Discharge pressure fluctuation buffer device for drilling pump

Abstract

The discharge pressure fluctuation buffer device for a drilling pump disclosed in the present invention comprises a housing with a stepped hollow cylindrical structure with openings at both ends, a cylinder sleeve assembly installed in the housing, a piston assembly installed in the cylinder sleeve assembly, a gland screwed to the top of the housing, a through hole a opened in the axial direction on the upper end face of the gland, a suction pipe assembly threadedly connected to the through hole a, a gas cylinder and a deflation pipe assembly threadedly connected to the top of the suction pipe assembly in sequence, a bracket arranged between the gas cylinder and the gland, an air hole a opened in the upper end face of the gland, an air charging pipe assembly threadedly connected to the air charging pipe assembly, the deflation pipe assembly, the gas cylinder, the suction pipe assembly, the gland, the housing, the cylinder sleeve assembly and the piston assembly are connected in sequence. The present invention alleviates the discharge pressure fluctuation of the drilling pump through the combined action of a spring and gas, reduces the maintenance cost of the device, improves the drilling efficiency, reduces the labor intensity of the on-site operators, saves energy and solves the problem of inconvenient on-site inflation in the oil field.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas exploration and development equipment, and relates to a discharge pressure fluctuation buffer device for a drilling pump. Background Art

[0002] During drilling operations, the pump's discharge pressure fluctuates significantly due to uneven displacement caused by the inherent kinematic characteristics of the pump's crank-connecting rod mechanism and the hysteresis associated with the opening and closing of the pump valve. This discharge pressure fluctuation causes vibration in the mud discharge pipeline, reducing the fatigue life of drilling system components such as the pump and swivel, and also affecting measurement-while-drilling (MWD) and logging-while-drilling (LWD) signal transmission. To mitigate these discharge pressure fluctuations and improve the reliability and fatigue life of the connections between the pump and the drilling rig's high-pressure pipeline components, a common approach is to install an airbag-type buffer device at the pump's discharge outlet. This device utilizes the compressibility of the inflatable bladder to mitigate discharge pressure fluctuations. While this approach is simple and easy to implement, it also has several drawbacks. First, the currently used buffer device places the inflatable bladder in direct contact with the mud, using mud compression to mitigate pressure fluctuations in the pump's discharge pipeline. Because mud contains a variety of chemical substances, rubber airbags are prone to aging after long-term exposure and need to be replaced regularly. This increases the maintenance cost of the buffer device, reduces drilling efficiency, and increases the labor intensity of on-site operators. Secondly, during use, the airbag needs to regularly check the gas pressure inside the airbag for airtightness reasons. When the pressure is too low, it needs to be inflated. When inflating on-site in the oil field, a separate inflator must be equipped and connected to the power supply for inflation, which is very inconvenient. Third, the working performance of the buffer device is closely related to the volume of the airbag. When the airbag is compressed by the mud, the effective working volume decreases, and the working performance of the buffer device is reduced accordingly. Fourth, the buffer device currently used uses a spherical shell, which is difficult to process and has high manufacturing costs. Summary of the Invention

[0003] The purpose of the present invention is to provide a discharge pressure fluctuation buffer device for a drilling pump, which solves the problem in the prior art that the air bag needs to be replaced regularly, resulting in increased maintenance costs of the buffer device and reduced drilling efficiency.

[0004] The technical solution adopted by the present invention is a discharge pressure fluctuation buffer device for a drilling pump, comprising a shell with a stepped hollow cylindrical structure with openings at both ends, a cylinder liner assembly installed in the shell, a piston assembly installed in the cylinder liner assembly, a pressure cover screwed to the top of the shell, a through hole a opened in the axial direction on the upper end face of the pressure cover, an intake pipe assembly threadedly connected to the through hole a, a gas cylinder and a discharge pipe assembly threadedly connected to the top of the intake pipe assembly in sequence, a bracket is arranged between the gas cylinder and the pressure cover, an air hole a opened on the upper end face of the pressure cover, an air hole a threadedly connected to the air charging pipe assembly, the air charging pipe assembly threadedly connected to the discharge pipe assembly, the discharge pipe assembly, the gas cylinder, the intake pipe assembly, the pressure cover, the shell, the cylinder liner assembly and the piston assembly are connected in sequence.

[0005] The present invention is also characterized in that:

[0006] The cylinder liner assembly includes a cylinder liner, the outer edge of the upper end of the cylinder liner is connected to the shell flange, a through hole b is radially provided on the upper section of the outer wall of the cylinder liner, a blocking plate is fixedly installed on the top of the cylinder liner, the pressure cover, the blocking plate and the shell are connected in sequence by screws, a countersunk hole a is axially opened on the end face of the blocking plate, a main column is provided in the countersunk hole a, the main column extends into the piston assembly at one end away from the countersunk hole, a column is provided between the blocking plate and the stepped transition end face in the cylinder liner, a spring is sleeved on the outer wall of the column, one end of the spring is fixedly connected to the lower end face of the blocking plate, and the other end of the spring is fixedly connected to the piston assembly, an air hole b is opened on the upper end face of the blocking plate, and the air hole b matches the air hole a.

