Water-cooled coal bed methane hydraulic fracturing system

Abstract

The utility model discloses a water -cooled coal bed gas hydraulic fracturing system, this system passes through integrated high -efficient water -cooling unit, effectively solved traditional coal bed gas hydraulic fracturing system in air -cooled heat dissipation efficiency low, energy consumption is high, loud and frequent maintenance technical problem. System adopts plate heat exchanger and circulating cooling water system, has realized the accurate control of hydraulic oil temperature, has improved system energy efficiency and operating stability significantly, especially suitable for coal mine underground limited space and high dust environment. The system has heat dissipation efficiency high, compact structure, energy consumption is low and maintenance cycle long etc. advantage, provides strong support for the efficient exploitation of coal bed gas.

Description

Technical Field

[0001] This utility model relates to the field of coalbed methane extraction technology, specifically to a water-cooled coalbed methane hydraulic fracturing system. This system achieves precise control of hydraulic oil temperature by integrating a high-efficiency water-cooling unit, thereby improving the efficiency and stability of coalbed methane hydraulic fracturing operations. Background Technology

[0002] A coalbed methane hydraulic fracturing system is a key technological equipment that uses high-pressure liquid to create fractures in coal seams to form channels for gas (methane) flow. It is a core piece of equipment in the field of unconventional natural gas extraction. The system mainly consists of a hydraulic actuator and a power system, with the power system including a hydraulic power unit and a cooling system.

[0003] However, existing coalbed methane hydraulic fracturing systems generally use natural convection cooling to regulate hydraulic oil temperature, which has the following technical drawbacks:

[0004] Insufficient heat dissipation efficiency: Because the thermal conductivity of gaseous media is significantly lower than that of liquid media, the heat exchange efficiency of traditional heat dissipation methods has inherent limitations. When the hydraulic system is running continuously under rated conditions, the heat dissipation power is difficult to match the heat generation power, leading to frequent oil temperature exceeding limits.

[0005] The contradiction between structural compactness and heat dissipation requirements: Traditional convection radiators need to be configured with large-area fin structures to meet heat dissipation requirements, which fundamentally conflicts with the goal of compact equipment design.

[0006] Energy consumption and noise pollution: Forced convection cooling relies on high-speed fans, which not only generate noise pollution of more than 85dB, but also consume 12%-15% of the total energy consumption of the system, seriously restricting the overall energy efficiency.

[0007] Impact of dust environment: In the mining environment (dust concentration as high as 1000mg / m³), the microchannel structure of the heat dissipation channel is easily affected by the deposition of suspended particulate matter. Experimental data shows that when the fin blockage rate reaches 60%, the heat dissipation efficiency decreases by 40%, directly leading to a reduction in the maintenance cycle to 1 / 3 of the normal operating condition.

[0008] The aforementioned technical deficiencies severely restrict the reliability, energy efficiency, and environmental adaptability of coalbed methane hydraulic fracturing systems, necessitating an efficient, compact, low-energy-consumption, and dust-resistant heat dissipation solution. Utility Model Content

[0009] In view of the problems and shortcomings of the existing technology, this utility model provides a water-cooled coalbed methane hydraulic fracturing system.

[0010] The technical solution of this utility model is as follows:

[0011] A water-cooled hydraulic fracturing system for coalbed methane includes:

[0012] The power system includes a drive unit, a hydraulic power unit, and an intelligent control system. The hydraulic power unit includes an oil supply unit, a pressurizing pump group, and a control valve group. The oil supply unit includes an oil tank. The pressurizing pump group is driven by the drive unit to pressurize the hydraulic oil in the oil tank and deliver it to the hydraulic actuator.

[0013] Hydraulic actuators are used to inject high-pressure water or fracturing fluid into coal seams;

[0014] The hydraulic power unit includes a water-cooled unit; the water-cooled unit includes a water pump, a heat exchanger, and a cooling water circulation pipeline. The heat exchanger is located on the return oil pipeline of the hydraulic power unit. The first port group is connected to the return oil pipeline, and the second port group is connected to the cooling water circulation pipeline. Heat exchange occurs between the circulating cooling water and the hydraulic oil. The cooling water circulation pipeline includes an inlet pipe and a return pipe. The inlet pipe is connected to the cooling water source through the water pump, and the return pipe is connected to the cooling water source, forming a closed-loop circulation system.

