A system and method for treating drilling fluid returns from an offshore oil and gas drilling platform

Abstract

The present application relates to a kind of offshore oil and gas drilling platform drilling flowback fluid processing device system and processing method, the processing device system includes the pretreatment reaction sled, vibration sieve cuttings separation sled, solid-liquid centrifugal separation sled and oil-water solid three-phase separation sled connected in turn along material liquid flow direction;Material connection is carried out between adjacent sleds by pipeline and control valve, and position connection is carried out by detachable connecting device;The vibration sieve cuttings separation sled is provided with guide pipeline in parallel, the inlet of the guide pipeline is connected with the outlet of pretreatment reaction sled, and the outlet of the guide pipeline is connected with the inlet of solid-liquid centrifugal separation sled.The device system provided by the present application can realize the continuous treatment and standard discharge of drilling flowback waste liquid, and improve the operation efficiency of offshore platform wellhead, meet the processing needs of different liquid quality.

Description

Technical Field

[0001] This invention relates to the field of drilling flowback fluid treatment technology, specifically to a treatment device system and method for drilling flowback fluid from offshore oil and gas drilling platforms. Background Technology

[0002] In recent years, with the development of oil and gas exploration and development, the number of multi-branch wells, horizontal wells, and wells in complex geological conditions has been increasing, making wellbore stability a more prominent issue. Oil-based drilling mud fluids have been widely used and developed due to their strong stability and lubrication capabilities. However, this has also led to a continuous increase in the amount of waste oil-based drilling mud fluids generated. Currently, a considerable amount of oil-based drilling mud fluids are disposed of directly through landfilling, reinjection into the formation, or centralized incineration on land without treatment. This not only wastes a large amount of mineral oil resources but also causes pollution of soil, surface water, and groundwater, directly or indirectly posing significant harm to the environment and human health. Therefore, it is necessary to carry out harmless or resource-based treatment of such oil-based drilling mud fluids.

[0003] In well completion and flowback operations on offshore platforms, the flowback waste fluid exhibits significant variations in volume, operation time, and composition from different wellheads. Oil-based drilling mud contains large amounts of emulsifiers, stabilizers, and other additives, resulting in a complex chemical composition and stable properties, making oil-water separation extremely difficult. Furthermore, the limited space on offshore platforms restricts the long-term storage and centralized treatment of well completion and flowback waste fluids. Currently, most existing processes utilize traditional oil-water separators, but the treated wastewater does not meet discharge standards and must be transported by ship to land for centralized treatment, leading to low efficiency and high operating costs for platform drilling and completion operations.

[0004] Meanwhile, existing oil-based drilling mud waste fluid treatment technologies have poor adaptability to the water quality of different wellhead runoff waste fluids. The treated waste fluids often fail to meet environmental protection standards for discharge, and the treatment efficiency is also insufficient to meet the production schedule requirements of offshore platforms, seriously affecting operational efficiency. Most existing equipment is relatively traditional, unable to cope with the treatment needs of different liquid qualities, resulting in poor treatment effects and complex equipment, which is not conducive to the actual treatment of runoff waste fluids from offshore platforms.

[0005] Therefore, providing a treatment device system and method for drilling flowback fluid from offshore oil and gas drilling platforms is a technical problem that needs to be solved in this field. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a device system and method for treating drilling flowback fluid from offshore oil and gas drilling platforms. Compared with the existing technology, the device system provided by this invention can realize continuous treatment and compliant discharge of drilling flowback waste fluid, improve the operating efficiency of offshore platform wellheads, and meet the treatment needs of different liquid qualities.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a treatment device system for drilling flowback fluid from an offshore oil and gas drilling platform. The treatment device system includes a pretreatment reaction skid, a vibrating screen cuttings separation skid, a solid-liquid centrifugal separation skid, and an oil-water-solid three-phase separation skid connected in sequence along the flow direction of the fluid.

[0009] Material connections between adjacent skids are made through pipelines and control valves, while positional connections are made through detachable connection devices.

[0010] The vibrating screen rock cuttings separation skid is equipped with a parallel connecting pipeline. The inlet of the connecting pipeline is connected to the outlet of the pretreatment reaction skid, and the outlet of the connecting pipeline is connected to the inlet of the solid-liquid centrifugal separation skid.

[0011] In this invention, by setting up a pretreatment reaction skid, a vibrating screen rock cuttings separation skid, a solid-liquid centrifugal separation skid, and an oil-water-solid three-phase separation skid, the system can handle different liquid qualities. Material connections are made via pipelines and control valves, improving the separation effect of the process oil, water, and solid phases, ensuring that the effluent water quality meets the standards, and allowing the purified oil phase to be directly input into the offshore production process without clogging the production process channels due to solid phase issues. In this invention, when the solid particles in the returned wastewater have a particle size <5mm and a low content, the vibrating screen rock cuttings separation skid can be selectively deactivated via a connecting pipeline. The activation or deactivation of the connecting pipeline can be controlled by a control valve. Only the combination of the pretreatment reaction skid, solid-liquid centrifugal separation skid, and oil-water-solid three-phase separation skid is used to complete the operation, thus meeting the needs for handling different liquid qualities and improving the flexibility of wastewater treatment. In this invention, the pipelines used for material connections are not particularly limited and can adopt conventional settings in the art, such as using high-pressure hoses to connect to pumps.

[0012] In this invention, each skid is small in size and light in weight, making it easy to transport and hoist. Each skid adopts an independent control system and uses a detachable connecting device to combine the skids in different positions. It can be used in combination according to the quality of the wastewater and can flexibly configure the position of each skid. The assembly of each skid can be selected according to the processing space, thereby coping with the limited space and load requirements at sea and keeping the equipment size within a minimum range, thus achieving efficient separation and treatment of oil-based drilling flowback fluid.

[0013] In this invention, there are no special limitations on the positional connection of the pretreatment reaction skid, the vibrating screen rock cuttings separation skid, the solid-liquid centrifugal separation skid, and the oil-water-solid three-phase separation skid. For example, they can be arranged horizontally in sequence through the connecting device or stacked vertically according to the site conditions. This invention can flexibly configure the position of each skid through the connecting device, thereby coping with different external environments and spaces.

