JPS6153600B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to a method for transporting a gas-liquid mixed two-phase flow in a long-distance pipeline.

[Conventional technology]

For example, one method of transporting crude oil extracted from an offshore oil field to an oil refinery via an underwater pipeline is to transport the gas extracted together with the crude oil.In such two-phase gas-liquid transport, Because the liquid portion is transported with a delay due to the difference in transportability between gas and liquid, the liquid portion is transported by extrusion through the pipeline through a liquid delivery pig.

By the way, when such a gas-liquid mixed two-phase flow is transported by a long-distance pipeline, as the length of the liquid pushed out by the pig increases, the transport resistance increases and the transport capacity is extremely reduced. In general, the pipeline is divided into lengths that allow for pig transportation, a relay station is interposed between the pipelines in each zone, and the transfer station applies pressure to the transported flow and sends it to the pipeline in the next zone. It is being said. In other words, Figure 1 shows a long-distance pipeline that connects an offshore oil field and an oil refinery base.The gas-liquid mixed two-phase flow of crude oil and gas sent from the oil extraction base A through the submarine pipeline 1 is transferred to the offshore platform. The pressure is boosted at relay station B, where a pig receiver, pig launcher, and transport flow booster are installed.
It is transferred to the next area's pipeline and transported.

Conventionally, as a method of transporting a gas-liquid mixed two-phase flow in such a long-distance pipeline, as shown in FIG. The system is equipped with a compressor 5 that pumps up the pressure of the liquid and sends it out, and a gas-liquid separator 4 separates the transport flow that reaches the relay station through the pipeline 1a in the front area into gas and liquid. However, a method is adopted in which the pressure of the gas component is increased by the compressor 5, and the pressure of the liquid component is increased by the pump 6, and then sent to the pipeline 1b in the next area. In addition,
In this method, the pipeline 1a in the front area
The pigs passing through are received by the pig receiver 2 by closing the valve 7, and the pigs passing through the pipeline 1b in the next section are received by the pig receiver 2.
is fired from.

[Problem that the invention seeks to solve]

However, in pipeline transportation of gas-liquid mixed two-phase flow, as mentioned above, the liquid component is transported later than the gas component, so the gas component that reaches the relay station first is transferred to the next area's pipeline. If it is sent to pipeline 1b, the liquid that arrives late will have to be sent to the next area, pipeline 1b, in the form of liquid-only transport, which eliminates the advantage of two-phase flow transport. Moreover, if such relaying were to be repeated at each relay station, the transport length of the liquid would become long and the transport capacity would be reduced. Therefore, in the conventional method, a flow control valve 8 is installed on the outlet side of the compressor 5 as shown in FIG.
is installed to suppress the delivery of the gas that arrived first and to send out the gas in conjunction with the delivery of the liquid.In this way, the system waits for the liquid to arrive before sending it to the next area pipeline. If this method is used, transportation in the pipeline will be intermittent, resulting in poor transportation efficiency, and for this reason, the pipeline length in one area will be limited to 150 km or less. Since it is necessary to use a compressor to pressurize and send out the amount of gas that can be sufficiently sent under the transport pressure of the transport stream, the installation of this compressor increases the equipment and maintenance costs of the relay station, and many relay stations There was a problem in that if it was adopted for long-distance pipelines that require

This invention was made in view of the above-mentioned circumstances, and its purpose is to transfer the gas that has reached the relay station to the next area using the transport pressure of the subsequent transport flow without waiting for the liquid to arrive. The liquid component is sent to the pipeline of the next area together with the gas component that reaches the next area, so that continuous and efficient transportation can be carried out. Therefore, the number of relay stations can be reduced by increasing the length of the pipeline in one area even slightly, and the equipment cost and maintenance cost of the relay station can be reduced by eliminating compressors for boosting the gas pressure from the relay station. Provides a method for transporting gas-liquid mixed two-phase flow in long-distance pipelines, which enables transportation in long-distance pipelines at low cost and can be adopted in existing pipelines by simply changing the relay equipment. It's about doing.

[Means to solve problems]

This invention is directed to a relay station of a long-distance pipeline that transports a two-layer flow of gas-liquid mixture, and which directs the gas component of the transport flow that has been transported through the pipeline in the front area of the relay station to the pipeline in the next area. a liquid storage tank for accumulating the liquid component of the transport flow that has been transported through the front section pipeline, and a pig receiver that stores the pig that has pushed out and transported the liquid component using the transport pressure of the subsequent transport flow. , comprising: a liquid distribution pipe connecting the liquid storage tank and a pipeline in the next zone; a pump provided on the liquid distribution pipeline; and a pig launcher for pushing the pig into the pipeline in the next zone. A relay facility is installed, and the gas portion of the transport stream transported through the pipeline in the previous area that reaches the relay station first is sent directly to the pipeline in the next area through the bypass pipe by the transport pressure of the subsequent transport flow. The liquid component that arrived at the relay station later than the gas component was accumulated in the liquid storage tank, and the pig that had pushed out and transported the liquid component was stored in the pig receiver and reached the relay station ahead of the subsequent transport stream. When the gaseous component is sent to the pipeline of the next section through the bypass pipeline, the liquid component in the liquid component storage tank is sent to the liquid component delivery pipeline by a pump, and this liquid component and the above-mentioned subsequent transportation are carried out. The method is characterized in that the gaseous portion of the stream is sent together with the pipeline of the next section, and then the pig is pushed out from the pig launcher to the pipeline of the next section.

