System and process for utilizing waste heat of produced water separated from oil field

Abstract

The invention provides an oil field separated produced water waste heat utilization system and process, the system comprises a sedimentation oil removal tank and a well group oil incoming pipeline, a heat exchange coil pipe is arranged in the sedimentation oil removal tank, and pipe orifices at the two ends of the heat exchange coil pipe penetrate through the sedimentation oil removal tank and then are connected into the well group oil incoming pipeline in parallel. Well group incoming oil enters the heat exchange coil pipe through the well group incoming oil pipeline, the well group incoming oil in the heat exchange coil pipe exchanges heat with a medium in the sedimentation oil removal tank, the well group incoming oil is conveyed back to the well group incoming oil pipeline after being heated, and finally the well group incoming oil pipeline is connected into the station yard oil and gas gathering and conveying treatment system. Heat transfer is achieved in the fluid flowing process through convective heat transfer in the sedimentation oil removal tank, the temperature of oil coming from a well group in the heat exchange coil tends to be uniform, waste heat of liquid in the sedimentation oil removal tank is absorbed, the temperature of the oil coming from the well group is increased, the follow-up treatment effect of produced water and the optimal reaction temperature of chemicals are guaranteed, and the production efficiency is improved. The device is especially suitable for treating produced water of a dehydration station and a combination station.

Description

Technical Field

[0001] The present invention belongs to the field of oil and gas gathering and transportation, and particularly relates to a waste heat utilization system and process for produced water separated from oilfields. Background Art

[0002] In terms of industrial and domestic energy use mainly based on fuel, heat energy utilization is a basic technology. Compared with energy-saving technologies for heat energy utilization, waste heat recovery and utilization technologies have the advantages of stable operation, simple operation, and significant energy-saving effects.

[0003] In recent years, remarkable results have been achieved in the utilization of waste heat resources in the industrial field of our country, especially the utilization of high-temperature and medium-temperature waste heat resources. Most of the current waste heat recovery technologies on the market are aimed at ultra-high temperatures, and there are not many waste heat recovery products for medium-low temperature and medium-high temperature. Compared with developed countries, there is still a certain gap in the utilization of low-temperature waste heat resources (low-grade waste heat resources) in the industrial field, and it is also very uneven among different enterprises in the industry. With the continuous deepening of energy-saving work, the utilization of low-temperature waste heat resources has increasingly become a hot spot and a difficult point in energy-saving work. Although many explorations have been carried out on the utilization of low-grade waste heat resources at present, generally speaking, the utilization of low-grade waste heat resources is still in its infancy.

[0004] The main source of waste heat resources in oilfield dehydration stations is produced water separated from oilfields, with a temperature ranging from 30°C to 60°C. The temperature is relatively stable, not affected by the external environment, and has no fluctuations, which is a very good cold and heat source, ensuring the high efficiency and economy of heat recovery and reducing the investment cost of the heating system energy. However, the difficulties in utilization are as follows: ① The produced water separated from oilfields has a high content of mineralized substances and corrosive substances, which has a significant impact on the long-term safe operation of equipment and pipe networks; ② For power generation, the efficiency is relatively low, the technology still needs to be mature, and the economic benefits are relatively low. Summary of the Invention

[0005] The purpose of the present invention is to provide a waste heat utilization system and process for produced water separated from oilfields to overcome the above technical defects.

[0006] To solve the above technical problems, the present invention provides a waste heat utilization system for produced water separated from oilfields, including a settling and degassing tank, and an oil pipeline from well groups. A heat exchange coil is arranged in the settling and degassing tank, and the two ends of the heat exchange coil penetrate out of the settling and degassing tank and are connected in parallel to the oil pipeline from well groups.

[0007] The heat exchange coil is arranged in the convection section of the settling and degassing tank.

[0008] A support for supporting the heat exchange coil is also arranged in the settling and degassing tank;

[0009] The support includes a column erected in the settling and degassing tank, a cross beam fixed at the top of the column, and the heat exchange coil is fixed on the cross beam through pipe clamps; the bottom of the column is fixed on the bottom of the settling and degassing tank.

[0010] A hole through which the first pipeline and the second pipeline pass through is provided on the tank wall of the sedimentation and oil removal tank, and the opening position of the hole is close to the bottom of the sedimentation and oil removal tank;

[0011] According to the medium flow direction, the inlet of the first pipeline is connected in parallel to the oil pipeline coming from the well group, and the outlet of the first pipeline is hermetically connected to the inlet of the heat exchange coil;

[0012] According to the medium flow direction, the outlet of the heat exchange coil is hermetically connected to the inlet of the second pipeline, and the outlet of the second pipeline is connected in parallel to the oil pipeline coming from the well group.

