Offshore platform gas-liquid separator and on-site rapid water separation process system

Abstract

The present application relates to the technical field of oilfield equipment, in particular to a gas phase separator for offshore platform, a liquid phase separator and an on-site quick water separation process system, through the novel gas phase separator for offshore platform and the liquid phase separator, the separation process is completed in the flow in the separation device with the structural feature of pipeline, the idle space of the original platform can be effectively utilized and integrated with the original process flow, the installation can be flexibly arranged according to the separation requirement, and the above characteristics have important significance under the condition of limited area and carrying capacity of the offshore oil production platform.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oilfield equipment, in particular to a gas-phase separator, a liquid-phase separator and an on-site rapid water separation process system for offshore platforms. BACKGROUND

[0002] In offshore oil production, satellite platforms are used in many places to produce oil. The produced liquid is transported to the central platform through the pipe network, and the treated reinjection water is transported to each platform through the pipe network for injection into the underground. This production mode is beneficial to maintaining the formation and reservoir pressure and stabilizing the liquid production. The problem of this production mode is that all oil and gas and water separation tasks of the oil wells are handled by the central platform, which is heavy. When the liquid production of the oil well increases or a new well is put into production in the area, it often exceeds the processing capacity of the central platform. In addition, the water content of the produced liquid in domestic offshore oilfields is more than 75%. This part of the water is transported to the central platform, and after treatment, it is transported back to the oil production platform for injection. The energy consumption is large, and the valuable subsea pipeline resources are occupied. If each oil production platform can realize rapid water separation and reinjection, the production load of the central platform can be reduced, and the power consumption and pipeline construction cost can be saved.

[0003] Some oil production platforms do not consider oil / gas / water separation at the beginning of the design, and the reserved space and carrying capacity are limited, so they are not suitable for increasing tank-type multi-phase separators according to the design mode of the central platform. Therefore, compared with the traditional separation process and device, the requirements of small footprint, light weight, safety and reliability, and high processing efficiency are proposed. Through literature retrieval, it is understood that the following technical progress exists for this problem:

[0004] Related papers:

[0005] [1] Li Ruifeng, Chen Jiaqing, Ji Yipeng, et al. Subsea compact multi-phase separation technology for offshore oil and gas development [J]. Petroleum Machinery, 2012.

[0006] The paper mentions that the horizontal single coil separator design idea was first proposed by a Norwegian company and is mainly used for gravity liquid-liquid separation. Its design concept is mainly based on four points: 1) reduce the inner diameter of the separator, shorten the sedimentation distance and time of water particles; 2) increase the interface area of the water phase, reduce the interface hydraulic load; 3) increase the shear force on the oil-water emulsion layer to accelerate the emulsion layering; 4) increase the axial flow rate to make the oil well production liquid in a turbulent state, thereby improving the oil-water separation efficiency.

[0007] Problems: The scheme mentioned in the paper mainly uses gravity as the separation principle, and the method is single. The present application utilizes the combined action of gravity, centrifugal force, shear friction, buoyancy and other forces, which can improve the separation efficiency and enhance the oil removal effect under complex conditions.

[0008] [2] Ding P, Dang W, Wang L, et al. Current situation and prospect of produced water reinjection treatment technology in oilfield[J]. Modern Chemical Industry, 2019

[0009] Abstract: Based on the analysis of the characteristics of oilfield produced water and the quality standards of reinjection water, this paper summarizes the widely used and effective oil-water separation processes for reinjection treatment, including gravity separation, air flotation, hydrocyclone technology, coarse granulation technology, filtration, coagulation sedimentation, chemical oxidation, biological treatment and membrane separation technology, and compares the advantages and disadvantages of various treatment methods in engineering application. At the same time, two new equipment for produced water treatment developed in China are introduced, which are small-scale pipeline oil-water separator applied to offshore oilfield and integrated pre-water separation device applied to high water cut period of land oilfield. Finally, the development trend of oilfield produced water treatment technology and equipment is prospected, and low cost, high efficiency, miniaturization and automation are the development direction of future produced water treatment technology and equipment.