[Effect]

In other words, in this invention, the gas portion of the transport flow that has been transported through the front area pipeline, which reaches the relay station first, is directly passed through the bypass pipe to the next without waiting for the liquid portion, which is delayed to arrive at the relay station. The liquid component that is sent to the pipeline in the zone and arrives at the relay station later than the gas component is temporarily accumulated in a liquid storage tank, and then the gas component of the subsequent transport flow that reaches the relay station is passed through the bypass pipe and transferred to the next zone. When sending the liquid to the pipeline in the next area, the liquid stored in the liquid storage tank is pressurized by a pump and sent to the pipeline in the next area together with the gas in the subsequent transport stream. For example, when relaying a transport flow to a pipeline in the next area, there is no need to wait for the liquid to arrive at the relay station late.
Continuous and efficient transport can be performed, and since the gas component of the transport flow is sent to the next pipeline by the transport pressure of the subsequent transport flow, the gas component is not transferred to the relay station. Since there is no need to provide a boost compressor, the equipment cost and maintenance cost of the relay station can be reduced.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

Figure 3 shows an example of relay equipment employed in this invention, in which 2 is a pig receiver;
3 is a pig launcher, 6 is a pump for liquid delivery, and 9 is a liquid storage tank with a closed structure. The front area pipeline 1a of the relay station is branched into the pig receiver 2 and the liquid storage tank 9, and the pipe line 1
Due to the difference in gravity, the gas component of the transport stream that has been transported a flows into the inlet side of the pig receiver 2, and the liquid component flows into the liquid storage tank 9. 10 is a bypass pipe connecting the inlet side of the pig receiver 2 and the outlet side of the pig launcher 3; 11 to 16 are gas branch flow switching valves; 17 is a liquid branch delivery pipe connected to the liquid storage tank 9; The pump 6, a flow control valve 18, and a check valve 19 are interposed in the pipeline 17, and the outlet side of the pipeline 17 and the pig launcher 3 are connected to the pipeline 1b of the next section.

Next, a description will be given of transportation of a gas-liquid mixed two-phase flow carried out by equipping a relay station with the above-mentioned relay equipment.

Now, let us assume that the gas component with a high transport speed among the gas-liquid two-phase flow transported through the pipeline 1a in the front area has reached the relay station. Said flow path switching valve 1
1 to 16 are switching valves 11 and 14 at this point.
is opened, and the other switching valves 12, 13 and 15, 16 are opened.
is switched to a closed state, so that the gaseous portion is sent through the bypass line 10 to the pipeline 1b of the next section, and is directly transferred to the next section pipe by the transport pressure of the subsequent transport flow. It is transported along line 1b. On the other hand, as the pig sent through pipeline 1a in the front area approaches the relay station, the liquid pushed out and transported by the pig reaches the relay station. The liquid flows into the liquid storage tank 9 under pressure from the liquid storage tank 9 and is accumulated therein. The branch pipe to the liquid storage tank 9 is designed to prevent pigs from entering, so that the pigs that reach the relay station are sent toward the pig receiver 2. When accumulation of liquid in the liquid storage tank 9 is started, the switching valves 11 to 16 are automatically switched so that the switching valve 11 is closed and the switching valves 12 and 13 are opened. (Other switching valves maintain their previous states...the same applies hereafter), all the liquid transported through the pipeline 1a in the previous area is transferred to the liquid storage tank 9.
Once accumulated, the pig is pushed by the subsequent transport flow (gas content) and is received into the pig receiver 2 through the switching valve 12. When the pig is stored in this way, the switching valves 11, 12, and 13 are switched in the opposite direction to the previous state (the pig stored in the pig receiver is then taken out), and thereby the gas is transferred to the bypass pipe. Pipeline 1b in the next area through route 10
will be sent to. When the relay transportation of this gas starts, the pressure of the gas sent through the pipeline 1a in the front section also acts on the liquid storage tank 9, and the pressure of this gas causes the liquid in the storage tank 9 to is delivered to the liquid delivery line 17 using the siphon principle. In addition,
If the storage tank 9 is located high above the relay station and the liquid that has reached the relay station is sent into the storage tank 9 by pressure from the rear, the liquid head pressure in the storage tank 9 will cause the liquid to be transferred to the delivery pipe. 17. Then, this liquid is pumped out by the pump 6 which is driven at the same time as the pig is housed, and is sent out through the check valve 19 while the flow rate is controlled to be constant by the flow rate regulating valve 18. It joins with the gas delivered through the bypass pipe line 10 and is sent to the next section, the pipeline 1b. When the liquid accumulated in the storage tank 9 is sent to the pipeline 1b of the next area, the switching valve 14 is closed at the same time as the sending is completed, and the switching valves 15 and 16 are simultaneously opened and the bypass pipe is opened. Road 10
As the gas that has passed through flows through the pig launcher 3, the pressure of the gas causes the pig to be pushed out of the pig launcher 3 and sent to the pipeline 1b in the next area. In addition, the above switching valve 1
4, 15, and 16 are reversely switched again after the extrusion of the pig ends, and after this, the next pig to be sent into the pig launcher 3 is charged. Furthermore, the time when the pig is pushed out from the pig launcher 3 and the time when the pig is stored in the pig receiver 2 are almost the same, and by repeating the above-mentioned relay operation,
A gas-liquid mixed two-phase flow is relayed in which the liquid component, which arrives at the relay station later than the gas component, is transported to the next area, the pipeline 1b, as a two-phase flow with the subsequent gas component.

