Water treatment device suitable for offshore thickened oil hot water injection exploitation

Abstract

The utility model discloses a water treatment device suitable for offshore heavy oil hot water injection exploitation, which comprises crude oil treatment equipment, scale removal and prevention equipment and water treatment equipment, an oil phase and a water phase are separated from a production well output liquid through the crude oil treatment equipment, the water phase separated from the production well output liquid is subjected to scale prevention through the scale removal and prevention equipment and is treated through the water treatment equipment, and the water treatment equipment is used for water treatment. The crude oil treatment equipment, the scale removing and preventing equipment and the water treatment equipment are connected through heat preservation pipelines. According to the water treatment device suitable for offshore thickened oil hot water injection exploitation, high-temperature water can be produced through the crude oil treatment equipment and treated through the scale removing and preventing equipment to achieve the purpose of reducing the scaling rate, and then hot water is conveyed to a wellhead platform through the water treatment equipment and the heat preservation pipeline to be injected into a well.

Description

TECHNICAL FIELD

[0001] The utility model relates to offshore oilfield development technical field especially, it is a kind of water treatment device suitable for offshore heavy oil hot water injection exploitation. BACKGROUND

[0002] With the development of economy, the demand for oil and gas resources gradually increases, and the Bohai oilfield is rich in heavy oil resources. The efficient development of offshore heavy oil resources plays a positive role in national energy security. The characteristics of heavy oil are high density, high viscosity and high freezing point, which increase the difficulty of its exploitation. Efficient exploitation of heavy oil is one of the problems faced by people.

[0003] In heavy oil exploitation, the flow resistance is large, which leads to low recovery rate. Thermal recovery can well solve these problems and has remarkable effect in heavy oil reservoir development. Thermal recovery mainly increases the temperature of oil layer through some process measures, reduces the viscosity of heavy oil, and makes heavy oil flow easily, so as to produce heavy oil. The mechanism of oil increase in hot water injection is as follows: first, based on heat carried by hot water, the viscosity of crude oil is reduced through heat reduction principle; second, auxiliary chemical agents / gas agents are added, such as gel, profile control agent and foam medium to expand swept volume, and gas and oil displacement agent to improve oil displacement efficiency; finally, through the synergistic effect of heat and chemical agents, thermal, gas and chemical combined displacement is realized, and the effect of agents is better than that of conventional water flooding at low temperature. Therefore, the swept range of hot water injection is larger, the oil washing efficiency is higher, and the recovery rate is further improved.

[0004] The source of hot water in hot water injection is an urgent problem to be solved. The source of hot water is usually divided into two forms: increasing heat exchange equipment to heat water source or using geothermal resources to provide heat source. The former has large initial investment and occupies a large area on offshore platform, so it is difficult to achieve good economic application. Using geothermal resources to provide heat source requires that the oil field has good geothermal resources and sufficient water, and the application range is small. There is no experience to be referred to for the design method of the source of hot water in hot water injection after heavy oil water flooding in offshore oilfield. It is urgent to develop water treatment process suitable for offshore heavy oil hot water injection.

[0005] Chinese patent document CN102635342A discloses a heavy oil thermal recovery method using heat exchanger to heat injection water. A heat exchanger is installed at the outlet of the oil field generator tail, and the high temperature tail gas of the generator is used to heat the injection water. This method has the problem of too large occupied area in the application process of offshore platform, and in the actual operation process, the heat exchange efficiency is low due to the too fast scaling rate of the heat exchanger, the temperature of hot water drops quickly, and continuous hot water injection cannot be realized.

[0006] Chinese patent document CN105239980A discloses a method for heating injected water by using a boiler to provide heat, and heating the water source to achieve the required water injection temperature of hot water flooding. The method has high requirements for water quality during application on offshore platforms, and the water source needs to be pretreated. However, due to the particularity of offshore platforms, fresh water resources are scarce, and the water source can only use seawater or well water, so the method has limitations.

[0007] The above patents cannot better adapt to the situation of limited space and insufficient fresh water resources on offshore platforms, and cannot solve the process method of hot water source in hot water injection after water flooding. The ground water treatment equipment designed in the patent does not need to add heating equipment, and uses the waste heat of platform equipment to form hot water above 90℃ to ensure the hot water source for hot water injection. Practical new type content

[0008] In view of the deficiencies of the prior art, the utility model provides a water treatment process suitable for offshore heavy oil hot water injection.