[0015] The heat exchanger is a plate heat exchanger, and the cooling medium and hydraulic oil use a counter-current heat exchange method.

[0016] The inlet of the first port group of the heat exchanger connected to the return oil pipeline is at the lower part of the heat exchanger, and the outlet is at the upper part of the heat exchanger. The inlet of the second port group of the heat exchanger connected to the cooling water circulation pipeline is at the upper part of the heat exchanger, and the outlet is at the lower part of the heat exchanger.

[0017] The water pump is a centrifugal pump, and the cooling water source is mine water.

[0018] The water-cooling unit also includes a filter and an auxiliary manifold. The filter is installed on the cooling water circulation pipeline to filter impurities in the cooling water, and the auxiliary manifold is used to connect various components.

[0019] The hydraulic actuator unit includes multiple hydraulic actuator assemblies arranged in parallel. Each hydraulic actuator assembly is connected to a pressure pump group through a first oil inlet pipe and to an oil tank through a return oil line.

[0020] The return oil pipeline includes a first return oil pipeline and a second return oil pipeline. The inlet of the first return oil pipeline is connected to the return oil pipeline of the hydraulic actuator, and the outlet is connected to the inlet of the first port group of the heat exchanger. The inlet of the second return oil pipeline is connected to the outlet of the first port group of the heat exchanger, and the outlet is connected to the oil tank.

[0021] Each hydraulic actuator assembly includes a hydraulic cylinder assembly and two valve box assemblies. The two valve box assemblies are connected to both ends of the hydraulic cylinder assembly via connecting sleeves. Their inlets are connected to the fluid supply pipes, and their outlets are connected to the high-pressure fluid outlet pipes, for alternately drawing in and discharging high-pressure water or fracturing fluid. The first port of the hydraulic cylinder assembly is connected to the oil inlet pipe via an electro-hydraulic reversing unit, and the second port is connected to the oil return pipe via an electro-hydraulic reversing unit.

[0022] The pressurizing pump group is configured in multiple parallel sets, and each set of pressurizing pumps is configured with at least two pressurizing pumps connected in series.

[0023] The pressurization pump is an axial piston variable pump.

[0024] The beneficial effects of this utility model are:

[0025] The water-cooled coalbed methane hydraulic fracturing system of this invention addresses the thermodynamic challenges of high-flow-rate, high-pressure hydraulic systems by proposing an innovative heat dissipation solution with the following significant advantages:

[0026] Highly efficient and precise temperature control. Utilizing a reverse heat exchange system combining a hydraulic oil circuit and a closed-loop circulating water cooling network, along with refined pressure regulation, it achieves precise thermal balance control of the hydraulic oil temperature at 35±2℃, effectively solving the temperature rise problem in large-displacement, high-pressure hydraulic systems during continuous operation. Compared to traditional air-cooling solutions, the water-cooling system leverages water's high specific heat capacity and thermal conductivity, significantly improving heat dissipation capacity per unit area and completely overcoming the thermal balance bottleneck under high-load conditions.

[0027] Compact and modular design. Utilizing a modular dual-body architecture and independent pump station system, it avoids the large-volume heat dissipation structures required by traditional air-cooled systems, making it more suitable for the installation needs of confined spaces in coal mines. By optimizing the internal turbulence units and high-density fin design of the radiator, heat exchange efficiency is significantly improved while maintaining structural compactness.

[0028] Energy conservation, environmental protection, and resource recycling. By recycling mine water for simultaneous cooling from multiple heat sources, the system reduces dependence on external cooling media, thus lowering overall energy consumption. It completely avoids the high noise and high energy consumption problems of traditional air-cooled systems, achieving green and low-carbon operation.

[0029] High reliability and low maintenance costs. The closed-loop water cooling system effectively avoids dust blockage problems, significantly extending maintenance cycles and reducing operating costs compared to traditional air cooling (where heat dissipation efficiency decreases by 40% when fin blockage reaches 60%). Precise temperature control through an intelligent control system prevents performance degradation and component failure caused by hydraulic system overheating, improving the long-term stability of the equipment.