[0014] Preferably, the detachable connection device includes a positioning rod and a positioning groove for receiving the positioning rod.

[0015] Preferably, the pretreatment reaction skid includes a pretreatment reaction device and a dosing device, wherein the dosing device is located at the top inlet of the pretreatment reaction device.

[0016] Preferably, the number of pretreatment reaction devices is at least two, for example, two, three or four, but not limited to the listed values. Other unlisted values ​​within the range are also applicable. The pretreatment reaction devices are arranged in parallel, and the outlet of each pretreatment reaction device is connected to the outlet manifold through a multi-way control valve.

[0017] Preferably, the pretreatment reaction device is equipped with a temperature regulation mechanism.

[0018] In this invention, the temperature regulating mechanism in the pretreatment reaction device can be set in a conventional manner in the art. The temperature regulating mechanism can be a conventional temperature regulating mechanism in the art, such as an electric heating mechanism, a steam heating mechanism, or a heat transfer oil heating mechanism.

[0019] Preferably, the dosing device includes an outer casing, which includes a cylindrical structure and an upper end face and a lower end face disposed at both ends of the cylindrical structure.

[0020] Preferably, the cylindrical structure includes an upper section, a middle section, and a lower section that are connected sequentially from top to bottom. The upper and lower sections are both columnar structures, and the diameters at both ends of the middle section are larger than the diameter at the middle, and the longitudinal cross-section is a funnel shape with central symmetry.

[0021] Preferably, the air supply pipe and the drug delivery pipe are concentrically arranged from the outside to the inside inside of the outer casing, and both the air supply pipe and the drug delivery pipe pass through the upper end face.

[0022] In this invention, the inlet of the dosing tube is generally connected to an external dosing device, and the inlet of the gas supply tube is generally connected to an external gas supply device. The connection can be made using sealing and rotating connection methods commonly used in the art.

[0023] Preferably, a first blocking wall is provided at the bottom of the gap formed by the gas supply pipe and the dosing pipe. The first blocking wall, the inner side wall of the gas supply pipe, and the outer side wall of the dosing pipe together constitute the gas supply gap. The gas inlet of the gas supply gap faces upward, and a first gas supply hole is provided on the side wall of the gas supply pipe.

[0024] Preferably, a second blocking wall is provided at the bottom of the gap formed by the inner sidewall of the upper section, the outer sidewall of the air supply pipe, and the upper end face. The second blocking wall, the outer sidewall of the air supply pipe, the inner sidewall of the upper section, and the upper end face together constitute an air supply chamber, and the second blocking wall has a second air supply hole.

[0025] Preferably, the bottom outlet of the dosing tube is located at the point of minimum diameter in the middle section.

[0026] Preferably, aeration holes are provided on the middle section, the lower section, and the lower end face.

[0027] Preferably, the sum of the number of aeration holes in the lower section and the lower end face is greater than the number of aeration holes in the middle section.

[0028] In this invention, the specially designed outer casing structure allows for the use of a larger space in the upper section to house the dosing pipe and air supply pipe, while reserving space for the air supply chamber, thereby increasing the air storage capacity and improving the aeration effect. The outlet of the dosing pipe is located at the smallest diameter point in the middle section, ensuring that the agent at the bottom opening of the dosing pipe is directly at the optimal aeration pressure position, thus improving the gas's ability to spray and disperse the agent, enhancing the uniformity of dosing and the reaction effect, reducing local airflow channels, and increasing the aeration speed. The sum of the number of aeration holes in the lower part and the lower end face is greater than the number of aeration holes in the middle section, which can prevent the accumulation of agent at the bottom. Increasing the number of aeration holes can accelerate the spraying of agent at the bottom and improve the dosing speed.

[0029] Preferably, the dosing device further includes a drive mechanism and a stirring blade. The drive mechanism is disposed on the upper end face of the outer casing, and the power output end of the drive mechanism drives the outer casing to rotate. The middle and lower sections of the outer casing are both provided with stirring blades in the circumferential direction.

[0030] In this invention, the dosing device is an integrated dosing and stirring structure, which reduces the complexity of the pretreatment reaction device, avoids having too many external components affecting the equipment layout, and reduces the risk of leakage caused by device complexity. During the dosing process, the dosing is carried out through the centrally located dosing pipe. Gas is introduced through the upper opening of the air supply pipe sleeved on the outside of the dosing pipe. The gas sequentially passes through the air supply gap, the first air supply hole, the air supply chamber, the second air supply hole, and the aeration hole into the device. The gas aeration causes the agent to be sprayed into the pretreatment reaction device from the aeration hole. Combined with stirring by the stirring blades, the uniformity of dosing and reaction efficiency are further improved.

[0031] In this invention, the driving mechanism can adopt any structure or device conventionally used for driving in the art. For example, the driving mechanism includes a motor and a gear. The motor drives the gear to rotate, and the power output end of the gear drives the outer sleeve to rotate, which in turn drives the stirring blade to rotate to achieve stirring.

[0032] Preferably, the vibrating screen rock cuttings separation skid includes a vibrating screening device, a sludge tank, a buffer water tank, and a lift pump. The solid phase outlet of the vibrating screening device is connected to the sludge tank, the liquid phase outlet of the vibrating screening device is connected to the buffer water tank, and the outlet of the buffer water tank is connected to the solid-liquid centrifugal separation skid via the lift pump.

[0033] Preferably, the solid-liquid centrifugal separation skid includes a centrifugal device, a sludge tank, a collection water tank, and a lift pump. The solid phase outlet of the centrifugal device is connected to the sludge tank, the liquid phase outlet of the centrifugal device is connected to the collection water tank, and the outlet of the collection water tank is connected to the oil-water-solid three-phase separation skid via the lift pump.

[0034] Preferably, the centrifugal device in the solid-liquid centrifugal separation skid includes a high-efficiency horizontal screw centrifuge.

[0035] Preferably, the oil-water-solid three-phase separation skid includes a centrifuge device, a platform separation device, a product water tank, and a white oil tank. The solid phase outlet of the centrifuge device is connected to the platform separation device, the water phase outlet of the centrifuge device is connected to the product water tank, and the oil phase outlet of the centrifuge device is connected to the white oil tank.

