Carbon dioxide fracturing cold pump full-closed recovery system and recovery method

Abstract

The application provides a carbon dioxide fracturing cold pump full-closed recovery system and a recovery method, and the system comprises a liquid CO2 recovery device, a CO2 pressure regulating pry, a liquid CO2 storage tank, a CO2 pressure regulating pry and a fracturing vehicle which are sequentially connected through pipelines along the CO2 flow direction, wherein the liquid CO2 recovery device is connected with the fracturing vehicle through a pipeline to recover the remaining liquid CO2 injected by the fracturing vehicle into an oil and gas well; the liquid CO2 recovery device is also connected with the pressure regulating pry through a pipeline to deliver the recovered liquid CO2 to the pressure regulating pry; the pressure regulating pry can deliver the liquid CO2 to the fracturing vehicle; and the CO2 pressure regulating pry can compress and cool gaseous CO2 to form liquid CO2 and deliver the liquid CO2 to the liquid CO2 storage tank. The recovery system can deliver CO2 at the discharge end of the fracturing pump vehicle to the recovery device at the CO2 fracturing site, then to the pressure regulating pry, and finally to the fracturing pump vehicle, so that full-closed CO2 discharge recovery is realized.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field exploration and development, and more specifically, to a fully enclosed recovery system and method for a carbon dioxide fracturing cold pump. Background Technology

[0002] With the continuous increase in carbon dioxide fracturing workload, carbon dioxide, white dry ice, is still being emitted directly into the air during the on-site carbon dioxide fracturing cold pump, venting, and depressurization processes. This affects the visibility of on-site personnel and poses a risk of asphyxiation. Therefore, in response to the current situation of direct carbon dioxide emission during the carbon dioxide fracturing cold pump, single-vehicle venting, and post-fracturing depressurization processes, research is being conducted on a fully enclosed recovery technology for carbon dioxide fracturing cold pumps.

[0003] This invention belongs to the field of oil and gas field exploration and development, and is applicable to carbon dioxide fracturing construction of oil and gas wells. It mainly consists of a carbon dioxide cold pump recovery device and a pressure regulating device, which can realize fully enclosed carbon dioxide emission recovery technology. Summary of the Invention

[0004] The purpose of this invention is to address at least one of the aforementioned deficiencies in the prior art. For example, one objective of this invention is to provide a fully enclosed recovery system for a carbon dioxide fracturing cold pump; another objective of this invention is to provide a fully enclosed recovery method for a carbon dioxide fracturing cold pump.

[0005] To achieve the above objectives, the present invention provides a fully enclosed recovery system for a carbon dioxide fracturing cold pump, characterized in that the system comprises: a liquid CO2 recovery device and a CO2 pressure regulating skid, and a liquid CO2 storage tank, a CO2 pressurizing skid and a fracturing truck connected sequentially along the CO2 flow direction via pipelines;

[0006] The liquid CO2 recovery unit is connected to the fracturing truck via pipeline to recover the remaining liquid CO2 injected into the oil and gas well by the fracturing truck. The liquid CO2 recovery unit is also connected to the CO2 booster skid via pipeline to transport the recovered gaseous CO2 to the CO2 booster skid. The CO2 booster skid can transport liquid CO2 to the fracturing truck. The CO2 pressure regulating skid can compress and cool the gaseous CO2 to form liquid CO2 and transport it to the liquid CO2 storage tank.

[0007] Alternatively, the liquid CO2 recovery device consists of a carbon dioxide manifold, an electric flat valve, an electric actuator, an electric plug valve, a power control cabinet, an explosion-proof cable tray, a tee, and a union flange. The working pressure of the liquid CO2 recovery device is not higher than 2000 psi.

[0008] Optionally, the working pressure of the carbon dioxide manifold is set to 10,000 to 15,000 psi, and after installing a union flange on the carbon dioxide manifold, the working pressure is set to 1,000 to 2,000 psi, the performance level is PR1, and the temperature level is -46 to 121°C.

[0009] Alternatively, the carbon dioxide manifold base is fixed, and the electric flat valves installed on the carbon dioxide manifold all have a concealed stem and a circular valve cavity structure.

[0010] Optionally, the carbon dioxide manifold has a hardness of 197-235 HBW after heat treatment, a minimum average impact value of ≥27 J for low-temperature impact test specimens at -46℃, a minimum impact value of ≥13.5 J for a single specimen, a coating thickness of 0.12-0.15 mm, and a coating hardness greater than 1100 HV.