[0010] Problems: The small-scale pipeline separator for offshore oilfield introduced in this paper adopts the process flow of produced liquid-pre-water separator-oil removal tank-sedimentation air flotation tank-buffer tank-two-stage filtration, and the oil-water separation time is 1 hour, which does not meet the rapid water separation requirement of oil production platform, and the sedimentation separation time is long and the equipment weight is large.

[0011] Related patents:

[0012] [3] CN201911358699.8, Oil-water separation device and oil-water separation method. China Petroleum and Natural Gas Co., Ltd.

[0013] Patent Abstract: The present application provides an oil-water separation device and an oil-water separation method. The oil-water separation device comprises a cyclone dehydrator, an electric dehydrator and a cyclone oil removal device. The cyclone dehydrator is used for oil-water separation of mixed liquid. The electric dehydrator has a shell and an electrode plate group and a coalescing element arranged in the shell. The first-stage water-containing crude oil separated by the cyclone dehydrator is transported to the electrode plate group for oil-water separation. The first-stage oil-containing sewage separated by the cyclone dehydrator is transported to the coalescing element for oil-water separation. The crude oil outlet is used for outputting the separated crude oil. The cyclone oil removal device is used for oil-water separation of the second-stage oil-containing sewage. The second oil phase outlet of the cyclone oil removal device is used for outputting the second-stage water-containing crude oil separated from the second-stage oil-containing sewage. The sewage outlet is used for outputting the sewage separated from the second-stage oil-containing sewage. The scheme integrates the processes of crude oil pre-dehydration, deep dehydration and sewage oil removal, realizes centralized and efficient treatment of crude oil, and reduces the burden of subsequent processes.

[0014] The existing problems: the patent adopts electromagnetic dewatering technology, which depends on the tank body, has large volume, and needs to be equipped with electrode plates and high-voltage power supply, and has certain requirements on safety and maintenance.

[0015] [4] CN202022101218.X, A cyclone separation device for oily sewage. Harbin Petroleum College

[0016] Patent Abstract: The utility model discloses a cyclone separation device for oily sewage relates to oil water separation field. The utility model discloses a cyclone chamber, inlet chamber, contraction chamber, base and rotating device, and one end of cyclone chamber is connected with inlet chamber, and one end of inlet chamber is connected with contraction chamber, and the cyclone chamber includes cyclone plate and rotating plate, and one end of cyclone plate is connected with the inner surface of rotating plate, and the inlet chamber includes inlet chamber main part, and the contraction chamber includes first contraction chamber, second contraction chamber and third contraction chamber, and the first contraction chamber, second contraction chamber and third contraction chamber are all half conical structure, and the rotating device includes rotating wheel and including rotating device, and the outer surface of rotating wheel is connected with rotating device, and the inner surface of rotating wheel is connected with the outer surface of cyclone plate, and three contraction chambers in the utility model make the equipment reach corresponding centrifugal force, and the required energy consumption is reduced, and the rotating device rotates and drives the rotating wheel to rotate, and the rotating frequency can be adjusted through the rotating device, and the equipment operation is more stable.

[0017] The existing problems: the patent adopts external power to provide centrifugal force, and there are moving parts, and the structure is complex. The pipeline separation technology of the present application utilizes the potential energy of hydraulic pressure to convert into rotational kinetic energy, and the device structure is simple and reliable, reduces power consumption, and is beneficial to energy saving and reducing equipment cost. SUMMARY

[0018] The purpose of the present application is to overcome the defects of the prior art, provide a gas phase separator for offshore platform, liquid phase separator and on-site rapid water separation process system, realize the main purpose of simple equipment structure, small occupation area, light weight and low cost, the whole separation process is completed in the flow in the separation device with pipeline as the structural feature, can effectively utilize the idle space of the original platform and integrate with the original process flow, and can be flexibly arranged and installed according to the separation requirement.

[0019] The technical scheme of the present application is:

[0020] The present application provides a gas phase separator for offshore platform, which comprises a first inner sleeve and a first outer sleeve arranged coaxially, the bottom of the first inner sleeve is located in the cavity of the first outer sleeve, and a first annular cavity is formed, and a first annular baffle is connected between the first inner sleeve and the first outer sleeve to close the top of the first annular cavity.