[0036] Preferably, the centrifugal device in the oil-water-solid three-phase separation skid includes a high-speed disc centrifuge.

[0037] Preferably, the treatment system further includes a platform mud tank, the outlet of which is connected to a pretreatment reaction skid.

[0038] Preferably, the platform mud tank is equipped with an analysis and testing device.

[0039] In this invention, a high-speed disc centrifuge is used to effectively separate solids from a liquid phase, ensuring that the separated oil phase meets recovery standards. The high-speed disc centrifuge is typically equipped with a spare drum and a rinsing water tank. The rinsing water tank supplies water to the high-speed disc centrifuge, allowing for the rapid installation and commissioning of the spare drum in case of centrifuge malfunction.

[0040] In a second aspect, the present invention provides a method for treating drilling flowback fluid from an offshore oil and gas drilling platform, wherein the method employs the offshore oil and gas drilling platform drilling flowback fluid treatment device system as described in the first aspect of the present invention.

[0041] The method includes the following steps:

[0042] The drilling flowback fluid is mixed with a reagent to obtain a pretreated liquid; then the pretreated liquid is separated to obtain water, oil phase and residue.

[0043] In the processing method provided by the present invention, a reagent is added to the drilling flowback fluid according to the fluid quality for mixing and reaction, and then separation is performed. This method can treat different fluid qualities and meet the requirements for discharge compliance. Specifically, the produced water meets the qualified standards for discharge, the oil phase meets the recovery standards, and the solid residue is sent to the platform separation device for further processing.

[0044] Preferably, the processing method includes the following steps:

[0045] (1) The drilling flowback fluid in the mud pit of the platform is tested by the analysis and detection device to obtain the flowback fluid parameters, including the particle size of solid particles in the drilling flowback waste fluid;

[0046] (2) The drilling flowback fluid in the platform mud pit described in step (1) is transported to the pretreatment reaction device. The type and concentration of the added agent are set according to the flowback fluid parameters obtained in step (1). The agent is added to the pretreatment reaction device through the dosing device and mixed with the flowback waste liquid. The dosing device stirs and aerates during the dosing process to obtain the pretreated liquid.

[0047] (3) If the solid particles in the drilling flowback waste liquid have a particle size of <5mm, the pretreated liquid obtained in step (2) is sent to a high-efficiency horizontal screw centrifuge through a connecting pipeline for solid-liquid separation. The obtained solid particles are sent to a sludge tank, and the obtained liquid phase is sent to a water collection tank. The liquid phase in the water collection tank is sent to a high-speed disc centrifuge through a lift pump for oil-water-solid three-phase separation. The separated product water is sent to a product water tank, the obtained oil phase is sent to a white oil tank, and the obtained residue is sent to a platform separation device.

[0048] If the solid particles in the drilling flowback waste fluid have a particle size ≥ 5 mm, the pretreated liquid obtained in step (2) is sent to a vibrating screen for screening. The rock cuttings obtained by screening are sent to a sludge tank for collection, and the liquid phase obtained is sent to a buffer tank. The liquid phase in the buffer tank is sent to a high-efficiency horizontal screw centrifuge for solid-liquid separation by a lift pump. The solid particles obtained are sent to a sludge tank, and the liquid phase obtained is sent to a collection tank. The liquid phase in the collection tank is sent to a high-speed disc centrifuge for oil-water-solid three-phase separation by a lift pump. The separated product water is sent to a product water tank, the obtained oil phase is sent to a white oil tank, and the obtained residue is sent to a platform separation device.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] (1) The treatment device system provided by the present invention has compatibility with water quality and quantity and strong impact resistance. By adding special agents, it can achieve effective separation of oil, water and solid in waste liquid. It adopts a three-stage separation process, including vibrating screen rock cuttings separation skid, solid-liquid centrifugal separation skid and oil-water-solid three-phase separation skid. It can process solid particles from large to small step by step, and has strong applicability to solid particles of different sizes and concentrations. After oil phase purification, it can be directly input into the marine production process and will not block the production process channel due to solid phase problems.

[0051] (2) The single skid in the treatment device system provided by the present invention is small in size and light in weight, making it easy to transport and hoist. Each skid adopts an independent control system and uses a detachable connection device to combine the skids in position. It can be used in combination according to the waste liquid water quality. The position of each skid can be flexibly configured, and the assembly of each skid can be selected according to the treatment space. This can cope with the narrow space at sea and thus efficiently achieve the separation and treatment of oil-based drilling flowback fluid.

[0052] (3) The treatment device system provided by the present invention is also applicable to the treatment of oily waste liquid returned from the wellhead of onshore oil and gas fields. It adopts a skid-mounted method and can be used for wellhead sewage treatment in various geographical environments and road conditions. It has the advantages of flexible and convenient mobile transportation and on-site installation. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the positional structure of a processing device system based on a horizontal arrangement in a specific embodiment of the present invention;

[0054] Figure 2 This is a schematic diagram of the positional structure of a processing device system based on a vertically stacked arrangement according to a specific embodiment of the present invention;

[0055] Figure 3 This is a schematic diagram of the processing device system based on the material flow direction provided in Embodiment 1 of the present invention;

[0056] Figure 4 This is a schematic diagram of the dosing device provided in Embodiment 1 of the present invention;

[0057] In the diagram, 101-Pretreatment reaction skid; 201-Vibrating screen rock cuttings separation skid; 301-Solid-liquid centrifugal separation skid; 401-Oil-water-solid three-phase separation skid; 501-Conducting pipeline; 601-Control valve; 701-Connecting pipeline; 801-Positioning groove; 901-Positioning rod; 110-Supporting and fixing structure; 210-Roller;

[0058] 1-Platform mud tank; 2-Analysis and detection device; 3-Dosing device; 4-Dosing device; 5-Multi-port control valve; 6-Check valve; 7-Vibrating screen device; 8-Sludge tank; 9-Buffer tank; 10-Lift pump; 11-High-efficiency horizontal screw centrifuge; 12-Collection tank; 13-High-speed disc centrifuge; 14-Platform separation device; 15-Product water tank; 16-White oil tank; 17-Pretreatment reaction device;

