the oil-water separation section 1200, and the oil-water mixture descends to the coarse-grained material layer 1100, and the sewage, impurities, etc. therein will continue to settle, and the natural gas introduced through the air inlet 13 can absorb the acidic gas in the oil-water mixture, such as carbon dioxide, hydrogen sulfide, etc., during the floating process, so as to increase its pH value, thereby achieving the purpose of removing the acidic gas in the oilfield crude oil and sewage. The design of the coarse-grained material layer 1100 can increase the chance of collision between oil droplets, bubbles and mechanical impurities, thereby improving the flotation effect. Finally, the main oil flows upward under the action of buoyancy and flotation, and finally passes through the crude oil area 11 and is discharged from the oil outlet 12. The sewage continues to sink and is collected by the water collector 14 to the sewage area 15 and then discharged through the water outlet 16, while the mechanical impurities and the like are precipitated and deposited at the bottom of the sewage separation section 1000.

[0079] Furthermore, the crude oil area 11 of the present embodiment is an overflow box structure with an opening at the top. The top height is the same as the top height of the oil-water separation section 1200. After the liquid level of the main oil in the oil-water separation section 1200 is higher than the top height of the crude oil area 11, it overflows into the crude oil area 11 and is discharged from the oil outlet 12 at the bottom of the crude oil area 11.

[0080] The inner diameter of the bottom of the sewage separation section 1000 of this embodiment gradually decreases to form a sand accumulation hopper, and a sand outlet 19 is set at the bottom of the sewage separation section 1000 to connect to the outside of the vertical three-phase separator 1, which can facilitate the centralized discharge and treatment of sediments.

[0081] The gas deoiler 2 of this embodiment is a common device in the prior art, and its interior is divided into an oil pollution section 2000 and a purified gas section 2100 from bottom to top. Figure 3As shown, the natural gas discharged from the gas outlet 17 of the vertical three-phase separator 1 passes through the pipeline and enters the gas deoiler 2 from the gas inlet 20, and the oil in the natural gas is further removed in the gas deoiler 2. The purified natural gas is concentrated in the purified gas section 2100 and finally discharged into the gas deacidifier 3 from the top gas outlet 22, while the separated crude oil and sewage are discharged from the oil outlet 21 and the sewage outlet 1 23 respectively.

[0082] The gas deacidifier 3 of this embodiment contains alkaline liquid inside. The purified natural gas passes through the alkaline liquid to remove acidic gases such as carbon dioxide and hydrogen sulfide, and is finally discharged to the natural gas pressure control unit 4. The natural gas pressure control unit 4 then sends the deacidified natural gas to the air inlet 13 of the vertical three-phase separator 1 in a quantitative manner, forming a natural gas circulation.

[0083] Example 3

[0084] The vertical oilfield three-phase separation system of this embodiment is further improved on the basis of Embodiment 2. In the vertical three-phase separator 1,

[0085] The oil inlet 10 is connected to the cyclone 100 in the oil-water separation section 1200, and the top of the cyclone 100 is connected to the oil-water separation section 1200;

[0086] It also includes a liquid distribution pipe 18, the top of which is connected to the bottom of the cyclone 100. The liquid distribution pipe 18 is arranged in the coarse-grained material layer 1100, and the oil-water mixture retained from the bottom of the cyclone 100 is distributed to various parts of the coarse-grained material layer 1100 through the liquid distribution pipe 18.

[0087] like Figure 2 As shown, the cyclone 100 is an existing structural component, which is a tubular object with a diameter larger than that of the oil inlet 10. A guide groove is arranged inside the cyclone to allow water with higher density and mechanical impurities to flow downward, while the gas phase and the main oil flow upward, thereby achieving preliminary separation.

[0088] The liquid distribution pipe 18 in this embodiment is connected to the bottom of the cyclone 100, and the liquid distribution pipe 18 is distributed to various parts of the coarse-grained material layer 1100. The liquid flowing into the liquid distribution pipe 18 through the cyclone 100 will be evenly distributed to various parts of the coarse-grained material layer 1100 by the liquid distribution pipe 18, thereby increasing the chance of contacting the floating natural gas bubbles and enhancing the flotation effect.