Note that the delivery pressure of the pump 6 is determined according to the mixing ratio of liquid and gas in the two-phase flow sent through the pipeline. When transporting by a pipeline with a length of 200km, the delivery pressure is approximately 70Kg/ ^cm2 (in this case, the pressure of the two-phase flow that reaches the relay station is approximately 50Kg/ ^cm2 if the oil content is high). (If the gas content is high, it will drop to about 40Kg/ ^cm2 ).

〔Effect of the invention〕

In this invention, the gas portion of the transport flow that has been transported through the front area pipeline, which reached the relay station first, is bypassed by the transport pressure of the subsequent transport flow without waiting for the liquid portion that reaches the relay station later. The liquid component that reaches the relay station later than the gas component is sent as it is to the pipeline in the next area through the pipe, and is temporarily accumulated in the liquid storage tank. When sending the liquid through the pipe to the pipeline in the next area, the liquid stored in the liquid storage tank is pressurized by a pump and sent to the pipeline in the next area along with the gas in the subsequent transport flow. , according to this invention,
The gas that has reached the relay station is sent to the pipeline in the next area using the transport pressure of the subsequent transport flow without waiting for the liquid to arrive, and the liquid is transferred to the next area along with the gas that arrives next. By sending out to the pipeline, continuous and efficient transportation can be carried out, and by doing so, the length of the pipeline in one area can be lengthened even slightly. , the number of relay stations can be reduced, and compressors for boosting the gas content can be eliminated from the relay stations, reducing the equipment costs and maintenance costs of the relay stations, and the transportation of gas-liquid mixed two-phase flow in long-distance pipelines can be reduced. It can be done at a cost. Note that this transportation method can also be implemented on existing pipelines by simply changing the relay equipment.

[Brief explanation of the drawing]

Fig. 1 is a piping diagram showing an example of a pipeline that transports a gas-liquid mixed two-phase flow via a relay station, Fig. 2 is a relay system diagram showing conventional relay equipment, and Fig. 3 is a piping diagram showing an example of a pipeline that transports a gas-liquid mixed two-phase flow through a relay station. FIG. 2 is a relay system diagram showing an example of relay equipment. 1a...Previous area pipeline, 1b...Next area pipeline, 2...Pig receiver, 3...Pig launcher, 6...Pump, 9...Liquid storage tank, 1
0... Bypass pipe line, 18... Flow rate control valve.

Claims (1)

[Scope of Claims] 1. To a relay station of a long-distance pipeline that transports a two-layer flow of gas-liquid mixture, the gas portion of the transport flow that has been transported through the pipeline in the previous area of this relay station is transferred to the pipeline in the next area. A gas bypass pipe leading to the front area, a liquid storage tank that accumulates the liquid part of the transport flow that has been transported through the pipeline in the previous area, and a pig that has pushed out and transported the liquid part using the transport pressure of the subsequent transport flow. a pig receiver, a liquid delivery pipe that connects the liquid storage tank with a pipeline in the next area, a pump installed in the liquid delivery pipe, and a pig launcher that pushes the pig into the pipeline in the next area. A relay facility is installed, and the gas portion of the transport stream transported through the pipeline in the previous area that reaches the relay station first is transferred directly to the pipe in the next area through the bypass pipeline due to the transport pressure of the subsequent transport flow. The liquid component that is sent to the line and reaches the relay station later than the gas component is accumulated in the liquid storage tank, and the pig that has pushed out and transported the liquid component is stored in the pig receiver and sent to the relay station ahead of the subsequent transport flow. When the gas that has reached the area is sent to the pipeline of the next area through the bypass pipe, the liquid in the liquid storage tank is sent to the liquid delivery pipe by a pump, and this liquid and A gas-liquid mixed two-phase flow in a long-distance pipeline, characterized in that the gas component of the subsequent transport flow is sent together to the pipeline in the next zone, and then the pig is pushed out from the pig launcher to the pipeline in the next zone. transportation method.