[0059] 411-Upper section; 412-Middle section; 413-Lower section; 414-Upper end face; 415-Lower end face; 41-Dosing pipe; 42-Air supply pipe; 43-First air supply hole; 44-Second air supply hole; 45-Aeration hole; 46-Agitator blade; 47-Drive mechanism; 48-First barrier wall; 49-Second barrier wall. Detailed Implementation

[0060] It should be understood that in the description of this invention, the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0061] It should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0062] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0063] In one specific embodiment, the present invention provides a system for treating drilling flowback fluid from offshore oil and gas drilling platforms, such as... Figure 1 and Figure 2As shown, the processing device system includes a pretreatment reaction skid 101, a vibrating screen rock cuttings separation skid 201, a solid-liquid centrifugal separation skid 301, and an oil-water-solid three-phase separation skid 401 connected sequentially along the material flow direction; adjacent skids are connected by pipelines and control valves 601 for material connection, and by a detachable connection device for positional connection; the vibrating screen rock cuttings separation skid 201 is provided with a parallel connecting pipeline 501, the inlet of the connecting pipeline 501 is connected to the outlet of the pretreatment reaction skid 101, and the outlet of the connecting pipeline 501 is connected to the inlet of the solid-liquid centrifugal separation skid 301.

[0064] In this invention, by setting up a pretreatment reaction skid 101, a vibrating screen rock cuttings separation skid 201, a solid-liquid centrifugal separation skid 301, and an oil-water-solid three-phase separation skid 401, the system can handle different liquid qualities. Material connections are established via pipelines and control valves 601, improving the separation effect of the process oil, water, and solid phases, ensuring that the effluent water quality meets standards, and allowing the purified oil phase to be directly input into the offshore production process without clogging the production process channels due to solid phase issues. In this invention, when the solid particles in the returned wastewater have a particle size <5mm and a low content, the vibrating screen rock cuttings separation skid 201 can be selectively shut down via the connecting pipeline 501. Only the pretreatment reaction skid 101, solid-liquid centrifugal separation skid 301, and oil-water-solid three-phase separation skid 401 are used to complete the task, thus meeting the needs for handling different liquid qualities and improving the flexibility of wastewater treatment. In this invention, the pipelines used for material connections are not particularly limited and can adopt conventional setups in the art, such as using high-pressure hoses to connect to pumps.

[0065] In this invention, each skid is small in size and light in weight, making it easy to transport and hoist. Each skid adopts an independent control system and uses a detachable connecting device to combine the skids in different positions. It can be used in combination according to the quality of the wastewater and can flexibly configure the position of each skid. The assembly of each skid can be selected according to the processing space, thereby coping with the limited space and load requirements at sea and keeping the equipment size within a minimum range, thus achieving efficient separation and treatment of oil-based drilling flowback fluid.

[0066] In some embodiments, the detachable connection device includes a positioning rod 901 and a positioning groove 801 for receiving the positioning rod 901.

[0067] In some of these embodiments, such as Figure 1As shown, the pretreatment reaction skid 101, the vibrating screen cuttings separation skid 201, the solid-liquid centrifugal separation skid 301, and the oil-water-solid three-phase separation skid 401 are arranged horizontally in sequence. Each skid is connected to the others via a detachable connection device, namely a positioning rod 901 and a positioning groove 801 for accommodating the positioning rod 901. The vibrating screen cuttings separation skid 201 is equipped with a parallel connecting pipe 501. The inlet of the connecting pipe 501 is connected to the outlet of the pretreatment reaction skid 101, and the outlet of the connecting pipe 501 is connected to the inlet of the solid-liquid centrifugal separation skid 301. Figure 2 As shown, the skids are arranged longitudinally, with the pretreatment reaction skid 101 and the vibrating screen rock cuttings separation skid 201 stacked vertically from top to bottom, and the solid-liquid centrifugal separation skid 301 and the oil-water-solid three-phase separation skid 401 stacked vertically from top to bottom. They are connected by the positioning rod 901 and the positioning groove 801 in the connecting device. The outlet of the pretreatment reaction skid 101 is connected to the inlet of the solid-liquid centrifugal separation skid 301 through the connecting pipe 501. Whether the connecting pipe 501 is activated is controlled by the control valve ( Figure 2 (Not shown in the image) Controlled, the outlet of the vibrating screen rock chip separation skid 201 is connected to the inlet of the solid-liquid centrifugal separation skid 301 through the connecting pipe 701. Each skid can be equipped with multiple connecting devices on the top, bottom or sides as needed to meet the needs of horizontal or vertical stacking arrangement.

[0068] In this invention, the bottom of each skid can be selectively provided with a support and fixing structure 110, and the support and fixing structure 110 is provided with rollers 210 to facilitate the movement, fixing and assembly of each skid. The overall device system can also be directly installed on a floating platform at sea, which has strong adaptability.

[0069] In some of these embodiments, such as Figure 3 As shown, the pretreatment reaction skid includes a pretreatment reaction device 17 and a dosing device 4, with the dosing device 4 located at the top inlet of the pretreatment reaction device 17.

[0070] In some embodiments, the number of pretreatment reaction devices 17 is at least two, for example, two, three or four, but not limited to the listed values. Other unlisted values ​​within the range are also applicable. The pretreatment reaction devices 17 are arranged in parallel, and the outlet of each pretreatment reaction device 17 is connected to the outlet manifold through a multi-way control valve 5.

[0071] In this invention, multiple pretreatment reaction devices 17 can be configured. The number of pretreatment reaction devices 17 can be selected according to the volume and parameters of the liquid to be treated, avoiding the need to wait for processing due to the long processing time of a single pretreatment reaction device 17. This allows for continuous processing of waste liquid without stopping the system, improving waste liquid treatment efficiency and throughput. Furthermore, based on changes in waste liquid parameters, the multi-way control valve 5 can control the flow of waste liquid into different pretreatment reaction devices 17, allowing for the selection of appropriate concentrations or types of reagents. This enables continuous processing of waste liquid based on parameter changes without stopping the system, thereby meeting the requirements for waste liquid treatment effect and precision. Additionally, a one-way valve 6 is installed between the multi-way control valve 5 and the pretreatment reaction device 17 to control the flow direction of the waste liquid.