[0089] Example 4

[0090] The vertical oilfield three-phase separation system of this embodiment is further improved on the basis of Embodiment 3. In the vertical three-phase separator 1, the air inlet 13 is connected to the aerator 130 in the sewage separation section 1000.

[0091] like Figure 2As shown, the aerator 130 of this embodiment can adopt structures such as diffusion plates, microporous tubes, perforated tubes and diffusion tubes, which can make the natural gas form a large number of fine bubbles with an average diameter of 0.1~5mm, which are dispersed in the sewage separation section 1000, and then fully contact with the descending oil-water mixture during the floating process. Under the action of the coarse-grained material layer 1100, the bubble size can be effectively controlled without generating large bubbles. In the coarse-grained material layer 1100, the bubble direction and the water flow direction will constantly change, and the chance of collision between the natural gas bubbles and oil droplets, mechanical particles, etc. is greatly increased.

[0092] Example 5

[0093] The vertical oilfield three-phase separation system of this embodiment is further improved on the basis of Example 4. The sewage area 15 is vertically arranged beside the vertical three-phase separator 1, and the height position of the water outlet 16 is lower than the height position of the lowest point of the oil-water separation section 1200; the top of the sewage area 15 is connected to the gas phase section 1300 of the vertical three-phase separator 1 through the gas phase balance pipe 151.

[0094] like Figure 2 As shown, the sewage area 15 of this embodiment is in the shape of a vertical tube, which, together with the structure of the vertical three-phase separator 1, greatly saves the space occupied by the equipment. Moreover, since the height position of the water outlet 16 is lower than the height position of the lowest point of the oil-water separation section 1200, the height difference from the lowest point of the oil-water separation section 1200 to the sewage interface 140 is greater than the height difference from the water outlet 16 to the sewage interface 140, the sewage can be discharged from the water outlet 16 by utilizing the pressure difference.

[0095] Furthermore, the top of the sewage area 15 is connected to the gas phase section 1300 of the vertical three-phase separator 1 through a gas phase balance pipe 151.

[0096] Since the sewage inevitably still contains gas phase, the gas phase continues to accumulate at the top of the sewage area 15, which will affect the normal discharge of the sewage. Therefore, a gas phase balance pipe 151 is set to connect the top of the sewage area 15 with the gas phase section 1300 of the vertical three-phase separator 1 to discharge the excess gas phase accumulated at the top of the sewage area 15 in time.

[0097] Furthermore, a mist collecting area 170 is provided at the top of the gas phase section 1300 connected to the gas outlet 17, which can collect the oil mist in the gas phase and reduce the oil content in the gas phase.

[0098] Example 6

[0099] The horizontal oilfield three-phase separation system of this embodiment includes:

[0100] The horizontal three-phase separator 5 includes an oil separation section 5000, an oil-water separation section 5100 and an oil outlet section 5200 in sequence from one end to the other in the horizontal direction; the horizontal three-phase separator 5 also includes an oil inlet 50, a cyclone 51, a liquid distribution pipe 52, an air inlet 53, a partition 54, an air inlet 56 and an air outlet 57; the oil inlet 50 is connected from the outside of the horizontal three-phase separator 5 to the oil separation section 5000; the outlet of the oil inlet 50 is connected to the cyclone 51; the top of the liquid distribution pipe 52 is connected to the bottom of the cyclone 51, and the oil-water mixture left at the bottom of the cyclone 51 is distributed to the oil separation section 5000 through the liquid distribution pipe 52. The gas inlet 4 53 is connected from the outside of the horizontal three-phase separator 5 to the bottom of the oil-water separation section 5000 to input natural gas; the partition 1 54 separates the oil-water separation section 5000 and the oil-water separation section 2 5100, and a gap is left from the top of the partition 1 54 to the top of the inner wall of the horizontal three-phase separator 5 for the overflow of the oil-water mixture; the gas inlet 56 is connected from the outside of the horizontal three-phase separator 5 to the bottom of the oil-water separation section 2 5100 to input natural gas; the tops of the oil-water separation section 5000 and the oil-water separation section 2 5100 are both connected with the gas outlet 4 57 to output the natural gas from the tops of the oil-water separation section 5000 and the oil-water separation section 2 5100;

