A retrofit method for converting a two-phase separator into a three-phase separator

Abstract

This invention discloses a method for converting a two-phase separator into a three-phase separator, relating to the field of marine oil engineering technology. The invention includes the following steps: S1, installing an external container near the two-phase separator, with the external container serving as the oil chamber of the converted three-phase separator, and the two-phase separator serving as the oil-water mixing chamber of the converted three-phase separator; S2, connecting the upper gas phase space of the external container to the gas phase space of the two-phase separator via a gas-connection pipeline, thereby balancing the pressure between the external container and the two-phase separator. This invention, by placing an external container near the two-phase separator to act as the oil chamber, and making the original two-phase separator serve as the oil-water mixing chamber, moves the newly added oil chamber from inside the separator to the outside. The conversion work mainly involves container placement and pipeline valve connection, reducing the disassembly and hot work of internal separator components, and helping to shorten the platform conversion downtime.

Description

Technical Field

[0001] This invention belongs to the field of marine oil engineering technology, and in particular relates to a method for converting a two-phase separator into a three-phase separator. Background Technology

[0002] Separators are key equipment in the oil, gas, and water treatment processes on offshore platforms, and are typically one of the largest pieces of equipment in the process. Their separation performance directly affects the normal production and overall efficiency of the platform's oil, gas, and water systems. As oilfield development progresses, parameters such as the gas-liquid ratio in the crude oil wellhead stream change. Some existing two-phase separators only have gas-liquid two-phase separation capabilities, which cannot meet the increasing demand for liquid-phase oil-water separation. Therefore, they need to be replaced by three-phase separators with oil, gas, and water three-phase separation capabilities.

[0003] Current retrofitting methods typically involve working on the existing two-phase separator body, disassembling the original components, redesigning and adjusting the internal structure, and adding components such as oil chambers to create the oil chambers and oil-water separation space required for three-phase separation. This type of retrofitting requires extensive disassembly, assembly, and hot work inside the separator, resulting in a large workload, low construction efficiency, and the need for platform shutdown during the retrofitting period, which directly increases production costs due to extended downtime.

[0004] On the other hand, three-phase separators typically rely on a weir plate of fixed height to create a liquid level difference between the oil chamber and the oil-water mixing chamber to achieve oil-water separation and oil phase overflow. Once the weir plate height is fixed, the separator's adaptability to different oil properties and different throughput is limited. When the oil properties or throughput change, it is difficult to easily adjust the oil-water separation capacity.

[0005] Therefore, how to enable a two-phase separator to separate oil and water without replacing the entire separator or extensively disassembling its internal components, and how to easily adjust this separation capability, is a technical problem that needs to be solved in this field. To address this, we provide a method for converting a two-phase separator into a three-phase separator to solve the aforementioned problem. Summary of the Invention

[0006] The purpose of this invention is to provide a method for converting a two-phase separator into a three-phase separator. This method involves setting an external container near the outside of the two-phase separator to serve as the oil chamber, and replacing the fixed-height weir plate with isolation valves of different heights. This reduces the need for large-scale disassembly and assembly work inside the separator and allows for adjustment of the oil-water separation capacity.

[0007] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution.

[0008] This invention relates to a method for converting a two-phase separator into a three-phase separator, comprising the following steps: S1. An external container is installed near the two-phase separator, so that the external container serves as the oil chamber of the modified three-phase separator, and the two-phase separator serves as the oil-water mixing chamber of the modified three-phase separator. S2. Connect the upper gas phase space of the external container to the gas phase space of the two-phase separator via a gas connection pipeline to achieve pressure balance between the external container and the two-phase separator. S3. Multiple isolation valves are spaced apart along the height direction on the cylinder wall of the two-phase separator, and the outlet of each isolation valve is connected to the external container via a liquid connection pipeline. The multiple isolation valves are located at different heights, which are equivalent to weirs at different heights. S4. An open drain port and a closed drain port are provided at the bottom of the external container; S5. By opening isolation valves at different heights, the liquid phase in the two-phase separator corresponding to the height of the isolation valve enters the external container through the liquid connection pipeline, thereby adjusting the oil-water separation capacity.

[0009] The present invention is further configured such that the external container is located near the liquid outlet of the two-phase separator.

[0010] The present invention is further configured such that the external container is a buffer tank or a tubular container.

[0011] The invention is further configured such that the isolation valve is located within a height range of one-quarter to three-quarters of the diameter of the two-phase separator cylinder wall, and the number of the isolation valve is 1 to 10.

[0012] The present invention is further configured such that a gas phase valve is provided on the gas connection pipeline, the outlets of each isolation valve are connected to the liquid phase manifold, and the liquid phase manifold is connected to an external container via a liquid phase main valve.

[0013] The present invention is further configured such that the open drain port and the closed drain port periodically discharge and replace the crude oil accumulated in the external container.

