Shale oil produced water deoiling and decarbonizing integrated device

Abstract

The utility model relates to the technical field of shale oil produced water treatment, and particularly discloses a shale oil produced water deoiling and decarburizing integrated device which comprises a water treatment container, an oil tank, a gas-liquid dissolving system and a gas stripping tower, a first-stage air flotation cavity, a second-stage air flotation cavity and a gas stripping tower buffer cavity are arranged in the water treatment container, and the first-stage air flotation cavity and the second-stage air flotation cavity are arranged in the gas stripping tower buffer cavity. The water treatment container is connected with a floating oil collecting pipe and an interstage water outlet pipe, the first-stage air flotation cavity, the second-stage air flotation cavity and the air stripping tower buffer cavity are respectively communicated with the oil tank through the floating oil collecting pipe, and the interstage water outlet pipe penetrates into the bottom of the water treatment container to enable one end of the interstage water outlet pipe to be communicated with the first-stage air flotation cavity and the other end of the interstage water outlet pipe to be communicated with the second-stage air flotation cavity; the gas stripping tower is located at the top of the water treatment container and communicated with the gas stripping tower buffer cavity, the water treatment container is connected with a liquid inlet pipe through a flange bolt, and the liquid inlet pipe is communicated with the first-stage air floatation cavity. And the dehydration and decarbonization effects of the produced water are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of shale oil produced water treatment, in particular to an integrated device for oil removal and carbon dioxide removal from shale oil produced water. Background Technique

[0002] Domestic oil fields have gradually started to exploit unconventional oil - shale oil. Shale oil refers to the petroleum resources contained in shale - dominated shale formations, which have different compositions and properties compared with conventional petroleum. Shale oil belongs to unconventional oil reservoirs, and the main characteristic of unconventional oil reservoirs is that the reservoir porosity and permeability are extremely low. Due to its extremely low porosity and permeability, the well production using conventional methods is extremely low, and the development value is relatively low. With the continuous progress of development technology, shale oil needs to be produced by horizontal wells combined with hydraulic fracturing. In order to improve the fracturing effect, carbon dioxide needs to be added as a pre - fluid, and the addition of carbon dioxide results in a large amount of carbon dioxide in the actual produced water.

[0003] Currently, the produced water after shale oil dehydration is mainly used for pressure - drive reuse. According to geological requirements, the pressure - drive recycled water needs to meet the requirements of oil and carbon dioxide content in the water. The traditional technology uses conventional large - tank sedimentation and atmospheric flotation for oil removal from the produced water, and the removal of carbon dioxide mainly uses adding alkaline agents for neutralization reactions or purification gas stripping processes. After adding alkali for neutralization, the disposal of waste is difficult, and there is also a problem that the treatment of VOCs in the open - type process does not meet the standards. The two processes of flotation and gas stripping have problems such as many single - body devices, large floor area, and repeated auxiliary supporting systems.

[0004] Therefore, it is necessary to propose an integrated device for oil removal and carbon dioxide removal from shale oil produced water to realize the organic coupling of flotation and gas stripping, greatly reduce the equipment size, share the supporting floating - oil collection and sewage discharge systems, improve the integration level of the device, and improve the dehydration and carbon dioxide removal effects of the produced water. Content of the Utility Model

[0005] The purpose of the utility model is to solve the problems of large floor area and high investment brought by two independent processes and equipment for traditional oil removal and carbon dioxide removal, as well as the problem of poor dehydration and carbon dioxide removal effects. Now, an integrated device for oil removal and carbon dioxide removal from shale oil produced water is provided.

[0006] The technical solution of the utility model is as follows:

[0007] Integrated device for removing oil and decarbonizing produced water from shale oil, comprising a water treatment container, an oil tank, a dissolved gas liquid system and a stripping tower. The water treatment container is provided with a first-stage air flotation chamber, a second-stage air flotation chamber and a stripping tower buffer chamber. The water treatment container is connected with an oil collecting floating oil pipe and an inter-stage water outlet pipe. The oil collecting floating oil pipe communicates the first-stage air flotation chamber, the second-stage air flotation chamber and the stripping tower buffer chamber with the oil tank respectively. The inter-stage water outlet pipe penetrates into the bottom of the water treatment container so that one end of the inter-stage water outlet pipe communicates with the first-stage air flotation chamber, and the other end of the inter-stage water outlet pipe communicates with the second-stage air flotation chamber;