[0013] A first electric control valve and a first temperature transmitter are installed on the first pipeline, and both the first electric control valve and the first temperature transmitter are located outside the sedimentation and oil removal tank;

[0014] A second electric control valve is installed on the oil pipeline coming from the well group;

[0015] A second temperature transmitter is installed in the convection section of the sedimentation and oil removal tank.

[0016] The present invention also provides a process for utilizing the waste heat of the produced water separated from the oilfield, including the following steps:

[0017] According to the waste heat utilization system of the produced water separated from the oilfield, both ends of the heat exchange coil are passed through the sedimentation and oil removal tank and then connected in parallel to the oil pipeline coming from the well group;

[0018] The oil coming from the well group enters the heat exchange coil through the oil pipeline coming from the well group. The oil from the well group in the heat exchange coil exchanges heat with the medium in the sedimentation and oil removal tank, and after the oil from the well group is heated, it is back - transported to the oil pipeline coming from the well group;

[0019] The oil pipeline coming from the well group is connected to the station - field oil - gas gathering and transportation processing system.

[0020] Before the oil from the well group enters the heat exchange coil through the oil pipeline coming from the well group, it is necessary to preset a heat exchange start temperature threshold in advance, and judge whether to start the waste heat utilization system of the produced water separated from the oilfield according to the heat exchange start temperature threshold. Specifically, it includes:

[0021] Preset a heat exchange start temperature threshold Y;

[0022] Obtain the temperature K of the oil from the well group in the oil pipeline coming from the well group;

[0023] Compare the heat exchange start temperature threshold Y and the temperature K of the oil from the well group;

[0024] If the temperature K of the oil from the well group falls within the heat exchange start temperature threshold Y, then close the second electric control valve and open the first electric control valve to start the waste heat utilization system of the produced water separated from the oilfield, and the two temperature transmitters respectively collect the medium temperatures inside and outside the tank to ensure heat exchange;

[0025] If the temperature K of the oil coming from the well group exceeds the heat exchange start temperature threshold Y, the second electric control valve is opened and the first electric control valve is closed to shut down the waste heat utilization system for the produced water separated from the oilfield.

[0026] The oil-gas gathering and transportation and treatment system at the station includes a metering device, a pig receiver, a heating furnace, a three-phase separator, and an oil storage tank connected in sequence through pipelines;

[0027] The inlet of the metering device is used to receive the oil coming to the station;

[0028] The pipeline for the oil coming from the well group is connected to the pipeline between the pig receiver and the heating furnace;

[0029] The liquid phase separated by the three-phase separator flows into the settling and oil removal tank.

[0030] The outlet pipeline of the settling and oil removal tank is connected to the buffer water tank, the outlet pipeline of the buffer water tank is connected to the inlet of the water treatment device, and the outlet of the water treatment device is connected to the purified water tank through a pipeline.

[0031] In the present invention, a heat exchange coil is added to the convection section of the settling and oil removal tank, and heat transfer is achieved during the fluid flow process by using the internal convective heat transfer of the settling and oil removal tank, so that the temperature of the oil coming from the well group in the heat exchange coil tends to be uniform, thereby absorbing the waste heat of the liquid in the settling and oil removal tank and raising the temperature of the oil coming from the well group, ensuring the subsequent treatment effect of the produced water and the optimal reaction temperature of the chemical agent, and being particularly suitable for the treatment of the produced water in dehydration stations and combined stations.

[0032] To make the above content of the present invention more obvious and understandable, the following specifically gives preferred embodiments and, in conjunction with the accompanying drawings, makes a detailed description as follows. Description of the Drawings

[0033] Figure 1 It is a schematic structural diagram of the waste heat utilization system for the produced water separated from the oilfield.

[0034] Figure 2 It is an assembly schematic diagram of the heat exchange coil and the support in the settling and oil removal tank.

[0035] Figure 3 It is a schematic structural diagram of the support.

[0036] Figure 4 It is an application schematic diagram of the waste heat utilization process for the produced water separated from the oilfield.

[0037] Figure 5 It is a flow chart of the waste heat utilization process for the produced water separated from the oilfield.