[0101] The gas deoiler 2 is connected to the gas outlet 457 of the horizontal three-phase separator 5 through a pipeline, receives the natural gas transmitted by the gas outlet 457 and performs oil and gas separation, and outputs the purified natural gas;

[0102] The gas deacidifier 3 is connected to the gas deoiler 2 through a pipeline, receives the purified natural gas output by the gas deoiler 2, removes acid gases such as carbon dioxide and hydrogen sulfide from it, and then outputs it;

[0103] The natural gas pressure control unit 4 has one end connected to the gas deacidifier 3 and the other end connected to the air inlet 4 53 and the air inlet 56 of the horizontal three-phase separator 5, and inputs the natural gas treated by the gas deacidifier 3 into the air inlet 4 53 and the air inlet 56.

[0104] The horizontal three-phase separation system of this embodiment is composed of four parts, namely, a horizontal three-phase separator 5 , a gas deoiler 2 , a gas deacidifier 3 and a natural gas pressure control unit 4 .

[0105] Among them, the horizontal three-phase separator 5 is as follows Figure 6As shown, the oilfield produced liquid or oilfield sewage is input into the oil-contaminated separation section 5000 through the oil inlet 2 50, and passes through the cyclone 2 51. Due to the structural characteristics of the cyclone 2 51, the water with higher density and mechanical impurities flow downward, and the gas phase and the main oil flow upward, thereby achieving preliminary separation. In the oil-contaminated separation section 5000, the gas phase rises to the top of the horizontal three-phase separator 5, the oil-water mixture is concentrated in the upper area, and the sludge and other impurities settle downward. Since the bottom of the cyclone 2 51 is connected to the liquid distribution pipe 2 52, the liquid distribution pipe 2 52 is horizontally distributed. The liquid retained at the bottom of the cyclone 51 can be evenly distributed to various places in the horizontal direction for sedimentation. At the same time, an air inlet 4 53 is provided below the liquid distribution pipe 52. Natural gas is introduced from the air inlet 4 53 and moves upward due to buoyancy. The liquid retained through the liquid distribution pipe 52 will fully contact with the natural gas. The natural gas can absorb the acidic gas in the oil-water mixture, such as carbon dioxide, hydrogen sulfide, etc., during the floating process, so as to increase its pH value, thereby achieving the purpose of removing the acidic gas in the crude oil and sewage in the oil field. Finally, in the oil separation section 500 0, the main oil and oil-water mixture flow upward under the action of buoyancy and flotation, and finally overflow to the oil-water separation section 2 5100 through the top of the partition 1 54, while the sewage impurities continue to sink and are finally discharged through the sewage outlet 3 580; after the main oil and oil-water mixture enter the oil-water separation section 2 5100, they continue to be stratified. At the same time, an air inlet 56 is provided in the oil-water separation section 2 5100 to allow natural gas to be introduced. The natural gas continues to float during the floating process. A crude oil heater 59 is also provided in the oil-water separation section 2 5100 to ensure that the oil-water separation section 2 The fluidity of the crude oil in 5100; after being separated again in the oil-water separation section 2 5100, the main oil and water enter the oil outlet section 5200 respectively and are discharged from different pipelines; in the horizontal three-phase separator 5 of this embodiment, the top of the three-phase separator corresponding to the oil separation section 5000 and the oil-water separation section 2 5100 is provided with an outlet port 4 57 connected to the top of the corresponding section, and the outlet port 4 57 is provided with a mist capture area 2 570 for collecting the gas phase generated during the separation process, and preliminarily capturing the oil mist in the gas phase before exhausting, so as to reduce the oil content of the gas.

[0106] The gas deoiler 2 of this embodiment is a common device in the prior art, and its interior is divided into an oil pollution section 2000 and a purified gas section 2100 from bottom to top. Figure 3 As shown, the natural gas discharged from the gas outlet four 57 of the horizontal three-phase separator 5 passes through the pipeline and enters the gas deoiler 2 from the gas inlet two 20, and the oil in the natural gas is further removed in the gas deoiler 2. The purified natural gas is concentrated in the purified gas section 2100 and finally discharged into the gas deacidifier 3 from the top gas outlet two 22, while the separated crude oil and sewage are discharged from the oil outlet two 21 and the sewage outlet one 23 respectively.

