Offshore gas-water alternate injection system

Abstract

The invention provides an offshore gas-water alternate injection system. The offshore gas-water alternate injection system comprises a water injection manifold, a gas injection manifold, an injection pipe and a connecting device. The connecting device is provided with an injection port, a water injection port and a gas injection port, wherein the water injection manifold is connected with the water injection port, the gas injection manifold is connected with the gas injection port, the top end of the injection pipe is connected with the injection port, and the bottom end of the injection pipe extends downwards to a target stratum. The water injection manifold can inject water into a target stratum through the gas injection port, the injection port and the injection pipe, and the gas injection manifold can inject gas into the target stratum through the gas injection port, the injection port and the injection pipe. A pressure relief pipeline is further arranged on the gas injection manifold, after the gas injection stage is completed and before the water injection stage is started, the system pressure can be relieved through the pressure relief pipeline, the system pressure is reduced to the water injection pressure or lower than the water injection pressure, and water can be injected normally. According to the offshore gas-water alternate injection system provided by the invention, rapid pressure release can be realized, and rapid switching of gas-water injection is completed.

Description

Technical Field

[0001] The invention relates to the technical field of marine engineering, and in particular to an offshore gas-water alternating injection system. Background Art

[0002] At present, domestic offshore oil fields are mainly developed by water injection, but the effect of water injection development on improving the recovery rate of water-sensitive oil reservoirs and low permeability oil fields is limited. In addition, the reserves of domestic offshore low permeability oil reservoirs are considerable, so gas injection development has become the development direction of offshore low permeability oil field development.

[0003] Gas injection development often faces difficulties such as gas channeling, and methods such as gas-water alternation and injection limit in gas injection wells need to be adopted to delay the occurrence of gas channeling. Among them, gas-water alternation can not only delay gas channeling, but also improve production time by complementing each other through the two injection methods.

[0004] The space of offshore oil and gas field platforms is limited, and due to the small number of offshore wells, injection wells often need to have both water and gas injection functions. However, the gas injection pressure is often relatively high, while the water injection pressure is relatively low. Therefore, after the gas injection is completed, the pressure in the system is generally higher than the water injection pressure, resulting in the inability to inject water. At present, after gas injection, injection wells in onshore and offshore oil fields are left to stand, and water is injected after the pressure in the injection well diffuses and decreases.

[0005] However, static pressure relief will cause the gas-water alternation time to be too long, resulting in a gap period between gas and water injection, thereby reducing production efficiency. Summary of the invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides an offshore gas-water alternating injection system, which aims to solve the problem in the related art that the system pressure is released by static means before water injection, resulting in a long gas-water alternating conversion time and reduced production efficiency.

[0007] The present invention provides an offshore gas-water alternating injection system, comprising: Water injection manifold; A gas injection manifold, wherein a pressure relief pipeline is provided on the gas injection manifold; An injection pipe, the injection pipe is used to extend into the target formation; A connecting device is provided with an injection port and a water injection port and an air injection port connected to the injection port, the inlet of the injection pipe is connected to the injection port, the air injection manifold is connected to the air injection port, and the water injection manifold is connected to the water injection port.

[0008] According to the offshore gas-water alternating injection system provided by the present invention, the injection pipe comprises an inner pipe and an outer pipe, the inner pipe and the outer pipe are nested, and a gap is left between the inner pipe and the outer pipe, the end of the inner pipe extends into a first target formation, and the end of the outer pipe extends into a second target formation, and the depth of the first target formation is greater than the depth of the second target formation; The connecting device is provided with a first air injection port, a second air injection port, a first water injection port, and a second water injection port. The first air injection port and the first water injection port are connected to the inner tube, the second air injection port and the second water injection port are connected to the outer tube, the first air injection port and the second air injection port are both connected to the air injection manifold, and the first water injection port and the second water injection port are both connected to the water injection manifold.

[0009] According to the offshore gas-water alternating injection system provided by the present invention, the gas injection manifold comprises: Gas injection main; a first gas injection branch pipeline, one end of which is connected to the gas injection main pipe, and the other end of which is connected to the first gas injection port; A second gas injection branch pipeline, one end of which is connected to the gas injection main pipe, and the other end of which is connected to the second gas injection port.

[0010] According to the offshore gas-water alternating injection system provided by the present invention, the water injection manifold comprises: Water injection main; a first water injection branch pipeline, one end of which is connected to the water injection main pipe, and the other end of which is connected to the first water injection port; A second water injection branch pipeline, one end of the second water injection branch pipeline is connected to the water injection main pipe, and the other end of the second water injection branch pipeline is connected to the second water injection port.