[0008] The stripping tower is located at the top of the water treatment container and communicates with the stripping tower buffer chamber. The water treatment container is connected with a liquid inlet pipe through flange bolts, and the liquid inlet pipe communicates with the first-stage air flotation chamber;

[0009] A stripping release device is installed at the bottom of the stripping tower buffer chamber. A liquid distribution pipe is arranged at the top of the stripping tower, and packing is arranged in the middle of the stripping tower. An inlet water pipe for the stripping tower is arranged on the gas tank. One end of the inlet water pipe for the stripping tower communicates with the second-stage air flotation chamber, and the other end of the inlet water pipe for the stripping tower passes through the stripping tower and communicates with the liquid distribution pipe. An outlet gas pipe is connected to the top of the stripping tower through flanges and bolts.

[0010] Furthermore, air flotation contact tanks are installed in both the first-stage air flotation chamber and the second-stage air flotation chamber;

[0011] The top of the air flotation contact tank in the first-stage air flotation chamber is open, and its bottom communicates with the liquid inlet pipe;

[0012] The top of the air flotation contact tank in the second-stage air flotation chamber is open, and its bottom communicates with the inter-stage water outlet pipe located in the second-stage air flotation chamber.

[0013] Furthermore, the dissolved gas liquid system includes a dissolved gas pump. The output end of the dissolved gas pump is connected with a bubble sieve, and the input end of the dissolved gas pump is connected with a purified water outlet pipe and a purified gas inlet pipe. The purified water outlet pipe communicates with the stripping tower buffer chamber, the purified gas inlet pipe communicates with the stripping release device, and the output end of the bubble sieve is respectively communicated with the liquid inlet pipe, the inter-stage water outlet pipe and the purified gas inlet pipe.

[0014] Furthermore, a liquid level regulating valve is installed on the purified water outlet pipe.

[0015] Furthermore, a vent opening is provided on the stripping tower.

[0016] Furthermore, the air flotation contact tank is funnel-shaped, and a dissolved gas liquid release device is installed at its bottom.

[0017] Furthermore, a first partition board and a second partition board are provided in the water treatment container. Both the first partition board and the second partition board are vertically arranged. The first partition board separates the first-stage air flotation chamber and the second-stage air flotation chamber, and the second partition board separates the second-stage air flotation chamber and the stripping tower buffer chamber.

[0018] The integrated device for removing oil and decarbonizing shale oil produced water of the present utility model has the first-stage air flotation chamber and the second-stage air flotation chamber cooperating with each other. The shale oil produced water is mixed with the dissolved air liquid through the liquid inlet pipe and introduced from the bottom of the first-stage air flotation chamber. The inter-stage water outlet pipe penetrates into the bottom of the water treatment container to connect the first-stage air flotation chamber and the second-stage air flotation chamber, enabling the liquid at the bottom of the first-stage air flotation chamber to enter the second-stage air flotation chamber. Using the principle of microbubble air flotation, in the first-stage air flotation chamber and the second-stage air flotation chamber, the oil floats on the liquid surface and the water is below the oil. As the oil liquid in the first-stage air flotation chamber and the second-stage air flotation chamber increases, the floating oil liquid will enter the floating oil collecting pipe located at the top of the water treatment container and then enter the oil tank to achieve the collection of oil. At the same time, the dissolved air liquid uses purified gas, and there is a gas-liquid mass transfer effect during the release process, which can simultaneously achieve the primary decarbonization effect. The remaining liquid after oil removal in the second-stage air flotation chamber will enter the air stripping tower through the air stripping tower water inlet pipe and then enter the packing. The air stripping tower is located at the top of the air stripping tower buffer chamber. The air stripping release device in the air stripping tower buffer chamber will release purified gas, that is, decarbonized natural gas. The purified gas will enter the air stripping tower buffer chamber through the air stripping release device, and the purified natural gas is released through the air stripping release device. When the produced water and the purified natural gas pass through the packing position, gas-liquid mass transfer can occur. At a certain temperature and equilibrium state, the solubility of a gas in a liquid is proportional to the equilibrium partial pressure of the gas. Due to the entry of the purified natural gas, the equilibrium partial pressure of carbon dioxide is reduced, so the solubility of carbon dioxide in water is reduced, and the carbon-containing natural gas is discharged from the gas phase space and enters the subsequent natural gas purification system through the outlet pipe, thereby realizing the two functions of removing oil and decarbonizing shale oil produced water. Compared with the traditional technology, this technical solution replaces the two independent processes of air flotation and air stripping, which have problems such as many single devices, large floor area, and repeated auxiliary supporting systems., and improves the dehydration and decarbonization effect of the produced water. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural reference diagram of the present utility model.

