An auxiliary device and testing system for testing the fatigue performance of sucker rods.

Abstract

This utility model discloses an auxiliary device and testing system for testing the fatigue performance of sucker rods. The auxiliary device includes a sucker rod joint and a sealing cylinder. The sucker rod joint is slidably inserted into both ends of the sealing cylinder, and the sealing cylinder and the sucker rod joint are sealed by a sealing element. The cylinder wall of the sealing cylinder has an inlet and an outlet between the sucker rod joints at both ends. This utility model immerses the sucker rod in a flowing liquid for fatigue testing. The liquid can remove the heat generated by internal friction of the sucker rod, reducing the cracking problem of carbon fiber sucker rods caused by internal friction heat generation, and enabling the fatigue test to reflect the environmental conditions of the sucker rod when used in an oil well.

Description

Technical Field

[0001] This utility model relates to the field of oilfield machinery performance testing technology, specifically to an auxiliary device and testing system for testing the fatigue performance of sucker rods. Background Technology

[0002] Carbon fiber sucker rods are sucker rods made of carbon fiber and resin composite materials. Compared with steel sucker rods, they have higher tensile strength and lower density. When used in oil pumping well production systems, they can increase the load-bearing capacity of the sucker rods.

[0003] During the use of sucker rods in oil wells, the load borne by the upstroke is much greater than that of the downstroke. During a single stroke, the load borne by the sucker rod changes significantly, and it is subjected to alternating loads. Numerous sucker rod fracture cases indicate that sucker rod fractures are fatigue fractures caused by alternating loads. Therefore, the fatigue performance of sucker rods is one of its main mechanical properties.

[0004] GB / T 43303-2023, "Oil and Gas Drilling and Production Equipment - Sucker Rods," provides fatigue testing methods. It requires a loading frequency below 150Hz and the use of a fatigue testing machine to test the fatigue performance of sucker rods. There are two types of fatigue testing machines: electro-hydraulic servo fatigue testing machines and electromagnetic excitation resonance fatigue testing machines. The former has a testing frequency of 0-80Hz, while the latter has a testing frequency of 80-250Hz. Extensive fatigue tests on sucker rods show that both types of fatigue testing machines can be used to test steel sucker rods. However, carbon fiber sucker rods, with an elastic modulus of approximately 130GPa, which is much lower than the 210GPa of steel sucker rods, will experience greater fatigue under alternating loads. Large expansion and contraction cause internal deformation of the material, resulting in strong internal friction. Actual fatigue tests show that at frequencies above 10Hz, frictional heat generation is very significant, and the surface temperature of the sucker rod rises rapidly, from room temperature to hot to the touch within minutes. Carbon fiber sucker rods contain resin materials, and the properties of the resin change significantly with temperature. High temperatures can cause changes in the performance of the carbon fiber sucker rod, leading to structural cracking. Once the structure is damaged, the performance of the sucker rod is compromised, making it impossible to complete the fatigue test. Even by reducing the test frequency to as low as 1Hz, the impact of temperature rise on the fatigue test cannot be avoided. Moreover, using a frequency of 1Hz to complete the standard requirement of one million fatigue cycles for sucker rods would require 278 hours, making the fatigue test too time-consuming.

[0005] During the use of carbon fiber sucker rods in oil wells, they are immersed in the produced fluid. The produced fluid carries away the heat generated by internal friction of the sucker rod. Therefore, fatigue tests on carbon fiber sucker rods should be conducted by immersing the sucker rod in the liquid to truly reflect its performance in the operating environment.

[0006] Publication No.: CN110793847A discloses a sucker rod fatigue test clamp based on staggered cylindrical surface clamping, including clamping plate A and clamping plate B connected by fasteners. The two are fixed in a relatively close manner to form a clamping head, clamping part and clamping tail of the clamping device. When the clamping part is a small cylindrical surface, its equivalent stress is greater than that of clamping on the entire cylindrical surface, and it is easier to undergo plastic deformation. Compared with the entire cylindrical surface as the clamping surface, when the sucker rod is clamped by the staggered small cylindrical surfaces, its deformation is spiral, which increases the friction coefficient and makes it easier to clamp. That is, under a smaller preload, it is possible to clamp the sucker rod and neither the clamping device nor the sucker rod will undergo plastic deformation.

[0007] The existing technology provides a sucker rod clamp, but it cannot solve the problem of internal friction-induced temperature rise and cracking in carbon fiber sucker rods.

[0008] Announcement No. CN116429606A discloses a fatigue testing machine for continuous sucker rods and its usage method, including a base, an electromagnetic vibrator, damping springs, a support seat, a low-cycle fatigue testing mechanism, lead screw columns, an adjusting lead screw sleeve, and a crossbeam; four damping springs are symmetrically arranged at the lower end of the base; a support seat is installed at the upper end of the base; a low-cycle fatigue testing mechanism is installed on the base inside the support seat; lead screw columns are symmetrically fixed on the top of the support seat; a crossbeam is movably installed between the lead screw columns through an adjusting lead screw sleeve; an electromagnetic vibrator is installed on the crossbeam through a bracket.