[0007] The cylinder liner adopts a stepped cylindrical structure with openings at both ends. The diameter of the upper section of the cylinder liner is larger than that of the lower section. The outer diameter of the upper section of the cylinder liner matches the upper opening of the shell, and the outer diameter of the lower section of the cylinder liner matches the lower opening of the shell.

[0008] The main column adopts a stepped shaft structure. A boss is provided at one end of the main column. The boss matches the countersunk hole a provided on the end face of the blocking plate. A groove is opened along the circumferential direction on the upper end face of the boss. A sealing ring c is installed in the groove. A through hole c is opened along the axial direction on the end face of the main column. The through hole c matches the through hole a.

[0009] The blocking plate is a stepped disc structure, with blind holes a evenly opened on the lower end surface of the blocking plate, and blind holes b corresponding to blind holes a opened on the upper surface of the stepped transition end surface of the cylinder liner. Both blind holes a and blind holes b match the columns, and a sealing gasket b is provided between the blocking plate and the cylinder liner.

[0010] The piston assembly includes a piston disc, a piston rod and a piston connected in sequence by screws. The upper end surface of the piston disc is fixed to the spring. The upper end surface of the piston rod is axially opened with a blind hole c. The size of the blind hole c matches the lower section of the main column. The lower section of the blind hole c is radially opened with an air hole c. The upper end surface of the piston disc and the upper end surface of the piston rod are both provided with a countersunk hole b that matches the column. A sealing ring b is provided between the countersunk hole b and the column.

[0011] The piston disc adopts a disc-shaped structure, and a through hole d is opened in the axial direction on the upper end surface of the piston disc. The through hole d matches the outer diameter of the lower section of the main column.

[0012] The piston rod adopts a stepped structure. The diameter of the upper section of the piston rod is larger than that of the lower section. The outer diameter of the upper section of the piston rod matches the inner diameter of the upper section of the cylinder liner, and the piston matches the inner diameter of the lower section of the cylinder liner.

[0013] The outer circumferential surface of the upper section of the piston rod and the outer circumferential surface of the piston disc are both circumferentially provided with annular grooves, and sealing rings g are provided in the annular grooves. A sealing ring e is provided between the piston and the cylinder liner, a sealing ring i is provided between the piston rod and the main column, and a sealing ring f is provided between the piston and the piston rod.

[0014] The suction pipe assembly includes a tee a, and the branch interface of the tee a is threadedly connected with a first one-way valve, an elbow and a breathable cap a in sequence. The main interface at one end of the tee a is connected to the through hole on the upper end face of the pressure cover through a joint, and the main interface at the other end of the tee a is threaded with a second one-way valve, and the second one-way valve is threadedly connected to the gas cylinder through a joint.

[0015] The vent pipe assembly includes a vent cap b, which is connected to a third one-way valve via a joint thread, and the third one-way valve is connected to the gas cylinder via a tee b main interface, and the tee b and the gas cylinder are connected via a joint thread;

[0016] The inflation pipe assembly includes an air pipe, an angle valve, and a tee c that are threadedly connected in sequence through a joint. The main interface at one end of the tee c is threadedly connected to a pressure gauge, and the main interface at the other end of the tee c is threadedly connected to the air hole a. The air pipe is threadedly connected to the deflation pipe assembly.

[0017] The beneficial effects of the present invention are:

[0018] (1) The combined action of the spring and gas can alleviate the fluctuation of the discharge pressure of the drilling pump, reduce the maintenance cost of the device, improve the drilling efficiency, reduce the labor intensity of on-site operators, and achieve effective utilization of energy. At the same time, when the working volume inside the device is reduced, the working performance of the device will not be greatly affected;

[0019] (2) A gas storage cylinder is set on the top of the device, and the gas stored in the gas cylinder is used to inflate the device through the inflation pipeline, which solves the problem of inconvenient inflation on the oil field site. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic structural diagram of a discharge pressure fluctuation buffer device for a drilling pump according to the present invention;

[0021] Figure 2 It is a structural schematic diagram of the housing of the discharge pressure fluctuation buffer device for a drilling pump of the present invention;

[0022] Figure 3This is a schematic structural diagram of a cylinder sleeve assembly of a discharge pressure fluctuation buffer device for a drilling pump according to the present invention;

[0023] Figure 4 It is a structural schematic diagram of the piston assembly of the discharge pressure fluctuation buffer device for the drilling pump of the present invention;

[0024] Figure 5 This is a structural diagram of the suction pipe assembly in the discharge pressure fluctuation buffer device for a drilling pump of the present invention;

[0025] Figure 6 This is a structural diagram of the air pipe assembly in the discharge pressure fluctuation buffer device for a drilling pump of the present invention;

[0026] Figure 7 This is a structural diagram of the bleed pipe assembly in the discharge pressure fluctuation buffer device for a drilling pump of the present invention;

[0027] Figure 8 It is a structural schematic diagram of the cylinder sleeve in the discharge pressure fluctuation buffer device for the drilling pump of the present invention;

