CN117553236A - Gas-liquid mixing and conveying device and method for oil-gas field - Google Patents

Abstract

The invention relates to a gas-liquid mixing and conveying device for an oil-gas field, which is arranged in a collecting and conveying pipeline (50) and is used for conveying an oil-gas medium downstream after being pressurized, and comprises a first pressure tank (1) and a second pressure tank (2). The first pressure tank is respectively communicated with the upstream end and the downstream end of the gathering and conveying pipeline through a first liquid inlet pipe (110) and a first liquid outlet pipe (120). Likewise, the second pressure tank is communicated with the upstream and downstream sections of the gathering line through a second liquid inlet pipe (210) and a second liquid outlet pipe (220). And a bidirectional pump (3) is arranged between the first pressure tank (1) and the second pressure tank (2), when the liquid level of the power liquid in the first pressure tank is reduced to the lower limit value, the power liquid in the second pressure tank is pumped into the first pressure tank by the bidirectional pump, and when the liquid level of the power liquid in the second pressure tank is reduced to the lower limit value, the power liquid in the first pressure tank is pumped into the second pressure tank by the bidirectional pump (3) in a reversing way, and the medium in the pressure tank is pressurized and conveyed to the downstream by utilizing the rising of the liquid level of the power liquid.

Description

Gas-liquid mixing and conveying device and method for oil-gas field

Technical Field

The invention relates to a conveying device for petroleum and natural gas, in particular to a gas-liquid mixing conveying device and a method for gas-liquid mixing conveying between a production well and a gas well of an oil field and an oil-gas combined station.

Background

The media developed in oil and gas fields are usually gas-liquid miscible phases, that is, the media extracted from the reservoir contains natural gas, water and silt in addition to petroleum, and the media extracted from the reservoir contains substances such as water, light hydrocarbons (light oil) and the like in addition to natural gas, and these miscible media (hereinafter referred to as "media") need to be transported by pipelines to an oil and gas treatment terminal station (combination station) to produce petroleum and natural gas products meeting industry standards. In the medium conveying process, pressurizing equipment (such as a pump) is needed to lift the pressure in the pipeline, so that the medium obtains kinetic energy for conveying.

The traditional pressurizing equipment can only independently pressurize liquid phase or gas phase, but cannot meet the requirement of gas-liquid mixed transportation, for example, if a liquid pump is used for transporting fluid which contains more gas, gas lock faults and the like can occur, so that the traditional transportation mode is that a transfer station (gas collecting station) is firstly constructed near a wellhead or in the middle of transportation, natural gas and oil water in a medium are settled and separated in the transfer station, and then the natural gas and the oil water are transported by different equipment and pipelines respectively. However, the transfer station (gas collecting station) has long construction period, large investment, high operation and maintenance cost, large occupied land, large occupied duty for station residence, difficult control of carbon-containing volatile matters generated in the oil-gas-water separation process, and easy emission of greenhouse gases, and the factors restrict the efficient and green development of the oil-gas field.

As a gas-liquid mixing and feeding device, the invention patent application of application No. 201811286148.0 discloses a double-cavity liquid reciprocating drive multiphase flow mixing and feeding device, which has a left tank a1, a right tank a2, a pump a3 and a control system a4 as shown in fig. 7 (the original drawing of the specification is labeled again). The upper ends of the left tank a1 and the right tank a2 are connected to a medium feed line (inlet end a5, outlet end a 6) through a first check valve a9 and a second check valve a10, respectively. The pump a3 is a one-way pump, is provided in an i-shaped pipe between the left tank a1 and the right tank a2, and is capable of transporting liquid in a direction indicated by a small arrow a. The control system a4 is electrically connected with an electromagnetic valve group a7 arranged on branch pipes at two sides of the pump a3 and a liquid level meter a8 arranged on the left tank a1 and the right tank a2, and can control the opening and closing of the electromagnetic valve group a7 according to the measured value of the liquid level meter a8, so that the pump a3 can exchange and convey liquid in the left tank a1 and the right tank a2.

For example, the solenoid valve a7 at the upper left and lower right in fig. 7 is opened, and the solenoid valve a7 at the lower left and upper right in fig. 7 is closed, that is, the liquid in the right tank a2 can be pumped to the left tank a1 in the direction of the small arrow C1-B1-a-B2-C2 in the drawing, and the liquid in the left tank a1 can be pumped to the right tank a2 in the opposite direction. Taking the pumping process in the direction of C1-B1-A-B2-C2 as an example, negative pressure is formed at the upper part of the right tank a2, so that an oil-gas-water mixed medium enters the right tank a2 from an inlet end a5 along a first one-way valve a9 with a small arrow D2 and is layered in the right tank a2 by gravity; meanwhile, positive pressure is formed at the upper part of the left tank a1, so that gas and oil at the upper part enter an outlet end a6 from a medium conveying pipeline of the second one-way valve a10 along the direction of a small arrow D1, and gas and liquid are prevented from entering a liquid pump to generate gas lock while gas and liquid are mixed and conveyed through alternate switching of a plurality of electromagnetic reversing valve groups. .

Compared with the traditional separate conveying method, the mixed conveying device is used for conveying the medium, so that the cost brought by arranging gas-liquid separation (and matched heating, storage, drying and the like) equipment can be greatly reduced, the process flows of standby, emergency, accident prevention and the like can be saved, the natural gas output pipeline is omitted, and the efficient and environment-friendly development of an oil field is facilitated.

However, the conventional mixing and conveying device is complex in structure, the switching work of the direction of the pumped liquid can be completed only by continuously and frequently controlling the electromagnetic valves, the electromagnetic valves are high in dosage, the manufacturing cost of equipment is high, a large amount of noise can be generated by frequently switching a large number of electromagnetic valves, any electromagnetic valve fails, the whole device cannot work, and the reliability of the device is reduced.

Disclosure of Invention

The invention aims to solve the problems of high manufacturing cost, high failure rate and low reliability caused by the fact that the electromagnetic valve of the existing mixing and conveying device is large in consumption and needs to be frequently switched.

The first technical scheme of the invention is a gas-liquid mixing and conveying device for an oil-gas field, which is arranged in a collecting and conveying pipeline 50 capable of mixing and conveying oil and natural gas, pressurizes the oil and the natural gas and conveys the oil and the natural gas downstream, and is characterized by comprising a first pressure tank 1, a second pressure tank 2, a two-way pump 3 and a control system 4.