[0072] In some embodiments, the pretreatment reaction apparatus 17 is internally equipped with a temperature control mechanism.

[0073] In this invention, the temperature regulation mechanism within the pretreatment reaction device 17 can be implemented using conventional methods within the art, such as electric heating, steam heating, or thermal oil heating. Simultaneous stirring and mixing occur within the pretreatment reaction device 17 to ensure uniform heating of the liquid, with the temperature generally controlled between 40-60°C. The temperature regulation mechanism can employ an automatic temperature control system to reduce manual operation and prevent excessively high temperatures from causing the volatilization of flammable or toxic gases, thus avoiding environmental and human harm.

[0074] In some of these embodiments, such as Figure 4 As shown, the dosing device 4 includes an outer casing, which includes a cylindrical structure and an upper end face 414 and a lower end face 415 disposed at both ends of the cylindrical structure.

[0075] In some embodiments, the cylindrical structure includes an upper section 411, a middle section 412, and a lower section 413 that are connected sequentially from top to bottom. The upper section 411 and the lower section 413 are both columnar structures. The diameters at both ends of the middle section 412 are larger than the diameter in the middle, and the longitudinal cross-section is a funnel shape with central symmetry.

[0076] In some embodiments, an air supply pipe 42 and a drug delivery pipe 41 are concentrically arranged inside the outer casing from the outside to the inside, and both the air supply pipe 42 and the drug delivery pipe 41 pass through the upper end face 414.

[0077] In this invention, the inlet of the dosing pipe 41 is generally connected to the external dosing device 3, and the inlet of the air supply pipe 42 is generally connected to the external air supply device. The connection can be achieved using sealing and rotating methods commonly used in the art. In this invention, the dosing pipe 41 adds chemicals according to the waste liquid's condition. The chemicals generally include commonly used demulsifiers, coagulants, demulsifiers, and flocculants to improve the subsequent separation of oil, water, and solids, ensuring the effluent quality meets standards. The demulsifier generally includes both liquid and solid forms, and the concentration is generally between 0.5% and 5%, with the specific concentration determined based on the water quality.

[0078] In some embodiments, a first blocking wall 48 is provided at the bottom of the gap formed by the gas supply pipe 42 and the dosing pipe 41. The first blocking wall 48, the inner side wall of the gas supply pipe 42, and the outer side wall of the dosing pipe 41 together constitute the gas supply gap. The gas inlet of the gas supply gap faces upward, and a first gas supply hole 43 is provided on the side wall of the gas supply pipe 42.

[0079] In some embodiments, a second blocking wall 49 is provided at the bottom of the gap formed by the inner sidewall of the upper section 411, the outer sidewall of the air supply pipe 42, and the upper end face 414. The second blocking wall 49, the outer sidewall of the air supply pipe 42, the inner sidewall of the upper section 411, and the upper end face 414 together constitute an air supply chamber. The second blocking wall 49 has a second air supply hole 44.

[0080] In some embodiments, the bottom outlet of the dosing tube 41 is located at the point of minimum diameter of the middle section 412.

[0081] In some embodiments, the middle section 412, the lower section 413, and the lower end face 415 are all provided with aeration holes 45.

[0082] In some embodiments, the sum of the number of aeration holes 45 in the lower section 413 and the lower end face 415 is greater than the number of aeration holes 45 in the middle section 412.

[0083] In this invention, by specifically designing the outer casing, the upper section 411, with its larger space, can accommodate the dosing pipe 41 and the air supply pipe 42 while reserving space for the air supply chamber, thereby increasing the air storage capacity and improving the aeration effect. The outlet of the dosing pipe 41 is located at the smallest diameter point in the middle section 412, ensuring that the agent at the bottom opening of the dosing pipe 41 is directly at the optimal aeration pressure position, thus improving the gas's ability to spray and disperse the agent, enhancing the uniformity of dosing and the reaction effect, narrowing the local airflow channel, and increasing the aeration speed. The sum of the number of aeration holes 45 in the lower part and the lower end face 415 is greater than the number of aeration holes 45 in the middle section 412, which can prevent the accumulation of agent at the bottom. Increasing the number of aeration holes 45 can accelerate the spraying of agent at the bottom and improve the dosing speed.

[0084] In some embodiments, the dosing device 4 further includes a drive mechanism 47 and a stirring blade 46. The drive mechanism 47 is disposed on the upper end face 414 of the outer casing. The power output end of the drive mechanism 47 drives the outer casing to rotate. The middle section 412 and the lower section 413 of the outer casing are both provided with stirring blades 46 in the circumferential direction.

[0085] In this invention, the dosing device 4 is an integrated dosing and stirring structure, which reduces the complexity of the pretreatment reaction device 17, avoids having too many external components that would affect the equipment layout, and reduces the risk of leakage due to device complexity. During the dosing process, the dosing is carried out through the centrally located dosing pipe 41. Gas is introduced through the upper opening of the air supply pipe 42 sleeved on the outside of the dosing pipe 41. The gas passes through the air supply gap, the first air supply hole 43, the air supply chamber, the second air supply hole 44, and the aeration hole 45 in sequence into the device. The gas aeration causes the agent to be sprayed into the pretreatment reaction device 17 from the aeration hole 45, and combined with the stirring blade 46, the uniformity of dosing and reaction efficiency are further improved.

[0086] In this invention, the drive mechanism 47 can adopt any structure or device conventionally used for driving in the art. For example, the drive mechanism 47 includes a motor and a gear. The motor drives the gear to rotate, and the power output end of the gear drives the outer sleeve to rotate, which in turn drives the stirring blade 46 to rotate to achieve stirring.

[0087] In some of these embodiments, such as Figure 3 As shown, the vibrating screen rock cuttings separation skid includes a vibrating screen device 7, a sludge tank 8, a buffer water tank 9, and a lift pump 10. The solid phase outlet of the vibrating screen device 7 is connected to the sludge tank 8, and the liquid phase outlet of the vibrating screen device 7 is connected to the buffer water tank 9. The outlet of the buffer water tank 9 is connected to the solid-liquid centrifugal separation skid via the lift pump 10.