[0028] Figure 9 This is a schematic structural diagram of a blocking plate in a discharge pressure fluctuation buffer device for a drilling pump according to the present invention;

[0029] Figure 10 It is a structural schematic diagram of the main column in the discharge pressure fluctuation buffer device for a drilling pump of the present invention;

[0030] Figure 11 This is a schematic structural diagram of the piston rod in the discharge pressure fluctuation buffer device for a drilling pump of the present invention;

[0031] Figure 12 It is a schematic structural diagram of the piston disc in the discharge pressure fluctuation buffer device for a drilling pump of the present invention;

[0032] Figure 13 It is a structural schematic diagram of the piston in the discharge pressure fluctuation buffer device for a drilling pump of the present invention;

[0033] Figure 14 This is a schematic structural diagram of the air permeable cap in the discharge pressure fluctuation buffer device for a drilling pump according to the present invention;

[0034] Figure 15 This is a schematic structural diagram of the upward movement of the piston of the discharge pressure fluctuation buffer device for a drilling pump according to the present invention;

[0035] Figure 16 It is a structural schematic diagram of the downward movement of the piston of the discharge pressure fluctuation buffer device for the drilling pump of the present invention.

[0036] In the figure: 1. Mud pipeline, 2. Screw a, 3. Sealing ring a, 4. Cylinder liner assembly, 5. Piston assembly, 6. Housing, 7. Sealing gasket a, 8. Screw b, 9. Gland, 10. Bolt a, 11. Washer a, 12. Bracket, 13. Intake pipe assembly, 14. Gas cylinder, 15. Bolt b, 16. Washer b, 17. Nut, 18. Inflation pipe assembly, 19. Deflating pipe assembly, 20. Sealing ring b, 21. Cylinder liner, 22. Column, 23. Main column, 24. Spring, 25. Sealing gasket b, 26. Blocking plate, 27 .Sealing ring c, 28. Sealing ring d, 29. Piston disc, 30. Piston rod, 31. Piston, 32. Sealing ring e, 33. Sealing ring f, 34. Sealing ring g, 35. Sealing ring h, 36. Sealing ring i, 37. Screw c, 38. Screw d, 39. Connector, 40. Tee a, 41. First one-way valve, 42. Elbow, 43. Breathing cap a, 44. Angle valve, 45. Trachea, 46. Pressure gauge, 47. Second one-way valve, 48. Third one-way valve, 49. Breathing cap b, 50. Tee b, 51. Tee c. DETAILED DESCRIPTION

[0037] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] The main structure of the discharge pressure fluctuation buffer device for the drilling pump of the present invention is as follows: Figure 1 As shown, the device primarily consists of a housing 6, a cylinder liner assembly 4, a piston assembly 5, an intake pipe assembly 13, an air charging pipe assembly 18, an air discharge pipe assembly 19, and a gas cylinder 14. The housing 6 is mounted on top of the mud pipeline 1 using a flange connection. The cylinder liner assembly 4 and piston assembly 5 are mounted inside the housing 6 to mitigate fluctuations in the drilling pump's discharge pressure. Mounted on top of the housing 6 are, in order, a gland 9, a bracket 12, an intake pipe assembly 13, a gas cylinder 14, an air discharge pipe assembly 19, and an air charging pipe assembly 18. The gland 9 secures the cylinder liner assembly 4, provides support for the bracket 12 and gas cylinder 14, and establishes a connection between the housing 6 and the gas cylinder 14. The intake pipe assembly 13 is used to inflate the gas cylinder 14. The air charging pipe assembly 18 is used to transfer gas stored in the gas cylinder 14 into the housing 6. The air discharge pipe assembly 19 is used to release excess gas from the gas cylinder 14, maintaining a constant pressure within the gas cylinder 14. The mud pipeline 1 and the housing 6, the housing 6 and the gland 9, the gland 9 and the bracket 12, and the bracket 12 and the gas cylinder 14 are connected by screw 2, screw b8, bolt a10, washer a11, bolt b15, washer b16, and nut 17. To prevent leakage of mud and gas, a sealing ring a3, a sealing ring b20, and a sealing gasket a7 are installed between the mud pipeline 1 and the housing 6, and between the housing 6 and the cylinder liner assembly 4.

[0039] The structure of the housing 6 is as follows Figure 2As shown, a stepped hollow cylindrical structure with openings at both ends is adopted, which is divided into three sections: upper, middle and lower. It is used to install the cylinder liner assembly 4 and is the main structure of the device. The upper end face of the shell 6 is provided with a screw hole that matches the screw b8, and is connected to the pressure cover 9 through the screw b8. The middle section of the shell 6 has a larger diameter and is the main space for the flow of high-pressure gas. The lower end face of the shell 6 is provided with a screw hole that matches the screw a2, and is connected to the mud pipeline 1 through the screw a2. The center holes of the upper and lower sections of the shell 6 respectively match the outer wall dimensions of the upper and lower sections of the cylinder liner 21, providing installation space for the cylinder liner 21 and playing a positioning role. The center hole and end face of the lower section of the shell 6 are respectively provided with annular grooves for installing the sealing ring b20 and the sealing ring a3.