The upper portion of the first pressure tank 1 is provided with a first liquid inlet pipe 110, the first liquid inlet pipe 110 is communicated with the upstream end of the collecting and delivering pipeline 50, the top of the upper side of the first liquid inlet pipe 110 is provided with a first liquid outlet pipe 120, the first liquid outlet pipe 120 is communicated with the downstream end of the collecting and delivering pipeline 50, the upper portion of the second pressure tank 2 is provided with a second liquid inlet pipe 210, the second liquid inlet pipe 210 is communicated with the upstream end of the collecting and delivering pipeline 50, and the top of the upper side of the second liquid inlet pipe 210 is provided with a second liquid outlet pipe 220, and the second liquid outlet pipe 220 is communicated with the downstream end of the collecting and delivering pipeline 50.

The first and second liquid inlet pipes 110 and 210 are respectively provided with a first one-way valve 11 and a second one-way valve 21, which allow upstream oil and gas to enter the first and second pressure tanks 1 and 2, and prevent backflow, and the first and second liquid outlet pipes 120 and 220 are respectively provided with a third one-way valve 12 and a fourth one-way valve 22, which allow oil and gas in the first and second pressure tanks 1 and 2 to enter the downstream end of the gathering line 50, and prevent backflow.

The first pressure tank 1 and the second pressure tank 2 are closed tank bodies, power liquid is respectively installed in the closed tank bodies, the bottoms of the first pressure tank 1 and the second pressure tank 2 are communicated through a liquid pumping pipe, a two-way pump 3 is installed in the liquid pumping pipe 31 and used for pumping power liquid in the first pressure tank 1 into the second pressure tank 2 or pumping power liquid in the second pressure tank 2 into the first pressure tank 1, when the power liquid is pumped out, negative pressure generated in the first pressure tank 1 or the second pressure tank 2 sucks petroleum and natural gas from the upstream end of the gathering pipeline 50, and meanwhile, when the power liquid is pumped out, positive pressure generated in the second pressure tank 2 or the first pressure tank 1 pressurizes the sucked petroleum and natural gas and then conveys the pumped petroleum and natural gas to the downstream end of the gathering pipeline 50.

The first pressure tank 1 is provided with a first liquid level meter 61, the second pressure tank 2 is provided with a second liquid level meter 62, when the first liquid level meter 61 detects that the liquid level of the power liquid in the first pressure tank 1 is reduced to a lower limit value, the control system 4 controls the bidirectional pump 3 to pump the power liquid in the second pressure tank 2 into the first pressure tank 1, when the second liquid level meter 62 detects that the liquid level of the power liquid in the second pressure tank 2 is reduced to a lower limit value, the control system 4 switches the pumping direction of the bidirectional pump (3), pumps the power liquid in the first pressure tank 1 into the second pressure tank 2, and enables the bidirectional pump 3 to interactively convey the power liquid between the first pressure tank 1 and the second pressure tank 2.

According to the gas-liquid mixing and conveying device, as long as the two-way pump 3 is arranged in the pump liquid pipe which is communicated with the first pressure tank 1 and the second pressure tank 2, the control system 4 controls the two-way pump 3 to change direction according to the liquid level of the power liquid in the pressure tanks, and gas-liquid pressurization can be carried out for gas-liquid mixing and conveying. Compared with the prior art, the device has the advantages that a large number of reversing electromagnetic valves are not required to be arranged, so that the cost is saved, the control is simpler, and the reliability of the device is improved.

The pump tube may be constituted by a single pump tube (31), and the bidirectional pump 3 mounted in the pump tube (31) is a bidirectional centrifugal pump 30.

Since the bi-directional centrifugal pump 30 is used to pump the power fluid bi-directionally, even if some bubbles are mixed into the bi-directional centrifugal pump 30, the gas in the pump can be automatically discharged. That is, in each impeller reverse rotation, a small amount of gas dissolved in water due to the centrifugal action of the impeller is trapped in the pump casing in the form of bubbles, and when the bi-directional centrifugal pump 30 is operated in forward rotation, the trapped gas in the pump casing is reversely discharged back to the original tank along with reverse water flow, so that gas lock failure due to gas accumulation is prevented.

The pump fluid pipe may also be constituted by a first pump fluid pipe 311 and a second pump fluid pipe 312,

the bidirectional pump 3 is composed of two unidirectional pumps, a first unidirectional pump (301) is installed in a first pump liquid pipe 311, a second unidirectional pump 302 is installed in a second pump liquid pipe 312, and the pumping directions of the first unidirectional pump 301 and the second unidirectional pump 302 are opposite.

Therefore, the two unidirectional pumps can be utilized to play a role of a bidirectional pump, and the cost is reduced.

Wherein the first unidirectional pump (301) and the second unidirectional pump (302) are preferably plunger pumps.

Since the outlet and the inlet are in the blocking state when the plunger pump is not pumping, abnormal flow of the power fluid between the first pressure tank 1 and the second pressure tank 2 due to the pressure difference can be prevented.

Preferably, the bottoms of the first pressure tank 1 and the second pressure tank 2 are respectively provided with a drain pipe 80, the drain pipes 80 are provided with normally closed drain valves 8, the downstream of the drain pipes 80 is connected to the collecting pipe 55, and the downstream of the collecting pipe 55 is connected with a collecting device.

When the gas-liquid mixing transportation device is stopped and maintained, the fluid or sediment and the like in the first pressure tank 1 and the second pressure tank 2 can be discharged through the drain pipe 80 and then sent to the device for treatment through the collecting pipe 55.

Preferably, the gas-liquid mixing and conveying device is further provided with a first bypass pipeline 53, an upstream end of the first bypass pipeline 53 is connected with an upstream end of the collecting and conveying pipeline 50, a downstream end of the first bypass pipeline 53 is connected to the collecting pipe 55, and the first bypass pipeline 53 is provided with a bypass check valve 531.