[0011] According to the offshore gas-water alternating injection system provided by the present invention, a first flow meter and a first flow regulating valve are provided on both the first gas injection branch pipeline and the second gas injection branch pipeline.

[0012] According to the offshore gas-water alternating injection system provided by the present invention, a second flow meter and a second flow regulating valve are provided on both the first water injection branch pipeline and the second water injection branch pipeline.

[0013] The offshore gas-water alternating injection system provided by the present invention further comprises a methanol injection pipeline, which is connected to the pressure relief pipeline and is located upstream of the pressure relief port.

[0014] The offshore gas-water alternating injection system provided by the present invention further includes a diesel injection pipeline, and the diesel injection pipeline is connected to the first gas injection branch pipeline and the second gas injection branch pipeline.

[0015] According to the offshore gas-water alternating injection system provided by the present invention, the first gas injection branch pipeline and the second gas injection branch pipeline are both provided with a first pressure detection device and a first safety valve.

[0016] According to the offshore gas-water alternate injection system provided by the present invention, a second pressure detection device and a second safety valve are provided on both the first water injection branch pipeline and the second water injection branch pipeline.

[0017] The present invention adopts the above technical solution, which has the following advantages: The offshore gas-water alternating injection system provided by the present invention comprises a water injection manifold, an air injection manifold, an injection pipe and a connecting device. The connecting device is provided with an injection port and a water injection port and an air injection port connected to the injection port. Among them, the downstream end of the water injection manifold is connected to the water injection port, and the downstream end of the air injection manifold is connected to the air injection port. The top of the injection pipe is connected to the injection port, and the bottom end of the injection pipe extends downward to the target formation. In this way, the water injection manifold can inject water into the target formation through the air injection port, the injection port and the injection pipe of the connecting device, and the air injection manifold can inject air into the target formation through the air injection port, the injection port and the injection pipe of the connecting device. A pressure relief pipeline is also provided on the air injection manifold of the offshore gas-water alternating injection system provided by the present invention. After the gas injection stage is completed and before the water injection stage begins, the system pressure can be released through the pressure relief pipeline to reduce the system pressure to the water injection pressure or lower than the water injection pressure, so that water can be injected normally. The offshore gas-water alternating injection system provided by the present invention can achieve rapid pressure release and complete rapid switching of gas and water injection. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a schematic diagram of a pipeline of an offshore gas-water alternating injection system provided by one embodiment of the present invention.

[0020] Reference numerals: 100: connecting device; 210: inner pipe; 220: outer pipe; 310: gas injection main pipe; 320: first gas injection branch pipeline; 330: second gas injection branch pipeline; 340: first flow meter; 350: first flow regulating valve; 360: first pressure gauge; 370: first shut-off valve; 410: water injection main pipe; 420: first water injection branch pipeline; 430: second water injection branch pipeline; 440: second flow meter; 450: second flow regulating valve; 460: second pressure gauge; 470: second shut-off valve; 500: methanol injection pipeline; 600: pressure relief pipeline; 700: diesel injection pipeline. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0023] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0024] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0026] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0027] The present invention provides an offshore gas-water alternating injection system, wherein a water injection manifold injects water into a target formation through a connecting device and an injection pipe, and a gas injection manifold injects gas into a target formation through a connecting device and an injection pipe. A pressure relief line arranged on the gas injection manifold can release the system pressure after the gas injection stage is completed and before the water injection stage begins, so that the system pressure drops quickly to the water injection pressure, and the gas-water alternation can be completed quickly.

[0028] Combine the following Figure 1 An offshore gas-water alternating injection system provided by an embodiment of the present invention is described.

[0029] An embodiment of the present invention provides an offshore gas-water alternating injection system, comprising a water injection manifold, a gas injection manifold, an injection pipe and a connecting device 100. The connecting device 100 is provided with an injection port, a gas injection port and a water injection port, and inside the connecting device 100, the gas injection port and the water injection port are both connected to the injection port.

[0030] The upstream end of the water injection manifold is used to communicate with the water supply equipment, and the downstream end of the water injection manifold is connected to the water injection port of the connecting device 100. The upstream end of the gas injection manifold is used to communicate with the gas supply equipment, and the downstream end of the gas injection manifold is connected to the gas injection port of the connecting device 100. The top end of the injection pipe is connected to the injection port of the connecting device 100, and the bottom end of the injection pipe extends downward to the target formation.