[0088] In some of these embodiments, such as Figure 3 As shown, the solid-liquid centrifugal separation skid includes a centrifugal device, a sludge tank 8, a water collection tank 12, and a lift pump 10. The solid phase outlet of the centrifugal device is connected to the sludge tank 8, the liquid phase outlet of the centrifugal device is connected to the water collection tank 12, and the outlet of the water collection tank 12 is connected to the oil-water-solid three-phase separation skid via the lift pump 10.

[0089] In some embodiments, the centrifugal device in the solid-liquid centrifugal separation skid includes a high-efficiency horizontal screw centrifuge 11.

[0090] In some of these embodiments, such as Figure 3As shown, the oil-water-solid three-phase separation skid includes a centrifuge device, a platform separation device 14, a product water tank 15, and a white oil tank 16. The solid phase outlet of the centrifuge device is connected to the platform separation device 14, the water phase outlet of the centrifuge device is connected to the product water tank 15, and the oil phase outlet of the centrifuge device is connected to the white oil tank 16.

[0091] In some embodiments, the centrifugal device in the oil-water-solid three-phase separation skid includes a high-speed disc centrifuge 13.

[0092] In this invention, a high-speed disc centrifuge 13 effectively separates solids from the liquid phase, ensuring that the separated oil phase meets recovery standards. The high-speed disc centrifuge 13 is typically equipped with a spare drum and a flushing water tank. The flushing water tank supplies water to the centrifuge 13. In case of centrifuge malfunction, the spare drum can be directly activated, enabling rapid installation and commissioning. Furthermore, the spare drum allows for 24-hour continuous processing, meeting the production requirements of the offshore platform wellhead at maximum discharge rates.

[0093] In some of these embodiments, such as Figure 3 As shown, the treatment system also includes a platform mud tank 1, the outlet of which is connected to the pretreatment reaction skid.

[0094] In some embodiments, the platform mud tank 1 is equipped with an analysis and detection device 2.

[0095] In this invention, in order to facilitate the detection of waste liquid parameters, multiple analytical detection devices 2 can be installed on the platform mud tank 1 to detect the liquid quality parameters of the waste liquid, such as pH and solid particle size, so as to control the type and concentration of the reagents added later.

[0096] In another specific embodiment, the present invention provides a method for treating drilling flowback fluid from an offshore oil and gas drilling platform, wherein the method employs a treatment device system for drilling flowback fluid from an offshore oil and gas drilling platform provided in a specific embodiment of the present invention.

[0097] The method includes the following steps:

[0098] The drilling flowback fluid is mixed with a reagent to obtain a pretreated liquid; then the pretreated liquid is separated to obtain water, oil phase and residue.

[0099] In the processing method provided by the present invention, a reagent is added to the drilling flowback fluid according to the fluid quality for mixing and reaction, and then separation is performed. This method can treat different fluid qualities and meet the requirements for discharge compliance. That is, the produced water meets the qualified standard for discharge, the oil phase meets the recovery standard, and the solid residue is sent to the platform separation device 14 for further processing.

[0100] In some embodiments, the processing method includes the following steps:

[0101] (1) The drilling flowback fluid in the platform mud pit 1 is tested by the analysis and detection device 2 to obtain the flowback fluid parameters, including the particle size of solid particles in the drilling flowback waste fluid.

[0102] (2) The drilling flowback fluid in the platform mud pit 1 described in step (1) is transported to the pretreatment reaction device 17. The type and concentration of the added agent are set according to the flowback fluid parameters obtained in step (1). The agent is added to the pretreatment reaction device 17 through the dosing device 4 and mixed with the flowback waste liquid. The dosing device 4 performs stirring and aeration during the dosing process to obtain the pretreated liquid.

[0103] (3) If the particle size of the solid particles in the drilling flowback waste liquid is <5mm, the pretreated liquid obtained in step (2) is sent to the high-efficiency horizontal screw centrifuge 11 through the connecting pipeline for solid-liquid separation. The obtained solid particles are sent to the sludge tank 8, and the obtained liquid phase is sent to the collection water tank 12. The liquid phase in the collection water tank 12 is sent to the high-speed disc centrifuge 13 through the lift pump 10 for oil-water-solid three-phase separation. The separated product water is sent to the product water tank 15, the obtained oil phase is sent to the white oil tank 16, and the obtained residue is sent to the platform separation device 14.

[0104] If the solid particles in the drilling flowback waste fluid have a particle size ≥ 5 mm, the pretreated liquid obtained in step (2) is sent to the vibrating screen 7 for screening. The rock cuttings obtained by screening are sent to the sludge tank 8 for collection. The liquid phase obtained is sent to the buffer tank 9. The liquid phase in the buffer tank 9 is sent to the high-efficiency horizontal screw centrifuge 11 by the lift pump 10 for solid-liquid separation. The solid particles obtained are sent to the sludge tank 8. The liquid phase obtained is sent to the collection tank 12. The liquid phase in the collection tank 12 is sent to the high-speed disc centrifuge 13 by the lift pump 10 for oil-water-solid three-phase separation. The separated product water is sent to the product water tank 15. The obtained oil phase is sent to the white oil tank 16. The obtained residue is sent to the platform separation device 14.

[0105] Example 1

[0106] This embodiment provides a system for treating drilling flowback fluid from offshore oil and gas drilling platforms, such as... Figure 3 As shown, the processing device system includes a pretreatment reaction skid, a vibrating screen rock cuttings separation skid, a solid-liquid centrifugal separation skid and an oil-water-solid three-phase separation skid connected in sequence along the direction of material flow, and also includes a platform mud tank 1, in which an analysis and detection device 2 is installed.