[0014] The present invention is further configured such that the two-phase separator is equipped with a separator interface level gauge and a interface level control system, the interface level control system controls the liquid phase outlet regulating valve of the original two-phase separator according to the interface level of the two-phase separator, and alarms for high liquid level and low liquid level of the two-phase separator.

[0015] The present invention is further configured such that an external container level gauge is provided on the external container, and the external container level gauge is equipped with a level control system; the level control system controls the opening of the liquid phase outlet regulating valve according to the liquid level of the external container, and alarms for high and low liquid levels of the external container.

[0016] The present invention is further configured such that a pressure gauge and a pressure control valve are provided on the top of the two-phase separator.

[0017] The present invention is further configured such that, when the external container is a tubular container, there are at least two tubular containers, the upper part of adjacent tubular containers is connected to a gas phase valve via a pipeline, and the lower part is connected to a valve via a pipeline. Each tubular container is provided with an open drain port and a closed drain port at its bottom. The volume of the oil chamber is adjusted by increasing or decreasing the number of tubular containers.

[0018] The present invention has the following beneficial effects.

[0019] 1. This invention uses an external container that serves as an oil chamber near the two-phase separator to make the original two-phase separator a mixing chamber for oil and water. The new oil chamber is moved from inside the separator to outside the separator. The modification work mainly involves the placement of the container and the connection of pipeline valves. This can reduce the disassembly and hot work of the internal components of the separator, which is conducive to shortening the downtime of platform modification, reducing the amount of modification work and engineering investment.

[0020] 2. This invention sets multiple isolation valves at different heights on the wall of the two-phase separator and connects them to an external container. The isolation valves at different heights are equivalent to weirs at different heights. By opening the isolation valves at different heights, liquid phases at different heights can be selected to enter the external container. This allows for adjustment of the oil-water separation capacity without altering the internal weirs of the separator, which is beneficial for adapting to changes in oil properties and throughput.

[0021] 3. The upper gas phase space of the external container of the present invention is connected to the gas phase space of the two-phase separator, so that the pressure of the two is balanced. The liquid phase can enter the external container under the action of liquid level difference. The open and closed drain ports at the bottom of the external container can periodically discharge and replace the crude oil accumulated in the container, which is conducive to the continuous operation of the external oil chamber. At the same time, by using tubular containers, the total volume of the external oil chamber can be adjusted by increasing or decreasing the number of tubular containers. The tubular containers are connected to each other through upper and lower pipeline valves. Each tubular container is equipped with an open and closed drain port at the bottom, which is conducive to flexible expansion according to the oil processing capacity requirements. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0023] Figure 1 This is a schematic diagram of the modified structure in Embodiment 2 of a method for converting a two-phase separator into a three-phase separator.

[0024] Figure 2This is a schematic diagram of the modified structure in Embodiment 3 of a method for converting a two-phase separator into a three-phase separator.

[0025] Figure 3 This is a schematic diagram of the modification structure in Embodiment 4 of a modification method for converting a two-phase separator into a three-phase separator.

[0026] Figure 4 This is a schematic diagram of the modified structure in Embodiment 5 of a method for converting a two-phase separator into a three-phase separator.

[0027] Figure 5 This is a schematic diagram of the modified structure in Embodiment Six of a method for converting a two-phase separator into a three-phase separator. Detailed Implementation

[0028] The technical solutions of the present invention will be described below with reference to the accompanying drawings. The described embodiments are only some embodiments of the present invention, and not all embodiments.

[0029] Example 1: This invention relates to a method for converting a two-phase separator into a three-phase separator, comprising the following steps: S1. An external container is installed near the two-phase separator, serving as the oil chamber of the modified three-phase separator, while the two-phase separator serves as the oil-water mixing chamber. The external container, a buffer tank or tubular container, is located near the liquid outlet of the two-phase separator. It is equipped with a level gauge and a level control system. The system controls the opening of the liquid phase outlet regulating valve based on the liquid level in the external container and provides alarms for high and low liquid levels. The original two-phase separator is equipped with a separator interface level gauge and a interface control system. This system controls the liquid phase outlet regulating valve based on the interface level of the two-phase separator and provides alarms for high and low liquid levels. The top of the two-phase separator is equipped with a pressure gauge and a pressure control valve. When the external container is a tubular container, at least two tubular containers are set. The upper part of adjacent tubular containers is connected to the gas phase valve via pipeline, and the lower part is connected to the valve via pipeline. The bottom of each tubular container is equipped with an open drain port and a closed drain port. The volume of the oil chamber is adjusted by increasing or decreasing the number of tubular containers. S2. Connect the upper gas phase space of the external container to the gas phase space of the two-phase separator via the gas connection pipeline to balance the pressure between the external container and the two-phase separator. A gas phase valve is installed on the gas connection pipeline. The outlets of each isolation valve are connected to the liquid phase manifold. The liquid phase manifold is connected to the external container via the liquid phase main valve. S3. Multiple isolation valves are installed at intervals along the height direction on the cylinder wall of the two-phase separator, and the outlet of each isolation valve is connected to an external container via a liquid connection pipeline. The multiple isolation valves are located at different heights, which are equivalent to weirs at different heights. The isolation valves are set within the range of one-quarter to three-quarters of the diameter of the cylinder wall of the two-phase separator, and the number of isolation valves is 1 to 10. S4. An open drain port and a closed drain port are installed at the bottom of the external container. The open drain port and the closed drain port are used to periodically discharge and replace the crude oil accumulated in the external container. S5. By opening isolation valves at different heights, the liquid phase in the two-phase separator corresponding to the height of the isolation valve enters the external container through the liquid connection pipeline, thereby adjusting the oil-water separation capacity.