[0011] Alternatively, the electric actuator of the liquid CO2 recovery device may be equipped with an explosion-proof motor insulation.

[0012] Alternatively, the liquid CO2 recovery device may be heat-treated to a hardness of 32–40 HRC, which meets the requirements of NACE MR0175.

[0013] Alternatively, the CO2 pressure regulating skid consists of a compressor, a delivery pump, a control system, a tee, and a buffer tank.

[0014] Another aspect of the present invention provides a fully enclosed recovery method for a carbon dioxide fracturing cold pump, wherein the method employs the aforementioned fully enclosed recovery system for a carbon dioxide fracturing cold pump.

[0015] The recycling method includes a first process and a second process:

[0016] The first process includes: injecting liquid CO2 into the oil and gas well using a fracturing truck, wherein 90-95% of the liquid CO2 is injected into the wellhead, and the remaining liquid CO2 is recovered through a liquid CO2 recovery device; the recovered liquid CO2 is pressurized by a booster skid and then re-enters the fracturing truck, forming the first cycle recovery process;

[0017] The second process includes: using a pressure regulating skid to compress and cool the gaseous CO2 discharged from the pressure boosting skid to form liquid CO2, which is then stored in a liquid CO2 storage tank. The liquid CO2 storage tank then transports the gaseous CO2 to the CO2 pressure regulating skid, where it is converted into liquid CO2 through pressure regulation, thus forming the second recycling process.

[0018] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0019] (1) The carbon dioxide fracturing cold pump fully enclosed recovery system of the present invention can realize the fully enclosed carbon dioxide emission recovery;

[0020] (2) The fully enclosed recovery system of the carbon dioxide fracturing cold pump of the present invention can transport CO2 from the discharge end of the fracturing pump truck to the recovery device at the CO2 fracturing site, and then transport it to the pressure regulating skid to supply the fracturing pump truck. Attached Figure Description

[0021] The above and other objects and / or features of the present invention will become clearer from the following description taken in conjunction with the accompanying drawings, in which:

[0022] Figure 1 A schematic diagram of the process connection of the fully enclosed recovery system of the carbon dioxide fracturing cold pump of the present invention is shown.

[0023] Figure 2 A front view schematic diagram of the carbon dioxide recovery device of the present invention is shown.

[0024] Figure 3 A top view schematic diagram of the carbon dioxide recovery device of the present invention is shown.

[0025] Explanation of key figure labels:

[0026] 1-Liquid CO2 storage tank; 2-CO2 pressurization skid; 3-Liquid CO2 recovery device; 31-Electric flat valve; 32-Electrical control cabinet; 4-Fracturing truck; 5-CO2 pressure regulating skid; 6-Wellhead;

[0027] a1 - First low-pressure pipeline; a2 - First low-pressure pipeline; a3 - Third low-pressure pipeline; a4 - Fourth low-pressure pipeline; a5 - Fifth low-pressure pipeline;

[0028] b1 - First high-pressure pipeline, b2 - Second high-pressure pipeline;

[0029] c1 - Dedicated vapor phase pipeline. Detailed Implementation

[0030] In the following description, a fully enclosed recovery system and recovery method for a carbon dioxide fracturing cold pump according to the present invention will be explained in detail with reference to exemplary embodiments.

[0031] Exemplary Example 1

[0032] This exemplary embodiment provides a fully enclosed recovery system for a carbon dioxide fracturing cold pump, characterized in that the system includes: a liquid CO2 recovery device and a CO2 pressure regulating skid, and a liquid CO2 storage tank, a CO2 pressurizing skid and a fracturing truck connected sequentially along the CO2 flow direction via pipelines;

[0033] The liquid CO2 recovery unit is connected to the fracturing truck via pipeline to recover the remaining liquid CO2 injected into the oil and gas well by the fracturing truck. The liquid CO2 recovery unit is also connected to the CO2 booster skid via pipeline to transport the recovered liquid CO2 to the CO2 booster skid. The CO2 booster skid can transport liquid CO2 to the fracturing truck. The CO2 pressure regulating skid can compress and cool gaseous CO2 to form liquid CO2 and transport it to the liquid CO2 storage tank.