[0040] The structure of the cylinder liner assembly 4 is as follows Figure 3 As shown, the piston assembly 5 is primarily composed of a cylinder liner 21, columns 22, a main column 23, a spring 24, a gasket b25, a sealing ring c27, a sealing ring d28, and a baffle 26. These components provide a channel for the piston assembly 5 to reciprocate upward and downward, isolating the enclosed gas within the housing 6 from the high-pressure mud. Four columns 22 and four sets of springs 24 are evenly distributed within the cylinder liner 21, with a main column 23 located in the center. Column 22 provides support for the springs to prevent bending and guides the reciprocating motion of the piston assembly 5. Spring 24 is used to automatically reset the piston assembly 5. To prevent gas leakage from within the housing 6, a gasket b25 is located between the cylinder liner 21 and the baffle 26, and sealing rings c27 and d28 are located on the main column 23.

[0041] The structure of the cylinder sleeve 21 is as follows Figure 8 As shown, it adopts a stepped structure with both ends open, divided into upper and lower sections, used to install the piston assembly 5 and provide a channel for its reciprocating motion, thereby isolating the high- and low-pressure gas areas. The upper section of the cylinder liner 21 has a larger diameter and is provided with a flange at the upper end for connection with the housing 6. Two rows of through holes b are evenly arranged along the radial direction on the upper section of the outer wall, which are used to connect the gas inside the upper section of the cylinder liner 21 with the gas inside the housing 6, forming a channel for gas flow between the two areas. Four blind holes b are opened on the upper surface of the stepped transition end surface of the cylinder liner 21. The size of the blind holes b matches that of the column 22 and is used for circumferential and axial positioning of the column 22. The lower section of the cylinder liner 21 has a smaller diameter and is sized to match that of the piston 31. It is the channel for the reciprocating motion of the piston 31. During normal operation of the device, high-pressure mud enters the lower section of the cylinder liner 21, pushing the piston 31 to reciprocate up and down inside it.

[0042] The blocking plate 26 adopts a stepped disc structure, such as Figure 9As shown. The plugging plate is primarily used to seal the gas inside the housing 6 and cylinder liner 21, while also providing support for the pillar 22, main pillar 23, and spring 24. A flange is provided on the upper portion of the plugging plate 26 for connection to the housing. A countersunk hole a is axially formed on the end face of the plugging plate 26, within which the main pillar 23 is located. The dimensions of the countersunk hole a match those of the main pillar 23 and the sealing ring d28, respectively, and serve to position and install the main pillar. Four blind holes a and slots corresponding to the blind holes b are evenly spaced 90° apart on the lower end face of the plugging plate 26. The dimensions of the blind holes a match those of the pillar 22, and the dimensions of the slots match those of the spring 24, achieving circumferential and axial positioning of the pillar 22 and spring 24. The plugging plate 26 is also provided with air holes b, which match those of the air holes a provided on the gland 9. The air holes b connect the interior of the housing with the inflation tube assembly 18, serving as a channel for the gas inside the gas cylinder 14 to be filled into the housing.

[0043] The main column 23 adopts a stepped shaft structure, such as Figure 10 As shown. A boss is provided on the upper part of the main column 23, and the size of the boss matches the countersunk hole a provided on the end face of the plugging plate 26, which is used to achieve positioning between it and the plugging plate 26. A groove is opened along the circumferential direction on the upper end face of the boss, and a sealing ring c27 is installed in the groove. The size of the lower section of the main column 23 matches the size of the through hole d provided on the upper end face of the piston disc 29 and the blind hole c in the center of the piston rod 30, which guides the piston assembly 5 to move up and down inside the cylinder sleeve 21. A through hole c is provided in the center of the main column 23, and the size of the through hole c matches the through hole a provided in the center of the pressure cover 9. The through hole c and the through hole a connect the intake pipe assembly 13 with the enclosed space between the piston rod and the cylinder sleeve 21, and are the channels for external air to enter this enclosed space and then enter the gas cylinder 14 from this enclosed space.

[0044] The structure of the piston assembly 5 is as follows: Figure 4 As shown, the device primarily consists of a piston rod 30, a piston disc 29, a piston 31, screws d38 and c37, and various sealing rings. It is installed within the cylinder liner 21. The lower piston 31 contacts the high-pressure mud, while the upper piston disc 29 contacts the spring 24 and high-pressure gas. By converting high-pressure mud pressure fluctuations into compression energy for the spring 24 and gas, it mitigates fluctuations in the drilling pump's discharge pressure while isolating the internal components from the mud. Screws d38 and c37 connect the piston 31 to the piston rod 30, and the piston rod 30 to the piston disc 29, respectively. To prevent mud leakage, a sealing ring e32 is provided between the piston 31 and the cylinder liner 21, and a sealing ring f33 is provided between the piston 31 and the piston rod 30. In order to prevent leakage of high-pressure gas inside the shell, a sealing ring g34 is provided between the cylinder liner 21 and the piston rod 30 and the piston disc 29, a sealing ring i36 is provided between the main column 23 and the piston rod 30, and a sealing ring h35 is provided between the column 22 and the piston rod 30.