Therefore, when the gas-liquid mixing and conveying device stops working, the medium in the collecting and conveying pipeline 50 can enter the first bypass pipeline 53 through the collecting pipe inlet 51, and then is sent to the collecting and collecting tank through the collecting pipe 55 for treatment. The bypass check valve 531 prevents the medium in the first bypass line 53 from flowing backward, and prevents the medium flowing in the gathering line 50 from adversely affecting the well

Preferably, a second bypass line 54 is provided, a first end of said second bypass line 54 being connected to said collection tube 55, a second end of said second bypass line 54 being connected to an upstream end of said collection tube 50,

a collection valve (550) is provided on the collection pipe 55, the collection valve (550) being located on the downstream side of the first end of the second bypass line 54.

Therefore, when the gas-liquid mixing and conveying device stops working, the collecting valve is closed, and under the condition that the collecting and conveying pipeline 50 is sufficient, a medium can enter the collecting and conveying pipeline 50 from the collecting pipe inlet 51 through the first bypass pipeline 53, the collecting pipe 55 and the second bypass pipeline 54 to be conveyed, so that the influence on production caused by shutdown maintenance of the gas-liquid mixing and conveying device is avoided.

Preferably, the hydraulic pump is characterized in that liquid supplementing ports are formed at the tops of the first pressure tank 1 and the second pressure tank 2 and are used for connecting liquid supplementing equipment.

Therefore, the power fluid (for example, water) can be injected into the first pressure tank 1 and the second pressure tank 2 through the water injection device connected with the fluid supplementing pipeline 7, and the medium can be directly injected into the first pressure tank 1 and the second pressure tank 2 according to the actual production condition (when the water content in the medium is high, for example, more than 95 percent), so that the medium is layered in the tank body, and the water at the lower layer is used as the power fluid.

The second technical scheme is a gas-liquid mixing transportation method for an oil-gas field, which is characterized by comprising the following steps:

step S01 of power fluid injection: the power liquid is injected into the first pressure tank 1 and the second pressure tank 2, so that the liquid level of the power liquid is above the upper limit value, and a bidirectional pump (3) is arranged between the first pressure tank 1 and the second pressure tank 2, so that the power liquid in the first pressure tank 1 and the power liquid in the second pressure tank 2 can be transmitted in an interactive way.

Forward pumping step S03: when the level of the power fluid in the second pressure tank 2 drops to the lower limit value, the control system 4 controls the bi-directional pump 3 to reverse, so that the bi-directional pump 3 pumps the power fluid in the first pressure tank 1 into the second pressure tank 2, the negative pressure generated in the first pressure tank 1 is utilized to suck the oil and the natural gas from the upstream end of the gathering and conveying pipeline 50, and the positive pressure generated in the second pressure tank 2 pressurizes the oil and the natural gas and conveys the oil and the natural gas to the downstream end of the gathering and conveying pipeline 50.

Reverse pumping step S05: when the level of the power liquid in the first pressure tank 1 drops to the lower limit value, the control system 4 controls the bi-directional pump 3 to reverse, so that the bi-directional pump 3 pumps in the reverse direction, the power liquid in the second pressure tank 2 is pumped into the first pressure tank 1, the negative pressure generated in the second pressure tank 2 is utilized to suck the oil and the natural gas from the upstream end of the gathering and conveying pipeline 50, and the positive pressure generated in the first pressure tank 1 pressurizes the oil and the natural gas and conveys the oil and the natural gas to the downstream end of the gathering and conveying pipeline 50.

And repeating the forward pumping step S02 and the reverse pumping step S05, and controlling the bidirectional pump 3 to reverse when the liquid level of the power liquid is reduced to the lower limit value, so that the power liquid flows in the first pressure tank 1 and the second pressure tank 2 alternately, and the first pressure tank 1 and the second pressure tank 2 suck oil and natural gas from the upstream end of the gathering pipeline 50 alternately, pressurize the oil and the natural gas and then convey the oil and the natural gas to the downstream end of the gathering pipeline 50.

According to the gas-liquid mixing and conveying method of the oil-gas field, the bidirectional pump 3 is controlled to reverse when the liquid level of the power liquid in the first pressure tank 1 or the second pressure tank 2 is reduced to the lower limit value, so that the gas-liquid mixing and conveying can be carried out on the pressurization of petroleum and natural gas. Compared with the prior art, the device has the advantages that a large number of reversing electromagnetic valves are not required to be arranged, so that the cost is saved, the control is simpler, and the reliability of the device is improved.

Preferably, in the forward pumping step S02 and the reverse pumping step S05, when the level of the power fluid drops to the lower limit value, the control system 4 controls the bidirectional pump 3 to stop for a certain period of time, and the pressure difference between the first pressure tank 1 and the second pressure tank 2 drops below a threshold value, and then the reversing is performed.

Since the bidirectional pump 3 is stopped for a certain time before reversing, and the pressure difference between the first pressure tank 1 and the second pressure tank 2 is reduced below the threshold value, and then the reversing is performed, the power fluid can be reversely flowed by using the pressure difference between the first pressure tank 1 and the second pressure tank 2. After the pressure difference is reduced, the bidirectional pump 3 is controlled to pump reversely, and compared with direct reversing, the bidirectional pump 3 receives smaller resistance when reversing, and meanwhile, the conflict of different working conditions between the first pressure tank 1 and the second pressure tank 2 can be avoided.

Drawings

Fig. 1 is a structural explanatory view of a gas-liquid mixing and transporting device according to the first embodiment;

fig. 2 is a structural explanatory diagram of a gas-liquid mixing and transporting device of the second embodiment;

FIG. 3 is a control flow diagram of the gas-liquid mixing and transporting device;

FIG. 4 is an explanatory diagram of the state of the power fluid in the pressure tank before the start of the bi-directional pump;

FIG. 5 is an explanatory view of a state in the first pressure tank sucking in oil and gas from the oil and gas well, and the second pressure tank pressurizing and transporting the oil and gas downstream;

fig. 6 is an explanatory diagram of the state in the pressure tank when the bi-directional pump is switched from the forward pumping to the reverse pumping;

fig. 7 is an explanatory diagram of a state in the pressure tank when the bi-directional pump is switched from reverse pumping to forward pumping;

fig. 8 is a structural explanatory diagram of a conventional mixing device.

Detailed Description

Embodiments of the invention are described in detail below with reference to the attached drawing figures, and the following description is illustrative of the invention as claimed.

