Sand liquid pumping system

Abstract

The utility model relates to the technical field of oil and gas exploitation equipment, and discloses a sand-liquid pumping system which comprises a sand-liquid mixing device, a first plunger pump, a second plunger pump and a pressure exchange device, an outlet of the sand-liquid mixing device is connected with a first inlet of the pressure exchange device, and a first outlet of the pressure exchange device is used for being connected with a liquid tank; an inlet of the first plunger pump and an inlet of the second plunger pump are used for being connected with a liquid tank, an outlet of the first plunger pump is connected with a second inlet of the pressure exchange device, and a second outlet of the pressure exchange device is used for being connected with a workplace. The pressure exchange device can selectively control the pipeline between the first outlet of the pressure exchange device and the liquid tank or the pipeline between the outlet of the first plunger pump and the second inlet of the pressure exchange device to be communicated, the outlet of the second plunger pump is used for being connected with a workplace, and the boost pressure of the first plunger pump is larger than that of the second plunger pump. Abrasion and erosion of the plunger pump can be reduced, and reliability of a fracturing operation system is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to oil and gas exploitation equipment technical field, concretely relates to a sand liquid pumping system. BACKGROUND

[0002] In the development of oil and gas resources, fracturing is often used to increase oil and gas production. During fracturing operation, proppants (such as quartz sand and ceramic sand, which are particulate materials capable of supporting fractures in the formation) and temporary blocking agents (which can temporarily block larger fractures to facilitate the development of new fractures) are usually added. When these particulate materials flow through the plunger pump, they can cause erosion of the seals and cavities inside the plunger pump. Sometimes, larger temporary blocking agents can also cause the seals of the pump to jam. Large-scale fracturing operations are long-lasting and require a large amount of sand, such as a single fracturing operation that lasts for about an hour or so, which requires the addition of 2000 cubic meters of fracturing fluid containing about 200 tons of proppants. Temporary blocking agents are sometimes added during the fracturing operation. After several hours of operation, the seals will be damaged.

[0003] In the prior art, all the liquid output by the high-pressure plunger pump enters the pressure booster device, which results in low efficiency and is not suitable for the condition of pumping liquid alone (in some cases, it is necessary to pump liquid without proppants into the well for displacement, etc.). If liquid is pumped, the sand mixing device needs to work continuously to provide clean water, which poses a high safety risk. High-pressure liquid has no overflow channel, which can easily cause pressure buildup. Once the system fails, there will be no liquid supply to the wellhead, which can cause proppants and other materials to settle and block the wellbore. SUMMARY

[0004] The utility model aims at least to solve the technical problem of proppants, temporary blocking agents, and the erosion of the plunger pump and the high-pressure manifold through which they flow, as well as the settlement and blockage of proppants and other materials in the wellbore in the prior art.

[0005] To solve the above technical problems, the utility model provides a sand liquid pumping system, which comprises a sand liquid mixing device, a first plunger pump, a second plunger pump, and a pressure exchange device. The outlet of the sand liquid mixing device is connected to the first inlet of the pressure exchange device. The first outlet of the pressure exchange device is used to connect to a liquid tank. The inlet of the first plunger pump and the inlet of the second plunger pump are used to connect to the liquid tank. The outlet of the first plunger pump is connected to the second inlet of the pressure exchange device. The second outlet of the pressure exchange device is used to connect to a work site. The pressure exchange device can selectively control the conduction of the pipeline between the first outlet of the pressure exchange device and the liquid tank or the pipeline between the outlet of the first plunger pump and the second inlet of the pressure exchange device. The outlet of the second plunger pump is used to connect to the work site. The pressurization pressure of the first plunger pump is greater than that of the second plunger pump.

[0006] In some embodiments, the outlet of the first plunger pump is connected to the second inlet of the pressure exchange device through a first high-pressure manifold, the second outlet of the pressure exchange device is connected to the work site through a second high-pressure manifold, and the outlet of the second plunger pump is connected to the second high-pressure manifold.

[0007] In some embodiments, the pressure exchange device comprises a booster device, a first outlet of the booster device is connected to the liquid tank through a first pipeline, and an outlet of the first plunger pump is connected to a second inlet of the booster device through a second pipeline,

[0008] A first control valve is arranged on the first pipeline close to the first outlet, a second control valve is arranged on the second pipeline close to the second inlet, and the first control valve and the second control valve are selectively opened.

