CN1297778C - Separator and phase-split conveying method for eliminating plug flow on serious segments by utilizing same - Google Patents

Abstract

The present invention relates to a separator and a phase-split conveying method for eliminating blocked flow on serious segments by using the separator. The separator comprises a shell body; the shell body is connected with a flow coming pipe and a gas ascending pipe; a liquid level sensor and a pressure sensor are arranged on the shell body; an ascending pipe which is inserted into the shell body extends to the bottom of the shell body; a liquid phase pump which is connected with the ascending pipe through a valve is arranged at a part of the ascending pipe, which extends out of the shell body; a control valve is arranged on the gas ascending pipe and approaches to the outlet of the shell body. The separator of the present invention is installed at the combined part of a mixed conveying pipeline and the ascending pipe; gas and liquid fluid in the mixed conveying pipeline enters the shell body of the separator through the flow coming pipe; liquid level signals and pressure signals are used for regulating the open degree of the control valve so that the liquid level and the pressure are stable; after gas and liquid are separated in the separator, the liquid which enters the ascending pipe is pressurized by the liquid phase pump to be conveyed to a platform device on shore; the gas enters the platform device on shore through the control valve and the gas ascending pipe. The present invention has the advantage of simple structure and can conveniently and accurately control the flow of the gas and the liquid to achieve the aim of eliminating the blocked flow on the serious segments.

Description

A separator and a phase-separation conveying method using it to eliminate severe slug flow

technical field

The invention relates to a separator and a method for eliminating severe slug flow by using the separator, in particular to a separator for mixed transportation of oil and gas and a seabed separation and phase-separation transportation method for eliminating severe slug flow by using the same.

Background technique

In offshore oil exploitation, it is often encountered that gas and liquid are transported at the same time. When the multi-phase gathering and transportation pipeline on the seabed reaches the offshore platform or onshore processing facility, it needs to be connected with the riser. Under certain conditions, the gathering and transportation pipeline and A detrimental flow pattern known as severe slug can occur in systems consisting of risers. This flow pattern will produce a liquid plug several times the height of the riser, which will cause periodic changes in the pressure in the gathering pipeline, thereby affecting the wellhead pressure, and will also cause the gas and liquid to flow out intermittently at the outlet of the riser, causing the gas to spray at a high speed in a short period of time. The outlet liquid plug enters the separator at a high speed, and the severe slug flow phenomenon brings many problems to the design and production. Because production facilities had to be scaled up, some separators were rated far larger than the actual liquid handling capacity, resulting in waste, and severe flow fluctuations made it difficult to control the separator and downstream processing facilities, sometimes even causing production interruptions.

Chinese patent CN1387617A "Method and system for suppressing and controlling slug flow in multiphase fluid flow" (publication date: December 25, 2002) and US patent US6390114B1 "Method and apparatus for suppressing and controlling slug flow in a multi- Phase Fluid Stream" (public date: May 21, 2002) announced a severe slug flow suppression method, which uses easy-to-implement gas-liquid single-phase flow measurement and combines multiple control variables such as liquid level and pressure to control Realize the control of severe slug flow; British patent GB2374161A "Gas injection controlling liquid slugs inpipeline riser" (public date: October 9, 2002) announced a serious slug flow control method of gas injection at the bottom of the riser, However, experiments have shown that this method requires a large amount of gas injection to completely eliminate severe slug flow, and can only weaken severe slug flow when the gas injection amount is small. The above-mentioned methods only achieve the effect of weakening severe slug flow, but have not fundamentally eliminated the conditions for severe slug flow.

Contents of the invention

In order to eliminate severe slug flow, the object of the present invention is to provide a separator, which can conveniently and accurately control the flow of gas and liquid, and achieve the purpose of eliminating severe slug flow.

Another object of the present invention is to provide a phase-splitting conveying method that eliminates severe slug flow.

The technical solution adopted in the present invention is: a separator, including a shell, the shell is connected with an incoming flow pipe and a gas rising pipe, a liquid level sensor and a pressure sensor are arranged on the shell, and the rising pipe is inserted into the shell and extends to At the bottom of the shell, valve 8 is set on the part where the riser tube protrudes from the shell. Valve 8 forms a bypass with the liquid phase pump through valve 9 and valve 10 at both ends of the riser tube, and a control valve is set on the gas riser tube near the outlet of the shell. valve.