[0021] The part of the pipe wall of the first inner sleeve located in the first outer sleeve cavity is provided with a group of first through holes, and an outer opening type normally open sealing door is elastically hinged on the first through hole, and the normally open sealing door is closed by the liquid in the first annular cavity through the rotation flow;

[0022] The upper end of the first outer sleeve is provided with a first liquid inlet communicated with the first annular cavity, the first liquid inlet is arranged along the tangent line of the first outer sleeve, the top of the first inner sleeve is a gas phase outlet, the bottom of the first inner sleeve is blocked, and the bottom of the first outer sleeve is a first liquid outlet.

[0023] The second inner sleeve and the second outer sleeve are coaxially arranged, the second inner sleeve penetrates the inner cavity of the second outer sleeve and forms a second annular cavity, and a pair of second annular baffles are connected between the second inner sleeve and the second outer sleeve and seal the top and bottom of the second annular cavity;

[0024] The part of the pipe wall of the second inner sleeve located in the second outer sleeve cavity is provided with a group of second through holes, and an outer opening type normally closed sealing door is elastically hinged on the second through hole, and the normally closed sealing door is opened by the liquid in the second annular cavity through the rotation flow;

[0025] The upper end of the second inner sleeve is provided with a second liquid inlet, and a rotation flow mechanism is arranged on the second inner sleeve, the bottom of the second inner sleeve is an oil and gas outlet, and the lower end of the second outer sleeve is provided with a second liquid outlet communicated with the annular cavity.

[0026] The above scheme is further preferably:

[0027] Preferably, the top pipe opening of the second inner sleeve is the second liquid inlet, and the rotation flow mechanism is a spiral guide vane arranged on the inner wall of the second inner sleeve.

[0028] Preferably, the rotation flow mechanism is the second liquid inlet arranged along the tangent line of the pipe wall of the second inner sleeve, and the top pipe opening of the second inner sleeve is blocked by an end cover.

[0029] The third aspect of the present application provides an on-site rapid water separation process system for offshore platforms, which comprises a dosing mechanism and a primary separator sequentially communicated through pipelines.

[0030] The fourth aspect of the present application provides an on-site rapid water separation process system for offshore platforms, which comprises a dosing mechanism, a primary separator and a secondary separator sequentially communicated through pipelines.

[0031] The above scheme is further preferably:

[0032] Preferably, the primary separators are multiple in parallel or in series.

[0033] Preferably, the secondary separators are multiple in parallel or in series.

[0034] Preferably, the dosing mechanism is an S-shaped pipeline, one end of the S-shaped pipeline is an inlet end, the other end is an outlet end, and a dosing branch is arranged on the S-shaped pipeline close to the inlet end.

[0035] Preferably, a dosing pump is connected to the dosing branch.

[0036] Compared with the prior art, the present application has the following advantages:

[0037] The present application uses the separation technology with the pipeline structure feature to complete the rapid separation of offshore produced liquid oil, gas and water and sewage treatment, and solves the problem of on-site water separation and on-site reinjection.

[0038] The main purpose is to realize simple equipment structure, small occupation and light weight, and safety and low cost.

[0039] All separation processes are completed in the flow in the separation device with the pipeline structure feature, which can effectively utilize the idle space of the original platform and integrate with the original process flow, and can be flexibly arranged and installed according to the separation requirements, and the above characteristics have important significance under the condition of limited area and carrying capacity of the offshore oil platform. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 It is a structural schematic view of a gas phase separator;

[0041] Figure 2 It is a structural schematic view of a liquid phase separator;

[0042] Figure 3 It is a cyclone mechanism of the first form in Example 2;

[0043] Figure 4 It is a cyclone mechanism of the second form in Example 2;

[0044] Figure 5 It is a process flow chart in Example 3;

[0045] Figure 6 It is a process flow chart in Example 4;

[0046] Figure 7 It is a structural schematic view of a dosing mechanism;