[0031] Thus, when the gas supply device supplies gas, the gas supply device can supply gas to the target formation through the gas supply manifold, the gas injection port of the connection device 100, the injection port of the connection device 100, and the injection pipe. When the water supply device supplies water, the water supply device can supply water to the target formation through the water supply manifold, the water injection port of the connection device 100, the injection port of the connection device 100, and the injection pipe.

[0032] In addition, since the gas injection pressure is often relatively high and the water injection pressure is relatively low, after the gas injection is completed, the pressure in the system is generally higher than the water injection pressure, resulting in the inability to inject water.

[0033] In order to solve this technical problem, in the offshore gas-water alternating injection system provided by an embodiment of the present invention, a pressure relief pipeline 600 is also provided on the gas injection manifold. When the gas injection stage ends and before the water injection stage begins, the pressure relief pipeline 600 is opened to release the internal pressure of the system through the gas injection manifold and the pressure relief pipeline 600. Specifically, the pressure can be reduced to the water injection pressure or lower than the water injection pressure and then the pressure relief pipeline 600 is cut off.

[0034] In the related technology, a static method is often adopted, and water is injected after the pressure in the system diffuses and drops. This pressure relief method wastes a lot of time, resulting in a gap period for gas and water injection, thereby reducing the production rate.

[0035] The offshore gas-water alternating injection system provided by the present invention can rapidly reduce the system pressure to the water injection pressure through the pressure relief pipeline 600, thereby realizing rapid switching between gas injection and water injection, and greatly improving the production time efficiency.

[0036] In some embodiments, the injection tube includes an inner tube 210 and an outer tube 220, which are coaxially nested and the outer diameter of the inner tube 210 is smaller than the inner diameter of the outer tube 220, so that a gap is left between the outer side of the inner tube 210 and the inner side of the outer surface.

[0037] The bottom of the inner tube 210 extends downward to a first target formation, and the bottom of the outer tube 220 extends downward to a second target formation, wherein the depth of the first target formation is greater than the depth of the second target formation.

[0038] The air injection port on the connection device 100 includes a first air injection port and a second air injection port, the water injection port includes a first water injection port and a second water injection port, and the injection port includes a first injection port and a second injection port. The first air injection port and the first water injection port are connected to the first injection port, and the second air injection port and the second water injection port are connected to the second injection port.

[0039] When the injection pipe is connected to the connecting device 100, the inner tube 210 of the injection pipe is connected to the first air injection port and the first water injection port through the first injection port, and the gap between the outer tube 220 of the injection pipe and the inner tube 210 is connected to the second air injection port and the second water injection port through the second injection port.

[0040] The gas supply equipment can supply gas to the first target formation through the gas injection manifold, the first gas injection port, the first injection port, and the inner tube 210 of the injection pipe, and can also supply gas to the second target formation through the second gas injection port, the second injection port, and the outer tube 220 of the injection pipe.

[0041] In this way, the gas can be injected in two ways, one way into the first target formation through the inner tube 210 and the other way into the second target formation through the outer tube 220, so that the upper and lower formations can be injected in layers.

[0042] The water supply equipment can supply water to the first target formation through the water injection manifold, the first water injection port, the first injection port, and the inner tube 210 of the injection pipe, and can also supply water to the second target formation through the second water injection port, the second injection port, and the outer tube 220 of the injection pipe.

[0043] In this way, water can be injected in two ways, one way into the first target formation through the inner tube 210, and the other way into the second target formation through the outer tube 220, so that the upper and lower formations can be injected in layers.

[0044] In some embodiments, the gas injection manifold includes a gas injection main pipe 310 , a first gas injection branch line 320 , and a second gas injection branch line 330 .

[0045] The upstream end of the gas injection main pipe 310 is used to connect to the gas supply equipment, and the downstream end of the gas injection main pipe 310 has two gas outlets, and the upstream end of the first gas injection branch pipeline 320 and the upstream end of the second gas injection branch pipeline 330 are respectively connected to one of the gas outlets. The downstream end of the first gas injection branch pipeline 320 is connected to the first gas injection port of the connecting device 100, and the downstream end of the second gas injection branch pipeline 330 is connected to the second gas injection port of the connecting device 100.

[0046] When in use, the gas supply equipment can supply gas to the gas injection main pipe 310, and divert the gas through the first gas injection branch pipeline 320 and the second gas injection branch pipeline 330, and supply the gas to the first gas injection port and the second gas injection port of the connecting device 100 respectively, and supply the gas to the first target formation and the second target formation respectively through the inner tube 210 and the outer tube 220.