[0107] The gas deacidifier 3 of this embodiment contains alkaline liquid inside. The purified natural gas passes through the alkaline liquid to remove acidic gases such as carbon dioxide and hydrogen sulfide, and is finally discharged to the natural gas pressure control unit 4. The natural gas pressure control unit 4 then sends the deacidified natural gas to the air inlet 4 53 and the air inlet 5 56 of the horizontal three-phase separator 5 in a quantitative manner, forming a natural gas circulation.

[0108] Example 7

[0109] The horizontal oilfield three-phase separation system of this embodiment is further improved on the basis of Example 6, and also includes a coarse-grained material layer 2 55, which is formed at one end of the oil-water separation section 2 5100 close to the partition 1 54; the air inlet 56 is located between the coarse-grained material layer 2 55 and the oil outlet section 5200.

[0110] like Figure 6 As shown, the coarse-grained material layer 2 55 of this embodiment is filled with commonly used water treatment three-dimensional fillers. The main oil and oil-water mixture overflowing from the partition 1 54 need to pass through the coarse-grained material layer 2 55 before entering the subsequent space of the oil-water separation section 2 5100. When passing through the coarse-grained material layer 2 55, the chance of collision between oil droplets, bubbles and mechanical impurities can be increased, and the flotation of natural gas input through the air inlet 56 is beneficial to the separation of oil and water. Two sewage outlets are provided at the bottom of the oil-water separation section 2 5100, the sewage outlet 4 581 is located between the partition 1 54 and the coarse-grained material layer 2 55, and the sewage outlet 5 582 is located between the coarse-grained material layer 2 55 and the oil outlet section 5200.

[0111] Example 8

[0112] The horizontal oilfield three-phase separation system of this embodiment is further improved on the basis of Embodiment 7. In the horizontal three-phase separator 5, the air inlet four 53 is connected to the aerator three 530, and the air inlet five 56 is connected to the aerator four 560.

[0113] like Figure 6 As shown, the structures of the aerator three 530 and the aerator four 560 of this embodiment are the same as the aerator structure in the vertical three-phase separator 1, and can adopt structures such as diffusion plates, microporous tubes, perforated tubes and diffusion tubes, which can make the natural gas form a large number of fine bubbles with an average diameter of 0.1~5mm. During the floating process, they are fully in contact with the descending oil-water mixture, increasing the chance of collision between the natural gas bubbles and oil droplets, mechanical particles, etc., and further enhancing the flotation and crystallization effects.

[0114] Example 9

[0115] This embodiment shows a structural form of a gas deacidifier 3, which is applicable to the vertical three-phase separation system and the horizontal three-phase separation system of the present invention. The gas deacidifier 3 includes an alkali liquid section 3000 and a natural gas section 3100 from bottom to top; the gas deacidifier 3 also includes an air inlet 30, an air outlet 31, a sewage outlet 2 32, an alkali liquid sampling tube 33 and an alkali liquid mist collector 34; the air inlet 30 is connected to the alkali liquid section 3000 from the outside of the gas deacidifier 3, and the purified gas transmitted from the gas deoiler 2 is input to the alkali liquid section 3000. The gas inlet three 30 is connected with the aerator two 300 in the alkali liquid section 3000; the gas outlet three 31 is connected from the external top of the gas deacidifier 3 to the natural gas section 3100, and outputs natural gas to the natural gas pressure control unit 4; the sewage outlet two 32 is connected from the external bottom of the gas deacidifier 3 to the alkali liquid section 3000 to discharge precipitated impurities; the alkali liquid sampling tube 33 is connected from the external gas deacidifier 3 to the alkali liquid section 3000; the alkali liquid mist collector 34 is arranged at the top of the natural gas section 3100 to absorb the alkali liquid in the natural gas.