[0030] This invention constructs a high-performance hydraulic cooling system suitable for coalbed methane extraction through efficient heat exchange, intelligent temperature control, compact design, and resource recycling. It solves the inherent defects of traditional air-cooling solutions in terms of efficiency, energy consumption, space adaptability, and environmental compatibility, and has significant engineering application value. Attached Figure Description

[0031] Figure 1 A perspective view of an embodiment;

[0032] Figure 2 for Figure 1 A three-dimensional diagram of the central power system;

[0033] Figure 3 for Figure 2 A-direction view;

[0034] Figure 4 for Figure 1 A three-dimensional view of the hydraulic actuator unit;

[0035] The components represented by the reference numerals in the diagram are:

[0036] 100. Drive unit; 200. Pressurized pump assembly; 300. Oil supply unit; 400. Water cooling unit; 500. Hydraulic actuator unit; 310. Oil tank; 410. Water pump; 420. Heat exchanger; 510. Hydraulic cylinder assembly; 520. Valve box assembly; 1. First oil inlet pipe; 2. First oil return pipe; 3. Water inlet pipe; 4. Water return pipe; 5. Second oil return pipe; 6. Second oil inlet pipe; 7. Third oil return pipe; 8. Liquid supply pipe; 9. High-pressure liquid outlet pipe; 10. Oil supply pipe. Detailed Implementation

[0037] The technical means adopted to achieve the intended purpose of this utility model will be further described below with reference to the accompanying drawings of the embodiments of this utility model.

[0038] Example

[0039] See Figure 1 A water-cooled coalbed methane hydraulic fracturing system includes a power system and a hydraulic actuator 500. The power system includes a drive unit 100, a hydraulic power unit, and an intelligent control system. The hydraulic power unit includes an oil supply unit 300, a pressurization pump group 200, a control valve group, and a water-cooling unit 400. The oil supply unit 300 includes an oil tank 310. The pressurization pump group 200 is driven by the drive unit 100 to pressurize the hydraulic oil in the oil tank 310 and deliver it to the hydraulic actuator 500. The circulation of the hydraulic oil is regulated by the control valve group. The hydraulic actuator 500 is used to inject high-pressure water or fracturing fluid into the coal seam. The intelligent control system is located on one side of the drive unit 100 and consists of a programmable control box and a data acquisition box, used to control the coordinated operation of the various units.

[0040] Specifically, the drive unit 100 primarily powers the pressurization pump, and includes a permanent magnet variable frequency motor, a bell-shaped housing, and a transfer case. The outlet of the oil tank 310 connects to the pressurization pump assembly 200, the outlet of the pressurization pump assembly 200 connects to the first oil inlet pipe 1, and the outlet of the first oil inlet pipe 1 connects to the hydraulic actuator 500. The pressurization pump assembly 200, driven by the drive unit 100, pressurizes the hydraulic oil in the oil tank 310. After being pressurized by the pressurization pump assembly 200, the oil in the oil tank 310 enters the hydraulic actuator 500 through the first oil inlet pipe 1. The hydraulic actuator 500 injects high-pressure water or fracturing fluid into the coal seam to create fractures and form a gas (methane) flow channel. After completing a work cycle, the hydraulic oil from the hydraulic actuator 500 returns to the oil tank 310 via the return oil line, completing one work cycle, and this process is repeated for the next work cycle.

[0041] Referring to 2 and 3, the water-cooled unit 400 includes a water pump 410, a heat exchanger 420, and a cooling water circulation pipeline. The heat exchanger 420 is located on the side of the oil tank 310 connected to the return oil pipeline. A first port group connects to the return oil pipeline, and a second port group connects to the cooling water circulation pipeline. The heat exchanger 420 is a plate heat exchanger, and the cooling medium and hydraulic oil exchange in a counter-current heat exchange manner. That is, the hydraulic oil in the return oil pipeline flows upward through the first connection end of the heat exchanger 420, and the cooling water in the cooling water circulation pipeline flows downward through the second connection end of the heat exchanger 420. Specifically, the inlet of the first port group of the heat exchanger 420 connected to the return oil pipeline is at the lower part of the heat exchanger 420, and the outlet is at the upper part of the heat exchanger 420. Similarly, the inlet of the second port group of the heat exchanger 420 connected to the cooling water circulation pipeline is at the upper part of the heat exchanger 420, and the outlet is at the lower part of the heat exchanger 420.