[0009] To achieve the above purpose, the application provides the following technical scheme:

[0010] A water treatment device suitable for offshore heavy oil hot water injection, comprising a crude oil treatment device, a scale prevention and removal device, and a water treatment device. The production well effluent is separated into oil phase and water phase by the crude oil treatment device. The water phase after separation of the production well effluent is prevented from scaling by the scale prevention and removal device, and is treated by the water treatment device, and is injected into each injection well by the water injection pump. The crude oil treatment device, the scale prevention and removal device, and the water treatment device are connected by heat preservation pipelines.

[0011] Optionally, the crude oil treatment device comprises a primary oil-water separator, a crude oil heat exchanger, a secondary oil-water separator, and an electric dehydrator. The production well effluent is connected with the inlet of the primary oil-water separator. The water phase outlet of the primary oil-water separator is connected with the inlet of the crude oil heat exchanger. The outlet of the crude oil heat exchanger is connected with the inlet of the secondary oil-water separator. The oil phase outlet of the secondary oil-water separator is connected with the inlet of the electric dehydrator. The water outlet of the electric dehydrator and the water phase outlet of the secondary oil-water separator are respectively connected with the scale prevention and removal device.

[0012] Optionally, the scale prevention and removal device comprises a scale prevention device. The water outlet of the electric dehydrator and the water phase outlet of the secondary oil-water separator are respectively connected with the inlet of the scale prevention device. The outlet of the scale prevention device is connected with the water treatment device. A chemical scale prevention agent injection port is arranged on the heat preservation pipeline connected with the outlet of the scale prevention device and the water treatment device.

[0013] Optionally, the water treatment device comprises an oil remover, an air flotation device, a production water buffer tank, a walnut shell filter and an injection water buffer tank, the outlet of the scale inhibitor is connected with the inlet of the oil remover, the outlet of the oil remover is connected with the inlet of the air flotation device, the outlet of the air flotation device is connected with the inlet of the production water buffer tank, the outlet of the production water buffer tank is connected with the inlet of the walnut shell filter, the outlet of the walnut shell filter is connected with the inlet of the injection water buffer tank, and the outlet of the injection water buffer tank is connected with the injection pump.

[0014] Optionally, a composite synergistic agent injection port is arranged on the heat preservation pipeline connected with the injection water buffer tank and the injection pump.

[0015] In conclusion, the water treatment device suitable for offshore heavy oil injection hot water exploitation provided by the utility model can produce high-temperature water by using the crude oil treatment device, and the water is treated by the scale removal and prevention device to reduce the scale formation rate, and then the hot water is delivered to the wellhead platform by the water treatment device and the heat preservation pipeline and injected into the well. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0017] Figure 1 Fig. 1 is a structural schematic view of the water treatment device suitable for offshore heavy oil injection hot water exploitation in an embodiment of the utility model.

[0018] 1, production well output liquid; 2, primary oil-water separator; 3, crude oil heat exchanger; 4, secondary oil-water separator; 5, electric dehydrator; 6, scale inhibitor; 7, chemical scale inhibitor injection port; 8, inclined plate oil remover; 9, air flotation device; 10, production water buffer tank; 11, walnut shell filter; 12, injection water buffer tank; 13, composite synergistic agent injection port; 14, water injection pump; 15, water injection well. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the utility model will be clearly and completely described in combination with the drawings in the embodiments of the utility model. Obviously, the described embodiments are only some embodiments of the utility model, not all the embodiments. Based on the embodiments in the utility model, all the other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the utility model.

[0020] In the description of the utility model, it needs to explain, the term "center", "upper", "lower", "left", "right", "vertical", "horizontal", "internal", "external" and so on indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawing, only for the convenience of describing the utility model and simplifying the description, and not indicate or imply that the system or element indicated must have a particular orientation, a particular orientation and operation, therefore, it cannot be understood as a limitation on the utility model. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0021] In the description of the utility model, it needs to explain, unless otherwise specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected, it can be mechanically connected, or it can be electrically connected, it can be directly connected, or it can be indirectly connected through an intermediate medium, it can be the communication inside two elements. For ordinary skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0022] In addition, the technical features involved in different embodiments of the utility model described below can be combined with each other as long as there is no conflict between them.