[0030] Example 2: like Figure 1 As shown, an external container is set near the liquid outlet of the two-phase separator. In this embodiment, the external container is a buffer tank. The buffer tank serves as the oil chamber of the modified three-phase separator, and the original two-phase separator serves as the oil-water mixing chamber of the modified three-phase separator.

[0031] The upper gas phase space of the external container is connected to the gas phase space of the two-phase separator via a gas-connected pipeline and a gas phase valve, ensuring pressure balance between the external container and the two-phase separator. This allows the liquid phase to flow into the external container under the influence of the liquid level difference. Within a height range of one-quarter to three-quarters of the diameter of the two-phase separator cylinder wall, three isolation valves at different heights are installed along the vertical direction. The outlets of all isolation valves converge and connect to a liquid phase manifold, which is connected to the external container via a main liquid phase valve. The isolation valves at different heights act as weirs at different heights. When one of the isolation valves is opened, the liquid phase corresponding to that valve height in the two-phase separator enters the external container through the liquid phase manifold and the main liquid phase valve, thus achieving oil-water separation. By switching between opening the isolation valves at different heights, the oil-water separation capacity can be adjusted according to the oil properties and throughput requirements.

[0032] The bottom of the external container is equipped with open and closed drain ports for periodically draining and replacing the crude oil accumulated inside, maintaining the liquid level and operation of the external oil chamber. An external container level gauge is installed on the external container, and a level control valve is installed on the liquid phase outlet pipeline of the external container. A level control system is also in place to control the opening of the liquid phase outlet regulating valve based on the external container's liquid level and to provide alarms for high and low liquid levels. The original two-phase separator has a pressure gauge and pressure control valve at its top, a separator interface level gauge, and a separator interface level control valve at its liquid phase outlet. The separator interface level gauge, separator interface level control valve, and pressure control valve are connected to the interface level control system. The interface level control system controls the opening of the separator interface level control valve based on the two-phase separator's interface level and provides an alarm when the interface level reaches a high or low level. The original safety valve (PSV) and other safety accessories on the top of the two-phase separator retain their original functions and are not new features in this embodiment.

[0033] Example 3: like Figure 2 As shown, the difference between this embodiment and Embodiment 1 lies in the number of isolation valves. In this embodiment, five isolation valves at different heights are installed along the height direction within a range of one-quarter to three-quarters of the diameter of the two-phase separator cylinder wall. The outlets of each isolation valve are connected to the liquid phase manifold, and then connected to the external container via the liquid phase main valve. Setting five isolation valves at different heights provides more options for liquid intake height, which is beneficial for finer adjustment of the oil-water separation capacity. The external container is still a buffer tank, and the configuration and connection method of the gas connection pipeline, gas phase valve, open drain port, closed drain port, liquid level control valve, pressure gauge, pressure control valve, separator interface gauge, separator interface control valve, and external container liquid level gauge are the same as in Embodiment 1.

[0034] Example 4: like Figure 3 As shown, the difference between this embodiment and Embodiment 1 lies in the form of the external container. In this embodiment, the external container is a tubular container, which serves as the oil chamber of the modified three-phase separator, while the original two-phase separator serves as the oil-water mixing chamber. The upper gas phase space of the external container is connected to the gas phase space of the two-phase separator via a gas-connected pipeline and a gas phase valve. Three isolation valves at different heights are installed within a range of one-quarter to three-quarters of the diameter of the two-phase separator cylinder wall. The outlets of each isolation valve are connected to the liquid phase manifold, which is then connected to the external container via a liquid phase main valve. Open and closed drain ports are provided at the bottom of the external container. A liquid level control valve is installed on the outlet pipeline of the external container. An external container level gauge is installed on the external container, and a separator interface gauge, pressure gauge, pressure control valve, and separator interface control valve are installed on the two-phase separator. The tubular container has a simple structure, is easy to arrange in groups, and is suitable for modification applications where platform space allows and a simplified container form is desired.