[0116] like Figure 4 As shown, the purified natural gas enters the alkali liquid section 3000 from the air inlet three 30, is dispersed into a large number of fine bubbles under the action of the aerator two 300, and is fully contacted with the alkali liquid to remove acidic gases such as carbon dioxide and hydrogen sulfide. The deacidified natural gas rises to the natural gas section 3100, passes through the alkali liquid mist collector 34, absorbs most of the alkali liquid and is discharged from the air outlet three 31 to the natural gas pressure control unit 4. Precipitated impurities will be generated during the deacidification of the natural gas, settle to the bottom of the alkali liquid section 3000, and be discharged from the sewage outlet two 32. The alkali liquid sampling tube 33 can regularly sample the alkali liquid in the alkali liquid section 3000, which is convenient for regularly judging whether the alkali liquid is invalid and replacing it in time to ensure the deacidification effect.

[0117] Example 10

[0118] This embodiment shows a structural form of a natural gas pressure control unit 4, which is applicable to the vertical three-phase separation system and the horizontal three-phase separation system of the present invention. The natural gas pressure control unit 4 includes a compressor 40, one end of which is connected to the gas outlet 31 of the gas deacidifier 3 through a pipeline, and the other end is connected to the gas inlet 13 of the vertical three-phase separator 1 through a pipeline, or is connected to the gas inlet 4 53 and the gas inlet 56 of the horizontal three-phase separator 5 through a pipeline.

[0119] The natural gas pressure control unit 4 also includes:

[0120] The air supply pipeline 41 is connected to the pipeline connected to the air outlet 31 of the compressor 40;

[0121] The gas pipeline 42 is connected to the compressor 40 and the pipeline of the vertical three-phase separator 1 or the horizontal three-phase separator 5 is connected.

[0122] like Figure 5 As shown, the deacidified natural gas output from the gas outlet 31 is quantitatively transported to the corresponding three-phase separator through the compressor 40 .

[0123] In the actual treatment process, if the main treatment is oilfield sewage, the amount of natural gas entering the three-phase separator may not be enough to make up for the gas lost with the sewage. At this time, the pressure in the pipeline from the compressor 40 to the gas outlet 31 will decrease. When the control valve 1 410 of the gas supply pipeline 41 detects that the pressure decrease exceeds a certain threshold, the control valve 1 410 will open, and hydrocarbon gas, such as natural gas acetylene, will be added to the compressor 40 to ensure the transmission gas volume of the compressor 40;

[0124] If the main processing is the oil well output liquid, the inlet liquid of the three-phase separator will contain a part of natural gas, and excess gas will be generated during the processing process. At this time, the pressure in the pipeline from the compressor 40 to the outlet 31 will increase. When the control valve 2 420 of the gas pipeline 42 detects that the pressure increase exceeds a certain threshold, the control valve 2 420 opens to supply gas to the outside, such as to natural gas users.

[0125] Embodiment 11

[0126] This embodiment shows a method for using a vertical three-phase separation system, comprising the following steps:

[0127] 1. Oilfield produced liquid or oilfield wastewater is input from the oil inlet 10 of the vertical three-phase separator 1, and natural gas transmitted by the compressor 40 is input from the gas inlet 13 of the vertical three-phase separator 1;

[0128] Second, the oilfield liquid or oilfield wastewater passes through the oil inlet 10 to the cyclone 100. The main oil and natural gas have a lower density. Natural gas and most of the crude oil will enter the oil-water separation section 1200 from the top of the cyclone 100, while the oil-water mixture has a higher density and will enter the liquid distribution pipe 18 through the bottom of the cyclone 100 to achieve preliminary oil-water separation. The liquid distribution pipe 18 evenly distributes the oil-water mixture to all parts of the coarse-grained material layer 1100 to facilitate subsequent separation;

[0129] The natural gas passes through the air inlet 13 to the aerator 130, and a large number of natural gas bubbles with an average diameter of 0.1-5 mm are generated and enter the sewage separation section 1000. The natural gas bubbles move upward under the action of buoyancy, and pass through the coarse-grained material layer 1100 and the oil-water separation section 1200 in sequence to the gas phase section 1300. During the upward floating process, the bubbles flow in the opposite direction to the sewage and the sinking impurities, and in the same direction as the main oil, which will play a flotation role on the sewage, the main oil, and the impurities, and accelerate the upward movement of the main oil and tiny bubbles. The coarse-grained material layer 1100 can strengthen the disturbance and prevent the bubbles from growing;

