High-pressure slurry pump piston

Abstract

The high-pressure slurry pump piston comprises a cylindrical piston core, the outer side of the piston core is sleeved with a piston rubber sheet, the piston rubber sheet is fixed to the piston core through a baffle located at the upper end of the piston rubber sheet, and the piston core is sleeved with the baffle; the outer side of the bottom end of the piston rubber is sleeved with supporting rubber, and the maximum outer diameter of the supporting rubber is smaller than the outer diameter of the bottom end of the piston core. The top end of the outer side of the piston rubber sheet comprises an arc-shaped face a and an arc-shaped face b which are connected through a connecting face, and the included angle between the connecting face and the outer side face of the piston rubber sheet is an obtuse angle. According to the high-pressure slurry pump, the operation requirement of the high-pressure slurry pump can be met, and long-time operation under the working pressure of 70 MPa is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas drilling and production equipment, and particularly relates to a piston of a high-pressure mud pump. Background Art

[0002] The mud pump is a core equipment in the drilling engineering. The reciprocating movement of the piston in the cylinder liner provides power for the circulation of the mud from the ground to the bottom of the well. In recent years, with the gradual advancement of the national oil and gas exploration and development towards ultra (extra) deep oil and gas layers, the power of the mud pump has reached 3000HP and the discharge pressure is as high as 70MPa. As the working conditions of the drilling operation have higher pressure and displacement, the reliability requirements for vulnerable parts are higher.

[0003] The existing piston can usually withstand a maximum working pressure of 52MPa. As a component with a relatively high movement frequency in the mud pump, the piston is prone to wear during work. When operating in an environment with a pressure above its own bearing capacity, the service life of the piston will be significantly shortened. Once the piston is worn out and cannot be used, the operation of the mud pump needs to be stopped to replace the piston. On the one hand, this leads to a reduction in the operation efficiency of the drilling rig, and on the other hand, it increases the working intensity of the operators. Summary of the Invention

[0004] The purpose of the present invention is to provide a piston of a high-pressure mud pump, which can meet the operation requirements of the high-pressure mud pump and achieve long-term operation under a working pressure of 70MPa.

[0005] The technical solution adopted by the present invention is that the piston of the high-pressure mud pump includes a piston core in a cylindrical shape. A piston rubber is sleeved outside the piston core. The piston rubber is fixed to the piston core through a baffle located at the upper end of the piston rubber, and the baffle is sleeved outside the piston core. A support rubber is sleeved outside the bottom end of the piston rubber, and the maximum outer diameter of the support rubber is smaller than the outer diameter of the bottom end of the piston core.

[0006] The outer top end of the piston rubber includes an arc surface a and an arc surface b, and the arc surface a and the arc surface b are connected through a connecting surface, and the included angle between the connecting surface and the outer side surface of the piston rubber is an obtuse angle.

[0007] The present invention is further characterized in that

[0008] The circular radii of both the arc surface a and the arc surface b are 2 - 4.

[0009] The included angle between the connecting surface and the outer side surface of the piston rubber is 110° - 120°.

[0010] The diameter of the inner cavity of the piston rubber gradually decreases from top to bottom, and the difference in the diameters of the upper and lower ends of the inner wall: the height of the inner wall = 1:50 - 1:70.

[0011] A snap ring that makes the baffle have a downward movement tendency is also sleeved on the piston core.

[0012] A rectangular annular groove is formed along the circumferential direction of the top end of the piston core, and the snap ring is located in the rectangular annular groove.

[0013] A sealing groove is formed along the axial direction of the inner bottom of the piston core, and a sealing ring is arranged in the sealing groove.

[0014] The materials of the piston rubber and the support rubber are both polyurethane.

[0015] The hardness of the support rubber is less than that of the piston rubber.

[0016] The material of the piston core is carbon steel.