[0009] In some embodiments, the first control valve and the second control valve are respectively independent control valves; or

[0010] The first control valve and the second control valve constitute an integrated three-way valve, the first outlet of the booster device and the second inlet of the booster device are the same interface, a first interface of the three-way valve is connected to the first outlet of the booster device, a second interface of the three-way valve is used to be connected to the liquid tank, and a third interface of the three-way valve is connected to the outlet pipeline of the first plunger pump.

[0011] In some embodiments, the first control valve and the second control valve are at least one of a stop valve, a plug valve, a throttle valve, a gate valve, a butterfly valve, and a ball valve.

[0012] In some embodiments, the pressure exchange device comprises a booster cylinder and a third control valve, the booster cylinder is provided with the first inlet and the second outlet, a booster cavity of the booster cylinder is provided with the first outlet and the second inlet, the first outlet is connected to a first passage of the third control valve, the second inlet is connected to a second passage of the third control valve, the first passage is further used to be connected to the liquid tank, and the second passage is further connected to the outlet of the first plunger pump,

[0013] The booster cylinder comprises a piston and a piston rod, the piston is arranged in the booster cavity, and the third control valve selectively controls the first passage or the second passage to be conducted according to the movement position of the piston in the booster cavity.

[0014] In some embodiments, the first position sensor and the second position sensor for monitoring the position of the piston are arranged on the supercharging cylinder, and the first position sensor and the second position sensor are arranged on the left and right sides of the supercharging cavity along the movement direction of the piston, and the first position sensor and the second position sensor are connected with the third control valve.

[0015] In some embodiments, a one-way valve is arranged on the pipeline connected with the first outlet and the pipeline connected with the second inlet, and the one-way valve is of a swing type, a swim bladder type or a valve body and valve seat structure type.

[0016] In some embodiments, a sand liquid supercharging pump is arranged on the pipeline between the outlet of the sand liquid mixing device and the first inlet of the pressure exchange device, and the output flow of the first plunger pump is greater than the output flow of the sand liquid supercharging pump.

[0017] In some embodiments, a pressure sensor is arranged on the outlet pipeline of the sand liquid supercharging pump, the first plunger pump and the second plunger pump, respectively.

[0018] A flow meter is further arranged on the outlet pipeline of the sand liquid supercharging pump.

[0019] The sand liquid pumping system provided by the embodiment of the utility model is arranged to include a sand liquid mixing device, a first plunger pump, a second plunger pump and a pressure exchange device, the outlet of the sand liquid mixing device is connected with the first inlet of the pressure exchange device, the first outlet of the pressure exchange device is connected with a liquid tank, the outlet of the first plunger pump is connected with the second inlet of the pressure exchange device, the second outlet of the pressure exchange device is used for connecting a work site, the pressure exchange device can selectively control the pipeline between the first outlet of the pressure exchange device and the liquid tank or the pipeline between the outlet of the first plunger pump and the second inlet of the pressure exchange device to be conducted, the outlet of the second plunger pump is used for connecting the work site, the supercharging pressure of the first plunger pump is greater than the supercharging pressure of the second plunger pump, the pressure exchange of a high-pressure cleaning liquid and a liquid containing a proppant can be realized, the proppant liquid flowing through the high-pressure plunger pump is effectively avoided, and the abrasion and erosion of the plunger pump are reduced; meanwhile, part of the high-pressure liquid is directly pumped into a wellbore through the second plunger pump, the convenience of pumping clean water alone can be ensured, and when the pressure exchange device fails, high-pressure liquid can still be continuously pumped into the wellbore, well blockage caused by the settlement of the proppant in the wellbore is avoided, and the reliability of the entire fracturing operation system is improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0021] Figure 1 Structure schematic view of a sand liquid pumping system according to an embodiment of the present application;

[0022] Figure 2 Structure schematic view of another sand liquid pumping system according to an embodiment of the present application.