The gas-liquid mixing and conveying device is mainly used for oil-gas field equipment. The field has an oil and gas well for the production of hydrocarbon organic resources such as oil and gas from the subsurface, and an oil and gas processing terminal station for the production of finished oil and gas products that meet industry standards. And a gathering pipeline for conveying a gas-oil-water miscible medium (hereinafter referred to as a medium) extracted from the oil-gas well is arranged between the oil-gas well and the oil-gas treatment terminal station. The gas-liquid mixing and conveying device is arranged on a collecting and conveying pipeline (see the collecting and conveying pipeline 50 in fig. 1), pressurizes a gas-water-oil medium extracted from an oil-gas well and then conveys the gas-water-oil medium to an oil-gas treatment terminal station for processing into oil and natural gas products.

Example 1

Fig. 1 shows the structure of a gas-liquid mixing and transporting device.

As shown in fig. 1, the gas-liquid mixing and conveying device mainly comprises a first pressure tank 1, a second pressure tank 2, a bidirectional pump 3 and a control system 4. The first pressure tank 1 and the second pressure tank 2 are closed tanks, and as shown in the lower side of fig. 1, the lower parts of the first pressure tank 1 and the second pressure tank 2 are communicated with each other through a pump liquid pipe 31. A bi-directional pump 3 is installed in the pump liquid pipe 31. The bi-directional pump 3 in this embodiment adopts a bi-directional centrifugal pump 30, and a bi-directional rotation type oil-gas mixing pump as in patent No. 202110028351.3 can be used.

In operation, the first pressure tank 1 and the second pressure tank 2 are filled with power fluid (see fig. 4), and the power fluid in one of the first pressure tank 1 and the second medium pressure tank 2 is pumped into the other of the two pressure tanks by switching the working state of the bidirectional centrifugal pump 30, that is, the power fluid in the first pressure tank 1 can be pumped into the second pressure tank 2, and the power fluid in the second pressure tank 2 can also be pumped into the first pressure tank 1.

A first liquid level meter 61 is arranged above a connecting port of the first pressure tank 1 and the pump liquid pipe 31 and is used for measuring the liquid level of power liquid (water) in the first pressure tank 1, and a second liquid level meter 62 is arranged above a connecting port of the pump liquid pipe 31 and is also arranged on the second pressure tank 2 and is used for measuring the liquid level of power liquid (water) in the second pressure tank 2.

As shown on the left side of fig. 1, the upper portion of the first pressure tank 1 is connected to the oil and gas well side (upstream end) of the gathering line 50 through a first liquid inlet pipe 110, and the top portion is connected to the oil and gas treatment end station side (downstream end) of the gathering line 50 through a first liquid outlet pipe 120. The junction of the first inlet pipe 110 and the oil and gas well side of the gathering line 50 serves as a manifold inlet 51; the junction of the first outlet pipe 120 with the hydrocarbon processing end station side of the gathering line 5 serves as the manifold outlet 52.

The first liquid inlet pipe 110 is provided with a first one-way valve 11, which allows the medium of the oil-gas well to enter the first pressure tank 1 and limits the liquid in the first pressure tank 1 to flow out reversely. The first liquid outlet pipe 120 is provided with a third one-way valve 12, which allows the liquid in the first pressure tank 1 to flow out, and restricts the external liquid from flowing back into the first pressure tank 1.

The second pressure tank 2 and the attachment are identical to the first pressure tank 1. That is, as shown on the right side of fig. 1, the upper portion of the second pressure tank 2 is connected to the manifold inlet 51 through the second liquid inlet pipe 210, and communicates with the upstream end of the collecting line 50. The top is connected to the manifold outlet 52 by a second outlet pipe 220 in communication with the downstream end of the manifold 50. The second liquid inlet pipe 210 is provided with a second one-way valve 21, which allows the medium of the oil-gas well to enter the second pressure tank 2 and limits the liquid in the second pressure tank 2 to flow out reversely. The second liquid outlet pipe 220 is provided with a fourth check valve 22, which allows the liquid in the second pressure tank 2 to flow out, and restricts the external liquid from flowing back into the second pressure tank 2.

The control system 4 is electrically connected with the bidirectional centrifugal pump 30, the first liquid level meter 61 and the second liquid level meter 62, namely, the first liquid level meter 61 and the second liquid level meter 62 read detection values in a wired or wireless mode to obtain liquid level information of the first pressure tank 1 and the second pressure tank 2, and generates control instructions according to the liquid level information to control the working state of the bidirectional centrifugal pump 30, namely, when the liquid level in the first pressure tank 1 drops to the position (lower limit value) of the first liquid level meter 61, the bidirectional centrifugal pump 30 is controlled to change direction, and power liquid in the second pressure tank 2 is conveyed into the first pressure tank 1, so that the liquid level in the first pressure tank 1 rises. Conversely, the power liquid in the first pressure tank 1 is conveyed into the second pressure tank 2 by controlling the reversing of the bidirectional centrifugal pump 30, so that the liquid level in the second pressure tank 2 is increased.

As shown in fig. 1, the bottoms of the first pressure tank 1 and the second pressure tank 2 are respectively provided with a drain pipe 80, the drain pipe 80 is provided with a normally closed drain valve 8, the downstream of the drain pipe 80 is connected to the collecting pipe 55, and the downstream of the collecting pipe 55 is connected to the collecting tank. When the gas-liquid mixing transportation device is stopped for production and maintenance, the fluid or sediment and the like in the first pressure tank 1 and the second pressure tank 2 can be discharged through the drain pipe 80 and then sent to the collecting tank for treatment through the collecting pipe 55.

The collecting pipe 55 is provided with a collecting valve 550, and the collecting valve 550 is in a closed state in a normal operation state. As shown in the left side of fig. 1, the gas-liquid mixing apparatus is further provided with a first bypass line 53, an upstream end of the first bypass line 53 is connected to the header inlet 51, a downstream end of the first bypass line 53 is connected to the header 55, and the first bypass line 53 is provided with a bypass check valve 531.