[0038] Description of the Reference Numerals:

[0039] 10. Settling and oil removal tank;

[0040] 20. Heat exchange coil;

[0041] 30. Well group incoming oil pipeline; 31. Second electric control valve;

[0042] 40. Bracket; 41. Column; 42. Cross beam; 43. Base plate; 44. Bottom plate; 45. Rib plate;

[0043] 51. First pipeline; 511. First electric control valve; 512. First temperature transmitter; 52. Second pipeline; 53. Second temperature transmitter. Detailed implementation manners

[0044] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0045] It should be noted that in the present invention, the up, down, left, and right in the drawings are regarded as the up, down, left, and right of the oilfield produced water heat recovery utilization system described in this specification.

[0046] Now, refer to the accompanying drawings to introduce the exemplary implementation manners of the present invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely, and to fully convey the scope of the present invention to those skilled in the art. The terms in the exemplary implementation manners shown in the drawings are not limitations on the present invention. In the drawings, the same unit / element uses the same reference numeral.

[0047] Unless otherwise specified, the terms (including scientific and technical terms) used herein have the ordinary meaning understood by those skilled in the art. In addition, it can be understood that the terms defined in the commonly used dictionary should be understood to have a meaning consistent with the context of their related fields, and should not be understood as idealized or overly formal meanings.

[0048] This implementation manner relates to an oilfield produced water heat recovery utilization system. Please refer to Figure 1 , which includes a sedimentation and oil removal tank 10 and a well group incoming oil pipeline 30. A heat exchange coil 20 is arranged in the sedimentation and oil removal tank 10. The two ends of the heat exchange coil 20 penetrate out of the sedimentation and oil removal tank 10 and are connected in parallel to the well group incoming oil pipeline 30.

[0049] The low-temperature well group incoming oil in the well group incoming oil pipeline 30 flows into the heat exchange coil 20, and the high-temperature medium is in the sedimentation and oil removal tank 10. At this time, the high-temperature medium exchanges heat with the low-temperature well group incoming oil. After the temperature of the low-temperature well group incoming oil rises, it is backfed to the well group incoming oil pipeline 30, and the well group incoming oil pipeline 30 then enters the next process.

[0050] The function of the conventional sedimentation oil removal tank 10 is to treat the sewage discharged from the three-phase separator, that is, it receives sewage at about 40°C. During the treatment process, the liquid temperature in the sedimentation oil removal tank 10 gradually decreases, and this heat is directly dissipated. The heat exchange coil 20 designed in this embodiment utilizes this heat (hereinafter referred to as waste heat) to raise the temperature of the oil coming from the well group, that is, to recover the waste heat of the liquid discharged from the three-phase separator. Since the three-phase separator belongs to the dehydration station or the combined station, it can also be said that the waste heat in the produced water is fully absorbed.

[0051] From top to bottom, the sedimentation oil removal tank 10 is: the oil floating area, the produced water convection area, and the sediment accumulation area. In order to maximize heat exchange, in this embodiment, the heat exchange coil 20 is arranged in the convection section of the sedimentation oil removal tank 10.

[0052] As Figure 2 shown, in order to fix the heat exchange coil 20 in the convection section of the sedimentation oil removal tank 10, a support 40 for supporting the heat exchange coil 20 is also provided in the sedimentation oil removal tank 10 in this embodiment. The number of supports 40 can be determined according to the volume of the sedimentation oil removal tank 10, the weight of the heat exchange coil 20, etc.

[0053] For the structure of the support 40, please refer to Figure 3 :

[0054] The support 40 includes a column 41 erected in the sedimentation oil removal tank 10. A cross beam 42 is fixed on the top of the column 41. The heat exchange coil 20 is fixed on the cross beam 42 through pipe clamps. In order to avoid damage caused by hard contact, a cushion plate 43 is also placed between the cross beam 42 and the column 41; the bottom of the column 41 is fixed (such as welded) to the bottom of the sedimentation oil removal tank 10.

[0055] Please continue to refer to Figure 3 , the bottom of the column 41 is fixed to the bottom of the sedimentation oil removal tank 10 through a bottom plate 44. The bottom plate 44 can increase the contact area between the two to improve stability. In addition, a rib plate 45 is also provided between the column 41 and the bottom plate 44, the purpose of which is to improve the strength of the support 40.