[0023] Reference signs:

[0024] 1 - sand liquid mixing device, 11 - sand liquid booster pump; 2 - first plunger pump; 3 - second plunger pump; 4 - pressure exchange device, 401 - first inlet, 402 - first outlet, 403 - second inlet, 404 - second outlet, 41 - booster device, 42 - first control valve, 43 - second control valve, 44 - one-way valve, 45 - booster cylinder, 451 - booster cavity, 452 - piston, 453 - piston rod, 46 - third control valve, 461 - first passage, 462 - second passage; 5 - liquid tank, 51 - liquid supply pump; 61 - first high-pressure manifold, 62 - second high-pressure manifold; 71 - first pipeline, 72 - second pipeline; 81 - first position sensor, 82 - second position sensor; 20 - work site. DETAILED DESCRIPTION

[0025] The various aspects and features of the present application will be described hereinafter with reference to the accompanying drawings.

[0026] It should be understood that various modifications can be made to the embodiments described herein. Therefore, the above description should not be taken as limiting, but merely as an example of the embodiments. Other modifications within the scope and spirit of the present application will occur to those skilled in the art.

[0027] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present application and, together with the general description of the present application given above, and the detailed description of the embodiments given below, serve to explain the principles of the present application.

[0028] These and other characteristics of the present application will become apparent from the following description of the preferred forms given, by way of non-limiting example, with reference to the attached drawings.

[0029] It should also be understood that, while the present application has been described in terms of specific embodiments, it is merely so as to provide an enabling description for the embodiments of the application. One skilled in the art will readily recognize many other ways to implement the present application. Accordingly, the scope of the present application is defined only by reference to the following claims.

[0030] The above and other aspects, features, and advantages of the present application will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate

[0031] Embodiments of the present application are described herein with reference to the accompanying drawings; however, various changes and modifications can be applied to the illustrated and described embodiments, and equivalents should be covered by the present application. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application, as claimed.

[0032] This description can use the phrases "in an embodiment," "in another embodiment," "in yet another embodiment," or "in other embodiments," which can refer to one or more embodiments of the application.

[0033] Figure 1 and Figure 2 A structural schematic diagram of a sand-liquid pumping system according to an embodiment of the present application is shown. As shown in Figure 1 and Figure 2 A sand-liquid pumping system according to an embodiment of the present application includes a sand-liquid mixing device 1, a first plunger pump 2, a second plunger pump 3, and a pressure exchange device 4. The outlet of the sand-liquid mixing device 1 is connected to the first inlet 401 of the pressure exchange device 4, and the first outlet 402 of the pressure exchange device 4 is used to be connected to a liquid tank 5. The inlet of the first plunger pump 2 and the inlet of the second plunger pump 3 are used to be connected to the liquid tank 5, the outlet of the first plunger pump 2 is connected to the second inlet 403 of the pressure exchange device 4, and the second outlet 404 of the pressure exchange device 4 is used to be connected to a work site 20. The pressure exchange device 4 can selectively control the conduction of the pipeline between the first outlet 402 of the pressure exchange device 4 and the liquid tank 5 or the pipeline between the outlet of the first plunger pump 2 and the second inlet 403 of the pressure exchange device 4. The outlet of the second plunger pump 3 is used to be connected to the work site 20, and the boost pressure of the first plunger pump 2 is greater than that of the second plunger pump 3.

[0034] Specifically, a sand liquid booster pump 11 is arranged on a pipeline between the outlet of the sand liquid mixing device 1 and the first inlet 401 of the pressure exchange device 4, and the sand liquid booster pump 11 is arranged close to the outlet of the sand liquid mixing device 1. The sand liquid mixing device 1 and the sand liquid booster pump 11 jointly constitute a sand mixing system.

[0035] The sand liquid mixing device 1 can be a mixing and stirring tank, a jet mixer, a stirring pump or other elements with mixing function, and can mix liquid and proppant, for example, the volume ratio of sand and liquid is 5%-100%, or water is added to the proppant so that the volume ratio of sand and liquid is 1:1 to 4:1, to realize a high-concentration sand mixing process. The sand liquid booster pump 11 can deliver the mixed sand at high pressure to the pressure exchange device 4. The liquid output by the sand liquid mixing device 1 is a proppant-containing liquid.