[0107] The pretreatment reaction skid includes a pretreatment reaction device 17 and a dosing device 4. The inlet of the dosing device 4 is connected to an external dosing device 3. The dosing device 4 is located at the top inlet of the pretreatment reaction device 17. There are three pretreatment reaction devices 17 arranged in parallel. The outlet of each pretreatment reaction device 17 is connected to an outlet manifold via a multi-way control valve 5. The outlet of the outlet manifold is connected to a vibrating screen device 7. The platform mud tank 1 is connected to an inlet manifold via a multi-way control valve 5. The outlet of the inlet manifold is connected to each of the pretreatment reaction devices 17. A one-way valve 6 is provided between the multi-way control valve 5 and the pretreatment reaction device 17. A temperature regulating mechanism is provided inside the pretreatment reaction device 17.

[0108] Among them, such as Figure 4 As shown, the dosing device 4 includes an outer casing, which comprises a cylindrical structure and an upper end face 414 and a lower end face 415 disposed at both ends of the cylindrical structure. The cylindrical structure includes an upper section 411, a middle section 412, and a lower section 413 connected sequentially from top to bottom. The upper section 411 and the lower section 413 are both columnar structures. The diameters at both ends of the middle section 412 are larger than the diameter at the middle, and its longitudinal cross-section is a centrally symmetrical funnel shape. Inside the outer casing, an air supply pipe 42 and a dosing pipe 41 are concentrically arranged from the outside to the inside, and both the air supply pipe 42 and the dosing pipe 41 pass through the upper end face 414. A first blocking wall 48 is provided at the bottom of the gap formed by the air supply pipe 42 and the dosing pipe 41. The first blocking wall 48, the inner side wall of the air supply pipe 42, and the outer side wall of the dosing pipe 41 together constitute the air supply gap. The gas inlet of the air supply gap faces upward, and a first air supply hole 43 is opened on the side wall of the air supply pipe 42. A second blocking wall 49 is provided at the bottom of the gap formed by the inner sidewall of the upper section 411, the outer sidewall of the air supply pipe 42, and the upper end face 414. The second blocking wall 49, the outer sidewall of the air supply pipe 42, the inner sidewall of the upper section 411, and the upper end face 414 together constitute an air supply chamber. The second blocking wall 49 has a second air supply hole 44. The bottom outlet of the dosing pipe 41 is located at the smallest diameter of the middle section 412. The middle section 412, the lower section 413, and the lower end face 415 are all provided with aeration holes 45. The sum of the number of aeration holes 45 in the lower section 413 and the lower end face 415 is greater than the number of aeration holes 45 in the middle section 412. The dosing device 4 also includes a drive mechanism 47 and a stirring blade 46. The drive mechanism 47 is located on the upper end face 414 of the outer jacket. The power output end of the drive mechanism 47 drives the outer jacket to rotate. The middle section 412 and the lower section 413 of the outer jacket are both provided with stirring blades 46 in the circumferential direction.

[0109] The vibrating screen rock cuttings separation skid includes a vibrating screen device 7, a sludge tank 8, a buffer water tank 9, and a lift pump 10. The inlet of the vibrating screen device 7 is connected to the outlet of the multi-way control valve 5. The solid phase outlet of the vibrating screen device 7 is connected to the sludge tank 8. The liquid phase outlet of the vibrating screen device 7 is connected to the buffer water tank 9. The outlet of the buffer water tank 9 is connected to the high-efficiency horizontal screw centrifuge 11 of the solid-liquid centrifugal separation skid through the lift pump 10.

[0110] The solid-liquid centrifugal separation skid includes a high-efficiency horizontal screw centrifuge 11, a sludge tank 8, a collection water tank 12, and a lift pump 10. The solid phase outlet of the high-efficiency horizontal screw centrifuge 11 is connected to the sludge tank 8, and the liquid phase outlet of the high-efficiency horizontal screw centrifuge 11 is connected to the collection water tank 12. The outlet of the collection water tank 12 is connected to the high-speed disc centrifuge 13 of the oil-water-solid three-phase separation skid through the lift pump 10.

[0111] The oil-water-solid three-phase separation skid includes a high-speed disc centrifuge 13, a platform separation device 14, a product water tank 15, and a white oil tank 16. The solid phase outlet of the high-speed disc centrifuge 13 is connected to the platform separation device 14, the water phase outlet of the high-speed disc centrifuge 13 is connected to the product water tank 15, and the oil phase outlet of the high-speed disc centrifuge 13 is connected to the white oil tank 16.

[0112] In this embodiment, the maximum processing capacity of the processing device system is 5m³. 3 The processing unit system employs explosion-proof design for all motors and electrical control cabinets, with an explosion-proof rating of EX dII BT4. The motors and electrical control cabinets meet IP65 or higher protection standards, satisfying the explosion-proof and open-air operation requirements of oilfield operations. All material inlets and outlets use unibody connections, and high-pressure hoses are used for pipelines. The maximum skid dimensions for each skid are: L≤4100mm, W≤2500mm, H≤3000mm, suitable for the compact space of offshore platforms and allowing for reasonable placement based on the platform's location.

[0113] In summary, the device system provided by this invention can achieve continuous treatment and compliant discharge of drilling flowback waste fluid, improve the operational efficiency of offshore platform wellheads, and meet the treatment needs of different liquid qualities.