Another technical solution adopted by the present invention is: a phase-separated conveying method for eliminating severe slug flow. A separator is installed at the junction of the mixed transportation pipeline and the riser so that the incoming flow of the mixed transportation pipeline and the separator The gas-liquid fluid in the mixed pipeline enters the shell of the separator through the incoming flow pipe, and the liquid level signal and pressure signal from the liquid level sensor and pressure sensor are used to adjust the opening of the control valve to make the liquid level After the gas and liquid are separated in the separator, the liquid enters the rising pipe extending into the lower part of the separator, and is pumped by the liquid phase pump to the onshore platform device, so that the gas enters the onshore platform through the gas rising pipe through the control valve device.

The preferred technical solution of the present invention can adopt a separator for tangential centrifugal separation, whose volume is 2 to 4 times the volume of the riser, and whose length-to-diameter ratio is 2.

The beneficial effects of the present invention are: the separator of the present invention has a simple structure, can accurately control the flow of gas and liquid very conveniently, and achieves the purpose of eliminating severe slug flow; using the separator of the present invention to eliminate severe slug flow The phase-separation transportation method is to install a separator at the joint position of the mixed transportation pipeline and the rising pipe to block the interaction before and after and cooperate with the automatic control technology. Through the control of the liquid level of the separator, the gas-liquid separation and separate transportation are realized. At the same time, the liquid can also be driven by the liquid phase pump to reduce the pipeline pressure. This method fundamentally eliminates the occurrence of serious slug flow, and the incoming flow is basically stratified flow, so the liquid level is easy to control, and a stable flow of gas and liquid can be obtained. In addition, a liquid phase pump is installed on the liquid riser to The pressure head is provided, the flow can be switched through the valve, and the flow rate of the pump can be controlled by the liquid level signal through the frequency conversion speed regulation technology, so as to ensure the stability of the liquid level and pressure of the separator. This very mature liquid-phase pump transportation scheme can greatly reduce the inlet pressure of the gathering pipeline, which is more beneficial to reservoirs with low energy in the later stage of production.

Description of drawings

Fig. 1 is a schematic diagram of gas-liquid flow and control system of the present invention;

Fig. 2 is the change of liquid holdup in the ascending pipe before and after the system realizes separation (adjusting control valve 6) and stopping separation (closing control valve 6), the abscissa in the figure is time, and the ordinate is liquid holdup;

Figure 3 shows the signal changes of the corresponding separator pressure sensor before and after the system achieves separation and stops separation so that the riser is mixed and conveyed. The abscissa in the figure is time, and the ordinate is absolute pressure.

In the figure, 1 flow pipe, 2 casing, 3 rising pipe, 4 gas rising pipe, 5 liquid level sensor, 6 control valve, 7 pressure sensor, 8 valve, 9 valve, 10 valve, 11 liquid phase pump, 12 mixing pipeline.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

Referring to Fig. 1, the separator includes a housing 2, on which is connected an incoming flow pipe 1 and a gas rising pipe 4, on which a liquid level sensor 5 and a pressure sensor 7 are arranged, and on which the rising pipe 3 is inserted into the housing 2 and It extends to the bottom of the shell 2, and the part of the rising pipe 3 protruding from the shell 2 is provided with a valve 8. The valve 8 forms a bypass with the liquid phase pump 11 through the valve 9 and the valve 10 at both ends of the rising pipe 3, and the gas rising pipe 4 A control valve 6 is arranged near the outlet of the housing 2 on the top.

The phase-separated conveying method to eliminate severe slug flow is to install a separator at the junction of the mixed transportation pipeline 12 and the rising pipe 3. The separator adopts tangential centrifugal separation, and its volume is 2 to 4 times the volume of the rising pipe 3, and the length The diameter ratio is 2. Make the mixed transportation pipeline 12 communicate with the incoming flow pipe 1 of the separator, the gas-liquid fluid in the mixed transportation pipeline 12 enters the shell 2 of the separator through the incoming flow pipe 1, and is sent out by the liquid level sensor 5 and the pressure sensor 7 The liquid level signal and pressure signal are used to adjust the opening of the control valve 6 to stabilize the liquid level and pressure. After the gas and liquid are separated in the separator, the liquid enters the rising pipe 3 extending into the lower part of the separator, and passes through the liquid phase pump 11. The pressurized transport of the liquid to the shore platform device, the flow of the liquid is switched through the valves 8, 9, 10, that is, the valve 8 is closed, and the valves 9 and 10 are opened. The liquid can also flow out directly through the valve 8 without passing through the liquid phase pump, that is, the valve 8 is opened, and valves 9 and 10 are closed, so that the gas enters the shore platform device through the control valve 6 through the gas riser 4.