[0017] The beneficial effect of the present invention is that the included angle at the top edge of the piston rubber of the high-pressure mud pump piston of the present invention is set as an obtuse angle, which can reduce the wear during the operation of the piston, thereby prolonging the service life of the piston, reducing the unnecessary downtime of the mud pump caused by the low piston life during the oil and gas exploitation process, and improving the speed and efficiency of oil and gas exploitation;

[0018] At the same time, the support rubber is prepared by using ordinary polyurethane material. On the one hand, it provides a certain support for the piston rubber, and on the other hand, it provides elasticity, reduces the rigidity of the piston rubber, and can also reduce the wear during the operation of the piston, increase the service life of the piston. By combining high-hardness polyurethane and ordinary polyurethane materials, the piston can withstand a working environment of 70 MPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram of the high-pressure mud pump piston of the present invention;

[0020] Figure 2 is Figure 1 an enlarged structural diagram of I in

[0021] Figure 3 is a taper diagram of the piston rubber in the high-pressure mud pump piston of the present invention.

[0022] In the figure, 1. piston core, 2. support rubber, 3. piston rubber, 4. baffle, 5. snap ring, 6. sealing ring, 7. sealing groove, 8. rectangular annular groove, 9. arc surface a, 10. arc surface b. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] Embodiment 1

[0025] As Figure 1As shown in the figure, the piston of the high-pressure mud pump of the present invention includes a piston core 1 in a cylindrical shape. A piston rubber 3 is sleeved outside the piston core 1. The piston rubber 3 is fixed to the piston core 1 through a baffle 4 located at the upper end of the piston rubber 3. The baffle 4 is sleeved outside the piston core 1.

[0026] Furthermore, a snap ring 5 that makes the baffle 4 have a downward movement tendency is also sleeved on the piston core 1. A rectangular annular groove is formed along the circumferential direction of the top end of the piston core 1, and the snap ring 5 is located in the rectangular annular groove.

[0027] A support rubber 2 for supporting the piston rubber 3 is sleeved outside the bottom end of the piston rubber 3. The maximum outer diameter of the support rubber 2 is smaller than the outer diameter of the bottom end of the piston core 1; this avoids the cylinder liner from wearing the support rubber 2 when the piston moves in the cylinder liner of the mud pump, which affects the support of the support rubber 2 for the piston rubber 3.

[0028] The outer top end of the piston rubber 3 is the working end, and its working end is in an arc shape, and the included angle between the end face of the working end and the outer side face of the piston rubber 3 is an obtuse angle, which increases the pressure resistance and wear resistance of the piston rubber 3 and extends the service life of the piston.

[0029] The material of the piston core 1 is carbon steel, specifically high-strength carbon steel, so that the piston of the present invention can better adapt to the working environment of 70 MPa.

[0030] A sealing groove 7 is axially formed along the inner side bottom of the piston core 1. A sealing ring 6 is arranged in the sealing groove 7. The piston rod of the mud pump is installed in the inner cavity of the piston core 1, and the sealing ring can make a sealed connection between the piston rod and the piston core 1.

[0031] Embodiment 2

[0032] The piston of the high-pressure mud pump of the present invention includes a piston core 1 in a cylindrical shape. An annular block is provided at the bottom end of the piston core 1, and the bottom end face of the annular block is flush with the bottom end face of the piston core 1. A snap ring 5, a baffle 4 and a piston rubber 3 are sleeved on the piston core 1 from top to bottom in sequence. The lower end face of the piston rubber 3 is attached to the upper end face of the annular block. A rectangular annular groove is formed along the circumferential direction of the top end of the piston core 1, and the snap ring 5 is located in the rectangular annular groove.

[0033] That is, the snap ring 5 makes the baffle 4 have a downward movement tendency, so that the baffle 4 presses the piston rubber 3, and the connection position between the piston rubber 3 and the piston core 1 is fixed, preventing the piston rubber 3 from sliding relative to the piston core 1 when the piston reciprocates in the cylinder liner, which affects the operation efficiency of the mud pump.

[0034] A support rubber 2 for supporting the piston rubber 3 is sleeved on the outer side of the bottom end of the piston rubber 3. The support rubber 2 and the piston rubber 3 are connected by glue. The maximum outer diameter of the support rubber 2 is smaller than the outer diameter of the bottom end of the piston core 1. The materials of both the piston rubber 3 and the support rubber 2 are polyurethane, and the hardness of the support rubber 2 is less than that of the piston rubber 3.