[0020] Reference numerals: 1, water treatment container; 3, dissolved air liquid system; 4, air stripping tower; 5, first-stage air flotation chamber; 6, second-stage air flotation chamber; 7, air stripping tower buffer chamber; 8, floating oil collecting pipe; 9, inter-stage water outlet pipe; 10, liquid inlet pipe; 11, air stripping release device; 12, liquid distribution pipe; 13, packing; 14, air stripping tower water inlet pipe; 15, outlet pipe; 16, air flotation contact tank; 17, dissolved air pump; 18, bubble sieve; 19, purified water outlet pipe; 20, purified gas inlet pipe; 22, liquid level regulating valve; 23, vent port; 24, dissolved air liquid release device; 25, first partition; 26, second partition. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] In order to make the technical means, technical features, utility model purpose and technical effects achieved by the present utility model easy to understand, the present utility model will be further described below with reference to specific illustrations.

[0022] Embodiment 1:

[0023] As Figure 1 shown, this embodiment provides an integrated device for removing oil and decarbonizing shale oil produced water, including a water treatment container 1, and also including a dissolved gas liquid system 3 and a stripping tower 4. A first-stage air flotation chamber 5, a second-stage air flotation chamber 6 and a stripping tower buffer chamber 7 are provided inside the water treatment container 1. A floating oil collection pipe 8 and an inter-stage water outlet pipe 9 are connected to the water treatment container 1 through flanges and bolts. The floating oil collection pipe 8 is respectively communicated with the first-stage air flotation chamber 5, the second-stage air flotation chamber 6 and the stripping tower buffer chamber 7. The inter-stage water outlet pipe 9 penetrates into the bottom of the water treatment container 1 so that one end thereof is communicated with the first-stage air flotation chamber 5 and the other end is communicated with the second-stage air flotation chamber 6;

[0024] The stripping tower 4 is located at the top of the water treatment container 1 and is communicated with the stripping tower buffer chamber 7. The stripping tower buffer chamber 7 shares a pressure vessel with the first-stage air flotation chamber 5 and the second-stage air flotation chamber 6. A liquid inlet pipe 10 is connected to the water treatment container 1 through flanges and bolts. The liquid inlet pipe 10 is communicated with the first-stage air flotation chamber 5;

[0025] A stripping release device 11 is installed at the bottom inside the stripping tower buffer chamber 7. A liquid distribution pipe 12 is provided at the top inside the stripping tower 4. Packing 13 is provided in the middle of the stripping tower 4. A stripping tower water inlet pipe 14 is provided on the gas tank. One end of the stripping tower water inlet pipe 14 is communicated with the second-stage air flotation chamber 6, and the other end of the stripping tower water inlet pipe 14 passes through the stripping tower 4 and is communicated with the liquid distribution pipe 12. An air outlet pipe 15 is connected to the top of the stripping tower 4 through flanges and bolts. The air outlet pipe 15 can discharge the mixed gas of carbon dioxide and natural gas in the produced water into the subsequent treatment system.