[0114] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A system for treating drilling flowback fluid from offshore oil and gas drilling platforms, characterized in that, The processing device system includes a pretreatment reaction skid, a vibrating screen rock cuttings separation skid, a solid-liquid centrifugal separation skid, and an oil-water-solid three-phase separation skid connected in sequence along the direction of material flow. Material connections between adjacent skids are made through pipelines and control valves, while positional connections are made through detachable connection devices. The vibrating screen rock cuttings separation skid is equipped with a parallel connecting pipeline. The inlet of the connecting pipeline is connected to the outlet of the pretreatment reaction skid, and the outlet of the connecting pipeline is connected to the inlet of the solid-liquid centrifugal separation skid. The pretreatment reaction skid includes a pretreatment reaction device and a dosing device, wherein the dosing device is located at the top inlet of the pretreatment reaction device; The dosing device includes an outer casing, which includes a cylindrical structure and an upper end face and a lower end face disposed at both ends of the cylindrical structure; The cylindrical structure includes an upper section, a middle section, and a lower section that are connected sequentially from top to bottom. The upper and lower sections are both columnar structures, and the diameters at both ends of the middle section are larger than the diameter in the middle, and the longitudinal cross-section is a funnel shape with central symmetry. Inside the outer casing, an air supply pipe and a drug delivery pipe are concentrically arranged from the outside to the inside, and both the air supply pipe and the drug delivery pipe pass through the upper end face; A first blocking wall is provided at the bottom of the gap formed by the gas supply pipe and the dosing pipe. The first blocking wall, the inner side wall of the gas supply pipe, and the outer side wall of the dosing pipe together constitute the gas supply gap. The gas inlet of the gas supply gap faces upward, and a first gas supply hole is opened on the side wall of the gas supply pipe. A second blocking wall is provided at the bottom of the gap formed by the inner side wall of the upper section, the outer side wall of the air supply pipe, and the upper end face. The second blocking wall, the outer side wall of the air supply pipe, the inner side wall of the upper section, and the upper end face together constitute an air supply chamber. A second air supply hole is opened in the second blocking wall. The bottom outlet of the dosing tube is located at the point of minimum diameter in the middle section; Aeration holes are provided in the middle section, lower section and lower end face; The sum of the number of aeration holes in the lower section and the lower end face is greater than the number of aeration holes in the middle section.

2. The processing apparatus system according to claim 1, characterized in that, The detachable connection device includes a positioning rod and a positioning groove for accommodating the positioning rod.

3. The processing apparatus system according to claim 1, characterized in that, The number of the pretreatment reaction devices is at least two, and the pretreatment reaction devices are arranged in parallel. The outlet of each pretreatment reaction device is connected to the outlet manifold through a multi-way control valve.

4. The processing apparatus system according to claim 1, characterized in that, The pretreatment reaction device is equipped with an internal temperature control mechanism.

5. The processing apparatus system according to claim 1, characterized in that, The dosing device also includes a drive mechanism and stirring blades. The drive mechanism is located on the upper surface of the outer casing. The power output end of the drive mechanism drives the outer casing to rotate. Stirring blades are arranged circumferentially in the middle and lower sections of the outer casing.

6. The processing apparatus system according to claim 1, characterized in that, The vibrating screen rock cuttings separation skid includes a vibrating screening device, a sludge tank, a buffer water tank, and a lift pump. The solid phase outlet of the vibrating screening device is connected to the sludge tank, and the liquid phase outlet of the vibrating screening device is connected to the buffer water tank. The outlet of the buffer water tank is connected to the solid-liquid centrifugal separation skid via the lift pump.

7. The processing apparatus system according to claim 6, characterized in that, The solid-liquid centrifugal separation skid includes a centrifugal device, a sludge tank, a collection water tank, and a lift pump. The solid phase outlet of the centrifugal device is connected to the sludge tank, the liquid phase outlet of the centrifugal device is connected to the collection water tank, and the outlet of the collection water tank is connected to the oil-water-solid three-phase separation skid via the lift pump.

8. The processing apparatus system according to claim 7, characterized in that, The centrifugal device in the solid-liquid centrifugal separation skid includes a high-efficiency horizontal screw centrifuge.

9. The processing apparatus system according to claim 8, characterized in that, The oil-water-solid three-phase separation skid includes a centrifuge device, a platform separation device, a product water tank, and a white oil tank. The solid phase outlet of the centrifuge device is connected to the platform separation device, the water phase outlet of the centrifuge device is connected to the product water tank, and the oil phase outlet of the centrifuge device is connected to the white oil tank.

10. The processing apparatus system according to claim 9, characterized in that, The centrifugal device in the oil-water-solid three-phase separation skid includes a high-speed disc centrifuge.

11. The processing apparatus system according to claim 10, characterized in that, The treatment system also includes a platform mud tank, the outlet of which is connected to a pretreatment reaction skid.

12. The processing apparatus system according to claim 11, characterized in that, The platform's mud pit is equipped with an analysis and testing device.

13. A method for treating drilling flowback fluid from an offshore oil and gas drilling platform, characterized in that, The treatment method employs the drilling fluid treatment device system for offshore oil and gas drilling platforms as described in claim 12; The method includes the following steps: The drilling flowback fluid is mixed with a reagent to obtain a pretreated liquid; then the pretreated liquid is separated to obtain water, oil phase and residue.

14. The processing method according to claim 13, characterized in that, The processing method includes the following steps: (1) The drilling flowback fluid in the mud pit of the platform is tested by the analysis and detection device to obtain the flowback fluid parameters, including the particle size of solid particles in the drilling flowback waste fluid; (2) The drilling flowback fluid in the platform mud pit described in step (1) is transported to the pretreatment reaction device. The type and concentration of the added agent are set according to the flowback fluid parameters obtained in step (1). The agent is added to the pretreatment reaction device through the dosing device and mixed with the flowback waste liquid. The dosing device stirs and aerates during the dosing process to obtain the pretreated liquid. (3) If the particle size of the solid particles in the drilling flowback waste liquid is <5mm, the pretreated liquid obtained in step (2) is sent to a high-efficiency horizontal screw centrifuge through a connecting pipeline for solid-liquid separation. The obtained solid particles are sent to a sludge tank, and the obtained liquid phase is sent to a water collection tank. The liquid phase in the water collection tank is sent to a high-speed disc centrifuge through a lift pump for oil-water-solid three-phase separation. The separated product water is sent to a product water tank, the obtained oil phase is sent to a white oil tank, and the obtained residue is sent to a platform separation device. If the solid particles in the drilling flowback waste fluid have a particle size ≥ 5 mm, the pretreated liquid obtained in step (2) is sent to a vibrating screen for screening. The rock cuttings obtained by screening are sent to a sludge tank for collection, and the liquid phase obtained is sent to a buffer tank. The liquid phase in the buffer tank is sent to a high-efficiency horizontal screw centrifuge for solid-liquid separation by a lift pump. The solid particles obtained are sent to a sludge tank, and the liquid phase obtained is sent to a collection tank. The liquid phase in the collection tank is sent to a high-speed disc centrifuge for oil-water-solid three-phase separation by a lift pump. The separated product water is sent to a product water tank, the obtained oil phase is sent to a white oil tank, and the obtained residue is sent to a platform separation device.

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