[0035] Further, the piston rubber 3 is made of high-hardness polyurethane material, and the support rubber 2 is made of ordinary polyurethane material. On the one hand, the support rubber 2 provides certain support for the piston rubber 3, and on the other hand, it provides elasticity for the piston rubber 3, reducing the rigidity of the piston rubber 3. It can reduce the wear during the piston operation and increase the service life of the piston. Through the combination of high-hardness polyurethane and ordinary polyurethane materials, the 70 MPa ultra-high pressure bearing capacity of the piston of the present invention is achieved.

[0036] As Figure 2 shown, the outer top end of the piston rubber 3 includes an arc surface a9 and an arc surface b10, that is, the working end of the piston rubber 3 includes the arc surface a9 and the arc surface b10. The arc surface a9 and the arc surface b10 are connected by a connecting surface. One end of the arc surface a9 away from the connecting surface is connected to the top surface of the piston rubber 3, and one end of the arc surface b10 away from the connecting surface is connected to the outer side surface of the piston rubber 3. The included angle between the connecting surface and the outer side surface of the piston rubber 3 is an obtuse angle.

[0037] A sealing groove 7 is axially opened along the inner side bottom of the piston core 1. A sealing ring 6 is arranged in the sealing groove 7. The inner cavity of the piston core 1 installs the piston rod of the mud pump. The sealing ring can make the piston rod and the piston core 1 be sealed and connected.

[0038] Embodiment 3

[0039] The high-pressure mud pump piston of the present invention includes a cylindrical piston core 1. A ring-shaped block is arranged at the bottom end of the piston core 1. The bottom end surface of the ring-shaped block is flush with the bottom end surface of the piston core 1. A snap ring 5, a baffle 4 and a piston rubber 3 are sleeved on the piston core 1 from top to bottom in sequence. The lower end surface of the piston rubber 3 is attached to the upper end surface of the ring-shaped block. A rectangular ring groove is axially opened along the circumference of the top end of the piston core 1. The snap ring 5 is located in the rectangular ring groove.

[0040] A support rubber 2 for supporting the piston rubber 3 is sleeved on the outer side of the bottom end of the piston rubber 3. The support rubber 2 and the piston rubber 3 are connected by glue. The maximum outer diameter of the support rubber 2 is smaller than the outer diameter of the bottom end of the piston core 1. The materials of both the piston rubber 3 and the support rubber 2 are polyurethane, and the hardness of the support rubber 2 is less than that of the piston rubber 3.

[0041] Further, the piston rubber 3 is made of high-hardness polyurethane material, and the support rubber 2 is made of ordinary polyurethane material.

[0042] The outer top end of the piston rubber 3 includes an arc surface a9 and an arc surface b10, that is, the working end of the piston rubber 3 includes the arc surface a9 and the arc surface b10, and the circular radii of the arc surface a9 and the arc surface b10 are both 2 - 4.

[0043] The arc surface a9 and the arc surface b10 are connected by a connecting surface. One end of the arc surface a9 away from the connecting surface is connected to the top surface of the piston rubber 3, and one end of the arc surface b10 away from the connecting surface is connected to the outer side surface of the piston rubber 3. The included angle between the connecting surface and the outer side surface of the piston rubber 3 is an obtuse angle, and the obtuse angle is 110° - 120°.

[0044] As Figure 3 shown, the diameter of the inner cavity of the piston rubber 3 gradually decreases from top to bottom. The inner cavity of the piston rubber 3 is similar to a truncated cone, and its taper is R:H = 1:50 - 1:70.

[0045] Wherein, R is the diameter difference between the upper and lower ends of the inner wall, that is, the upper end diameter R1 of the inner cavity of the piston rubber 3 - the lower end diameter R2; H is the height of the inner wall.

[0046] The tapered design of the inner cavity of the piston rubber 3 can effectively ensure the sealing performance between the piston rubber 3 and the piston core 1, and prevent the high - pressure mud from stabbing the piston rubber 3 or the piston rod of the mud pump.

[0047] At the inner bottom of the piston core 1, a sealing groove 7 is axially opened along the piston core 1. A sealing ring 6 is arranged in the sealing groove 7. The inner cavity of the piston core 1 installs the piston rod of the mud pump. Through the sealing ring, the piston rod and the piston core 1 can be hermetically connected.