[0056] As Figure 1 shown, holes for the first pipeline 51 and the second pipeline 52 to penetrate through are opened on the tank wall of the sedimentation oil removal tank 10. The opening position is close to the bottom of the sedimentation oil removal tank 10. Specifically:

[0057] According to the medium flow direction, the inlet of the first pipeline 51 is connected in parallel to the oil pipeline 30 coming from the well group, that is, Figure 4 as shown, the inlet of the first pipeline 51 is connected to the oil pipeline 30 coming from the well group, and the outlet of the first pipeline 51 is hermetically connected to the inlet of the heat exchange coil 20; according to the medium flow direction, the outlet of the heat exchange coil 20 is hermetically connected to the inlet of the second pipeline 52, and the outlet of the second pipeline 52 is connected in parallel to the oil pipeline 30 coming from the well group, that is,Figure 4 The outlet of the second pipeline 52 shown goes to the oil pipeline 30 for the well group coming oil.

[0058] That is to say, according to Figure 1 As shown, the well group coming oil in the oil pipeline 30 for the well group coming oil enters the heat exchange coil 20 through the first pipeline 51. After heat exchange occurs, the well group coming oil in the heat exchange coil 20 is backfed to the oil pipeline 30 for the well group coming oil through the second pipeline 52.

[0059] The first pipeline 51 and the second pipeline 52 realize the parallel connection of the heat exchange coil 20 to the oil pipeline 30 for the well group coming oil. In this way, the well group coming oil in the oil pipeline 30 for the well group coming oil can directly enter the next process without passing through the heat exchange coil 20, or can enter the next process after heat exchange through the heat exchange coil 20, that is, there are two options.

[0060] To achieve the switching between the above two options, as Figure 4 shown, a first electric control valve 511 and a first temperature transmitter 512 are installed on the first pipeline 51. Both the first electric control valve 511 and the first temperature transmitter 512 are located outside the sedimentation and oil removal tank 10; a second electric control valve 31 is installed on the oil pipeline 30 for the well group coming oil; a second temperature transmitter 53 is installed in the convection section of the sedimentation and oil removal tank 10.

[0061] When the temperature of the well group coming oil in the oil pipeline 30 for the well group coming oil does not need to be raised, the first electric control valve 511 can be closed and the second electric control valve 31 can be started, then the well group coming oil in the oil pipeline 30 for the well group coming oil directly enters the next process.

[0062] When the temperature of the well group coming oil in the oil pipeline 30 for the well group coming oil is too low, for example, only 3°C - 8°C in winter, the second electric control valve 31 needs to be closed and the first electric control valve 511 needs to be started. At this time, the well group coming oil in the oil pipeline 30 for the well group coming oil first enters the heat exchange coil 20 through the first pipeline 51. After heat exchange occurs, the well group coming oil is heated to 15°C - 20°C, and the well group coming oil in the heat exchange coil 20 is backfed to the oil pipeline 30 for the well group coming oil through the second pipeline 52 and finally enters the next process.

[0063] This embodiment also provides a process for utilizing the waste heat of the produced water separated from the oilfield, including the following steps:

[0064] According to the structure of the waste heat utilization system for the produced water separated from the oilfield, the two ends of the heat exchange coil 20 are passed through the sedimentation and oil removal tank 10 and are connected in parallel to the oil pipeline 30 for the well group coming oil. At this time, the well group coming oil enters the heat exchange coil 20 through the oil pipeline 30 for the well group coming oil. The well group coming oil in the heat exchange coil 20 exchanges heat with the medium in the sedimentation and oil removal tank 10. After the well group coming oil is heated, it is backfed to the oil pipeline 30 for the well group coming oil, and finally the oil pipeline 30 for the well group coming oil is connected to the station field oil and gas gathering and transportation processing system.

[0065] Please refer toFigure 5 , the station oil and gas gathering, transportation and treatment system includes a metering device, a pig receiver, a heating furnace, a three-phase separator, and an oil storage tank connected in sequence through pipelines. Chemicals are added between the pig receiver and the heating furnace, and the heating furnace needs to use gas.

[0066] The inlet of the metering device is used to receive the oil coming from the station; the oil pipeline from the well group 30 is connected to the pipeline between the pig receiver and the heating furnace; the liquid phase separated by the three-phase separator flows into the settling and degreasing tank 10.