[0045] The structure of the piston rod 30 is as follows Figure 11 As shown, it adopts a stepped structure, divided into upper and lower sections. The upper section is connected to the piston disc 29, and the lower section is connected to the piston 31. The interaction between the impact force of the mud and the reaction force of the spring 24 and the compressed gas drives the piston 31 and the piston disc 29 to reciprocate up and down. The piston rod section 30 has a larger diameter, its size matching the inner bore size of the upper section of the cylinder liner 21. The upper end surface of the piston rod 30 is evenly provided with four stepped countersunk holes and screw holes. The countersunk holes are used to install the sealing ring h35 and the column 22, and the screw holes are used to install the screw c37, which connects the piston disc 29 to the piston rod. The center of the piston rod 30 is also provided with a groove for installing the sealing ring i36. The lower section of the piston rod 30 has a smaller diameter and is provided with an annular groove on the lower end surface for installing the sealing ring f33. The piston 31 is connected to the piston rod 30 by screw d38. A blind hole c is axially opened on the upper end surface of the piston rod 30. The size of the blind hole c matches the lower section of the main column 23. The main column 23 serves as a guide for the reciprocating motion of the piston rod. Four air holes c are evenly arranged at 90° intervals in the circumferential direction on the lower section of the blind hole c. The air hole c is composed of the blind hole c at the center of the piston rod 30, the through hole c of the main column 23, and the through hole a at the center of the gland 9. The air channel is connected to the enclosed space formed between the piston assembly 5 and the cylinder liner 21. It is a channel for external air to enter this enclosed space and then enter the gas cylinder 14 from this space.

[0046] The piston disc 29 adopts a disc-shaped structure, such as Figure 12 As shown, it is connected to the piston rod 30 by screws 3c7, providing support for the spring, isolating the high-pressure gas area inside the housing from the low-pressure gas area between the cylinder liner and the piston assembly, and at the same time bearing the reaction force of the spring and the compressed gas. Its structure is as shown in FIG. Figure 12 As shown. Piston disc 29 is evenly spaced 90° apart with four counterbores b and slots. Counterbores b are used to mount the pillars 22 and sealing ring h35. The slots are sized to match the spring 24 and provide circumferential and axial positioning of the spring. The through-hole d in the center of piston disc 29 is used to mount the main pillar 23 and sealing ring i36. The outer circumferential surface of piston disc 29 is circumferentially grooved, with sealing ring g34 positioned within the grooves.

[0047] The piston 31 adopts a cylindrical structure, such as Figure 13 As shown, the piston is connected to the piston rod 30 via screws d38, isolating the high-pressure mud from the low-pressure gas region formed between the cylinder liner 21 and the piston assembly 5, and withstanding the impact of the mud and the reaction force of the piston rod. A countersunk hole is located in the center of the piston for mounting screws d38. Two annular grooves are provided around the piston for mounting sealing rings e32.

[0048] The structure of the suction pipe assembly 13 is as follows Figure 5As shown, it mainly consists of a breather cap a43, an elbow 42, a first one-way valve 41, a connector 39, a tee a40, and a second one-way valve 47. The suction pipe assembly 13 is installed between the gland 9 and the gas cylinder 14. It is a channel for external air to enter the device and then enter the gas cylinder from the device. All parts are connected by threads. The one-way valve is used to achieve one-way flow of gas. The breather cap is as shown. Figure 13 As shown, it adopts a cylindrical shell structure. The upper end and circumference of the breather cap are closed surfaces to prevent rainwater and foreign matter from entering the pipe. The lower end surface is evenly provided with air holes, and air enters the breather cap through the lower end surface. The center of the lower end surface of the breather cap is provided with a screw hole for connection.

[0049] The structure of the inflation tube assembly 18 is as follows: Figure 6 As shown, the device primarily consists of a gas pipe 45, an angle valve 44, a connector 39, a tee c51, and a pressure gauge 46. It is installed between the exhaust pipe assembly 19 and the gland 9 and is used to charge the high-pressure gas inside the gas cylinder 14 into the interior of the housing 6. The various components of the gas charging pipe assembly are connected by threads. An angle valve 44 is provided within the gas charging pipe assembly to control the opening and closing of the gas charging circuit, thereby charging the high-pressure gas from the gas cylinder into the interior of the housing 6. A pressure gauge 46 is used to display the gas pressure inside the device in real time during the charging process. When the charging pressure reaches the specified value, the angle valve 44 is closed to stop the charging.

[0050] The structure of the vent pipe assembly 19 is as follows: Figure 7 As shown, the assembly is primarily composed of a connector 39, a tee b50, a third one-way valve 48, and a vent cap b49. It is installed on the top of the gas cylinder 14, and each component is connected by threads. A connector 39 is provided on the side of the deflation pipe assembly 19 for connecting to the inflation pipe assembly 18. The third one-way valve 48 is used to control the pressure of the gas inside the gas cylinder, ensuring that the gas pressure inside the gas cylinder remains within a set value range. When the pressure inside the gas cylinder exceeds the set pressure of the third one-way valve 48, the third one-way valve 48 opens, and the gas is discharged from the interior of the gas cylinder 14 through the third one-way valve 48 into the vent cap b49. The high-pressure gas in the vent cap b49 is buffered and diverted within the vent cap b49, and is ultimately discharged through the air holes located on the lower end surface of the vent cap b49. The vent cap is used to prevent rainwater and foreign matter from entering the pipeline, and at the same time, it reduces the pressure of the high-pressure gas discharged from the gas cylinder to prevent harm to personnel.