In the case of low flow rate, the pressure of the separator is approximately equal to the sum of the back pressure at the outlet of the riser 3 and the liquid phase gravity head at the height of the riser 3. This pressure is acceptable for relatively shallow sea areas, but for the current increasingly In many deep-sea oil areas, if the pressure is too high, it will have a negative impact on the oil well. Therefore, installing a liquid phase pump 11 on the riser 3 to provide a pressure head can solve this problem well. The flow of liquid can pass through the valve. 8, 9, 10 switching, the flow rate of the pump can be controlled by the liquid level signal 5 through the frequency conversion speed regulation technology, so as to ensure the stability of the separator liquid level and pressure.

Figure 2 is a comparison diagram of the experiment, in which valve 8 was opened and valves 9 and 10 were closed. At the beginning of the experiment, adjust the control valve 6 to keep the gas and liquid completely separated, and you can see that the liquid holdup rate of the riser 3 is 1, indicating that the pipe is full; when the control valve 6 is closed at 195 seconds, the gas and liquid flow out from the riser 3, and you can see the system Severe slug flow quickly appeared in the middle, the liquid holdup of the riser 3 fluctuated violently, the pipeline 12 was sometimes completely empty and sometimes completely full, and the outlet gas-liquid flowed intermittently.

In Figure 3, valve 8 is open and valves 9 and 10 are closed. At the beginning of the experiment, adjust the control valve 6 to keep the gas and liquid completely separated, the liquid holdup rate of the riser 3 is 1, which means the pipe is full, and the pressure of the separator is also constant; at the 195th second, the control valve 6 is closed, and the gas and liquid flow out from the riser 3 , Severe slug flow soon appeared in the system, and the pressure signal of the separator also changed periodically, with an amplitude as high as 1.4 bar. At this time, the working status of the upstream and downstream production facilities was difficult to stabilize, which was very unfavorable to normal production.

It can be seen from the comparison of the above experimental results that the present invention can well eliminate the severe slug flow phenomenon.

Claims (3)

1. A separator, comprising a housing (2), connected with an incoming flow pipe (1) and a gas riser pipe (4) on the housing (2), it is characterized in that said housing (2) is provided with The liquid level sensor (5) and the pressure sensor (7), the riser pipe (3) is inserted into the casing (2) and extends to the bottom of the casing (2), and the riser pipe (3) extends out of the casing (2) The valve (8) is set in the part of the rising pipe (3), and the valve (8) forms a bypass with the liquid phase pump (11) through the valve (9) and the valve (10) at the two ends of the rising pipe (3). The said gas rising pipe ( 4) A control valve (6) is set near the outlet of the housing (2), and the liquid level signal and pressure signal from the liquid level sensor (5) and pressure sensor (7) are used to adjust the opening of the control valve (6). 2. A phase-splitting conveying method for eliminating severe slug flow, characterized in that a separator is installed at the junction of the mixed transportation pipeline (12) and the riser (3), so that the mixed transportation pipeline (12) is separated from the The flow pipe (1) of the separator is connected, and the gas-liquid fluid in the mixed pipeline (12) enters the shell (2) of the separator through the flow pipe (1), and the liquid level sensor (5) and the pressure sensor ( 7) The transmitted liquid level signal and pressure signal are used to adjust the opening of the control valve (6) to stabilize the liquid level and pressure. After the gas and liquid are separated in the separator, the liquid enters the rising pipe extending into the lower part of the separator ( 3), pressurized by the liquid phase pump (11) and transported to the onshore platform device, so that the gas enters the onshore platform device through the control valve (6) through the gas riser pipe (4). 3. A kind of phase-separated conveying method for eliminating severe slug flow according to claim 2, characterized in that said separator adopts tangential centrifugal separation, and its volume is 2 to 4 of the volume of the riser (3). times, the aspect ratio is 2.

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