[0026] Preferably, air flotation contact tanks 16 are installed in both the first-stage air flotation chamber 5 and the second-stage air flotation chamber 6. For the air flotation contact tank 16 in the first-stage air flotation chamber 5, its top is open and its bottom is communicated with the liquid inlet pipe 10. For the air flotation contact tank 16 in the second-stage air flotation chamber 6, its top is open and its bottom is communicated with the inter-stage water outlet pipe 9 located in the second-stage air flotation chamber 6. Preferably, the dissolved air liquid system 3 includes a dissolved air pump 17. The output end of the dissolved air pump 17 is connected with a bubble sieve 18. The input end of the dissolved air pump 17 is connected with a purified water outlet pipe 19 and a purified gas inlet pipe 20. The purified water outlet pipe 19 is communicated with the air-lift tower buffer chamber 7, and the purified gas inlet pipe 20 is communicated with the air-lift release device 11. The output end of the bubble sieve 18 is respectively communicated with the liquid inlet pipe 10, the inter-stage water outlet pipe 9 and the purified gas inlet pipe 20. The dissolved air pump 17 and the bubble sieve 18 cooperate to input the dissolved air liquid into the liquid inlet pipe 10 and the inter-stage water outlet pipe 9, and enter the first-stage air flotation chamber 5 and the second-stage air flotation chamber 6 together with the produced water. Due to the existence of the air flotation contact tank 16, when the dissolved air liquid and the produced water enter the first-stage air flotation chamber 5 and the second-stage air flotation chamber 6, they first enter the air flotation contact tank 16, and then overflow from the top to the external first-stage air flotation chamber 5 and the second-stage air flotation chamber 6. This process provides time for bubbles to adhere to particulate impurities and emulsions in the produced water to float to the liquid surface, and also provides time for natural gas to dissolve in the produced water, improving the filtration effect of oil.

[0027] Preferably, a liquid level regulating valve 22 is installed on the purified water outlet pipe 19, and the liquid level regulating valve 22 facilitates the discharge of purified water.

[0028] Preferably, an air vent 23 is provided on the air-lift tower 4 to adjust the air pressure in the air-lift tower 4.

[0029] Preferably, the air flotation contact tank 16 is funnel-shaped, and a dissolved air liquid release device 24 is installed at its bottom.

[0030] Preferably, a first partition plate 25 and a second partition plate 26 are welded in the water treatment container 1. The first partition plate 25 and the second partition plate 26 are both vertically placed. The first partition plate 25 separates the first-stage air flotation chamber 5 and the second-stage air flotation chamber 6, and the second partition plate 26 separates the second-stage air flotation chamber 6 and the air-lift tower buffer chamber 7.

[0031] During operation, the first-stage air flotation chamber 5 and the second-stage air flotation chamber 6 cooperate with each other. The shale oil produced water is introduced from the bottom of the first-stage air flotation chamber 5 through the liquid inlet pipe 10. The inter-stage water outlet pipe 9 penetrates into the bottom of the water treatment container 1 to connect the first-stage air flotation chamber 5 and the second-stage air flotation chamber 6, enabling the liquid at the bottom of the first-stage air flotation chamber 5 to enter the second-stage air flotation chamber 6. Using the microbubble principle, in the first-stage air flotation chamber 5 and the second-stage air flotation chamber 6, the oil floats on the liquid surface and the water is below the oil. As the oil liquid in the first-stage air flotation chamber 5 and the second-stage air flotation chamber 6 increases, the oil liquid will enter the floating oil collection pipe 8 located at the top of the water treatment container 1, and the floating oil collection pipe 8 outputs the oil for collection. The remaining liquid in the second-stage air flotation chamber 6 will enter the air stripping tower 4 through the air stripping tower water inlet pipe 14 and then enter the packing 13. The air stripping tower 4 is located at the top of the air stripping tower buffer chamber 7. The air stripping release device 11 in the air stripping tower buffer chamber 7 will release the water dissolved with natural gas, that is, the dissolved gas liquid. The dissolved gas liquid will enter the air stripping tower buffer chamber 7 through the air stripping release device 11, and the purified natural gas will be released through the air stripping release device 11. The produced water and the purified natural gas can be exchanged when passing through the packing 13. At a certain temperature and equilibrium state, the solubility of a gas in a liquid is proportional to the equilibrium partial pressure of the gas. Due to the entry of the purified natural gas, the equilibrium partial pressure of carbon dioxide is reduced. Therefore, the solubility of carbon dioxide in water is reduced and it is discharged from the gas phase space through the outlet pipe 15 and enters the subsequent natural gas purification system, thereby realizing the two functions of oil removal and carbon dioxide removal from the shale oil produced water. Compared with the traditional technology, this technical solution replaces the two independent processes of air flotation and air stripping, which have problems such as many individual devices, large floor area, and duplication of auxiliary supporting systems, and improves the dehydration and decarbonization effects of the produced water.