[0034] In this embodiment, the liquid CO2 recovery device consists of a carbon dioxide manifold, an electric flat valve, an electric actuator, an electric plug valve, a power control cabinet, an explosion-proof cable tray, a tee, and a union flange. The working pressure of the liquid CO2 recovery device is no higher than 2000 psi.

[0035] In this embodiment, the working pressure of the carbon dioxide manifold is set to 10,000 to 15,000 psi. After installing a union flange on the carbon dioxide manifold, the working pressure is set to 1,000 to 2,000 psi. The performance level is PR1, and the temperature level is -46 to 121°C.

[0036] In this embodiment, the carbon dioxide manifold base is fixed, and the electric flat valves installed on the carbon dioxide manifold all have a concealed stem and a circular valve cavity structure.

[0037] In this embodiment, the carbon dioxide manifold has a hardness of 197-235 HBW after heat treatment, a minimum average impact value of ≥27 J for low-temperature impact test specimens at -46℃, a minimum impact value of ≥13.5 J for a single specimen, a coating thickness of 0.12-0.15 mm, and a coating hardness greater than 1100 HV.

[0038] In this embodiment, the electric actuator of the liquid CO2 recovery device is insulated with an explosion-proof motor.

[0039] In this embodiment, the heat treatment hardness of the liquid CO2 recovery device is 32-40 HRC, which meets the requirements of NACE MR0175.

[0040] In this embodiment, the CO2 pressure regulating skid consists of a compressor, a delivery pump, a control system, a three-way valve, and a buffer tank.

[0041] Exemplary Example 2

[0042] This exemplary embodiment provides a fully enclosed recovery method for a carbon dioxide fracturing cold pump, wherein the method employs the fully enclosed recovery system for a carbon dioxide fracturing cold pump described in Exemplary Embodiment 1.

[0043] In this embodiment, as Figure 1 As shown, the entire process A of the recycling method includes a first process B and a second process C:

[0044] The first process B includes: injecting liquid CO2 into oil and gas wells using a fracturing truck, wherein 90-95% of the liquid CO2 is injected into the wellhead, and the remaining liquid CO2 is recovered through a liquid CO2 recovery device; the recovered liquid CO2 is pressurized by a booster skid and then re-enters the fracturing truck, forming the first cycle recovery process;

[0045] The second process C includes: using a pressure regulating skid to compress and cool the gaseous CO2 discharged from the pressure boosting skid to form liquid CO2, which is then stored in a liquid CO2 storage tank. The liquid CO2 storage tank can transport the existing gaseous CO2 to the CO2 pressure regulating skid, where it is converted into liquid CO2 through pressure regulation, thus forming the second recycling process.

[0046] To better understand the exemplary embodiments described above, further explanation is provided below with specific examples.

[0047] Example

[0048] like Figure 1 As shown, the characteristics of a fully enclosed recovery technology for a carbon dioxide fracturing cold pump are:

[0049] according to Figure 1 Install and connect the CO2 pressure regulating skid, cold pump unit, and piping according to the diagram on site, following the numerical order and arrow direction;

[0050] The liquid CO2 storage tank 1 is connected to the CO2 booster skid 2 via a first low-pressure pipeline a1. The CO2 booster skid 2 is connected to the fracturing truck 4 via a second low-pressure pipeline a2. The fracturing truck 4 is connected to the wellhead 6 via a second high-pressure pipeline b2. The fracturing truck 4 is connected to the liquid CO2 recovery device 3 via a first high-pressure pipeline b1. The liquid CO2 recovery device 3 is connected to the CO2 booster skid 2 via a third low-pressure pipeline a3. The CO2 booster skid 2 is connected to the CO2 pressure regulating skid 5 via a fourth low-pressure pipeline a4. The CO2 pressure regulating skid 5 is connected to the liquid CO2 storage tank 1 via a fifth low-pressure pipeline a5, forming a closed loop. The liquid CO2 storage tank 1 can also transport the existing gaseous CO2 to the CO2 pressure regulating skid 5 via a dedicated gas phase pipeline c1, where it is converted into liquid CO2 through pressure regulation.

[0051] Connect the high-pressure and low-pressure pipelines to the CO2 recovery unit. The high-pressure pipeline is the carbon dioxide inlet, and the low-pressure pipeline is the carbon dioxide outlet.

[0052] After connection, power on the unit to preheat the recovery device, and then use the liquid CO2 recovery device for recovery; the liquid CO2 recovery device is as follows: Figure 2 and Figure 3 As shown, it includes a carbon dioxide manifold, an electric flat valve 31, an electric actuator, an electric plug valve, a power control cabinet 32, an explosion-proof cable tray, a tee, and a union flange.