[0042] In one specific embodiment, see Figure 3 The return oil pipeline includes a first return oil pipe 2 and a second return oil pipe 5. The inlet of the first return oil pipe 2 is connected to the return oil pipeline of the hydraulic actuator 500, and the outlet is connected to the lower part of the heat exchanger 420. The inlet of the second return oil pipe 5 is connected to the upper part of the heat exchanger 420, and the outlet is connected to the oil tank 310 through multiple branch pipes. The cooling water pipeline includes an inlet water pipe 3 and a return water pipe 4. The inlet of the inlet water pipe 3 is connected to the water source through the water pump 410, and the outlet is connected to the upper part of the heat exchanger 420. The inlet of the return water pipe 4 is connected to the lower part of the heat exchanger 420, and the outlet is connected to the water source.

[0043] The water-cooling unit 400 also includes a filter and an auxiliary manifold. The filter is installed on the cooling water circulation pipeline to filter impurities in the cooling water, and the auxiliary manifold is used to connect various components. The water source is mine water.

[0044] During operation, after the hydraulic oil completes one working cycle in the hydraulic actuator unit 500, it enters the heat exchanger 420 through the first return oil pipe 2, flows upward through the heat exchanger 420, and then flows back to the oil tank 310 through the second return oil pipe 5. The cooling medium enters the upper inlet of the heat exchanger 420 sequentially through the centrifugal pipeline pump, filter, and auxiliary manifold, flows downward through the heat exchanger 420, and fully exchanges heat with the high-temperature hydraulic oil returning from the hydraulic actuator unit 500 before flowing out from the lower outlet back to the water source, thus achieving the purpose of fully cooling the high-temperature hydraulic oil.

[0045] Specifically, the inlet pipe 3 is connected to the inlet of the water-cooled plate heat exchanger 420 via a flange connection; the return pipe 4 is mainly welded from a flange and a seamless steel pipe, and is connected to the outlet of the high-performance water-cooled plate heat exchanger 420 via bolts. The first oil inlet pipe 1 is mainly welded from a flange and a seamless steel pipe; the second oil return pipe 5 is mainly composed of a flange, a flexible rubber joint, and a seamless steel pipe. The water pump 410 is a centrifugal pump.

[0046] The main function of the hydraulic actuator 500 is to inject high-pressure water or fracturing fluid into the coal seam, driven by the high-pressure oil in the power system, to create fractures and form a channel for gas (methane) flow. (See also...) Figure 4 The hydraulic actuator unit 500 includes multiple hydraulic actuator assemblies arranged in parallel. Each hydraulic actuator assembly is connected to the pressure pump group 200 via a first oil inlet pipe 1 and to the oil tank 310 via a return oil line. Each hydraulic actuator assembly constitutes an independent working unit, supplied with high-pressure oil by the pressure pump group 200. After completing one working cycle, the hydraulic oil returns to the oil tank 310. In this embodiment, two sets of hydraulic actuator assemblies are provided, but the specific number is not limited and can be set as needed.

[0047] The hydraulic actuator assembly includes a hydraulic cylinder assembly 510 and a valve box assembly 520. The first port of the hydraulic cylinder assembly 510 is connected to the second inlet pipe 6 via an electro-hydraulic reversing unit, and the second port is connected to the third return pipe 7 via the same electro-hydraulic reversing unit. The second inlet pipe 6 is connected to the first inlet pipe 1, and the number of first and second inlet pipes is the same as that of the hydraulic actuator assembly. The third return pipe 7 is connected to the first return pipe 2, allowing hydraulic oil to form a circulation loop sequentially through "oil tank 310 - pressurized pump assembly 200 - hydraulic cylinder of hydraulic actuator unit 500" to drive the reciprocating movement of the hydraulic cylinder piston.