[0130] 3. The main oil in the vertical three-phase separator 1 continuously floats up and enters the oil-water separation section 1200, the sewage continuously sinks to the sewage separation section 1000, and the impurities are precipitated and deposited at the bottom of the sewage separation section 1000;

[0131] Fourth, the water collector 14 of the sewage separation section 1000 collects sewage and transmits it to the sewage area 15, and finally discharges it from the water outlet 16. The sewage area 15 is vertically arranged, and a sand outlet 150 is arranged at the bottom. The sediment mixed in the sewage is discharged from the sand outlet 150. Since a small amount of natural gas may be mixed in the sewage, in order to avoid the accumulation of natural gas in the sewage area 15, which leads to an increase in pressure and affects sewage discharge, the natural gas is timely transmitted to the gas phase section 1300 through the gas phase balance pipe 151;

[0132] The main oil in the vertical three-phase separator 1 continuously flows upward under the action of buoyancy and natural gas flotation, and is concentrated in the oil-water separation section 1200. When the main oil level in the oil-water separation section 1200 is higher than the top height of the crude oil area 11, the main oil overflows into the crude oil area 11 and is finally discharged from the oil outlet 12.

[0133] The natural gas in the gas phase section 1300 is de-oiled in the mist collecting area 170 and then transmitted from the gas outlet 17 to the gas de-oiler 2;

[0134] 5. The natural gas is further separated from oil and gas in the gas de-oiler 2, and the purified natural gas is output from the gas outlet 22 at the top of the gas de-oiler 2 to the gas de-acidifier 3, and the separated main oil and sewage are respectively discharged from the oil outlet 21 and the sewage outlet 1 23 at the bottom of the gas de-oiler 2;

[0135] 6. The purified natural gas passes through the air inlet 30 to the aerator 2 300, generating a large number of natural gas bubbles which are input into the alkali liquid section 3000, so that the natural gas is fully in contact with the alkali liquid in the alkali liquid section 3000, removing the acidic gases hydrogen sulfide and carbon dioxide. The bubbles float up to the natural gas section 3100 through the alkali liquid section 3000, and are transmitted to the compressor 40 from the air outlet 31 after passing through the alkali liquid mist collector 34. The alkali liquid mist collector 34 absorbs most of the alkali liquid in the natural gas. After being transmitted to the vertical three-phase separator 1 through the compressor 40, the natural gas bubbles in the vertical three-phase separator 1 will effectively absorb the alkali liquid in the floating process. Collect the acidic gases such as carbon dioxide and hydrogen sulfide dissolved in the oilfield production liquid or oilfield sewage, so that the pH of the sewage water body flowing downward in the vertical three-phase separator 1 quickly reaches a stable state, and due to the rapid increase in pH, scales such as calcium carbonate and magnesium carbonate will be quickly generated. Under the action of the coarse-grained material layer 1100 and the floating bubbles, the crystal nuclei of the scale will grow rapidly, thereby forming a precipitate deposited at the bottom of the sewage separation section 1000 and discharged through the sand outlet 19, thereby ensuring that the pH of the sewage discharged from the water outlet 16 meets the standard and does not generate scale, so as to simplify the subsequent treatment process of the sewage;

[0136] The impurities, sewage and other sediments produced by the alkali liquid section 3000 are discharged from the bottom sewage outlet 2 32. The alkali liquid is regularly analyzed through the alkali liquid sampling tube 33, and the invalid alkali liquid is replaced in time to ensure the gas deacidification effect;

[0137] 7. The compressor 40 quantitatively transmits the natural gas transmitted from the gas outlet 31 to the gas inlet 13 of the vertical three-phase separator 1;

[0138] When the amount of natural gas transmitted by the gas outlet 31 is less than the amount required to be transmitted by the compressor 40, the gas supply pipeline 41 supplies gas to the natural gas pressure control unit 4. When the process of this embodiment mainly treats oilfield sewage, the amount of natural gas entering the vertical three-phase separator 1 may be insufficient to replenish the amount of gas lost with the sewage. At this time, the pressure in the pipeline from the compressor 40 to the gas outlet 31 will be reduced. When the control valve 1 410 of the gas supply pipeline 41 detects that the pressure decrease exceeds a certain threshold, the control valve 1 410 will open, and hydrocarbon gas, such as natural gas acetylene, will be supplemented to the compressor 40 to ensure the transmission gas volume of the compressor 40.