[0036] The liquid tank 5 is connected with the inlet of the first plunger pump 2 and the inlet of the second plunger pump 3, and can supply liquid to the first plunger pump 2 and the second plunger pump 3. The high-pressure liquid output by the first plunger pump 2 enters the pressure exchange device 4 through the second inlet 403 of the pressure exchange device 4, and after pressure exchange with the sand liquid delivered by the sand liquid mixing device 1, the high-pressure liquid flows out from the second outlet 404 and is delivered into the wellbore; the sand liquid flows out from the first outlet 402 and is delivered into the liquid tank 5. The high-pressure liquid output by the first plunger pump 2 is a high-pressure cleaning liquid (a liquid for oilfield process without proppant or only containing trace impurities).

[0037] In the embodiment, the pressure exchange device 4 can realize pressure exchange of the high-pressure cleaning liquid and the proppant-containing liquid, and through selective conduction of corresponding pipelines, different liquids can be delivered to different positions, so as to avoid the proppant-containing liquid flowing through the high-pressure plunger pump and reduce the abrasion and erosion of the plunger pump, for example, the damage of the liquid end, the valve body and the valve seat of the plunger pump is reduced.

[0038] The first plunger pump 2 after pressure exchange by the pressure exchange device 4 only pumps the fluid without proppant or temporary plugging agent, or only contains a small amount of impurity particles, such as less than 1% of the high-pressure liquid, which can increase the service life of the first plunger pump 2 and the pipeline by more than 1 times. In addition, in the embodiment, the power fluid of the pressure exchange device 4 comes from the first plunger pump 2, not hydraulic oil, etc., and a small amount of liquid mixing is allowed during liquid energy exchange, reducing system failure caused by hydraulic oil leakage. In addition, in the embodiment, part of the high-pressure liquid is directly pumped into the wellbore by the second plunger pump 3, which can ensure the convenience of pumping clean water alone, and can still have high-pressure liquid continuously pumped into the wellbore when the pressure exchange device 4 fails, avoiding well plugging caused by proppant settlement in the wellbore, and improving the reliability of the entire fracturing operation system. The boost pressure of the first plunger pump 2 is set to be slightly greater than the boost pressure of the second plunger pump 3, which can overcome the flow resistance of the clean liquid and high-concentration sand liquid in the pressure exchange device 4, the flow resistance of the one-way valve, etc., further avoid the proppant liquid flowing through the first plunger pump 2, and reduce the erosion of the plunger pump.

[0039] The work site 20 can be an oil and gas wellbore (referred to as wellbore) for oil and gas fracturing operation, and the outlet of the first plunger pump 2 (after the pressure exchange device 4) and the outlet of the second plunger pump 3 can be connected to the wellhead of the wellbore through pipelines. The work site 20 can also be a work site in other fields, for example, the plunger pump can be used for conveying ore slurry in mine exploitation. The specific application scenario of the work site 20 is not specifically limited by the present application. In the embodiment, the wellbore for oil and gas fracturing operation is taken as the work site 20, and the sand liquid pumping system is described. In some embodiments, as shown in FIGS. Figure 1 and Figure 2 The outlet of the first plunger pump 2 is connected to the second inlet 403 of the pressure exchange device 4 through the first high-pressure manifold 61, the second outlet 404 of the pressure exchange device 4 is connected to the work site 20 through the second high-pressure manifold 62, and the outlet of the second plunger pump 3 is connected to the second high-pressure manifold 62.

[0040] The high-pressure liquid output by the first plunger pump 2 is delivered to the pressure exchange device 4 through the first high-pressure manifold 61 for pressure exchange, and the high-pressure clean liquid output after the pressure exchange device 4 enters the second high-pressure manifold 62. The clean liquid output by the second plunger pump 3 enters the second high-pressure manifold 62 and is combined with the high-pressure clean liquid output by the pressure exchange device 4, and the combined clean liquid is delivered to the wellbore through the pipeline. The high-pressure liquid output by the boost device 41 enters the high-pressure manifold and is combined with the clean liquid output by the plunger pump, and then mixed and delivered to the wellbore in the pipeline.