[0023] The embodiment provides a water treatment device suitable for offshore heavy oil hot water injection exploitation, as shown in the figure, including crude oil treatment equipment, scale removal and prevention equipment and water treatment equipment, production well effluent 1 is separated into oil phase and water phase through the crude oil treatment equipment, the water phase of the production well effluent 1 after separation is prevented from scaling through the scale removal and prevention equipment, the water quality is improved through the water treatment equipment, and is injected into each injection well 15 through the water injection pump 14, the crude oil treatment equipment, the scale removal and prevention equipment and the water treatment equipment are connected through the heat preservation pipeline. Figure 1 Optionally, the crude oil treatment equipment comprises a primary oil-water separator 2, a crude oil heat exchanger 3, a secondary oil-water separator 4 and an electric dehydrator 5, the production well effluent 1 is connected with the inlet of the primary oil-water separator 2, the water phase outlet of the primary oil-water separator 2 is connected with the inlet of the crude oil heat exchanger 3, the outlet of the crude oil heat exchanger 3 is connected with the inlet of the secondary oil-water separator 4, the oil phase outlet of the secondary oil-water separator 4 is connected with the inlet of the electric dehydrator 5, and the water outlet of the electric dehydrator 5 and the water phase outlet of the secondary oil-water separator 4 are connected with the scale removal and prevention equipment respectively. The hot water source of the embodiment is the waste heat of the secondary oil-water separator 4 and the electric dehydrator 5, and the high-temperature water above 95 DEG C provided through the crude oil treatment equipment enters the subsequent equipment.

[0024]

[0025] ​The crude oil heat exchanger 3, the first oil-water separator 2, the second oil-water separator 4 and the electric dehydrator 5 are all commercially available products. The crude oil heat exchanger 3 is composed of a shell, a heat transfer tube bundle, a tube plate, a baffle plate (baffle) and a tube box and the like. The two fluids for heat exchange, one flowing in the tube, is called the tube side fluid; the other flowing outside the tube is called the shell side fluid. In order to improve the heat transfer coefficient of the fluid outside the tube, a plurality of baffle plates are usually installed in the shell. The baffle plate can increase the speed of the shell side fluid, force the fluid to pass through the tube bundle multiple times horizontally according to the specified route, and enhance the degree of fluid turbulence. The oil-water mixture is heated to facilitate better separation in the subsequent process. The first oil-water separator 2 preliminarily filters and separates large particles of oil dirt in the waste water, and the temperature of the output liquid of the first oil-water separator 2 is above 75°C. The second oil-water separator 4 further processes small particles of oil dirt in the waste water. The outlet of the electric dehydrator 5 is connected to the sewage treatment system, and the electric dehydrator 5 is composed of an oil inlet distributor, a high-voltage lead-in rod, a high-voltage electrically insulated suspension, an electrode assembly and a top transformer. The principle of water separation is that in the process of electrophoresis, water droplets collide, the weakened interface film breaks, water droplets merge and increase, and the oil phase and water phase are fully separated.

[0026] Optionally, the scale removal and prevention device comprises a scale preventer 6, the water outlet of the electric dehydrator 5 and the water phase outlet of the second oil-water separator 4 are respectively connected to the inlet of the scale preventer 6, the outlet of the scale preventer 6 is connected to the water treatment device, and a chemical scale inhibitor injection port 7 is arranged on the heat preservation pipeline connected to the water treatment device. In this embodiment, the scale preventer 6 is a quantum scale preventer 6. The high-temperature water above 95°C produced by the second separator and the electric dehydrator 5 is connected to the inlet of the quantum scale preventer 6 through a heat preservation pipeline, and after physical scale removal, a chemical scale inhibitor is injected through the chemical scale inhibitor injection port 7 for chemical scale prevention, so that hot water scale prevention treatment is performed before the water treatment device process.

[0027] In this embodiment, the quantum scale preventer 6 is a commercially available product. The quantum scale preventer 6 applies an energy resonance field to the water to form different vibration waves to achieve the effects of scale removal and prevention. The red vibration wave can remove rust and prevent corrosion, the black vibration wave can prevent calcium carbonate and other salt scaling, and the green vibration wave can kill bacteria and algae to solve microbial congestion. The chemical scale inhibitor injection port 7 injects a chemical scale inhibitor to prevent or interfere with the precipitation and scaling of insoluble inorganic salts, thereby playing a scale prevention function. In combination with the physical scale prevention means of the quantum scale preventer 6, the scaling problem of the system can be effectively solved.