[0139] When the amount of natural gas transmitted by the gas outlet three 31 is greater than the amount that the compressor 40 needs to transmit, the gas pipeline 42 is used to supply gas to the outside. When the process of this embodiment mainly processes the oil well output liquid, the inlet liquid of the vertical three-phase separator 1 will contain a part of natural gas, and excess gas will be generated during the processing. At this time, the pressure in the pipeline from the compressor 40 to the gas outlet three 31 will increase. When the control valve two 420 of the gas pipeline 42 detects that the pressure increase exceeds a certain threshold, the control valve two 420 opens to supply gas to the outside, such as to natural gas users.

[0140] Through the process of this embodiment, there is no need to heat the oil well production fluid or oily wastewater in advance, and it can be treated at room temperature. Moreover, through the process of this embodiment, the oil content of the wastewater reaches the re-injection standard, and the pH of the water body is stabilized, thereby avoiding the generation of new scale while removing scale, and causing mechanical impurities such as scale to form large particles, which provides convenience for subsequent water treatment.

[0141] The examples described in the present invention are merely descriptions of the preferred implementation modes of the present invention, and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made to the technical solutions of the present invention by engineers and technicians in this field should all fall within the protection scope of the present invention.

Claims

1. An oilfield three-phase separation process, characterized in that: The steps include:

1. Density difference separation: the oilfield liquid or oilfield wastewater is input into the three-phase separator. Under the action of density difference, the oil and natural gas in the oilfield liquid or oilfield wastewater float up, and the water flows downward; 2. Gas flotation: natural gas is introduced into the three-phase separator. The oil-water mixture in the three-phase separator contacts the natural gas after passing through the coarse-grained material layer. Hydrogen sulfide and carbon dioxide diffuse from the crude oil and sewage into the natural gas bubbles and are carried away by the bubbles. The pH value of the water body rises rapidly to near the stable state. Due to the rapid change of pH, a large number of tiny mechanical impurities are rapidly formed in the three-phase separator in a short period of time. These bubbles, mechanical impurities, oil droplets and other tiny particles in the water act as crystal seeds, providing crystallization cores for the growth and aggregation of particles, thereby quickly forming scale sedimentation. Natural gas floats tiny bubbles, oil droplets and mechanical impurities during the rising process.

3. Gas phase circulation: collect the natural gas gas phase discharged from the three-phase separator, remove carbon dioxide and hydrogen sulfide, and then use it as the input gas for step 2 for recycling.

2. The oilfield three-phase separation process according to claim 1, characterized in that: In step three, the collected natural gas is treated to remove oil, carbon dioxide and hydrogen sulfide before being recycled.

3. A vertical oilfield three-phase separation system, characterized in that: An oilfield three-phase separation process according to claim 2, comprising: A vertical three-phase separator, the interior of which includes a sewage separation section, a coarse-grained material layer, an oil-water separation section and a gas phase section from bottom to top; the three-phase separator also includes an oil inlet, a crude oil area, an oil outlet 1, an air inlet 1, a water collector and an air outlet 1; the oil inlet is connected to the oil-water separation section from the outside of the three-phase separator; the crude oil area is arranged in the oil-water separation section to collect the crude oil overflowing from the top of the oil-water separation section; the oil outlet 1 of the self-supporting three-phase separator is connected to the bottom of the crude oil area to discharge the separated crude oil; the air inlet 1 of the self-supporting three-phase separator is connected to the sewage separation section to input natural gas; the water collector is arranged in the sewage separation section below the air inlet 1 to collect sewage; a sewage area is arranged outside the vertical three-phase separator, the sewage area is connected to the water collector to receive the sewage transmitted by the water collector, and the sewage area is provided with a water outlet to discharge the sewage; the top of the air outlet 1 of the self-supporting three-phase separator is connected to the gas phase section to output natural gas; A gas deoiler, which is connected to the gas outlet 1 of the vertical three-phase separator through a pipeline, receives the natural gas transmitted by the gas outlet 1 and performs oil and gas separation, and outputs the purified natural gas; A gas deacidifier, which is connected to the gas deoiler through a pipeline, receives the purified natural gas output by the gas deoiler, removes acid gases such as carbon dioxide and hydrogen sulfide from it, and then outputs it; A natural gas pressure control unit, one end of which is connected to the gas deacidifier, and the other end of which is connected to the gas inlet 1 of the vertical three-phase separator, and the natural gas treated by the gas deacidifier is input into the gas inlet 1; In the vertical three-phase separator, a coarse granular material layer is added between the sewage separation section and the oil-water separation section; The oil inlet is connected to the cyclone in the oil-water separation section, and the top of the cyclone is connected to the oil-water separation section; It also includes a liquid distribution pipe, the top of which is connected to the bottom of the cyclone. The liquid distribution pipe is arranged in the coarse-grained material layer, and the oil-water mixture retained from the bottom of the cyclone is distributed to various parts of the coarse-grained material layer through the liquid distribution pipe.