[0051] A discharge pressure fluctuation buffer device for a drilling pump, which uses the dual effects of high-pressure gas and a spring to alleviate fluctuations in the discharge pressure of the drilling pump by arranging a cylinder sleeve and a piston structure inside the shell. The piston and cylinder sleeve isolate the mud in the discharge pipeline from the working area inside the device, preventing the mud from directly contacting the various components inside the device, extending the service life of each component, reducing the maintenance cost of the device and the labor intensity of on-site workers, and improving the quality and efficiency of drilling operations. By arranging a gas cylinder, an air intake line, an air charging line, and an air exhaust line in the device, the device can fully absorb and utilize the energy generated by the up and down reciprocating motion of the piston assembly to inflate the gas cylinder. When the gas pressure inside the device decreases and affects the working performance, the gas stored in the gas cylinder is used to inflate the device, solving the problem of inconvenient on-site inflation in the oil field.

[0052] The working principle of the discharge pressure fluctuation buffer device for drilling pump of the present invention is as follows: Figure 15 、 Figure 16 As shown. Before operation, first, the device is filled with gas of a specified pressure through the inflation pipe assembly 18. During operation, the area between the piston 31 and the mud pipeline 1 is the high-pressure mud activity area, recorded as Area I. The closed area formed between the piston assembly 5 and the cylinder liner 21 and the closed area formed by the center hole of the piston rod 30, the center hole of the main column 23, and the center hole of the blocking plate 26 are the low-pressure gas activity area. The two areas are connected by the air holes provided on the circumferential surface of the lower section of the piston rod, recorded as Area II. The upper area of ​​the piston disc 29 is connected to the internal area of ​​the shell 6 through the air holes provided in the upper section of the cylinder liner, which is the high-pressure gas activity area, recorded as Area III.

[0053] When the mud pressure in the mud pipeline 1 increases, the piston 31 moves upward. The working principle of the device is as follows: Figure 15As shown. The mud in region I is in direct contact with piston 31. Under the thrust of the mud, the piston drives piston rod 30 and piston disc 29 to move upward synchronously, compressing spring 24, reducing the effective volume of region III, and compressing the high-pressure gas in region III. As the piston continues to move upward, the reaction force exerted on the piston disc by the spring and compressed gas in region III gradually increases. When the piston rises to a certain position, the thrust of the mud on the piston equals the reaction force exerted on the piston disc by the spring and gas, and the piston reaches an equilibrium position and stops moving. During the upward movement of the piston, the spring in the device and the gas in region III absorb some of the pressure energy of the mud in region I, causing the pressure in mud pipeline 1 to drop. During this process, the effective volume of enclosed region II increases, and the gas pressure within it gradually decreases, forming a negative pressure with the external gas. When the force exerted by the external gas on the spool of first one-way valve 41 becomes greater than the force exerted by the valve spring on the spool, first one-way valve 41 opens, and external gas enters through the intake pipe assembly 13 and fills region II. When the piston stops moving, the volume of region II no longer increases. At this time, the force exerted by the external atmosphere on the spool of first one-way valve 41 is less than the force exerted by the valve spring on the spool, and first one-way valve 41 closes. Since second one-way valve 47, located in the intake pipe assembly, is installed in reverse, it remains closed during this process. To prevent mud in region I from entering region II, sealing rings e32 and f33 are installed between piston 31 and cylinder liner 21, and between piston 31 and piston rod 30, respectively. To prevent leakage of high-pressure gas within region III, seals b20, g34, h35, 3i6, c27, d28, gasket a7, and b25 are installed. To prevent slurry leakage within region I, seal a3 is installed between slurry pipeline 1 and housing 6.

[0054] When the mud pressure in the mud pipeline 1 decreases, the piston 31 moves downward. The working principle of the device is as follows: Figure 16As shown, the force exerted by the mud on piston 31 decreases, and piston assembly 5 moves downward under the combined action of spring 24 and the high-pressure gas in region III. During this downward movement of piston assembly 5, spring 24 gradually returns to its original position, the volume of region III gradually increases, and the force exerted by spring 24 and the gas in region III on piston disc 29 gradually decreases. When piston assembly 5 descends to a certain position, the combined force exerted by spring 24 and the gas in region III on piston disc 29 equals the thrust of the mud on piston 31, causing piston assembly 5 to stop moving and return to an equilibrium position. During this downward movement of the piston, the energy released by the spring and the gas in region III is absorbed by the mud in region I, causing the pressure in mud pipeline 1 to rise. During this process, the volume of the closed area II decreases and the gas pressure inside it gradually increases. When the force of the gas inside area II acting on the valve core of the second one-way valve 47 in the intake pipe assembly 13 is greater than the force of the spring 24 on the valve core, the second one-way valve 47 opens, and the gas in area II enters the interior of the gas cylinder 14 through the second one-way valve 47. When the piston 31 stops moving, the volume of area II no longer decreases. At this time, the force of the gas in area II acting on the valve core of the second one-way valve 47 is less than the force of the valve spring 24 on the valve core, and the second one-way valve 47 is closed. The first one-way valve 41 in the intake pipe assembly 13 is always in a closed state under the action of the spring 24.