[0035] Example 5: like Figure 4 As shown, this embodiment increases the number of tubular containers compared to Embodiment 3. The external containers in this embodiment include two tubular containers: an external container and an expansion tubular container. The upper part of the external container is connected to the gas phase space of the two-phase separator via a gas-connecting pipeline and a gas phase valve. Isolation valves at different heights on the cylinder wall, a liquid phase manifold, and a liquid phase main valve are also connected to the external container. The upper part of the expansion tubular container is connected to the gas phase space of the external container via a pipeline and a gas phase valve. The lower part of the expansion tubular container is connected to the external container via a pipeline and a lower connecting valve, so that the two tubular containers together form the oil chamber. Open and closed drain ports are respectively provided at the bottom of the expansion tubular container. Adding one tubular container increases the total volume of the external oil chamber, which is beneficial for improving the oil processing capacity of the three-phase separator.

[0036] Example 6: like Figure 5 As shown, this embodiment further increases the number of tubular containers compared to Embodiment 4. The external container system in this embodiment includes three tubular containers: an external container, an expanded tubular container, and an expanded tubular container. The upper part of the expanded tubular container is connected to the gas phase space of the external container via pipelines and a gas phase valve, and the lower part is connected to the external container via pipelines and a lower connecting valve. The bottom of the expanded tubular container is equipped with open and closed drain ports. These three tubular containers together constitute the oil chamber, further increasing the total volume of the external oil chamber. In actual modification, the number of tubular containers can be determined according to the required oil processing capacity, and the oil chamber volume can be flexibly adjusted by adding or removing tubular containers.

Claims

1. A method for converting a two-phase separator into a three-phase separator, characterized in that, Includes the following steps: S1. An external container is installed near the two-phase separator, so that the external container serves as the oil chamber of the modified three-phase separator, and the two-phase separator serves as the oil-water mixing chamber of the modified three-phase separator. S2. Connect the upper gas phase space of the external container to the gas phase space of the two-phase separator via a gas connection pipeline to achieve pressure balance between the external container and the two-phase separator. S3. Multiple isolation valves are spaced apart along the height direction on the cylinder wall of the two-phase separator, and the outlet of each isolation valve is connected to the external container via a liquid connection pipeline. The multiple isolation valves are located at different heights, which are equivalent to weirs at different heights. S4. An open drain port and a closed drain port are provided at the bottom of the external container; S5. By opening isolation valves at different heights, the liquid phase in the two-phase separator corresponding to the height of the isolation valve enters the external container through the liquid connection pipeline, thereby adjusting the oil-water separation capacity.

2. The method for converting a two-phase separator into a three-phase separator according to claim 1, characterized in that: The external container is located near the liquid outlet of the two-phase separator.

3. The method for converting a two-phase separator into a three-phase separator according to claim 1, characterized in that: The external container is a buffer tank or a tubular container.

4. A method for converting a two-phase separator into a three-phase separator according to claim 1, characterized in that: The isolation valves are located within one-quarter to three-quarters of the diameter of the two-phase separator cylinder wall, and the number of isolation valves is 1 to 10.

5. A method for converting a two-phase separator into a three-phase separator according to claim 1, characterized in that: A gas phase valve is installed on the gas connection pipeline, and the outlets of each isolation valve are connected to the liquid phase manifold. The liquid phase manifold is connected to an external container via a liquid phase main valve.

6. A method for converting a two-phase separator into a three-phase separator according to claim 1, characterized in that: The open and closed drain ports periodically discharge and replace the crude oil accumulated in the external container.

7. A method for converting a two-phase separator into a three-phase separator according to claim 1, characterized in that: The two-phase separator is equipped with a separator interface level gauge and an interface level control system. The interface level control system controls the liquid phase outlet regulating valve of the original two-phase separator according to the interface level of the two-phase separator, and alarms are triggered for high and low liquid levels of the two-phase separator.

8. A method for converting a two-phase separator into a three-phase separator according to claim 1, characterized in that: The external container is equipped with an external container level gauge, which is also equipped with a level control system. The level control system controls the opening of the liquid phase outlet regulating valve of the external container according to the liquid level of the external container, and provides alarms for high and low liquid levels in the external container.

9. A method for converting a two-phase separator into a three-phase separator according to claim 1, characterized in that: The top of the two-phase separator is equipped with a pressure gauge and a pressure control valve.

10. A method for converting a two-phase separator into a three-phase separator according to claim 3, characterized in that: When the external container is a tubular container, at least two tubular containers are provided. The upper part of adjacent tubular containers is connected to a gas phase valve via a pipeline, and the lower part is connected to a valve via a pipeline. Each tubular container is provided with an open drain port and a closed drain port at its bottom. The volume of the oil chamber is adjusted by increasing or decreasing the number of tubular containers.

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