[0048] Two groups of wear tests were carried out on the high - pressure mud pump piston based on Example 3.

[0049] Test 1

[0050] Five five - cylinder drilling pumps were used. The model of the five - cylinder drilling pump is QDP - 3000U. The test medium is clear water, and the test pressure is 70 MPa.

[0051] The pistons were respectively placed in the corresponding five - cylinder drilling pumps for continuous operation for 200 hours. After 200 hours, the pistons were taken out. No damage occurred to the pistons, and during the 200 hours, the five five - cylinder drilling pumps worked normally without any abnormal operation.

[0052] Test 2

[0053] Five five - cylinder drilling pumps were used. The model of the five - cylinder drilling pump is QDP - 3200U. In order to simulate the actual oilfield working condition environment, the test medium is oil - based mud, and the mud specific gravity is 2 g / cm 3 , and the test pressure is 70 MPa.

[0054] Four groups of the pistons of the present invention and one group of commonly used existing pistons were respectively placed in corresponding five-cylinder drilling pumps for continuous operation for 400 hours. Among the four groups of five-cylinder drilling pumps using the pistons of the present invention, two groups completed 400 hours of continuous operation. One group had the piston damaged after 350 hours of continuous operation, and the other group had the piston damaged after 380 hours of continuous operation. However, the five-cylinder drilling pump using the existing piston only operated for 70 hours before the piston was damaged, causing the five-cylinder drilling pump to be unable to continue operating.

[0055] It can be seen therefrom that the average service life of the piston of the high-pressure mud pump of the present invention is 382.5 hours under the working condition environment of 70 MPa, far exceeding the operation time of the existing piston under the working condition environment of 70 MPa. It reduces the downtime of the mud pump caused by the low piston life during oil and gas exploitation and improves the oil and gas exploitation efficiency.

Claims

1. High-pressure mud pump piston, characterized in that, It includes a cylindrical piston core (1), a piston rubber (3) is sleeved outside the piston core (1), the piston rubber (3) is fixed to the piston core (1) through a baffle (4) located at the upper end of the piston rubber (3), and the baffle (4) is sleeved outside the piston core (1); a support rubber (2) is sleeved outside the bottom end of the piston rubber (3), and the maximum outer diameter of the support rubber (2) is smaller than the outer diameter of the bottom end of the piston core (1). The outer top end of the piston rubber (3) includes an arc surface a (9) and an arc surface b (10), the arc surface a (9) and the arc surface b (10) are connected through a connecting surface, and the included angle between the connecting surface and the outer side surface of the piston rubber (3) is an obtuse angle.

2. The high-pressure mud pump piston according to claim 1, characterized in that, The circular radii of both the arc surface a (9) and the arc surface b (10) are 2 to 4.

3. The high-pressure mud pump piston according to claim 1, characterized in that, The included angle between the connecting surface and the outer side surface of the piston rubber (3) is 110° to 120°.

4. The high-pressure mud pump piston according to claim 1, characterized in that, The diameter of the inner cavity of the piston rubber (3) gradually decreases from top to bottom, and the diameter difference between the upper and lower ends of the inner wall: the height of the inner wall = 1:50 to 1:

70.

5. The high-pressure mud pump piston according to any one of claims 1 to 4, characterized in that, A snap ring (5) that makes the baffle (4) tend to move downward is also sleeved on the piston core (1).

6. The high-pressure mud pump piston according to claim 5, characterized in that, A rectangular annular groove is formed in the circumferential direction of the top end of the piston core (1), and the snap ring (5) is located in the rectangular annular groove.

7. The high-pressure mud pump piston according to any one of claims 1 to 4, characterized in that, A sealing groove (7) is axially formed in the inner bottom of the piston core (1), and a sealing ring (6) is arranged in the sealing groove (7).

8. The high-pressure mud pump piston according to any one of claims 1 to 4, characterized in that, The materials of both the piston rubber (3) and the support rubber (2) are polyurethane.

9. The high-pressure mud pump piston according to claim 8, characterized in that, The hardness of the support rubber (2) is less than the hardness of the piston rubber (3).

10. The high-pressure mud pump piston according to any one of claims 1 to 4, characterized in that, The material of the piston core (1) is carbon steel.

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