[0055] During normal operation of the drilling pump, the pressure in the mud line 1 fluctuates continuously, rising and falling. Consequently, the piston assembly 5 also reciprocates up and down. When the pressure in the mud line 1 increases, the spring 24 and high-pressure gas in the device absorb some of the mud's energy, reducing the pressure. When the pressure in the mud line decreases, the spring 24 and high-pressure gas release their stored energy, increasing the discharge pressure. This repetitive interaction allows the device to mitigate fluctuations in the discharge pressure of the drilling pump. During the up-and-down reciprocating motion of the piston assembly, the volume within region II continuously changes. By providing the intake pipe assembly 13 and utilizing the reciprocating motion of the piston assembly 5, external air is automatically filled into and stored within the gas cylinder 14. When the gas pressure within the gas cylinder exceeds a specified value, the third one-way valve 48 on the exhaust pipe assembly 19 automatically opens to release the pressure. When the pressure within the gas cylinder 14 falls below the specified value, the third one-way valve 48 automatically closes, ensuring that the gas pressure within the gas cylinder 14 never exceeds the set value. After the device has been working for a long time, the gas pressure in area III decreases and the working performance of the device declines. At this time, the angle valve 44 set on the inflation pipe assembly 18 is opened, and the high-pressure gas stored in the gas cylinder 14 will enter the area III through the gas pipe 45, angle valve 44, tee c51, pressure cover 9, and blocking plate 26 in sequence. During the inflation process, the pressure gauge 46 set on the inflation pipe assembly 18 will display the gas pressure inside area III in real time. When the gas pressure reaches the set value, the angle valve 44 is closed to stop inflation.

[0056] The discharge pressure fluctuation buffer device for a drilling pump of the present invention has the following advantages:

[0057] (1) By arranging a cylinder sleeve, a piston and a spring inside the device, the mud is in direct contact with the piston. The piston continuously reciprocates up and down under the interaction of the fluctuating discharge pressure of the drilling pump and the spring and high-pressure gas. The combined action of spring compression and gas compression alleviates the fluctuation of the discharge pressure of the drilling pump. The contact area between the piston and the mud is small and the service life is long, thereby reducing the maintenance cost and frequency of the device, improving the efficiency of drilling operations, and reducing the labor intensity of on-site operators.

[0058] (2) A gas cylinder is installed on the top of the device. During the normal operation of the device, the energy generated by the reciprocating motion of the piston is used to automatically inflate the gas cylinder through the suction pipe. When the gas pressure inside the device decreases, the gas stored in the gas cylinder can be used to inflate the device through the charging pipe, thus solving the problem of inconvenient on-site gas charging in the oil field.

[0059] (3) This device reduces the discharge pressure fluctuation of the drilling pump through the combined action of the spring and gas. When the working volume inside the device is reduced, the working performance of the device will not be greatly affected. At the same time, the maintenance cost of the device can be reduced, and the efficient use of energy can be achieved.

[0060] (4) The device adopts a hollow stepped cylindrical shell, which has a simple shell structure, is easy to process, and has low manufacturing cost.