Therefore, when the gas-liquid mixing and conveying device stops working, the medium in the collecting and conveying pipeline 50 can enter the first bypass pipeline 53 through the collecting pipe inlet 51, and then is sent to the collecting and collecting tank through the collecting pipe 55 for treatment. The bypass check valve 531 prevents the medium in the first bypass line 53 from flowing back to the oil and gas well, and prevents the medium flow in the gathering line 50 from adversely affecting the oil well.

As shown on the right side of fig. 1, the gas-liquid mixing apparatus is further provided with a second bypass line 54, a first end of the second bypass line 54 is connected to the collecting pipe 55, and a second end of the second bypass line 54 is connected to the collecting pipe outlet 52, i.e., the second bypass line 54 communicates with the upstream side of the collecting valve 550.

Therefore, the gas-liquid mixing device is stopped due to the reasons, and the gathering line 50 is not disconnected.

As shown in fig. 1, the side parts of the first pressure tank 1 and the second pressure tank 2 are respectively provided with an overhaul window and a pressure gauge 9, so that the conditions inside the tank body can be monitored in real time, and workers can conveniently enter the first pressure tank 1 and the second pressure tank 2 for overhaul.

As shown in fig. 1, fluid-filling ports are formed at the top of the first pressure tank 1 and the second pressure tank 2, and the fluid-filling ports are connected to fluid-filling equipment through fluid-filling pipes 7 to fill fluid. That is, in actual production, the power fluid (water) can be injected into the first pressure tank 1 and the second pressure tank 2 by the fluid replenishment device connected to the fluid replenishment pipe 7. Because the medium (oil and natural gas) produced by the oil and gas well is usually mixed with water, the free water in the medium can be used as an automatic power liquid compensation mechanism according to actual production conditions, namely, when the medium contains the free water after entering the pressure tank, the free water is mixed with the power liquid in the pressure tank due to gravity difference to be used as the supplement to the power liquid.

Fig. 3 shows a control flow of the gas-liquid mixing apparatus, and the control flow will be described below with reference to fig. 4 to 6. The control flow mainly comprises the following steps:

step S01 of power fluid injection: the first pressure tank 1 and the second pressure tank 2 are filled with a power fluid (water). As shown in fig. 4, in order to ensure sufficient power fluid, excessive power fluid can be directly injected, so that the first pressure tank 1 and the second pressure tank 2 are full of power fluid, and the excessive power fluid flows out from the first liquid outlet pipe 120 and the second liquid outlet pipe 220, so that the production is not affected.

In addition, an upper limit value may be set, and if the power fluid is higher than the upper limit value, the power fluid is considered to be full. The upper limit value may be set, for example, at a lower limit value, that is, at a tank internal volume between the upper limit value and the lower limit value greater than or equal to the upper limit value. Therefore, one forward or reverse pumping can fully fill the pressure tank with power liquid, and fully convey the medium entering the pressure tank downstream after being pressurized. By setting the upper limit value, for example, when the power liquid level in the first pressure tank 1 is lowered from the upper limit value to the lower limit value when the power liquid in the first pressure tank 1 is pumped to the second pressure tank 2, the power liquid pumped into the second pressure tank 2 can convey all of the oil and natural gas above the power liquid downstream (see fig. 6 and 7).

Starting step S02: when the first pressure tank 1 and the second pressure tank 2 are full of the power fluid, the control system 4 sends a command to operate the bi-directional centrifugal pump 30, and starts the bi-directional centrifugal pump to pump forward.

Forward pumping step S03: when receiving the start-up command or the reversing command, the bidirectional centrifugal pump 30 pumps the power liquid in the first pressure tank 1 into the second pressure tank 2 according to the command forward. In the forward pumping, the level of the power fluid in the first pressure tank 1 gradually decreases, and the level of the power fluid in the second pressure tank 2 gradually increases.

Fig. 5 is an explanatory diagram of a state in the pressure tank when the first pressure tank sucks in oil and gas from the oil and gas well and the second pressure tank pressurizes and conveys the oil and gas downstream.

As the power fluid in the first pressure tank 1 is pumped into the second pressure tank 2, the level of the power fluid in the first pressure tank 1 (i.e., the oil-water interface in the first pressure tank 1 in fig. 5) is lowered, so that a negative pressure is formed on the upper side of the first pressure tank 1, and under the action of the negative pressure, the medium (gas, oil, water miscible fluid) in the oil and gas well is sucked into the first pressure tank 1 through the first liquid inlet pipe 110 and the first check valve 11.

After the medium (mixed phase fluid of gas, oil and water) enters the first pressure tank 1, the gas, oil and water therein are layered by gravity, as shown in fig. 5, the upper layer is gas, the middle layer is oil, the lower layer is water, and the water in the medium is mixed into the power fluid.

Meanwhile, as the power fluid in the second pressure tank 2 increases, the medium composed of natural gas and petroleum at the top of the second pressure tank 2 is pressurized and delivered to the oil and gas treatment terminal station through the second check valve 22 and the second liquid outlet pipe 220 into the downstream section of the gathering line 50.

Fig. 6 is an explanatory diagram of the state in the pressure tank when the bi-directional pump is switched from the forward pumping to the reverse pumping.

As shown in fig. 6, when the liquid level in the first pressure tank 1 decreases and the liquid level decreases to the lower limit value position, the second pressure tank 2 is filled with the liquid, and the medium such as oil and gas is completely discharged, whereby the bidirectional centrifugal pump 30 starts the reversing operation.

Initially, only power fluid is present in the second pressure tank 2, and excess power fluid is routed to the oil and gas treatment end station via the second outlet pipe 220 and the collecting line 50 (downstream section) to be treated.

The first pressure tank liquid level judging step S04: the control system 4 determines whether the first level gauge 61 detects that the level of the power fluid in the first pressure tank 1 (i.e., the height of the oil-water interface in the first pressure tank 1 in fig. 6) falls to the position (lower limit value) of the first level gauge 61, and when it detects that the level of the power fluid falls to the position (lower limit value), the control system 4 sends a reversing instruction to the bidirectional centrifugal pump 30, and the process proceeds to step S05 to reverse the bidirectional centrifugal pump 30 and pump the power fluid reversely.