[0009] The existing technology provides a fatigue testing machine, but it cannot solve the problem of internal friction-induced temperature rise and cracking in carbon fiber sucker rods.

[0010] Publication No. CN106442291A discloses a corrosion fatigue life prediction method and its application based on a BP neural network. The method selects maximum stress, stress ratio, loading frequency, and solution pH as the main factors affecting corrosion fatigue life. It designs and manufactures a matching corrosion solution circulation device for corrosion fatigue testing, conducts a series of corrosion fatigue cyclic failure experiments on high-strength sucker rod samples under specific production environments, collects and organizes experimental data, and divides it into training samples and prediction samples. It sets the parameters of the artificial neural network, establishes a nonlinear mapping between influencing factors and corrosion fatigue life, trains and tests the neural network, and predicts the corrosion fatigue life of new samples.

[0011] The existing technology provides a method for testing the relationship between corrosion and fatigue performance of sucker rods, but it cannot solve the problem of internal friction-induced temperature rise and cracking in carbon fiber sucker rods.

[0012] In summary, the technical solutions, technical problems to be solved, and beneficial effects of the above-disclosed technologies are all different from those of this utility model. For more technical features, technical problems to be solved, and beneficial effects of this utility model, the above-disclosed technical documents do not provide any technical inspiration. Utility Model Content

[0013] To address the aforementioned deficiencies in existing technologies, the purpose of this invention is to provide an auxiliary device and testing system for testing the fatigue performance of sucker rods. This system allows the sucker rod to be immersed in a flowing liquid for fatigue testing, thus solving the problem of internal friction-induced temperature rise and cracking in carbon fiber sucker rods. Furthermore, fatigue tests conducted using this device better reflect the performance of the sucker rod in its operating environment.

[0014] To achieve the above objectives, the present invention adopts the following technical solution:

[0015] On the one hand, this utility model provides an auxiliary device for testing the fatigue performance of sucker rods, including a sucker rod joint and a sealing cylinder; the sucker rod joint is slidably inserted into both ends of the sealing cylinder, and the sealing cylinder and the sucker rod joint are sealed by a sealing element, and the cylinder wall of the sealing cylinder is provided with an inlet and an outlet between the sucker rod joints at both ends.

[0016] Furthermore, the oil rod connector includes a retaining ring, a retaining sleeve, and a clamping handle;

[0017] Specifically, the inner wall of the retaining ring is provided with a first conical surface, the outer wall of the retaining sleeve is provided with a second conical surface, the retaining sleeve is inserted into the retaining ring, the first conical surface and the second conical surface are engaged, and the retaining sleeve is provided with a slit opening;

[0018] Specifically, the clamping handle is connected to the clasp port, the first conical surface faces the clamping handle, and the outer diameter of the clamping handle is smaller than the outer diameter of the clasp.

[0019] Furthermore, a limiting step is provided on the outer wall of the retaining ring of one of the two oil rod joints, and the limiting step contacts and limits the sealing cylinder.

[0020] Furthermore, a straight handle portion is provided at the end of the clamping handle away from the retaining ring.

[0021] Furthermore, the sealing element is a sealing groove and a sealing ring, and the sealing element is disposed on the inner wall of the sealing cylinder or the outer wall of the retaining ring.

[0022] Furthermore, the clamping handle is connected to the retaining ring port via an external threaded connector.

[0023] Secondly, this utility model provides a sucker rod fatigue performance testing system, including a fatigue testing machine, a water pump, a constant temperature water tank, and an auxiliary device for sucker rod fatigue performance testing as described in one aspect; the water pump is connected to the liquid inlet on the sealing cylinder through a water inlet pipe, and the constant temperature water tank is connected to the liquid outlet on the sealing cylinder through a water outlet pipe, and the constant temperature water tank contains a cooling medium.

[0024] Furthermore, the cooling medium is water or oil.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] This invention involves immersing the sucker rod in a flowing liquid for fatigue testing. The liquid can carry away the heat generated by internal friction in the sucker rod, reducing the cracking problem of carbon fiber sucker rods caused by internal friction heat generation, and enabling the fatigue test to reflect the environmental conditions when the sucker rod is used in the oil well. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of an auxiliary device for testing the fatigue performance of sucker rods according to this utility model.

[0028] Figure 2 This is a schematic diagram of the structure of the first oil rod joint in this utility model.

[0029] Figure 3 This is a schematic diagram of the structure of the second oil rod connector in this utility model.

[0030] Figure 4 This is a schematic diagram of the sealing cylinder in this utility model.