[0067] Take Figure 5 as an example, the waste heat utilization process of the produced water separated from the oilfield will be described in detail below. Specifically:

[0068] The oil coming from the station at 20°C to 28°C passes through the metering device and the pig receiver in sequence, and then converges with the oil from the well group at 15°C to 20°C after heat exchange through the heat exchange coil 20. At this time, chemicals are added to the converged mixed oil, and then it is processed by the heating furnace and the three-phase separator in sequence. Finally, the crude oil separated by the three-phase separator enters the oil storage tank.

[0069] As Figure 5 shown, the temperature of the oil and gas after being heated by the heating furnace is 41°C. When it enters the three-phase separator, the associated gas separated by the three-phase separator is exported, the separated crude oil enters the oil storage tank, and the separated sewage is 40°C at this time. The 40°C sewage (i.e., Figure 4 the water inlet pipeline of the three-phase separator in

[0070] enters the settling and degreasing tank 10 and exchanges heat with the heat exchange coil 20 in the settling and degreasing tank 10. The oil from the well group at 3°C to 8°C is heated to 15°C to 20°C, realizing the waste heat utilization in the settling and degreasing tank 10. Figure 4 After the heat exchange, the temperature of the liquid in the settling and degreasing tank 10 drops from 38°C to 36°C. At this time, the outlet pipeline of the settling and degreasing tank 10 (i.e.,

[0071] the outlet pipeline of the settling and degreasing tank shown in

[0072] is connected to the buffer water tank, the outlet pipeline of the buffer water tank is connected to the inlet of the water treatment device, and the outlet of the water treatment device is connected to the purified water tank through a pipeline.

[0073] It should be noted that before the oil from the well group enters the heat exchange coil 20 through the oil pipeline of the well group 30, it is necessary to set a heat exchange start temperature threshold in advance, and judge whether to start the waste heat utilization system of the produced water separated from the oilfield according to the heat exchange start temperature threshold. Specifically, it includes:

[0074] Preset the heat exchange start temperature threshold Y;

[0075] Obtain the well group incoming oil temperature K of the well group incoming oil pipeline 30;

[0076] Compare the heat exchange start temperature threshold Y and the well group incoming oil temperature K;

[0077] If the well group incoming oil temperature K (for example, 15 °C) falls within the heat exchange start temperature threshold Y (for example, with a value of 1 - 10 °C), then close the second electric control valve 31 and open the first electric control valve 511 to start the oilfield-produced produced water waste heat utilization system. Two temperature transmitters respectively collect the medium temperatures inside and outside the tank to ensure heat exchange; if the well group incoming oil temperature K (for example, 15 °C) exceeds the heat exchange start temperature threshold Y, it indicates that the well group incoming oil temperature K is close to the produced water temperature and the heat exchange efficiency is low, and there is no need to utilize the waste heat of the produced water. Then open the second electric control valve 31 and close the first electric control valve 511 to close the oilfield-produced produced water waste heat utilization system.

[0078] This embodiment utilizes the "natural convection" advantage of the settling and oil removal tank to recover and successfully utilize the 10 °C heat release temperature difference provided by the produced water (the temperature difference refers to the temperature difference between the produced water and the wellsite incoming oil. The produced water temperature is high and the wellsite incoming oil temperature is low, and the produced water releases heat to raise the temperature of the wellsite incoming oil). A heat exchange coil and a temperature transducer are arranged in the convection section inside the tank, and an electric control valve is arranged outside the tank, which not only ensures the subsequent treatment effect of the produced water and the optimal reaction temperature of the chemical agent, but also can fully absorb the waste heat in the produced water. The whole process realizes unattended and automatic control.

[0079] This embodiment applies the oilfield-produced produced water waste heat utilization process to a certain dehydration station and a certain joint station. After actual inspection, it is found that when the temperature difference is 5 °C, the heat energy absorbed from the produced water is not less than 4.7 kW·h / m 3 , and the waste heat recovery efficiency is not less than 80%.

[0080] Those of ordinary skill in the art can understand that the above embodiments are specific examples for implementing the present invention, and in practical applications, various changes can be made in form and details without departing from the spirit and scope of the present invention.

Claims

1. A system for utilizing waste heat from produced water in an oil field, comprising a sedimentation oil removal tank (10) and an oil pipeline (30) from a well group, characterized in that: A heat exchange coil (20) is arranged in the sedimentation and oil removal tank (10), and the pipe openings at both ends of the heat exchange coil (20) pass through the sedimentation and oil removal tank (10) and are connected in parallel to the oil pipeline (30) of the well group.