In this embodiment, the liquid level detected by the first liquid level meter 61 is set at a height higher than the inlet of the pump liquid pipe 31, so as to ensure that no oil gas passes through the pump liquid pipe 31 and the bi-directional centrifugal pump 30, and only the power liquid (water) is pumped. Because water and oil gas are difficult to dissolve mutually, the bidirectional centrifugal pump 30 is guaranteed to pump water only, and the air lock fault of the bidirectional centrifugal pump 30 is avoided.

Reverse pumping step S05: the bi-directional centrifugal pump 30 changes the pumping direction according to the reversing instruction, pumps the power liquid in the reverse direction, and pumps the power liquid in the second pressure tank 2 into the first pressure tank 1.

As the power fluid in the second pressure tank 2 is pumped into the first pressure tank 1, the level of the power fluid in the second pressure tank 2 is lowered, so that negative pressure is formed on the upper side of the second pressure tank 2, and under the action of the negative pressure, the medium (gas, oil, water miscible fluid) in the oil and gas well is sucked into the second pressure tank 2 through the second liquid inlet pipe 210 and the second check valve 21.

After the medium (gas, oil and water mixed phase fluid) enters the second pressure tank 2, the gas, oil and water therein are layered by gravity, as shown in fig. 7, the upper layer is gas, the middle layer is oil, the lower layer is water, and the water in the medium is mixed into the power fluid.

At the same time, the power fluid in the first pressure tank 1 increases, so that the top fluid (gas, oil and a part of water) in the first pressure tank 1 flows out of the first pressure tank 1 from the first outlet pipe 120 through the first check valve 12 into the gathering line 50 (downstream section) to be delivered to the oil and gas treatment end station.

Fig. 7 is an explanatory diagram of the state in the pressure tank when the bi-directional pump is switched from the reverse pumping to the forward pumping.

As shown in fig. 7, as the power fluid in the second pressure tank 2 decreases, when the level of the power fluid in the second pressure tank 2 (i.e., the oil-water interface in the second pressure tank 2 in fig. 7) decreases to the lower limit position, the first pressure tank 1 is filled with the power fluid, and all the media such as oil and gas are discharged, and the bidirectional centrifugal pump 30 starts the reversing operation.

A second pressure tank liquid level judging step S06: the control system 4 determines whether the second level gauge 62 detects that the level of the power fluid in the second pressure tank 2 (i.e., the height of the oil-water interface in the second pressure tank 2 in fig. 7) has fallen to the position (lower limit value) of the second level gauge 62. When detected, the process returns to step S03,

the control system 4 sends a reversing instruction to the bi-directional centrifugal pump 30, and the bi-directional centrifugal pump 30 changes the pumping direction according to the instruction, pumps the power liquid in the first pressure tank 1 in the forward direction, and pumps the power liquid into the second pressure tank 2. In the forward pumping, the level of the power fluid in the first pressure tank 1 gradually decreases, and the level of the power fluid in the second pressure tank 2 gradually increases.

Repeating steps S02 to S06, when the power fluid falls to the lower limit position, the control system 4 sends an instruction for changing the pumping direction, controls the bidirectional centrifugal pump 30 to change the pumping direction, enables the power fluid to flow alternately between the first pressure tank 1 and the second pressure tank 2, and allows the first pressure tank 1 and the second pressure tank 2 to suck oil and natural gas alternately from the upstream end of the gathering line 50, pressurizes the oil and natural gas and then conveys the oil and natural gas to the downstream end of the gathering line 50.

Since only the power fluid flows through the bi-directional centrifugal pump 30 in the whole process, the air lock is not caused by the entering of natural gas and petroleum components.

The gas-liquid mixing and conveying device provided by the embodiment has a simple structure, and can realize gas-liquid mixing and conveying by controlling reversing work of the bidirectional pump by using the control system 4. Compared with the prior art, on one hand, a large number of reversing electromagnetic valves do not need to be arranged, so that the cost is saved, the control complexity is reduced (consistency of actions among the electromagnetic valves does not need to be considered); on the other hand, the fault rate can be reduced, and the reliability of the device is improved.

It is noted that, since the bi-directional centrifugal pump 30 is used as the bi-directional pump, even if some bubbles are mixed into the bi-directional centrifugal pump 30, it is advantageous to automatically discharge the gas in the pump. That is, in each impeller reverse rotation process, a small amount of gas dissolved in water due to the centrifugal action of the impeller is blocked in the pump shell in the form of bubbles, and when the bidirectional centrifugal pump 30 is operated in forward rotation, the gas blocked in the pump body is reversely discharged back to the original tank along with reverse water flow, so that gas accumulation can be effectively prevented, and gas lock faults can be eliminated.

As a modification, when the level gauge (first level gauge 61, second level gauge 62) detects that the level of the power fluid in the pressure tank (first pressure tank 1, second pressure tank 2) has fallen to the lower limit value (level gauge position), the control system 4 does not immediately send a reversing instruction, but sends a stop instruction, stops pumping the bi-directional centrifugal pump 30, and after waiting for a certain time, sends a reversing instruction to the bi-directional centrifugal pump 30, and controls the bi-directional centrifugal pump 30 to change the pumping direction. The waiting time is set according to the pressure difference between the first pressure tank 1 and the second pressure tank 2, that is, when the bidirectional centrifugal pump 30 is commutated, the pressure difference between the two is reduced below the threshold value and then the two are commutated. Thus, during a stop, the pressure difference between the first pressure tank 1 and the second pressure tank (2) will cause the power fluid to flow in reverse through the bi-directional centrifugal pump 30. After the pressure difference is reduced below the threshold value, the bidirectional centrifugal pump 30 is controlled to reverse, and compared with direct reversing, when the bidirectional centrifugal pump 30 reverses, the pumping direction is consistent with the flowing direction of the power liquid, the bidirectional centrifugal pump 30 receives smaller load, and meanwhile, the conflict of different working conditions between the first pressure tank (1) and the second pressure tank (2) can be avoided.

In practical application, taking a metering station oil well 5 port of a certain oil field as an example:

before the gas-liquid mixing and conveying device provided by the embodiment is installed, the total daily medium amount of an oil well is 80 tons, the water content is 81.2 percent (including 15 tons of petroleum and 260 cubic meters of natural gas), the wellhead conveying pressure is 1.0Mpa, and the medium temperature is 32 ℃.