[0048] Two valve box assemblies 520 are provided, connected to both ends of the hydraulic cylinder assembly 510 via connecting sleeves. The inlets of the two valve box assemblies 520 are connected to supply pipes 8, and the outlets are connected to high-pressure outlet pipes 9. The two valve box assemblies 520 alternate between intake and discharge conditions; that is, when one end is receiving fluid, the other end is discharging, and vice versa. The supply pipes 8 of the valve box assemblies 520 are used to deliver low-pressure water or fracturing fluid into the coal seam. After being pressurized by the hydraulic cylinder, the fluid enters the high-pressure outlet pipe 9 from the other valve box. The high-pressure outlet pipe 9 is used to inject high-pressure water or fracturing fluid into the coal seam to create fractures and form a gas (methane) flow channel.

[0049] Specifically, the valve box assembly 520 includes a left valve box assembly 520 and a right valve box assembly 520. The left and right valve box assemblies and the hydraulic cylinder assembly 510 are connected together via a connecting sleeve assembly. The left and right valve box assemblies are bolted to a valve box support, and the hydraulic cylinder assembly 510 is bolted to a hydraulic cylinder support. The supply pipe 8 and the high-pressure outlet pipe 9 are bolted to the suction ports of the left and right valve box assemblies 520 and 520, respectively. The hydraulic power unit supplies oil to the hydraulic actuator 500 and controls the reversing action of the hydraulic piston in the hydraulic cylinder through the electro-hydraulic reversing unit and control valve group. The electro-hydraulic reversing unit is bolted to the hydraulic cylinder assembly 510.

[0050] See Figure 2 To improve work efficiency and match the working pressure of the hydraulic actuator 500, two sets of pressure pumps are connected in parallel in the pressure pump group 200. Each set of pressure pumps has at least two pressure pumps connected in series. The pressure pumps are preferably axial piston variable pumps. The number of first oil inlet pipes 1 is the same as that of the hydraulic actuator assembly, and they are connected to the two sets of pressure pump groups 200 through the hydraulic integrated unit and pipelines respectively.

[0051] Working principle:

[0052] The water-cooled coalbed methane hydraulic fracturing system relies on the drive unit 100 to drive the pressurization pump group 200, which draws hydraulic oil from the oil tank 310 into the pressurization pump group 200 to complete the high-low pressure conversion of the hydraulic oil. The pressurization pump group 200 adopts load-sensitive technology to intelligently regulate the flow rate in real time in response to load changes. The output high-pressure hydraulic oil enters the hydraulic cylinder assembly 510 through the first oil inlet pipe 1. The hydraulic piston rod inside the hydraulic cylinder assembly 510 achieves reciprocating motion. The piston ends are linked to the special rubber pistons in the cylinder liners on both sides of the valve box assembly 520 through the mud rod. Its suction and discharge functions are precisely controlled by the cone valve group inside the valve box, forming a closed-loop volumetric exchange system. The electro-hydraulic reversing unit of the hydraulic circuit establishes a bidirectional path. The system return oil enters the first return oil pipe 2 through the third return oil pipe 7, and is introduced into the heat exchanger 420 for forced convection heat exchange. The cooling medium and hydraulic oil achieve efficient heat exchange through the counter-flow plate heat exchanger 420. The cooled hydraulic oil returns to the oil tank 310 through the second return oil pipe 5, forming a closed-loop circulation system of "power output - load response - thermal management". This design significantly improves energy utilization efficiency while ensuring thermodynamic stability through the coordinated control of modular water-cooling network and intelligent variable frequency drive.

[0053] The water-cooled coalbed methane hydraulic fracturing system combines advanced water-cooling heat dissipation technology and intelligent control technology, and its technical effect is remarkable. It is suitable for scenarios that require high-pressure fluid injection, such as coal mine roof pre-fracturing, oilfield injection enhancement, and chemical high-pressure fluid injection.

[0054] The above description represents a preferred embodiment of the present invention. However, the present invention is not limited to the above-described embodiments and examples. Within the scope of knowledge possessed by those skilled in the art, all variations, equivalent substitutions, and improvements made without departing from the concept of the present invention should be included within the protection scope of the present invention.