2. The oilfield produced water waste heat utilization system according to claim 1, characterized in that: The heat exchange coil (20) is arranged in the convection section of the sedimentation and oil removal tank (10).

3. The oilfield produced water waste heat utilization system according to claim 1 or 2, characterized in that: A bracket (40) for supporting the heat exchange coil (20) is also provided in the sedimentation and oil removal tank (10); The support (40) comprises a column (41) erected in the sedimentation and oil removal tank (10); a crossbeam (42) is fixed to the top of the column (41); the heat exchange coil (20) is fixed to the crossbeam (42) by means of a pipe clamp; and the bottom of the column (41) is fixed to the bottom of the sedimentation and oil removal tank (10).

4. The oilfield produced water waste heat utilization system according to claim 2, characterized in that: A hole is opened on the tank wall of the sedimentation and oil removal tank (10) for the first pipeline (51) and the second pipeline (52) to pass through, and the opening position of the hole is close to the tank bottom of the sedimentation and oil removal tank (10); According to the flow direction of the medium, the inlet of the first pipeline (51) is connected in parallel to the oil pipeline (30) of the well group, and the outlet of the first pipeline (51) is sealed and connected to the inlet of the heat exchange coil (20); According to the flow direction of the medium, the outlet of the heat exchange coil (20) is sealed and connected to the inlet of the second pipeline (52), and the outlet of the second pipeline (52) is connected in parallel to the oil pipeline (30) of the well group.

5. The oilfield produced water waste heat utilization system according to claim 4, characterized in that: A first electric regulating valve (511) and a first temperature transmitter (512) are installed on the first pipeline (51), and the first electric regulating valve (511) and the first temperature transmitter (512) are both located outside the sedimentation and oil removal tank (10); A second electric regulating valve (31) is installed on the oil pipeline (30) of the well group; A second temperature transmitter (53) is installed in the convection section of the sedimentation and oil removal tank (10).

6. A process for utilizing waste heat from produced water in oil fields, characterized in that: The following steps are involved: According to the oilfield produced water waste heat utilization system according to any one of claims 1 to 5, the two end pipe openings of the heat exchange coil (20) are passed through the sedimentation oil removal tank (10) and then connected in parallel to the well group oil pipeline (30); The oil from the well group enters the heat exchange coil (20) through the well group oil pipeline (30), the well group oil in the heat exchange coil (20) exchanges heat with the medium in the sedimentation and oil removal tank (10), and the well group oil is heated and then returned to the well group oil pipeline (30); The well group oil pipeline (30) is connected to the station oil and gas gathering and transportation processing system.

7. The process for utilizing waste heat from produced water from oil fields according to claim 6, characterized in that: Before the oil from the well group enters the heat exchange coil (20) through the well group oil pipeline (30), a heat exchange start temperature threshold needs to be set in advance, and whether to start the oilfield produced water waste heat utilization system is determined according to the heat exchange start temperature threshold, specifically including: Preset heat exchange start temperature threshold Y; Obtaining the well group oil temperature K of the well group oil pipeline (30); Compare the heat exchange start temperature threshold Y and the well group oil temperature K; If the oil temperature K of the well group falls within the heat exchange start temperature threshold value Y, the second electric regulating valve (31) is closed, and the first electric regulating valve (511) is opened to start the oil field produced water waste heat utilization system, and two temperature transmitters respectively collect the medium temperatures inside and outside the tank to ensure heat exchange; If the oil temperature K of the well group exceeds the heat exchange start temperature threshold value Y, the second electric regulating valve (31) is opened and the first electric regulating valve (511) is closed to close the oilfield produced water waste heat utilization system.

8. The process for utilizing waste heat from oilfield produced water according to claim 6, characterized in that: The station oil and gas gathering and transportation processing system includes a metering device, a ball collecting device, a heating furnace, a three-phase separator, and an oil storage tank which are sequentially connected through pipelines; The inlet of the metering device is used to receive oil from the station; The oil pipeline (30) of the well group is connected to the pipeline between the ball receiving device and the heating furnace; The liquid phase separated by the three-phase separator flows into the sedimentation and oil removal tank (10).

9. The process for utilizing waste heat from produced water in oil fields according to claim 6 or 8, characterized in that: The water outlet pipeline of the sedimentation and oil removal tank (10) is connected to the buffer water tank, the outlet pipeline of the buffer water tank is connected to the inlet of the water treatment device, and the outlet of the water treatment device is connected to the purified water tank through a pipeline.

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