A bottom water back-mixing process flow

Abstract

A bottom water reintegration process, belonging to the field of oilfield surface operations technology, includes the following steps: Wellhead fluid flows through a first heating device to be heated to a set temperature, and then enters the external overflow tank through the inlet mixing manifold. A fourth valve is installed on the inlet mixing manifold to control its on / off state. After sedimentation and separation of crude oil in the external overflow tank, under the pressure inside the external overflow tank, the crude oil enters the external buffer tank through the top connecting pipeline and the fifth valve. The associated gas in the crude oil enters the produced gas pipeline through the sixth valve and proceeds to the next process flow. This bottom water reintegration process reduces the processing difficulty of the combined station, while making full use of the temperature of the heavy oil and extra-heavy oil produced fluids to ensure that the water integration temperature reaches the design requirements. It also makes full use of the hot high-temperature separated water to heat the bottom water to reach the design temperature.

Description

Technical Field

[0001] This invention belongs to the field of surface operation technology in oil production engineering, and specifically relates to a bottom water re-mixing process. Background Technology

[0002] Currently, the heavy and extra-heavy oil gathering process at the Shuguang Oil Production Plant of Liaohe Oilfield involves the following steps: wellhead oil production process - metering and transfer station - heat treatment - external pump - combined station. However, due to the oilfield being in the mid-to-late stage of development, the crude oil has a water content as high as 70-90%, causing many inconveniences for the combined station in processing crude oil. The excessive water content mainly increases the time and dosage of the dehydration process. Furthermore, because steam injection requires high-dryness steam, while the steam injection boiler normally produces 75% dryness, the resulting high-temperature separation water is usually transported to the nearby underground oil-water blending process or to the metering and transfer station, and then pumped to the combined station for treatment. Currently, the temperature of the oil-water blending does not meet the design requirements, but to achieve the required temperature, the natural gas consumption of the water-jacketed furnace has increased. Additionally, there is a problem with the incompatibility between the imported water and the formation fluids. These issues result in excessively high crude oil production and processing costs, and also cause a significant waste of heat. Summary of the Invention

[0003] To address the aforementioned problems, this invention proposes a bottom water re-mixing process, comprising the following steps: Wellhead liquid flows through a first heating device to be heated to a set temperature, and then enters the external overflow tank through the inlet mixing manifold. A fourth valve is installed on the inlet mixing manifold to control its on / off state. After the crude oil settles and separates in the external overflow tank, under the pressure inside the external overflow tank, the crude oil enters the external buffer tank through the top connecting pipeline and the fifth valve. The associated gas in the crude oil enters the produced gas pipeline after passing through the sixth valve and proceeds to the next process flow.

[0004] Furthermore, the external mixed liquid in the external buffer tank enters the external pump via the external pipeline, and then enters the next process flow via the first flow meter.

[0005] Furthermore, the bottom height of the overflow tank is higher than the top height of the mixing tank.

[0006] Furthermore, the bottom height of the external overflow tank is higher than the top height of the external buffer tank.

[0007] Furthermore, when the oil-water interface tester installed inside the overflow tank detects that the liquid level of the bottom water is less than or equal to the minimum value of the bottom water, the electric valve closes to prevent crude oil from entering the water mixing tank.

[0008] Furthermore, after the externally transported mixed liquid has settled and passed the required standards in the externally transported overflow tank, it flows through the bottom water output pipeline, passes through the electric valve, then through the second flow meter, and finally flows to the top of the water mixing tank. The hot-injected high-temperature separated water is injected into the water mixing tank through the hot-injected high-temperature separated water pipeline and the second valve. After mixing with the externally transported bottom water, it is heated by the second heating device installed in the water mixing tank and then enters the next process flow through the mixing pipeline.

[0009] Furthermore, the solution enters the next process flow via a water mixing pump and a third flow meter installed on the mixing pipeline.

[0010] Furthermore, the hot-injected high-temperature separated water is injected into the standby tank through the hot-injected high-temperature separated water pipeline and the first valve. The hot-injected high-temperature separated water in the standby tank is then injected into the mixing pipeline through the third valve and the standby tank pipeline.