The gas-liquid mixing device provided by the embodiment is installed at a metering station collecting pipe near an oil well. The parameters of the gas-liquid mixing and conveying device are as follows:

the pump 3 is a bidirectional centrifugal pump, rated displacement is 7 cubic meters per hour, lift is 70 meters, rated rotating speed is 2900r/min, and variable frequency control is carried out. The upper limit of the liquid level of the first pressure tank and the liquid level of the second pressure tank are 900mm, the lower limit of the liquid level of the first pressure tank and the liquid level of the second pressure tank are 400mm, the effective volume between the upper limit and the lower limit of the liquid level is 0.15 cubic meter, the time for the liquid level to run from the upper limit to the lower limit is 72s, and the reversing is converted into 1200 times per day.

After the device runs for 30min, the inlet and outlet pressures are respectively 0.48Mpa and 1.05Mpa, the fluctuation rate is not more than 10%, and the device can stably run.

After the gas-liquid mixing and conveying device is operated, the total daily medium amount of the oil well is measured to be 82 tons, the water content is 81.2 percent (including 15.3 tons of petroleum and 310 cubic meters of natural gas), the wellhead conveying pressure is 0.48Mpa, the medium temperature is 32 ℃, namely, the wellhead pressure is reduced by 0.52Mpa, the daily oil increasing amount is 0.3 ton, the daily gas increasing amount is 50 cubic meters, the operation parameters of the device meet the design targets, and the user requirements of the oil field are met.

Example two

Fig. 2 shows another structure of the gas-liquid mixing and transporting device.

As shown in fig. 2, this embodiment is basically the same as the first embodiment except that the bi-directional pump 3 is constituted by two unidirectional pumps, which employ plunger pumps. The bottoms of the first pressure tank 1 and the second pressure tank (2) are communicated through a first pump liquid pipe 311 and a second pump liquid pipe 312, the first unidirectional pump 301 is installed in the first pump liquid pipe 311, the second unidirectional pump 302 is installed in the second pump liquid pipe 312, and the pumping directions of the first unidirectional pump 301 and the second unidirectional pump 302 are opposite. In fig. 2, the first pump fluid pipe 311 and the second pump fluid pipe 312 have a height difference therebetween, and are actually located at the same height.

The first embodiment is the same as the first embodiment, and the first unidirectional pump 301 and the second unidirectional pump 302 can be prevented from being air-locked, and the two unidirectional pumps are utilized to play a role of a bidirectional pump, so that the cost is reduced. Since the outlet and the inlet are in the blocking state when the plunger pump is not pumping, abnormal flow of the power fluid due to the pressure difference between the first pressure tank 1 and the second pressure tank 2 can be prevented.

The control of the first unidirectional pump 301 and the second unidirectional pump 302 is the same as that of the centrifugal bidirectional pump in the first embodiment, that is, the unidirectional pump being pumped is stopped, and the unidirectional pump in a stopped state is started for reversing after the power liquid in the pressure tank is stabilized or after a certain time is delayed. The specific control process is described above, and is not described in detail herein.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims.

For example, normally open service valves are provided on both sides of the centrifugal bi-directional pump 30 or the first unidirectional pump 301 and the second unidirectional pump 302, so as to isolate the centrifugal bi-directional pump 30 or the first unidirectional pump 301 and the second unidirectional pump 302, and facilitate the disassembly and the maintenance of the centrifugal bi-directional pump 30 or the first unidirectional pump 301 and the second unidirectional pump 302 by workers.

Because natural gas is easy to be mixed with petroleum and not easy to be mixed with water, the possibility of entering gas in the bidirectional pump 3 can be effectively reduced by increasing the lower limit value of the judgment liquid level, but the medium amount sucked in a single tank body is reduced, and the productivity is reduced; while lowering the lower limit value easily causes gas to enter the centrifugal bi-directional pump 30 or the first unidirectional pump 301 or the second unidirectional pump 302, the risk of airlock failure is increased, but the capacity can be increased. In actual production, the lower limit value can be adjusted by a worker according to the need, for example, the lower limit value can be adjusted by an oil field with less gas and the upper limit value can be adjusted by an oil field with more gas.

Claims (10)

1. The gas-liquid mixing and conveying device for the oil and gas field is arranged in a collecting and conveying pipeline (50) capable of mixing and conveying oil and natural gas, pressurizes the oil and the natural gas and conveys the oil and the natural gas to the downstream, and is characterized by comprising a first pressure tank (1), a second pressure tank (2), a bidirectional pump (3) and a control system (4),

the upper part of the first pressure tank (1) is provided with a first liquid inlet pipe (110), the first liquid inlet pipe (110) is communicated with the upstream end of the gathering pipeline (50), the top of the upper side of the first liquid inlet pipe (110) is provided with a first liquid outlet pipe (120), the first liquid outlet pipe (120) is communicated with the downstream end of the gathering pipeline (50),

a second liquid inlet pipe (210) is arranged at the upper part of the second pressure tank (2), the second liquid inlet pipe (210) is communicated with the upstream end of the collecting and conveying pipeline (50), a second liquid outlet pipe (220) is arranged at the top of the upper side of the second liquid inlet pipe (210), the second liquid outlet pipe (220) is communicated with the downstream end of the collecting and conveying pipeline (50),

a first one-way valve (11) and a second one-way valve (21) are respectively arranged in the first liquid inlet pipe (110) and the second liquid inlet pipe (210), the upstream petroleum and natural gas are allowed to enter the first pressure tank (1) and the second pressure tank (2) to prevent backflow,

a third one-way valve (12) and a fourth one-way valve (22) are respectively arranged in the first liquid outlet pipe (120) and the second liquid outlet pipe (220), so that petroleum and natural gas in the first pressure tank (1) and the second pressure tank (2) are allowed to enter the downstream end of the gathering and conveying pipeline (50) to prevent backflow,