[0047] In addition, the first gas injection branch pipeline 320 and the second gas injection branch pipeline 330 can adjust the gas flow rate, thereby controlling the flow rate of gas supplied to the first target formation and the second target formation.

[0048] In some embodiments, the water injection manifold includes a water injection main pipe 410 , a first water injection branch pipeline 420 , and a second water injection branch pipeline 430 .

[0049] The upstream end of the water injection main pipe 410 is used to connect to the water supply equipment, and the downstream end of the water injection main pipe 410 has two liquid outlets, and the upstream end of the first water injection branch line 420 and the upstream end of the second water injection branch line 430 are respectively connected to one of the liquid outlets. The downstream end of the first water injection branch line 420 is connected to the first water injection port of the connecting device 100, and the downstream end of the second water injection branch line 430 is connected to the second water injection port of the connecting device 100.

[0050] When in use, the water supply equipment can supply water to the water injection main pipe 410, and divert water through the first water injection branch pipeline 420 and the second water injection branch pipeline 430, and supply water to the first water injection port and the second water injection port of the connecting device 100 respectively, and supply water to the first target formation and the second target formation respectively through the inner pipe 210 and the outer pipe 220.

[0051] In addition, the first water injection branch pipeline 420 and the second water injection branch pipeline 430 can adjust the liquid flow rate, thereby controlling the flow rate of water supplied to the first target formation and the second target formation.

[0052] Specifically, a first flow meter 340 and a first flow regulating valve 350 are provided on both the first gas injection branch pipeline 320 and the second gas injection branch pipeline 330. The first flow meter 340 can be used to detect the gas flow of the first gas injection branch pipeline 320 or the second gas injection branch pipeline 330 in real time, and the first flow regulating valve 350 is used to adjust the gas flow of the first gas injection branch pipeline 320 or the second gas injection branch pipeline 330. The operator controls the opening of the first flow regulating valve 350 and observes the first flow meter 340, so that the gas of the upper and lower layers is injected according to a certain ratio.

[0053] A second flow meter 440 and a second flow regulating valve 450 are provided on both the first water injection branch pipeline 420 and the second water injection branch pipeline 430. The second flow meter 440 can be used to detect the liquid flow of the first water injection branch pipeline 420 or the second water injection branch pipeline 430 in real time, and the second flow regulating valve 450 is used to adjust the liquid flow of the first water injection branch pipeline 420 or the second water injection branch pipeline 430. The operator controls the opening of the second flow regulating valve 450 and observes the second flow meter 440, so that the liquids of the upper and lower layers are injected according to a certain ratio.

[0054] In some embodiments, a first pressure detection device and a first safety valve are disposed on both the first gas injection branch pipeline 320 and the second gas injection branch pipeline 330 .

[0055] The first pressure detection device may be a first pressure gauge 360, and a detection end of the first pressure gauge 360 ​​is connected to the first gas injection branch pipeline 320 or the second gas injection branch pipeline 330. The first safety valve is a first shut-off valve 370, and both ends of the first shut-off valve 370 are connected to the corresponding first gas injection branch pipeline 320 or the second gas injection branch pipeline 330.

[0056] The first pressure gauge 360 ​​is used to monitor the gas injection pressure of the first gas injection branch pipeline 320 or the second gas injection branch pipeline 330 in real time. When the pressure value exceeds the limit value, the first shut-off valve 370 can be controlled to close urgently to stop gas injection.

[0057] Similarly, a second pressure detection device and a second safety valve are provided on the first water injection branch pipeline 420 and the second water injection branch pipeline 430 .

[0058] The second pressure detection device may be a second pressure gauge 460, and a detection end of the second pressure gauge 460 is connected to the first water injection branch pipeline 420 or the second water injection branch pipeline 430. The second safety valve is a second shut-off valve 470, and both ends of the second shut-off valve 470 are connected to the corresponding first water injection branch pipeline 420 or the second water injection branch pipeline 430.

[0059] The second pressure gauge 460 is used to monitor the water injection pressure of the first water injection branch pipeline 420 or the second water injection branch pipeline 430 in real time. When the pressure value exceeds the limit value, the second shut-off valve 470 can be controlled to close urgently to stop water injection.

[0060] In some embodiments, a methanol injection pipeline 500 is further included. The methanol injection pipeline 500 is connected to the pressure relief pipeline 600 and is located upstream of the pressure relief port.