[0041] The first high-pressure manifold 61 and the second high-pressure manifold 62 ensure the reliability of the delivery pipeline of the plunger pump 2, and also facilitate the effective mixing of the cleaning liquid from the first plunger pump 2 and the second plunger pump 3 through the second high-pressure manifold 62. In this embodiment, the outlet pipeline of the plunger pump and the inlet pipeline of the work site 20 are set as high-pressure manifolds to facilitate the delivery of high-pressure liquids ≥175MPa and ensure the reliability of liquid delivery. The inner wall of the high-pressure manifold can be provided with a wear-resistant and corrosion-resistant layer to improve the service life of the high-pressure manifold.

[0042] In some embodiments, such as Figure 1 As shown, the pressure exchange device 4 includes a pressure boosting device 41. The first outlet 402 of the pressure boosting device 41 is connected to the liquid tank 5 via a first pipeline 71, and the outlet of the first plunger pump 2 is connected to the second inlet 403 of the pressure boosting device 41 via a second pipeline 72.

[0043] A first control valve 42 is provided on the first pipeline 71 near the first outlet 402, and a second control valve 43 is provided on the second pipeline 72 near the second inlet 403. The first control valve 42 and the second control valve 43 are selectively opened.

[0044] When the first control valve 42 is opened and the second control valve 43 is closed, the sand-liquid booster pump 11 delivers the sand-liquid mixed by the sand-liquid mixing device 1 to the cavity of the booster device 41. The original liquid in the booster device 41 is returned to the liquid tank 5 or the liquid supply pump 51 through a one-way valve or other control.

[0045] Liquid tank 5 can supply liquid to sand-liquid mixing device 1. Liquid tank 5 is connected to the inlet of first plunger pump 2 and the inlet of second plunger pump 3 through liquid supply pump 51, and can supply liquid to first plunger pump 2 and second plunger pump 3. To ensure a certain liquid supply pressure, the pumping pressure of liquid supply pump 51 is set to ≥0.4MPa.

[0046] When the second control valve 43 is opened and the first control valve 42 is closed, the high-pressure liquid output by the first plunger pump 2 enters the booster device 41 through the second control valve 43, thereby boosting the low-pressure liquid in the cavity and outputting it. The boosted high-pressure clean liquid enters the second high-pressure manifold 62 and then flows into the wellbore.

[0047] At relatively large sand slurry flow rates (e.g., 5m³ / h) 3When the high-pressure pumping is required (e.g., the pumping rate is higher than 1000 L / min), a larger number of first plunger pumps 2 and a larger number of pressure boosting devices 41 can be provided to deliver the pressure boosted liquid to the second high-pressure manifold 62; when only the pressure boosted liquid is required, only the second plunger pump 3 can be used to pump the high-pressure cleaning liquid to the second high-pressure manifold 62. For example, in the embodiment, there are two first plunger pumps 2, one second plunger pump 3, and two pressure boosting devices 41, and each pressure boosting device 41 is provided with a first control valve 42 and a second control valve 43. The first plunger pump 2 and the second plunger pump 3 can also be high-pressure centrifugal pumps, or a combination of plunger pumps and high-pressure centrifugal pumps.

[0048] In some embodiments, the first control valve 42 and the second control valve 43 are independent control valves, which can be used to precisely control different pipelines.

[0049] In other embodiments, the first control valve 42 and the second control valve 43 form an integrated three-way valve, the first outlet 402 of the pressure boosting device 41 and the second inlet 403 of the pressure boosting device 41 are the same interface, the first interface of the three-way valve is connected with the first outlet 402 of the pressure boosting device 41, the second interface of the three-way valve is used to be connected with the liquid tank 5 (or the pipeline between the liquid tank 5 and the liquid supply pump 51), and the third interface of the three-way valve is connected with the liquid outlet pipeline of the first plunger pump 2. The use of the three-way valve can reduce the number of pipelines and control valves, reduce the cost, and facilitate the control of a single three-way valve.

[0050] Preferably, a piston can be arranged in the pressure boosting device 41, which can move along the length direction of the pressure boosting device 41, and can block the clean liquid and the sand-liquid mixture, so that the mixing ratio can be reduced to within 5%. In order to better control the movement speed of the valve connected with the pressure boosting device 41 and the first plunger pump 2, a sensor can be arranged on the pressure boosting device 41 to monitor the movement position of the piston, so as to avoid the impact of the piston in the cavity.