[0028] Optionally, the water treatment device comprises an oil remover, an air flotation device 9, a production water buffer tank 10, a walnut shell filter 11 and an injection water buffer tank 12, the outlet of the scale inhibitor 6 is connected with the inlet of the oil remover, the outlet of the oil remover is connected with the inlet of the air flotation device 9, the outlet of the air flotation device 9 is connected with the inlet of the production water buffer tank 10, the outlet of the production water buffer tank 10 is connected with the inlet of the walnut shell filter 11, the outlet of the walnut shell filter 11 is connected with the inlet of the injection water buffer tank 12, and the outlet of the injection water buffer tank 12 is connected with the injection pump.

[0029] Optionally, a composite synergistic agent injection port 13 is arranged on the heat preservation pipeline connected with the injection water buffer tank 12 and the injection pump. By adding gel, foam, profile control agent, oil displacement agent and gas and other composite synergistic agents through the composite synergistic agent injection port 13, the high-temperature water after adding the agents is finally injected into the injection well 15 through the injection pump 14, and the composite synergistic agent addition process is completed.

[0030] In the embodiment, the inclined plate oil remover 8, the air flotation device 9 and the walnut shell filter 11 are all commercially available products. The outlet of the inclined plate oil remover 8 is connected with the inlet of the air flotation device 9, and the internal structure of the inclined plate oil remover 8 mainly comprises a coalescence zone, an inclined plate zone, an oil chamber and a water chamber. The oily sewage entering the container firstly passes through the coalescence zone to coalesce larger oil droplets, and then passes through the inclined plate zone to further separate oil and water. The separated water at the outlet of the inclined plate oil remover 8 contains less than 300 ppm of oil, and the suspended matter is 50-80 mg / L. The outlet of the air flotation device 9 is connected with the inlet of the walnut shell filter 11. The air flotation device 9 generates a large number of micro-bubbles, the bubbles rise and adhere to oil beads and suspended solid particles, carrying them to the liquid surface to form scum, so as to remove oil and suspended solid particles in the sewage. The separated water at the outlet of the air flotation device 9 contains 60-100 ppm of oil, and the suspended matter is less than 30 mg / L. The outlet of the walnut shell filter 11 is connected with the inlet of the injection pump 14 to complete the injection of hot water. The walnut shell filter 11 forms an oil film on the surface of the filter material by virtue of the hydrophobic agglomeration of oil beads on the surface of the filter material, and then the oil film is washed away by the shear force of the water flow between the filter layer pores, and the formed coarse particle oil beads float and separate. The separated water at the outlet of the walnut shell filter 11 contains less than 30 ppm of oil, and the suspended matter is less than 10 mg / L. The water separated by the separator is treated by the water treatment system to meet the requirements of injection into the oil layer, avoid reservoir damage, and meet the quality requirements of injection water for hot water injection.

[0031] The working process of the embodiment is as follows: the produced liquid 1 of a certain offshore oilfield platform production well is first subjected to oil-water separation treatment through a crude oil treatment system, wherein the temperature of the produced liquid of the first-stage oil-water separator 2 is above 75°C; in order to improve the separation efficiency of the second-stage oil-water separator 4, the outlet of the first-stage oil-water separator 2 is connected to the inlet of the crude oil heat exchanger 3 to raise the temperature of the treated liquid to above 95°C, and the outlet of the crude oil heat exchanger 3 is connected to the inlet of the second-stage oil-water separator 4 for the second oil-water separation, wherein the temperature of the produced liquid of the second-stage oil-water separator 4 is above 95°C; the high-temperature water produced by the second-stage oil-water separator 4 is connected to a clean and anti-fouling system through a pipeline, and the remaining oil-water mixture is further introduced into an electric dehydrator 5 through an insulation pipeline for the third oil-water separation, wherein the temperature of the produced liquid of the electric dehydrator 5 is above 95°C; the high-temperature water above 95°C produced by the second-stage separator and the electric dehydrator 5 is connected to the inlet of a quantum anti-fouling device 6 through an insulation pipeline, and after physical descaling, the water is injected into the quantum anti-fouling device 6 through a chemical anti-fouling agent injection port 7 to perform chemical anti-fouling, so that the hot water anti-fouling treatment is completed before the three-stage water treatment process; the high-temperature water after the anti-fouling treatment is connected to a water treatment system through an insulation pipeline, the outlet of an inclined plate oil remover 8 is connected to the inlet of an air flotation device 9, and the first and second water quality treatments are performed; the treated hot water enters a production water buffer tank 10 and is then connected to a walnut shell filter 11 for the last water treatment process, and the water quality meets the requirements of injection into the oil layer; the high-temperature water after the treatment is further conveyed through an insulation pipeline, and a composite synergistic agent, such as gel, foam, profile control agent, oil displacement agent and gas, is added through a composite synergistic agent injection port 13; finally, the high-temperature water after the addition of the agent is injected into an injection well 15 through a water injection pump 14, so that the water treatment process flow of offshore heavy oil injection with hot water recovery is completed.