[0061] Specifically, an angle valve is provided at the downstream end of the pressure relief line 600, and the downstream end of the methanol injection line 500 is connected to the upstream side of the angle valve of the pressure relief line 600. When the angle valve is opened for pressure relief, the methanol injection line 500 supplies methanol to the upstream end of the angle valve, which can effectively prevent the generation of hydrates.

[0062] In some embodiments, a diesel injection pipeline 700 is further included, and the diesel injection pipeline 700 is connected to the first gas injection branch pipeline 320 and the second gas injection branch pipeline 330. The function of the diesel injection pipeline 700 is to replace the injection pipe after the water injection stage is completed and before the gas injection stage begins. Since the temperature is low during water injection, after the water injection stage is completed, the ambient temperature in the injection pipe is low. If the injection is switched directly to gas, high-pressure gas may generate hydrates in a low-temperature environment. Therefore, diesel is first injected to replace the injection pipe, and then methanol is injected to remove water for the second time, and then gas is injected.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. An offshore gas-water alternating injection system, characterized in that: include: Water injection manifold; An air injection manifold, wherein a pressure relief pipeline (600) is provided on the air injection manifold; An injection pipe, the injection pipe is used to extend into the target formation; A connecting device (100), wherein the connecting device (100) is provided with an injection port and a water injection port and an air injection port connected to the injection port, the inlet of the injection pipe is connected to the injection port, the air injection manifold is connected to the air injection port, and the water injection manifold is connected to the water injection port.

2. The offshore gas-water alternating injection system according to claim 1, characterized in that: The injection pipe comprises an inner pipe (210) and an outer pipe (220), the inner pipe (210) and the outer pipe (220) are nested, and a gap is left between the inner pipe (210) and the outer pipe (220), an end of the inner pipe (210) extends into a first target formation, and an end of the outer pipe (220) extends into a second target formation, and the depth of the first target formation is greater than the depth of the second target formation; The connecting device (100) is provided with a first air injection port, a second air injection port, a first water injection port, and a second water injection port; the first air injection port and the first water injection port are in communication with the inner tube (210); the second air injection port and the second water injection port are in communication with the outer tube (220); the first air injection port and the second air injection port are both connected to the air injection manifold; and the first water injection port and the second water injection port are both connected to the water injection manifold.

3. The offshore gas-water alternating injection system according to claim 2, characterized in that: The gas injection manifold comprises: Gas injection main (310); a first gas injection branch pipeline (320), wherein one end of the first gas injection branch pipeline (320) is connected to the gas injection main pipe (310), and the other end of the first gas injection branch pipeline (320) is connected to the first gas injection port; A second gas injection branch pipeline (330), one end of the second gas injection branch pipeline (330) is connected to the gas injection main pipe (310), and the other end of the second gas injection branch pipeline (330) is connected to the second gas injection port.

4. The offshore gas-water alternating injection system according to claim 2, characterized in that: The water injection manifold comprises: Water injection main (410); a first water injection branch pipeline (420), wherein one end of the first water injection branch pipeline (420) is connected to the water injection main pipe (410), and the other end of the first water injection branch pipeline (420) is connected to the first water injection port; A second water injection branch pipeline (430), one end of the second water injection branch pipeline (430) is connected to the water injection main pipe (410), and the other end of the second water injection branch pipeline (430) is connected to the second water injection port.

5. The offshore gas-water alternating injection system according to claim 3, characterized in that: The first gas injection branch pipeline (320) and the second gas injection branch pipeline (330) are both provided with a first flow meter (340) and a first flow regulating valve (350).

6. The offshore gas-water alternating injection system according to claim 4, characterized in that: The first water injection branch pipeline (420) and the second water injection branch pipeline (430) are both provided with a second flow meter (440) and a second flow regulating valve (450).

7. The offshore gas-water alternating injection system according to claim 1, characterized in that: It also includes a methanol injection pipeline (500), which is connected to the pressure relief pipeline (600) and is located upstream of the pressure relief port.

8. The offshore gas-water alternating injection system according to claim 3, characterized in that: It also includes a diesel injection pipeline (700), wherein the diesel injection pipeline (700) is connected to the first gas injection branch pipeline (320) and the second gas injection branch pipeline (330).

9. The offshore gas-water alternating injection system according to claim 3, characterized in that: The first gas injection branch pipeline (320) and the second gas injection branch pipeline (330) are both provided with a first pressure detection device and a first safety valve.

10. The offshore gas-water alternating injection system according to claim 4, characterized in that: The first water injection branch pipeline (420) and the second water injection branch pipeline (430) are both provided with a second pressure detection device and a second safety valve.

Images