Claims

1. A water-cooled coalbed methane hydraulic fracturing system, comprising: The power system includes a drive unit (100), a hydraulic power unit and an intelligent control system. The hydraulic power unit includes an oil supply unit (300), a pressurizing pump group (200) and a control valve group. The oil supply unit (300) includes an oil tank (310). The hydraulic actuator (500) is used to inject high-pressure water or fracturing fluid into the coal seam; The pressurizing pump unit (200) is driven by the drive unit (100) to pressurize the hydraulic oil in the oil tank (310) and deliver it to the hydraulic actuator unit (500). The hydraulic power unit is characterized by further including a water cooling unit (400). The water-cooled unit (400) includes a water pump (410), a heat exchanger (420), and a cooling water circulation pipeline. The heat exchanger (420) is installed on the return oil pipeline of the hydraulic power unit. The first port group is connected to the return oil pipeline, and the second port group is connected to the cooling water circulation pipeline. Heat exchange is performed between the circulating cooling water and the hydraulic oil. The cooling water circulation pipeline includes an inlet pipe (3) and a return pipe (4). The inlet pipe (3) is connected to the cooling water source through the water pump (410), and the return pipe (4) is connected to the cooling water source to form a closed-loop circulation system.

2. The hydraulic fracturing system according to claim 1, characterized in that, The heat exchanger (420) is a plate heat exchanger (420), and the cooling medium and hydraulic oil adopt a counter-current heat exchange method.

3. The hydraulic fracturing system according to claim 2, characterized in that, The inlet of the first port group of the heat exchanger (420) connected to the return oil pipeline is at the lower part of the heat exchanger (420), and the outlet is at the upper part of the heat exchanger (420). The inlet of the second port group of the heat exchanger (420) connected to the cooling water circulation pipeline is at the upper part of the heat exchanger (420), and the outlet is at the lower part of the heat exchanger (420).

4. The hydraulic fracturing system according to claim 1, characterized in that, The water pump (410) is a centrifugal pump, and the cooling water source is mine water.

5. The hydraulic fracturing system according to claim 1, characterized in that, The water-cooling unit (400) also includes a filter and an auxiliary manifold. The filter is installed on the cooling water circulation pipeline to filter impurities in the cooling water, and the auxiliary manifold is used to connect various components.

6. The hydraulic fracturing system according to claim 1, characterized in that, The hydraulic actuator (500) includes multiple hydraulic actuator assemblies arranged in parallel. Each hydraulic actuator assembly is connected to the pressurization pump group (200) through the first oil inlet pipe (1) and to the oil tank (310) through the oil return pipe.

7. The hydraulic fracturing system according to claim 1 or 6, characterized in that, The return oil pipeline includes a first return oil pipe (2) and a second return oil pipe (5). The inlet of the first return oil pipe (2) is connected to the return oil pipeline of the hydraulic actuator (500), and the outlet is connected to the inlet of the first port group of the heat exchanger (420). The inlet of the second return oil pipe (5) is connected to the outlet of the first port group of the heat exchanger (420), and the outlet is connected to the oil tank (310).

8. The hydraulic fracturing system according to claim 6, characterized in that, Each hydraulic actuator assembly includes a hydraulic cylinder assembly (510) and two valve box assemblies (520). The two valve box assemblies (520) are connected to both ends of the hydraulic cylinder assembly (510) via connecting sleeves. Their inlets are respectively connected to the fluid supply pipe (8) and their outlets are respectively connected to the high-pressure fluid outlet pipe (9) for alternately sucking in and discharging high-pressure water or fracturing fluid. The first port of the hydraulic cylinder assembly (510) is connected to the oil inlet pipe via an electro-hydraulic reversing unit, and the second port is connected to the oil return pipe via an electro-hydraulic reversing unit.

9. The hydraulic fracturing system according to claim 1 or 6, characterized in that, The pressurizing pump group (200) is configured in parallel with multiple groups, and each group of pressurizing pumps is configured with at least two pressurizing pumps connected in series.

10. The hydraulic fracturing system according to claim 9, characterized in that, The pressurization pump is an axial piston variable pump.

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