[0047] Figure: 1, gas phase outlet, 2, first inner sleeve, 3, first annular baffle, 4, first liquid inlet, 5, first outer sleeve, 6, first annular cavity, 7, normally open sealing door, 8, first through hole, 9, first liquid outlet, 10, oil and gas outlet, 11, second liquid inlet, 12, second inner sleeve, 13, second annular baffle, 14, second outer sleeve, 15, second annular cavity, 16, normally closed sealing door, 17, second through hole, 18, second liquid outlet, 19, helical guide vane, 20, end cover, 21, S-shaped pipeline, 22, dosing branch, 23, dosing pump. DETAILED DESCRIPTION

[0048] The application is further illustrated below in conjunction with the drawings and examples. Example 1

[0049] As Figure 1 A gas phase separator for offshore platforms, comprising a first inner sleeve 2 and a first outer sleeve 5 arranged coaxially, the bottom of the first inner sleeve 2 being located in the cavity of the first outer sleeve 5 and forming a first annular cavity 6, and a first annular baffle 3 being connected between the first inner sleeve 2 and the first outer sleeve 5 to close the top of the first annular cavity 6.

[0050] The part of the wall of the first inner sleeve 2 located in the cavity of the first outer sleeve 5 is provided with a group of first through holes 8, and a normally open sealing door 7 of the out-opening type is elastically hinged on the first through holes 8, and the normally open sealing door 7 is closed by the liquid in the first annular cavity 6 through rotation.

[0051] The elastically hinged structure is selected from elastic hinges and elastic hinge connections.

[0052] The upper end of the first outer sleeve 5 is provided with a first liquid inlet 4 communicating with the first annular cavity 6, the first liquid inlet 4 is arranged along the tangent of the first outer sleeve 5, the top of the first inner sleeve 2 is a gas phase outlet 1, the bottom of the first inner sleeve 2 is blocked, and the bottom of the first outer sleeve 5 is a first liquid outlet 9.

[0053] Working principle:

[0054] The mixed liquid enters the first annular cavity 6 through the first liquid inlet 4, forming a downward rotating flow, and the oil, gas and water are stratified under the action of centrifugal force, with the water layer on the outside, the oil layer in the middle, and the gas layer in the innermost layer close to the outer wall of the first inner sleeve 2. At this time, the gas can enter the first inner sleeve 2 through the first through hole 8 and be separated and discharged, and the oil-water mixed liquid phase is discharged at the bottom of the first outer sleeve 5.

[0055] In addition, when the gas in the first annular cavity 6 is in an emptying state, the oil and water approach the normally open sealing door 7, and under the action of friction and pressure, the normally open sealing door 7 is pushed to close, preventing the oil and water from entering the first inner sleeve 2.

[0056] When there is a continuous gas layer outside the normally open sealing door 7, the normally open sealing door 7 is opened again under the elastic action of the elastic hinge and enters the exhaust state again;

[0057] The gas / liquid separation is completed through the above process, and the separation effect can be fine-tuned by selecting elastic hinges with different elastic forces during use. Example 2

[0058] As Figures 2 to 4 A liquid separator for offshore platforms comprises a second inner sleeve 12 and a second outer sleeve 14 arranged coaxially, the second inner sleeve 12 penetrates the inner cavity of the second outer sleeve 14 and forms a second annular cavity 15, and a pair of second annular baffles 13 are connected between the second inner sleeve 12 and the second outer sleeve 14 to close the top and bottom of the second annular cavity 15.

[0059] The part of the pipe wall of the second inner sleeve 12 located in the cavity of the second outer sleeve 14 is provided with a group of second through holes 17, and the second through holes 17 are elastically hinged with an outer opening type normally closed sealing door 16, and the normally closed sealing door 16 is opened by the liquid in the second annular cavity 15.

[0060] The upper end of the second inner sleeve 12 is provided with a second liquid inlet 11, and the second inner sleeve 12 is provided with a cyclone mechanism, the bottom of the second inner sleeve 12 is an oil and gas outlet 10, and the lower end of the second outer sleeve 14 is provided with a second liquid outlet 18 communicating with the annular cavity.

[0061] The cyclone mechanism has two forms, which are:

[0062] The first kind: the cyclone mechanism is a spiral flow guide piece 19 arranged on the inner wall of the second inner sleeve 12, and the top pipe opening of the second inner sleeve 12 is the second liquid inlet 11.