[0011] The beneficial effects of this invention are as follows: This invention provides a process flow for bottom water reinjection in oilfields to reduce the processing difficulty of the joint station, while making full use of the temperature of the heavy oil and extra-heavy oil produced liquids to make the water injection temperature reach the design requirements, and making full use of the hot high-temperature separated water to heat the bottom water to make it reach the design temperature. Attached Figure Description

[0012] Figure 1 This is a flow chart of the bottom water re-mixing process of the present invention.

[0013] The attached diagram is labeled as follows: 1. First valve, 2. Second valve, 3. Third valve, 4. Fourth valve, 5. Fifth valve, 6. Sixth valve, 7. First flow meter, 8. Second flow meter, 9. Third flow meter, 10. First heating device, 11. Second heating device, 12. External pump, 13. Water mixing pump, 14. Electric valve, 15. Oil-water interface tester, 16. Spare tank, 17. Water mixing tank, 18. External overflow tank, 19. External buffer tank, 20. Hot injection high-temperature separation water pipeline, 21. Inlet mixing manifold, 22. Top connecting pipeline of external buffer tank, 23. Produced gas pipeline, 24. Spare tank pipeline, 25. Liquid mixing pipeline, 26. Bottom water output pipeline, 27. External pipeline. Detailed Implementation

[0014] A bottom water re-mixing process, such as Figure 1As shown, the steps are as follows: The wellhead liquid flows through the first heating device 10 and is heated to the set temperature. It then enters the external overflow tank 18 through the inlet mixing manifold 21. A fourth valve 4 is installed on the inlet mixing manifold 21 to control its opening and closing. After the crude oil settles in the external overflow tank 18, it is separated. Under the pressure inside the external overflow tank 18, the crude oil enters the external buffer tank 19 through the top connecting pipeline 22 and the fifth valve 5. The associated gas in the crude oil enters the production gas pipeline 23 after passing through the sixth valve 6 and enters the next process flow. The associated gas in the crude oil is a substance that is separated from the gas in the crude oil due to the pressure reduction during crude oil production.

[0015] The external mixed liquid in the external buffer tank 19 enters the external pump 12 through the external pipeline 27, and then enters the next process flow through the first flow meter 7.

[0016] The bottom height of the overflow tank 18 is higher than the top height of the water mixing tank 17.

[0017] The bottom height of the external overflow tank 18 is higher than the top height of the external buffer tank 19.

[0018] When the oil-water interface tester 15 installed inside the overflow tank 18 detects that the liquid level of the bottom water is less than or equal to the minimum value of the bottom water, the electric valve 14 closes to prevent crude oil from entering the water mixing tank 17.

[0019] The external mixed liquid, after being settled in the external overflow tank 18, flows through the bottom water output pipeline 26, through the electric valve 14, further through the second flow meter 8, and further to the top of the water mixing tank 17. The hot-injected high-temperature separated water is injected into the water mixing tank 17 through the hot-injected high-temperature separated water pipeline 20 and the second valve 2, and after being mixed with the external bottom water, it is heated by the second heating device 11 set in the water mixing tank 17 and then enters the next process flow through the liquid mixing pipeline 25.

[0020] The solution enters the next process flow via the water mixing pump 13 and the third flow meter 9 installed on the mixing pipeline 25.

[0021] Among them, the hot-injected high-temperature separated water is injected into the standby tank 16 through the hot-injected high-temperature separated water pipeline 20 and the first valve 1 in sequence. The hot-injected high-temperature separated water in the standby tank 16 is then injected into the mixing pipeline 25 through the third valve 3 and the standby tank pipeline 24.