[0051] Optionally, the first control valve 42 and the second control valve 43 are at least one of a stop valve, a plug valve, a throttle valve, a gate valve, a butterfly valve, and a ball valve.

[0052] The above control valves are mainly divided into two types, namely, rotary valves and linear motion valves, wherein the rotary valves include throttle valves, plug valves, butterfly valves, ball valves, etc., and the linear motion valves include throttle valves, stop valves, gate valves, etc.

[0053] Optionally, a check valve 44 can be arranged on the inlet and outlet pipelines of the pressure boosting device 41 to ensure the flow direction of the liquid. The check valve 44 is of a swing type, a swim bladder type, or a valve body and valve seat structure type.

[0054] The pipeline between the plunger pump and the high-pressure manifold is usually provided with at least one of a check valve and a plug valve. The first high-pressure manifold 61 and the second high-pressure manifold 62 are usually provided with safety valves.

[0055] In some embodiments, as shown in Figure 2 The pressure exchange device 4 includes a booster cylinder 45 and a third control valve 46. The first inlet 401 and the second outlet 404 are arranged on the booster cylinder 45. The booster cavity 451 of the booster cylinder 45 is provided with the first outlet 402 and the second inlet 403. The first outlet 402 is connected with the first passage 461 of the third control valve 46. The second inlet 403 is connected with the second passage 462 of the third control valve 46. The first passage 461 is further connected with the liquid tank 5. The second passage 462 is further connected with the outlet of the first plunger pump 2.

[0056] The booster cylinder 45 includes a piston 452 and a piston rod 453. The piston 452 is arranged in the booster cavity 451. The third control valve 46 selectively controls the first passage 461 or the second passage 462 to be conducted according to the movement position of the piston 452 in the booster cavity 451.

[0057] The first outlet 402 and the second inlet 403 are interfaces for entering and exiting the booster cavity 451. The piston 452 and the piston rod 453 are connected together. At least one section between the piston rod 453 and the cylinder body of the booster cylinder 45 has a small gap, which can avoid the sand liquid (less than 3%) from entering the cavity where the piston 452 is located. The third control valve 46 can control the on-off of the first passage 461 and the second passage 462 according to the position of the piston 452. For example, when it is monitored that the piston 452 is located at the leftmost side of the booster cavity 451, the first passage 461 is conducted and the second passage 462 is disconnected. The sand liquid in the sand liquid mixing device 1 enters the booster cylinder 45 for pressure exchange and then flows into the liquid tank 5 through the first passage 461. When it is monitored that the piston 452 is located at the rightmost side of the booster cavity 451, the second passage 462 is conducted and the first passage 461 is disconnected. The first plunger pump 2 provides high-pressure liquid for the booster cylinder 45. The high-pressure liquid is pressurized by the booster cylinder 45 and then discharged to the second high-pressure manifold 62 through the second outlet 404, and then flows together with the high-pressure liquid of the second plunger pump 3 to be delivered to the wellbore.

[0058] To ensure the realization of pressure exchange, in this embodiment, the cross-sectional area of the piston 452 is set to be greater than or equal to the cross-sectional area of the piston rod 453. When the cross-sectional area of the piston 452 is equal to the maximum cross-sectional area of the piston rod 453, the discharge pressure of the first plunger pump 2 is slightly higher than the discharge pressure of the second plunger pump 3. When the cross-sectional area of the piston 452 is greater than the maximum cross-sectional area of the piston rod 453, the discharge pressure (pressure) of the first plunger pump 2 is less than or equal to the discharge pressure of the second plunger pump 3.

[0059] Compared with the arrangement of the pressurizing device 41, the pulsation problem of the liquid discharge can be reduced, the two liquid discharge cavities can be linked, the difficulty of linkage control is reduced, and thus the liquid discharge pulsation problem is reduced.

[0060] As shown in Figure 2 In this embodiment, a one-way valve 44 can be arranged on the pipeline connected with the first outlet 402 and the pipeline connected with the second inlet 403. The one-way valve 44 is of a swing type, a swim bladder type, or a valve body and valve seat structure type. The valve arranged in the first channel 461 and the second channel 462 can be a valve switched by a linear motion actuator or a valve switched by a rotary actuator.