the first pressure tank (1) and the second pressure tank (2) are airtight tank bodies, power fluid is respectively arranged in the first pressure tank (1) and the second pressure tank (2), the bottoms of the first pressure tank (1) and the second pressure tank (2) are communicated through a pump fluid pipe, a two-way pump (3) is arranged in the pump fluid pipe (31) and used for pumping the power fluid in the first pressure tank (1) into the second pressure tank (2) or pumping the power fluid in the second pressure tank (2) into the first pressure tank (1), when the power fluid is pumped out, negative pressure generated in the first pressure tank (1) or the second pressure tank (2) sucks petroleum and natural gas from the upstream end of the gathering pipeline (50), and meanwhile when the power fluid pump is utilized, positive pressure generated in the second pressure tank (2) or the first pressure tank (1) pressurizes the sucked petroleum and natural gas and then conveys the pumped petroleum and natural gas to the downstream end of the gathering pipeline (50),

a first liquid level meter (61) is arranged on the first pressure tank (1), a second liquid level meter (62) is arranged on the second pressure tank (2),

when the first liquid level meter (61) detects that the liquid level of the power liquid in the first pressure tank (1) is reduced to the lower limit value, the control system (4) controls the bidirectional pump (3) to pump the power liquid in the second pressure tank (2) into the first pressure tank (1), and when the second liquid level meter (62) detects that the liquid level of the power liquid in the second pressure tank (2) is reduced to the lower limit value, the control system (4) switches the pumping direction of the bidirectional pump (3) to pump the power liquid in the first pressure tank (1) into the second pressure tank (2), so that the bidirectional pump (3) can alternately convey the power liquid between the first pressure tank (1) and the second pressure tank (2).

2. A gas-liquid mixing and transporting device for oil and gas fields according to claim 1, characterized in that the pump liquid pipe is constituted by a single pump liquid pipe (31), and a bi-directional pump (3) installed in the pump liquid pipe (31) adopts a bi-directional centrifugal pump (30).

3. The gas-liquid mixing and transporting device for oil and gas fields according to claim 1, wherein,

the liquid pumping pipe is composed of a first liquid pumping pipe (311) and a second liquid pumping pipe (312),

the bidirectional pump (3) is composed of two unidirectional pumps, a first unidirectional pump (301) is installed in a first pump liquid pipe (311), a second unidirectional pump (302) is installed in a second pump liquid pipe (312), and the pumping directions of the first unidirectional pump (301) and the second unidirectional pump (302) are opposite.

4. A gas-liquid mixing transportation device for oil and gas fields according to claim 3, characterized in that the first unidirectional pump (301) and the second unidirectional pump (302) are plunger pumps.

5. A gas-liquid mixing and conveying device for oil and gas fields according to claim 2 or 4, characterized in that the bottoms of the first pressure tank (1) and the second pressure tank (2) are respectively provided with a blow-down pipe (80), the blow-down pipe (80) is provided with a normally closed blow-down valve (8), the downstream of the blow-down pipe (80) is connected to a collecting pipe (55), and the downstream of the collecting pipe (55) is connected to a collecting device.

6. A gas-liquid mixing and conveying device for oil and gas fields according to claim 5, characterized in that the gas-liquid mixing and conveying device is further provided with a first bypass line (53), the upstream end of the first bypass line (53) is connected to the upstream end of the collecting and conveying line (50), the downstream end of the first bypass line (53) is connected to the collecting pipe (55), and the first bypass line (53) is provided with a bypass check valve (531).

7. A gas-liquid mixing transportation device for oil and gas fields according to claim 6, characterized in that a second bypass line (54) is provided, a first end of the second bypass line (54) being connected to the collecting pipe (55), a second end of the second bypass line (54) being connected to the upstream end of the collecting and transportation line (50),

a collection valve (550) is provided on the collection pipe (55), the collection valve (550) being located on the downstream side of the first end of the second bypass line (54).

8. The gas-liquid mixing and conveying device for oil and gas fields according to claim 7, wherein liquid supplementing ports are formed at the tops of the first pressure tank (1) and the second pressure tank (2) and are used for connecting liquid supplementing equipment.

9. The gas-liquid mixing and conveying method for the oil-gas field is characterized by comprising the following steps of:

a power fluid injection step (S01): the power fluid is injected into the first pressure tank (1) and the second pressure tank (2), so that the liquid level of the power fluid is above the upper limit value, a bidirectional pump (3) is arranged between the first pressure tank (1) and the second pressure tank (2), and the power fluid in the first pressure tank (1) and the power fluid in the second pressure tank (2) can be transmitted in an interactive way;

forward pumping step (S03): when the liquid level of the power liquid in the second pressure tank (2) is reduced to the lower limit value, a control system (4) controls a bidirectional pump (3) to reverse, so that the bidirectional pump (3) pumps forward, the power liquid in the first pressure tank (1) is pumped into the second pressure tank (2), oil and natural gas are sucked from the upstream end of the collecting and conveying pipeline (50) by utilizing the negative pressure generated in the first pressure tank (1), the positive pressure generated in the second pressure tank (2) pressurizes the oil and the natural gas and then conveys the oil and the natural gas to the downstream end of the collecting and conveying pipeline (50),

reverse pumping step (S05): when the liquid level of the power liquid in the first pressure tank (1) is reduced to the lower limit value, the control system (4) controls the bidirectional pump (3) to reverse, so that the bidirectional pump (3) pumps the power liquid in the second pressure tank (2) into the first pressure tank (1), the negative pressure generated in the second pressure tank (2) is utilized to suck the petroleum and the natural gas from the upstream end of the gathering pipeline (50), the positive pressure generated in the first pressure tank (1) pressurizes the petroleum and the natural gas and then conveys the petroleum and the natural gas to the downstream end of the gathering pipeline (50),

and repeating the forward pumping step (S02) and the reverse pumping step (S05), and controlling the bidirectional pump (3) to reverse when the liquid level of the power liquid is reduced to a lower limit value, so that the power liquid flows in the first pressure tank (1) and the second pressure tank (2) alternately, and the first pressure tank (1) and the second pressure tank (2) suck petroleum and natural gas from the upstream end of the gathering pipeline (50) alternately, pressurize the petroleum and the natural gas and then convey the petroleum and the natural gas to the downstream end of the gathering pipeline (50).

10. The gas-liquid mixing method for oil and gas fields according to claim 9, wherein in the forward pumping step (S02) and the reverse pumping step (S05), when the level of the power fluid falls to a lower limit value, the control system (4) controls the bi-directional pump (3) to stop for a certain time, and the reversing is performed after the pressure difference between the first pressure tank (1) and the second pressure tank (2) falls below a threshold value.