[0022] The first heating device 10 is connected to one end of the inlet mixing manifold 21, which is equipped with a fourth valve 4. The other end of the inlet mixing manifold 21 is connected to the outlet overflow tank 18, which is connected to the outlet buffer tank 19 via the top connecting pipeline 22. The outlet overflow tank 18 is equipped with an oil-water interface monitor. The upper end of the outlet buffer tank 19 is connected to the output gas pipeline 23, which is equipped with a valve 6. The bottom of the outlet buffer tank 19 is connected to the outlet pipeline 27. The front end of the outlet pump 12 is connected to the outlet pipeline 27, and the rear end of the outlet pump 12 is connected to the first flow meter 7. The hot injection high-temperature separation water pipeline 20 is connected to the second valve. After connection 2, it is connected to the top of the water mixing tank 17. The hot injection high-temperature separation water pipeline 20 is connected to the first valve 1 and then connected to the spare tank 16 through the spare tank pipeline 24. The lower part of the spare tank 16 is connected to the valve 3 and then connected to the liquid mixing pipeline 25 through the spare pipeline 24. The liquid mixing pipeline 25 is connected to the water mixing pump 13. The water mixing pump 13 is connected to the third flow meter 9 and then enters the next process. The water mixing tank 17 is equipped with a second heating device 11 to ensure that the water mixing temperature meets the water mixing requirements. One end of the bottom water output pipeline 26 is connected to the bottom of the external overflow tank 18 and then connected to the electric valve 14. The electric valve 14 is connected to the flow meter 8 through a fixed connection and then connected to the top of the water mixing tank 17.

[0023] During operation, the wellhead fluid is heated to the design temperature by the first heating device 10 and then enters the external overflow tank 18 through the inlet mixing manifold 21 and the fourth valve 4. After settling and separation in the external overflow tank 18, the crude oil enters the buffer tank 19 through the top connecting pipeline 22 of the external buffer tank due to the internal pressure of the external overflow tank 18. The associated gas in the crude oil enters the production gas pipeline 23 through the valve 6 and enters the next process flow.

[0024] The external mixed liquid enters the external pump 12 via the external pipeline 12 and then enters the next process flow via the first flow meter 7;

[0025] The bottom height of the overflow tank 18 is higher than the top height of the water mixing tank 17 and the buffer tank 19. When the oil-water interface tester 15 detects that the liquid level of the bottom water is less than or equal to the minimum value of the bottom water, the electric valve 14 is closed to prevent crude oil from entering the water mixing tank 17.

[0026] After the external mixed liquid settles and passes the test in the external overflow tank 18, it enters the electric valve 14 through the bottom water output pipeline 26, flows further through the second flow meter 8, and then enters the top of the water mixing tank 17. After the hot-injected high-temperature separated water mixes with the external bottom water, it is heated and passes the test in the second heating device 11, and then enters the next process flow through the liquid mixing pipeline 25.

[0027] The working principle of this invention is as follows: After the produced liquid entering the metering and transfer station is initially separated in the buffer tank, the crude oil overflows from the top of the external overflow tank to the buffer tank, and is further transported to the joint station by the external pump. The produced water is mixed with the high-temperature separated water of the hot injection, heated and qualified, and then water is added to the oil well through the water injection process to facilitate the production of crude oil.

[0028] The function of the first valve 1 is to control whether the hot-injected high-temperature separated water flows into the spare tank 16;

[0029] The function of the second valve 2 is to control whether the hot-injected high-temperature separated water flows into the water mixing tank 17;

[0030] The function of the third valve 3 is to control whether the hot-injected high-temperature separation water in the spare tank 16 flows into the mixing pipeline 25;

[0031] The function of the fourth valve 4 is to control whether the wellhead fluid flows into the external overflow tank 18.

[0032] The function of the fifth valve 5 is to control whether the crude oil in the external overflow tank 18 flows into the external buffer tank 19;

[0033] The function of the sixth valve 6 is to control whether the gas is discharged through the output gas pipeline 23 to the next process flow.

[0034] The function of the first flow meter 7 is to measure the flow rate of the liquid in the external transmission pipeline 27;

[0035] The function of the second flow meter 8 is to measure the flow rate of the liquid in the bottom water output pipeline 26;

[0036] The function of the third flow meter 9 is to measure the flow rate of the liquid in the mixing pipeline 25;

[0037] The function of the first heating device 10 is to heat the wellhead liquid;

[0038] The function of the second heating device 11 is to heat the liquid in the water mixing tank 17;

[0039] The function of the external pump 12 is to extract the liquid from the external buffer tank 19;

[0040] The function of the water mixing pump 13 is to extract the liquid from the water mixing tank 17;

[0041] The function of electric valve 14 is to control whether the bottom water in the overflow tank 18 flows into the mixing tank 17;

[0042] The function of the oil-water interface tester 15 is to monitor the liquid level of crude oil in the external overflow tank 18;

[0043] The purpose of the spare tank 16 is to store hot-injection high-temperature separated water for later use;

[0044] The water mixing tank 17 ensures that the temperature of the water inside the water mixing tank meets the design temperature requirements.