[0061] In some embodiments, as shown in Figure 2 The first position sensor 81 and the second position sensor 82 arranged on the pressurizing cylinder 45 for monitoring the position of the piston are arranged on the left and right sides of the pressurizing cavity 451 along the movement direction of the piston 452, and are connected with the third control valve 46.

[0062] The position of the piston 452 can be accurately monitored by the first position sensor 81 and the second position sensor 82, and the liquid flow direction can be accurately controlled by the third control valve 46, so that the proppant liquid can be prevented from flowing through the high-pressure plunger pump. In specific implementations, the position of the piston 452 can also be monitored by a displacement sensor.

[0063] Figure 2 Only one piston device is shown in the figure. In specific implementations, at least one first plunger pump 2 can be connected with one piston cylinder (the pressurizing cylinder 45), a plurality of first plunger pumps 2 can correspond to a plurality of pressurizing cylinders 45, and the number of the first plunger pumps 2 is usually not less than the number of the piston cylinders. The first plunger pump 2 and the second plunger pump 3 can also be high-pressure centrifugal pumps, or a combination of the plunger pump and the high-pressure centrifugal pump.

[0064] In some embodiments, a sand-liquid pressurizing pump 11 is arranged on the pipeline between the outlet of the sand-liquid mixing device 1 and the first inlet 401 of the pressure exchange device 4, and the output flow of the first plunger pump 2 is greater than the output flow of the sand-liquid pressurizing pump 11.

[0065] As shown in Figure 1 The high-pressure liquid and the low-pressure fluid in the pressurizing device 41 can be mixed. The flow of the first plunger pump 2 output to the first high-pressure manifold 61 is set to be slightly greater than the flow output by the sand-liquid pressurizing pump 11, so that the sand-liquid can be prevented from flowing into the flow path of the clean liquid.

[0066] The flow outputted by the pressure boosting device 41 to the second high-pressure manifold 62 is equivalent to the working flow of the first plunger pump 2, and the plunger pump 3 can quickly increase the flow, so that the flow can be quickly increased or reduced, and the difficulty of adjusting the flow by the pressure boosting device 41 is reduced.

[0067] In some embodiments, a pressure sensor is arranged on the outlet pipeline of the sand liquid pressure boosting pump 11, the first plunger pump 2 and the second plunger pump 3 respectively, and a flow meter is further arranged on the outlet pipeline of the sand liquid pressure boosting pump 11.

[0068] As shown in Figure 1 When the pressure boosting device 41 is used, a pressure sensor is usually arranged on the sand liquid pressure boosting pump 11, the plunger pump (including the first plunger pump 2 and the second plunger pump 3) and the pressure boosting device 41, for monitoring the liquid pressure in the liquid passage; a flow meter is further arranged on the output position of the sand liquid pressure boosting pump 11, the sand mixing system is provided with a sand metering device, or the proppant addition amount signal of other devices can be obtained, so as to ensure that the concentration of the liquid outputted by the sand liquid mixing device 1 meets the requirements, the control system can obtain the sand concentration and flow of the sand mixing system outputted by the signal system; the control system can also obtain the flow outputted by the second plunger pump 3, and the flow of the clean liquid, the sand amount are adjusted by adjusting the sand addition amount, the liquid flow of the sand liquid mixing device 1 and the liquid inlet flow (low pressure) of the second plunger pump 3, so as to ensure that the sand concentration of the liquid entering the operation site 20 meets the requirements of the fracturing operation process parameters.

[0069] The stroke of the conventional fracturing plunger pump is usually not higher than 12 inches, while the stroke of the piston movement in the embodiment is usually higher than 12 inches, and can even reach more than 1 m, so that the movement frequency of the piston is reduced, and even if the valve body and the valve seat are used, the service life of the vulnerable parts can be improved.

[0070] The above description is only the preferred embodiment of the present application and the explanation of the applied technology. Those skilled in the art should understand that the disclosure range involved in the present application is not limited to the technical solutions formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above disclosed concept. For example, the technical solutions formed by the mutual replacement of the above features and the technical features disclosed in the present application (but not limited to) having similar functions.