[0063] The second kind: the cyclone mechanism is the second liquid inlet 11 arranged along the tangent line of the pipe wall of the second inner sleeve 12, and the top pipe opening of the second inner sleeve 12 is blocked by an end cover 20.

[0064] Working principle:

[0065] The mixed liquid enters the inside of the second inner sleeve 12 through the second liquid inlet 11, forms a downward spiral flow, and is stratified under the action of centrifugal force, with the gas layer in the inner layer, the oil layer in the middle, and the water layer in the outermost layer. At this time, the water pushes the normally closed sealing door 16 to open under the action of centrifugal force, and then the water enters the second annular cavity 15 through the second through hole 17 and is discharged through the second liquid outlet 18.

[0066] When the water layer is in the emptying state, the oil or gas contacts the normally closed sealing door 16, and because the oil or gas has a larger density than water, the centrifugal force acting on the normally closed sealing door 16 is small, and the normally closed sealing door 16 is restored to the closed state under the elastic force of the elastic hinge;

[0067] When the gas layer is in the emptying state, the oil and water approach the normally open sealing door 7, and under the action of friction and pressure, the normally open sealing door 7 is pushed to close, preventing the oil and water from entering the first inner sleeve 2;

[0068] When there is a continuous gas layer outside the normally open sealing door 7, the normally open sealing door 7 is opened again under the action of the elasticity to enter the gas exhausting state;

[0069] Through the above process, the gas / liquid separation is completed, and in use, by selecting different elastic force elastic hinges, the separation effect can be fine-tuned. Embodiment 3

[0070] This embodiment is a process application of the above embodiments, specifically:

[0071] For example, Figure 5 A rapid water separation process on a sea platform includes a dosing mechanism and a primary separator connected in sequence through a pipeline, wherein the primary separator is the gas phase separator for a sea platform in embodiment 1, and also the liquid phase separator for a sea platform in embodiment 2.

[0072] When the mixed liquid in the liquid pipeline only needs to be exhausted to meet the reinjection standard, the primary separator selects the gas phase separator for a sea platform in embodiment 1, and the oil-water mixed liquid separated by the gas phase separator is directly collected into the reinjection pipeline to realize the working requirement of rapid exhaust and reinjection;

[0073] When the mixed liquid in the liquid pipeline contains a large amount of water and only needs to separate water to meet the reinjection standard, the primary separator selects the liquid phase separator for a sea platform in embodiment 2, and the water separated by the liquid phase separator is directly collected into the reinjection pipeline to realize the working requirement of rapid water separation and reinjection. Embodiment 4

[0074] This embodiment is a process application of the above embodiments, specifically:

[0075] For example, Figure 6 A rapid water separation process on a sea platform includes a dosing mechanism, a primary separator, and a secondary separator connected in sequence through a pipeline, wherein the primary separator and the secondary separator are respectively the gas phase separator for a sea platform in claim 1 and the liquid phase separator for a sea platform in claim 2.

[0076] The gas in the mixed liquid is first discharged through the gas-phase separator, and then the water is separated through the liquid-phase separator, and the cooperation of the gas-phase separator and the liquid-phase separator has better separation effect.

[0077] In addition, as a further preferred mode of the embodiment, the primary separators are in parallel or in series, and the secondary separators are also in parallel or in series.

[0078] During field work, the liquid phase separated by the separator is detected, and according to the specific requirements of the field reinjection water, multiple sets of primary separators and secondary separators can be combined in parallel or in series to meet the specific working condition requirements. Embodiment 5

[0079] This embodiment is to optimize the dosing mechanism in the above-mentioned embodiments, specifically:

[0080] For example, Figure 7 The dosing mechanism is an S-shaped pipeline 21, one end of the S-shaped pipeline 21 is an inlet end, and the other end is an outlet end, and a dosing branch 22 is arranged on the S-shaped pipeline 21 close to the inlet end, and a dosing pump 23 is connected to the dosing branch 22.

[0081] Working principle:

[0082] The liquid inlet pipeline is connected to the S-shaped pipeline 21, the mixed liquid medicine is pumped into the S-shaped pipeline 21 by the dosing pump 23, mixed with the mixed liquid, and has a better mixing effect on the medicine and the mixed liquid under the action of the flow channel shape of the S-shaped pipeline 21.