[0045] The overflow tank 18 performs oil-water separation, and the floating oil on top is transported to the overflow buffer tank 19 by the upward pressure of the water below the floating oil. The pipeline below the fourth valve 4 needs to extend below the middle of the overflow tank 18, and its function is to achieve preliminary oil-water separation during the floating process of the incoming liquid.

[0046] The external buffer tank 19 ensures a certain liquid level, which can guarantee the safe operation of the external pump 12.

[0047] The function of the hot-injection high-temperature separation water pipeline 20 is to transport hot-injection high-temperature separation water;

[0048] The function of the inlet mixing manifold 21 is to transport wellhead fluid to the external overflow tank 18;

[0049] The function of the top connecting pipeline 22 of the external output buffer tank is to transport the external mixed liquid in the external output overflow tank 18 to the external output buffer tank 19.

[0050] The function of the output gas pipeline 23 is to discharge the gas in the external buffer tank 19 to the next process flow;

[0051] The function of the standby tank pipeline 24 is to transport the hot-injected high-temperature separated water in the standby tank 16 to the mixing pipeline 25, where it is mixed with the liquid in the mixing pipeline 25.

[0052] The function of the mixing pipeline 25 is to transport the bottom water in the external overflow tank 18 to the next process flow;

[0053] The function of the bottom water output pipeline 26 is to transport the mixed liquid in the mixing tank 17 to the mixing tank 17;

[0054] The function of the export pipeline 27 is to transport the export mixture in the export buffer tank 19 to the next process flow.

[0055] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A bottom water re-mixing process, characterized in that, The steps are as follows: The wellhead liquid flows through the first heating device (10) and is heated to the set temperature. It enters the external overflow tank (18) through the inlet mixed transport manifold (21). The inlet mixed transport manifold (21) is equipped with a fourth valve (4) to control its opening and closing. After the crude oil settles in the external overflow tank (18), it is separated. Under the pressure inside the external overflow tank (18), the crude oil enters the external buffer tank (19) through the top connecting pipeline (22) and the fifth valve (5). The associated gas in the crude oil enters the production gas pipeline (23) after passing through the sixth valve (6) and enters the next process flow. The external mixed liquid in the external buffer tank (19) enters the external pump (12) through the external pipeline (27), and enters the next process flow through the first flow meter (7); The bottom height of the overflow tank (18) is higher than the top height of the water mixing tank (17); The bottom height of the external overflow tank (18) is higher than the top height of the external buffer tank (19); When the oil-water interface tester (15) installed inside the overflow tank (18) detects that the liquid level of the bottom water is less than or equal to the minimum value of the bottom water, the electric valve (14) closes to prevent crude oil from entering the water mixing tank (17). After the external mixed liquid settles and passes the test in the external overflow tank (18), it flows through the bottom water output pipeline (26) and electric valve (14), then through the second flow meter (8), and then to the top of the water mixing tank (17). The hot-injected high-temperature separated water is injected into the water mixing tank (17) through the hot-injected high-temperature separated water pipeline (20) and the second valve (2) and mixed with the external bottom water. After being heated and qualified by the second heating device (11) set in the water mixing tank (17), it enters the next process flow through the liquid mixing pipeline (25). The solution enters the next process flow via the water mixing pump (13) and the third flow meter (9) installed on the mixing pipeline (25); The hot-injected high-temperature separated water is injected into the standby tank (16) through the hot-injected high-temperature separated water pipeline (20) and the first valve (1). The hot-injected high-temperature separated water in the standby tank (16) is then injected into the mixing pipeline (25) through the third valve (3) and the standby tank pipeline (24).

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