[0053] After carbon dioxide is recovered, it is recycled into a storage tank for storage or reuse via a CO2 pressurization skid and a pressure regulating skid, thus completing the fully enclosed carbon dioxide recovery process.

[0054] Although the present invention has been described above in conjunction with exemplary embodiments and accompanying drawings, those skilled in the art should understand that various modifications can be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. A fully enclosed recovery system for a carbon dioxide fracturing cold pump, characterized in that, The system includes: a liquid CO2 recovery device and a CO2 pressure regulating skid, and a liquid CO2 storage tank, a CO2 pressurization skid, and a fracturing truck connected sequentially along the CO2 flow direction via pipelines. The liquid CO2 recovery unit is connected to the fracturing truck via pipeline to recover the remaining liquid CO2 injected into the oil and gas well by the fracturing truck; the liquid CO2 recovery unit is also connected to the CO2 booster skid via pipeline to transport the recovered gaseous CO2 to the CO2 booster skid. The CO2 booster skid can deliver liquid CO2 to the fracturing truck; The CO2 pressure regulating skid can compress and cool gaseous CO2 to form liquid CO2, which is then transported to a liquid CO2 storage tank.

2. The fully enclosed recovery system for carbon dioxide fracturing cold pumps according to claim 1, characterized in that, The liquid CO2 recovery device consists of a carbon dioxide manifold, an electric flat valve, an electric actuator, an electric plug valve, a power control cabinet, an explosion-proof cable tray, a tee, and a union flange. The working pressure of the liquid CO2 recovery device is no higher than 2000 psi.

3. The fully enclosed recovery system for carbon dioxide fracturing cold pumps according to claim 2, characterized in that, The working pressure of the carbon dioxide manifold is set to 10,000 to 15,000 psi. After installing a union flange on the carbon dioxide manifold, the working pressure is set to 1,000 to 2,000 psi. The performance level is PR1 and the temperature level is -46 to 121°C.

4. The fully enclosed recovery system for carbon dioxide fracturing cold pumps according to claim 2, characterized in that, The carbon dioxide manifold base is fixed, and the electric flat valves installed on the carbon dioxide manifold all have a concealed stem and a circular valve cavity structure.

5. The fully enclosed recovery system for carbon dioxide fracturing cold pumps according to claim 2, characterized in that, The carbon dioxide manifold has a hardness of 197-235 HBW after heat treatment. The minimum average impact value of the low-temperature impact test specimen at -46℃ is ≥27J, and the minimum impact value of a single specimen is ≥13.5J. The coating thickness is 0.12-0.15mm, and the coating hardness is greater than 1100HV.

6. The fully enclosed recovery system for carbon dioxide fracturing cold pumps according to claim 2, characterized in that, The electric actuator of the liquid CO2 recovery device is insulated with an explosion-proof motor.

7. The fully enclosed recovery system for carbon dioxide fracturing cold pumps according to claim 1, characterized in that, The liquid CO2 recovery device has a heat treatment hardness of 32-40 HRC, which meets the requirements of NACE MR0175.

8. The fully enclosed recovery system for carbon dioxide fracturing cold pumps according to claim 1, characterized in that, The CO2 pressure regulating skid consists of a compressor, a delivery pump, a control system, a tee, and a buffer tank.

9. A fully enclosed recovery method for a carbon dioxide fracturing cold pump, characterized in that, The method employs the fully enclosed carbon dioxide fracturing cold pump recovery system as described in any one of claims 1-8; the method includes a first process and a second process: The first process includes: injecting liquid CO2 into the oil and gas well using a fracturing truck, wherein 90-95% of the liquid CO2 is injected into the wellhead, and the remaining liquid CO2 is recovered through a liquid CO2 recovery device; the recovered liquid CO2 is pressurized by a booster skid and then re-enters the fracturing truck, forming the first cycle recovery process; The second process includes: using a pressure regulating skid to compress and cool the gaseous CO2 discharged from the pressure boosting skid to form liquid CO2, which is then stored in a liquid CO2 storage tank; the liquid CO2 storage tank then transports the gaseous CO2 to the CO2 pressure regulating skid, where it is converted into liquid CO2 through pressure regulation, thus forming the second recycling process.

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