[0071] Furthermore, although the operations are described in a specific order, this should not be construed as requiring these operations to be performed in the specific order shown or in a sequential order. Multitasking and parallel processing may be advantageous in certain environments. Similarly, while several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of this invention. Certain features described in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

[0072] Although the subject matter has been described using language specific to structural features and / or methodological logic, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are merely illustrative examples of implementing the claims.

Claims

1. A sand slurry pumping system characterized by, The sand-liquid mixing device, the first plunger pump, the second plunger pump and the pressure exchange device, the outlet of the sand-liquid mixing device is connected with the first inlet of the pressure exchange device, the first outlet of the pressure exchange device is used for being connected with a liquid tank; the inlet of the first plunger pump and the inlet of the second plunger pump are used for being connected with the liquid tank, the outlet of the first plunger pump is connected with the second inlet of the pressure exchange device, the second outlet of the pressure exchange device is used for being connected with a work site, the pressure exchange device can selectively control the pipeline between the first outlet of the pressure exchange device and the liquid tank or the pipeline between the outlet of the first plunger pump and the second inlet of the pressure exchange device to be conducted, the outlet of the second plunger pump is used for being connected with the work site, the boost pressure of the first plunger pump is greater than the boost pressure of the second plunger pump.

2. The sand slurry pumping system of claim 1, wherein, The outlet of the first plunger pump is connected with the second inlet of the pressure exchange device through a first high-pressure manifold, the second outlet of the pressure exchange device is connected with the work site through a second high-pressure manifold, and the outlet of the second plunger pump is connected to the second high-pressure manifold.

3. The sand slurry pumping system of claim 1, wherein, The pressure exchange device comprises a boost device, the first outlet of the boost device is connected with the liquid tank through a first pipeline, the outlet of the first plunger pump is connected with the second inlet of the boost device through a second pipeline, A first control valve is arranged on the first pipeline and close to the first outlet, a second control valve is arranged on the second pipeline and close to the second inlet, and the first control valve and the second control valve are selectively opened.

4. The sand slurry pumping system of claim 3, wherein, The first control valve and the second control valve are independent control valves; or The first control valve and the second control valve constitute an integrated three-way valve, the first outlet of the boost device and the second inlet of the boost device are the same interface, the first interface of the three-way valve is connected with the first outlet of the boost device, the second interface of the three-way valve is used for being connected with the liquid tank, and the third interface of the three-way valve is connected with the outlet pipeline of the first plunger pump.

5. The sand slurry pumping system of claim 3, wherein, The first control valve and the second control valve are at least one of a stop valve, a plug valve, a throttle valve, a gate valve, a butterfly valve and a ball valve.

6. The sand slurry pumping system of claim 1, wherein, The pressure exchange device comprises a boost cylinder and a third control valve, the boost cylinder is provided with the first inlet and the second outlet, the boost cavity of the boost cylinder is provided with the first outlet and the second inlet, the first outlet is connected with the first channel of the third control valve, the second inlet is connected with the second channel of the third control valve, the first channel is also used for being connected with the liquid tank, and the second channel is also connected with the outlet of the first plunger pump, The boost cylinder comprises a piston and a piston rod, the piston is arranged in the boost cavity, and the third control valve selectively controls the first channel or the second channel to be conducted according to the movement position of the piston in the boost cavity.

7. The sand slurry pumping system of claim 6, wherein, The first position sensor and the second position sensor for monitoring the position of the piston are arranged on the left and right sides of the pressure chamber along the movement direction of the piston, and are connected with the third control valve.

8. The sand slurry pumping system of claim 1, wherein, A one-way valve is arranged on the pipeline connected with the first outlet and the pipeline connected with the second inlet, and the one-way valve is of a swing type, a fish maw type or a valve body and valve seat structure type.

9. The sand slurry pumping system of claim 1, wherein, A sand liquid booster pump is arranged on the pipeline between the outlet of the sand liquid mixing device and the first inlet of the pressure exchange device, and the output flow of the first plunger pump is greater than the output flow of the sand liquid booster pump.

10. The sand slurry pumping system of claim 9, wherein, Pressure sensors are arranged on the outlet pipelines of the sand liquid booster pump, the first plunger pump and the second plunger pump respectively. A flow meter is arranged on the outlet pipeline of the sand liquid booster pump.

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