[0083] In addition, a one-way valve is installed at the connection between the dosing branch 22 and the S-shaped pipeline 21 to prevent liquid from flowing back into the dosing branch 22.

[0084] The separation technology with the pipeline structure feature is adopted to complete the rapid separation of offshore produced liquid oil / gas / water multiphase and sewage treatment, and to solve the problem of on-site water separation and on-site reinjection.

[0085] The main purpose is to realize simple equipment structure, small occupation, light weight, safety and low cost.

[0086] All separation processes are completed in the separation device with the pipeline structure feature in the flow, which can effectively utilize the idle space of the original platform and integrate with the original process flow, and can be flexibly arranged and installed according to the separation requirements, and the above characteristics have important significance under the condition of limited area and carrying capacity of the offshore oil platform.

Claims

1. A gas phase separator for offshore platforms, characterized in that: It includes a first inner sleeve and a first outer sleeve arranged coaxially, the bottom of the first inner sleeve is located inside the cavity of the first outer sleeve and forms a first annular cavity, and a first annular baffle that closes the top of the first annular cavity is connected between the first inner sleeve and the first outer sleeve. The portion of the inner tube wall located inside the first outer tube cavity is provided with a set of first through ports. An outwardly opening normally open sealing door is elastically hinged to the first through port. The normally open sealing door is closed by being pushed by the liquid swirling inside the first annular cavity. The upper end of the first outer sleeve is provided with a first liquid inlet communicating with the first annular cavity. The first liquid inlet is arranged along the tangent of the first outer sleeve. The top of the first inner sleeve is the gas phase outlet, the bottom of the first inner sleeve is sealed, and the bottom of the first outer sleeve is the first liquid outlet.

2. A liquid phase separator for offshore platforms, characterized in that: It includes a second inner sleeve and a second outer sleeve arranged coaxially, the second inner sleeve penetrates the inner cavity of the second outer sleeve and forms a second annular cavity, and a pair of second annular baffles are connected between the second inner sleeve and the second outer sleeve to close the top and bottom of the second annular cavity; The portion of the inner tube wall located inside the second outer tube cavity is provided with a set of second through ports. An outward-opening normally closed sealing door is elastically hinged to the second through ports. The normally closed sealing door is opened by the liquid swirling inside the second annular cavity. The second inner sleeve is provided with a second liquid inlet at the upper end and a swirling mechanism on the second inner sleeve. The bottom of the second inner sleeve is an oil and gas outlet, and the lower end of the second outer sleeve is provided with a second liquid outlet communicating with the annular cavity. The top opening of the second inner sleeve is the second liquid inlet, and the swirling mechanism is a spiral guide vane disposed on the inner wall of the second inner sleeve; The swirling mechanism is the second liquid inlet arranged along the tangent of the second inner sleeve wall, and the top opening of the second inner sleeve is sealed by an end cap.

3. An on-site rapid water separation process system for offshore platforms, characterized in that: It includes a dosing mechanism and a primary separator connected in sequence by pipelines, wherein the primary separator is the gas phase separator for offshore platforms as described in claim 1 or the liquid phase separator for offshore platforms as described in claim 2.

4. An on-site rapid water separation process system for offshore platforms, characterized in that: It includes a dosing mechanism, a primary separator, and a secondary separator connected in sequence by pipelines, wherein the primary separator and the secondary separator are the gas phase separator for offshore platforms as described in claim 1 and the liquid phase separator for offshore platforms as described in claim 2, respectively.

5. The offshore platform on-site rapid water separation process system according to claim 3 or 4, characterized in that: The primary separator can be multiple units connected in parallel or in series.

6. The offshore platform on-site rapid water separation process system according to claim 4, characterized in that: The secondary separator can be multiple units connected in parallel or in series.

7. The offshore platform on-site rapid water separation process system according to any one of claims 3 to 6, characterized in that: The dosing mechanism is an S-shaped pipe, with one end being the inlet and the other end being the outlet. A dosing branch is provided on the S-shaped pipe near the inlet.

8. The on-site rapid water separation process system for offshore platforms according to claim 7, characterized in that: A dosing pump is connected to the dosing branch.

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