Claims

1. A discharge pressure fluctuation buffer device for a drilling pump, characterized in that: The invention comprises a shell (6) of a stepped hollow cylindrical structure with openings at both ends, wherein a cylinder sleeve assembly (4) is installed in the shell (6), wherein a piston assembly (5) is installed in the cylinder sleeve assembly (4), wherein a gland (9) is screwed to the top of the shell (6), wherein a through hole a is opened in the axial direction on the upper end surface of the gland (9), wherein an intake pipe assembly (13) is threadedly connected to the through hole a, wherein a gas cylinder (14) and an exhaust pipe assembly (19) are threadedly connected to the top of the intake pipe assembly (13), wherein a bracket (12) is arranged between the gas cylinder (14) and the gland (9), wherein an air hole a is opened in the upper end surface of the gland (9), wherein an air filling pipe assembly (18) is threadedly connected to the air filling pipe assembly (18), wherein the air filling pipe assembly (18) is threadedly connected to the through hole a. A deflation pipe assembly (19), wherein the deflation pipe assembly (19), the gas cylinder (14), the air intake pipe assembly (13), the gland (9), the shell (6), the cylinder sleeve assembly (4) and the piston assembly (5) are connected in sequence; the cylinder sleeve assembly (4) comprises a cylinder sleeve (21), the outer edge of the upper end of the cylinder sleeve (21) is flange-connected to the shell (6), the upper section of the outer wall of the cylinder sleeve (21) is provided with a through hole b in the radial direction, a plugging plate (26) is fixedly mounted on the top of the cylinder sleeve (21), the gland (9), the plugging plate (26) and the shell (6) are connected in sequence by screws (8), a countersunk hole a is opened in the axial direction on the end surface of the plugging plate (26), a main column (23) is provided in the countersunk hole a, and a side of the main column (23) away from the countersunk hole The end of the plugging plate (26) extends into the piston assembly (5), a column (22) is provided between the blocking plate (26) and the stepped transition end surface in the cylinder sleeve (21), a spring (24) is sleeved on the outer wall of the column (22), one end of the spring (24) is fixedly connected to the lower end surface of the plugging plate (26), and the other end of the spring (24) is fixedly connected to the piston assembly (5), and the upper end surface of the plugging plate (26) is provided with an air hole b, and the air hole b matches the air hole a; the blocking plate (26) is a stepped disc structure, and the lower end surface of the blocking plate (26) is evenly provided with blind holes a, and the upper surface of the stepped transition end surface of the cylinder sleeve (21) is provided with blind holes b corresponding to the blind holes a, and the blind holes a and the blind holes b are both aligned with the column (22). The piston assembly (5) comprises a piston disc (29), a piston rod (30) and a piston (31) which are connected in sequence by screws. The upper end surface of the piston disc (29) is fixedly connected to the spring (24). The upper end surface of the piston rod (30) is provided with a blind hole c in the axial direction. The size of the blind hole c matches the lower section of the main column (23). The lower section of the blind hole c is provided with an air hole c in the radial direction. The upper end surface of the piston disc (29) and the upper end surface of the piston rod (30) are both provided with a countersunk hole b matching the column (22). A sealing ring h (35) is provided between the countersunk hole b and the column (22).The air intake pipe assembly (13) comprises a tee a (40), a branch interface of the tee a (40) being threadedly connected with a first check valve (41), an elbow (42) and a breathable cap a (43) in sequence, a main interface at one end of the tee a (40) being connected to a through hole on the upper end surface of the gland (9) via a joint (39), a main interface at the other end of the tee a (40) being threadedly connected with a second check valve (47), and the second check valve (47) being threadedly connected to the gas cylinder (14) via a joint (39). ; 2. The discharge pressure fluctuation buffer device for a drilling pump according to claim 1, characterized in that: The cylinder sleeve (21) adopts a stepped cylindrical structure with openings at both ends; the diameter of the upper section of the cylinder sleeve (21) is greater than the diameter of the lower section; the outer diameter of the upper section of the cylinder sleeve (21) matches the upper opening of the shell (6); and the outer diameter of the lower section of the cylinder sleeve (21) matches the lower opening of the shell (6).

3. The discharge pressure fluctuation buffer device for a drilling pump according to claim 1, characterized in that: The main column (23) adopts a stepped shaft structure. A boss is arranged at one end of the main column (23). The boss matches the countersunk hole a arranged on the end face of the blocking plate (26). A groove is opened in the circumferential direction on the upper end face of the boss. A sealing ring c (27) is installed in the groove. A through hole c is opened in the axial direction on the end face of the main column (23). The through hole c matches the through hole a.

4. The discharge pressure fluctuation buffer device for a drilling pump according to claim 1, characterized in that: The piston disc (29) adopts a disc-shaped structure, and a through hole d is opened in the axial direction on the upper end surface of the piston disc (29), and the through hole d matches the outer diameter of the lower section of the main column (23); The piston rod (30) adopts a stepped structure, the diameter of the upper section of the piston rod (30) is larger than the diameter of the lower section, the outer diameter of the upper section of the piston rod (30) matches the inner diameter of the upper section of the cylinder sleeve (21), and the piston (31) matches the inner diameter of the lower section of the cylinder sleeve (21).

5. The discharge pressure fluctuation buffer device for a drilling pump according to claim 1, characterized in that: The upper outer circumferential surface of the piston rod (30) and the outer circumferential surface of the piston disc (29) are both provided with annular grooves along the circumferential direction, and sealing rings g (34) are provided in the annular grooves. A sealing ring e (32) is provided between the piston (31) and the cylinder sleeve (21), a sealing ring i (36) is provided between the piston rod (30) and the main column (23), and a sealing ring f (33) is provided between the piston (31) and the piston rod (30).

6. The discharge pressure fluctuation buffer device for a drilling pump according to claim 1, characterized in that: The venting pipe assembly (19) comprises a vent cap b (49), the vent cap b (49) being threadedly connected to a third one-way valve (48) via a joint (39), the third one-way valve (48) being connected to the gas cylinder (14) via a main interface of a three-way connection b (50), and the three-way connection b (50) and the gas cylinder (14) being threadedly connected via a joint (39); The inflation pipe assembly (18) comprises an air pipe (45), an angle valve (44), and a tee (51) which are threadedly connected in sequence via a joint (39); a main interface at one end of the tee (51) is threadedly connected to a pressure gauge (46); a main interface at the other end of the tee (51) is threadedly connected to the air hole a; and the air pipe (45) is threadedly connected to the deflation pipe assembly (19).

Images