[0032] In the above-mentioned hot water source acquisition method for injection with hot water recovery, the heating method does not need to add heating equipment, saves platform space, reduces the initial investment cost, and the offshore platform mainly uses the platform crude oil treatment equipment and sewage treatment equipment to efficiently separate oil and water from the produced liquid of the oil well, and uses the high-temperature water produced by the oil-water separator as the hot water source. This design process can adapt to the present situation of limited space and insufficient fresh water resources on offshore platforms, and can be adapted to local conditions, utilize waste heat and save costs.

[0033] In the above-mentioned hot water source acquisition method for injection with hot water recovery, the separation water produced by the second-stage oil-water separator 4 and the electric dehydrator 5 can reach a temperature of above 90°C, and the heating capacity can reach the required temperature of the hot water injection water. The clean and anti-fouling equipment and the water treatment equipment can improve the quality of the high-temperature water to meet the quality requirements of the injection water for injection with hot water recovery. This design process can adapt to the present situation of limited space and insufficient fresh water resources on offshore platforms, and can be adapted to local conditions, utilize waste heat and save costs.

[0034] It should be explained finally: above only is the preferred embodiment of the utility model and is not used for limiting the utility model, although the utility model has been explained in detail with reference to foregoing embodiment, for the skilled person in the art, it still can modify the technical scheme recorded in foregoing each embodiment or make equivalent replacement to part technical features, any modification, equivalent replacement, improvement etc. made within the spirit and principle of the utility model should be contained in the protection scope of the utility model.

Claims

1. A water treatment device suitable for offshore heavy oil hot water injection production, characterized in that, The production well effluent is separated into oil phase and water phase by the crude oil treatment equipment, the water phase is prevented from scaling by the scale prevention and removal equipment, and is treated by the water treatment equipment, and is injected into each injection well by the injection pump.

2. The water treatment device suitable for offshore heavy oil thermal water injection production according to claim 1, characterized in that, The crude oil treatment equipment includes a first oil-water separator, a crude oil heat exchanger, a second oil-water separator, and an electric dehydrator, the production well effluent is connected with the inlet of the first oil-water separator, the water phase outlet of the first oil-water separator is connected with the inlet of the crude oil heat exchanger, the outlet of the crude oil heat exchanger is connected with the inlet of the second oil-water separator, the oil phase outlet of the second oil-water separator is connected with the inlet of the electric dehydrator, and the water outlet of the electric dehydrator and the water phase outlet of the second oil-water separator are respectively connected with the scale prevention and removal equipment.

3. The water treatment device suitable for offshore heavy oil thermal water injection production according to claim 2, characterized in that, The scale prevention and removal equipment includes a scale preventer, the water outlet of the electric dehydrator and the water phase outlet of the second oil-water separator are respectively connected with the inlet of the scale preventer, the outlet of the scale preventer is connected with the water treatment equipment, and a chemical scale inhibitor injection port is arranged on the heat preservation pipeline connected with the outlet of the scale preventer and the water treatment equipment.

4. The water treatment device suitable for offshore heavy oil thermal water injection production according to claim 3, characterized in that, The water treatment equipment includes an oil remover, an air flotation device, a production water buffer tank, a walnut shell filter, and an injection water buffer tank, the outlet of the scale preventer is connected with the inlet of the oil remover, the outlet of the oil remover is connected with the inlet of the air flotation device, the outlet of the air flotation device is connected with the inlet of the production water buffer tank, the outlet of the production water buffer tank is connected with the inlet of the walnut shell filter, the outlet of the walnut shell filter is connected with the inlet of the injection water buffer tank, and the outlet of the injection water buffer tank is connected with the injection pump.

5. The water treatment device suitable for offshore heavy oil thermal water injection production according to claim 4, characterized in that, A composite synergistic agent injection port is arranged on the heat preservation pipeline connected with the injection water buffer tank and the injection pump.

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