4. A vertical oilfield three-phase separation system according to claim 3, characterized in that: In the vertical three-phase separator, air inlet one is connected to aerator one in the sewage separation section.

5. A vertical oilfield three-phase separation system according to claim 4, characterized in that: The sewage area is arranged vertically beside the vertical three-phase separator, and the height of the water outlet is lower than the height of the lowest point of the oil-water separation section; the top of the sewage area is connected to the gas phase section of the vertical three-phase separator through a gas phase balance pipe.

6. A horizontal oilfield three-phase separation system, characterized in that: An oilfield three-phase separation process according to claim 2, comprising: A horizontal three-phase separator, wherein the interior thereof includes an oil-water separation section, an oil-water separation section 2 and an oil outlet section in sequence from one end to the other end in the horizontal direction; the horizontal three-phase separator also includes an oil inlet 2, a cyclone 2, a liquid distribution pipe 2, an air inlet 4, a partition 1, an air inlet 5 and an air outlet 4; the oil inlet 2 is connected to the oil-water separation section from the outside of the horizontal three-phase separator; the outlet of the oil inlet 2 is connected to the cyclone 2; the top end of the liquid distribution pipe 2 is connected to the bottom of the cyclone 2, and the oil-water mixture left at the bottom of the cyclone 2 is distributed to the oil-water separation section through the liquid distribution pipe 2 The separation section is arranged at various places in the horizontal direction; the air inlet 4 is connected from the outside of the horizontal three-phase separator to the bottom of the oil-water separation section to input natural gas; the partition 1 separates the oil-water separation section and the oil-water separation section 2, and a gap is left from the top of the partition 1 to the top of the inner wall of the horizontal three-phase separator for the overflow of the oil-water mixture; the air inlet 5 is connected from the outside of the horizontal three-phase separator to the bottom of the oil-water separation section 2 to input natural gas; the tops of the oil-water separation section and the oil-water separation section 2 are both connected with an air outlet 4 to output the natural gas from the tops of the oil-water separation section and the oil-water separation section 2; A gas deoiler, which is connected to the gas outlet 4 of the horizontal three-phase separator through a pipeline, receives the natural gas transmitted by the gas outlet 4 and performs oil and gas separation, and outputs the purified natural gas; A gas deacidifier, which is connected to the gas deoiler through a pipeline, receives the purified natural gas output by the gas deoiler, removes acid gases such as carbon dioxide and hydrogen sulfide from it, and then outputs it; A natural gas pressure control unit, one end of which is connected to the gas deacidifier, and the other end of which is connected to the gas inlet 4 and the gas inlet 5 of the horizontal three-phase separator, and the natural gas treated by the gas deacidifier is input into the gas inlet 4 and the gas inlet 5; It also includes a coarse-grained material layer 2, which is formed at one end of the oil-water separation section 2 close to the partition 1; the air inlet 5 is located between the coarse-grained material layer 2 and the oil outlet section.

7. A horizontal oilfield three-phase separation system according to claim 6, characterized in that: In the horizontal three-phase separator, air inlet four is connected to aerator three, and air inlet five is connected to aerator four.

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