[0032] The above is only a preferred embodiment of the present invention and is not intended to limit the scope of implementation of the present invention. That is, all equivalent changes and modifications made according to the content of the patent application scope of the present invention shall fall within the technical scope of the present invention.

Claims

1. An integrated device for removing oil and carbon from produced water of shale oil, comprising a water treatment container (1), characterized in that: It also comprises a gas-liquid dissolving system (3) and an air stripping tower (4); a first-stage air flotation chamber (5), a second-stage air flotation chamber (6) and an air stripping tower buffer chamber (7) are provided in the water treatment container (1); an oil collecting pipe (8) and an interstage water outlet pipe (9) are connected to the water treatment container (1); the oil collecting pipe (8) connects the first-stage air flotation chamber (5), the second-stage air flotation chamber (6) and the air stripping tower buffer chamber (7) to the oil tank (2) respectively; the interstage water outlet pipe (9) penetrates the bottom of the water treatment container (1); one end of the interstage water outlet pipe (9) is connected to the first-stage air flotation chamber (5), and the other end of the interstage water outlet pipe (9) is connected to the second-stage air flotation chamber (6); The air stripping tower (4) is located at the top of the water treatment container (1) and is in communication with the air stripping tower buffer chamber (7); the air stripping tower buffer chamber (7) is in communication with a clean water outlet pipe (19); the water treatment container (1) is connected with a liquid inlet pipe (10); and the liquid inlet pipe (10) is in communication with the first-stage air flotation chamber (5); A gas stripping releaser (11) is installed at the bottom of the gas stripping tower buffer chamber (7), a liquid distribution pipe (12) is provided at the top of the gas stripping tower (4), a filler (13) is provided in the middle of the gas stripping tower (4), a gas stripping tower water inlet pipe (14) is provided on the gas tank, one end of the gas stripping tower water inlet pipe (14) is connected to the second-stage air flotation chamber (6), the other end of the gas stripping tower water inlet pipe (14) passes through the gas stripping tower (4) and is connected to the liquid distribution pipe (12), and the top of the gas stripping tower (4) is connected to an air outlet pipe (15).

2. The integrated device for removing oil and carbon from produced water of shale oil according to claim 1, characterized in that: An air flotation contact tank (16) is installed in both the first-stage air flotation chamber (5) and the second-stage air flotation chamber (6); The top of the air flotation contact tank (16) in the first-stage air flotation chamber (5) is open, and the bottom thereof is connected to the liquid inlet pipe (10); The top of the air flotation contact tank (16) in the second-stage air flotation chamber (6) is open, and the bottom thereof is connected to the inter-stage water outlet pipe (9) located in the second-stage air flotation chamber (6).

3. The integrated device for removing oil and carbon from produced water of shale oil according to claim 2, characterized in that: The gas-liquid system (3) comprises a gas-dissolving pump (17), the output end of the gas-dissolving pump (17) is connected to a bubble filter (18), the input end of the gas-dissolving pump (17) is connected to a clean water outlet pipe (19) and a purified gas inlet pipe (20), the purified gas inlet pipe (20) is respectively connected to the gas-dissolving pump (17) and the gas lift releaser (11), and the output end of the bubble filter (18) is respectively connected to a liquid inlet pipe (10), an interstage water outlet pipe (9) and a purified gas inlet pipe (20).

4. The integrated device for removing oil and carbon from produced water of shale oil according to claim 3, characterized in that: A liquid level regulating valve (22) is installed on the purified water outlet pipe (19).

5. The integrated device for removing oil and carbon from produced water of shale oil according to claim 1, characterized in that: The stripping tower (4) is provided with a vent (23).

6. The integrated device for removing oil and carbon from produced water of shale oil according to claim 2, characterized in that: The air flotation contact tank (16) is funnel-shaped, and a dissolved gas liquid releaser (24) is installed at the bottom.

7. The integrated device for removing oil and carbon from produced water of shale oil according to claim 1, characterized in that: A first partition (25) and a second partition (26) are provided in the water treatment container (1); the first partition (25) and the second partition (26) are both placed vertically; the first partition (25) separates the first-stage air flotation chamber (5) from the second-stage air flotation chamber (6); and the second partition (26) separates the second-stage air flotation chamber (6) from the air stripping tower buffer chamber (7).

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