[0031] In the diagram: 1-carbon fiber sucker rod, 2-clamping ring, 3-clamping sleeve, 4-sealing cylinder, 5-inlet, 6-outlet, 7-sealing groove and sealing ring, 8-clamping handle, 9-limiting step, 10-upper clamping block, 11-lower clamping block. Detailed Implementation

[0032] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0033] Example 1:

[0034] Please see Figures 1 to 4This utility model provides an auxiliary device for testing the fatigue performance of sucker rods, including a sealing cylinder 4, a first sucker rod connector, and a second sucker rod connector. The first sucker rod connector is slidably inserted into one port of the sealing cylinder 4, and the second sucker rod connector is slidably inserted into the other port of the sealing cylinder 4. The first sucker rod connector or the second sucker rod connector is positioned with the sealing cylinder 4 by a positioning element. The inner wall of the sealing cylinder 4 is sealed with the first sucker rod connector and the second sucker rod connector by a sealing element. The cylinder wall of the sealing cylinder 4 is provided with a liquid inlet 5 and a liquid outlet 6, which are located between the first sucker rod connector and the second sucker rod connector.

[0035] Furthermore, the first oil rod connector and the second oil rod connector include a retaining ring 2, a retaining sleeve 3, and a clamping handle 8. The inner wall of the retaining ring 2 is provided with a first conical surface, and the outer wall of the retaining sleeve 3 is provided with a second conical surface. The retaining sleeve 3 is inserted into the retaining ring 2, and the first conical surface and the second conical surface are engaged. The retaining sleeve 3 is provided with a slit to facilitate compression and shrinkage. The clamping handle 8 is provided with an external threaded connector to connect to the port of the retaining ring 2. The first conical surface faces the clamping handle 8, that is, the large-diameter end of the first conical surface is close to the clamping handle 8. The outer diameter of the clamping handle 8 is smaller than the outer diameter of the retaining ring 2.

[0036] Specifically, a limiting step 9 is provided on the outer wall of one of the retaining rings 2 in the first oil rod connector and the second oil rod connector. The limiting step 9 serves as a positioning element. In this embodiment, the limiting step 9 is provided on the outer wall of the retaining ring 2 of the second oil rod connector.

[0037] Specifically, the end of the clamping handle 8 away from the retaining ring 2 is provided with a straight handle portion for easy clamping.

[0038] Specifically, the sealing element is a sealing groove and a sealing ring 7, and the sealing element is disposed on the inner wall of the sealing cylinder 4 or the outer wall of the retaining ring 2.

[0039] Example 2:

[0040] The fatigue performance of carbon fiber sucker rods was tested using the apparatus described in Example 1. The carbon fiber sucker rod 1 sample was clamped on a fatigue testing machine and subjected to fatigue testing. During the test, a water pump continuously pumped water, allowing water to flow through the sealed cylinder 4, which promptly carried away the heat generated by friction within the carbon fiber sucker rod 1.

[0041] Based on the above description, the specific implementation steps are as follows:

[0042] Insert the carbon fiber sucker rod 1 into the sleeve 3, and then place the sleeve 3 into the retaining ring 2. Because of the tapered geometry of the outer surface of the sleeve 3 and the inner hole of the retaining ring 2, stretching the carbon fiber sucker rod 1 will cause the retaining ring 2 to press against the tapered surface of the outer surface of the sleeve 3, and make the sleeve 3 hold the carbon fiber sucker rod 1 tightly, thus realizing the connection between the first oil rod joint and the carbon fiber sucker rod 1.

[0043] The other end of the carbon fiber sucker rod 1 is connected to the second rod joint in the same way, thus completing the assembly and preparation of the fatigue test specimen of the carbon fiber sucker rod 1.

[0044] The carbon fiber sucker rod 1 fatigue test specimen is inserted into the sealing cylinder 4, so that the positions of the sealing rings 7 at both ends of the sealing cylinder 4 are aligned with the outer sealing cylinder sections of the first sucker rod joint and the second sucker rod joint, respectively. The limiting step 9 on the outer wall of the retaining ring 2 in the second sucker rod joint positions the sealing cylinder 4.

[0045] Connect the inlet pipe to the liquid inlet 5 on the sealing cylinder 4, connect the outlet pipe to the liquid outlet 6 on the sealing cylinder 4, connect the other end of the inlet pipe to the water pump, and connect the other end of the outlet pipe to the water storage tank.

[0046] Turn on the water pump. The water pump draws water from the water storage tank and pressurizes it. The water flows into the sealing cylinder 4 along the inlet pipe. After passing through the sealing cylinder 4, the water flows back to the water storage tank along the outlet pipe.

[0047] The water storage tank is equipped with a thermostat to achieve cooling and heating. For example, cooling is achieved through heat dissipation fins and a cooling fan, while heating is achieved through an electric heater. The thermostat is used to control the water temperature in the outlet tank to maintain a certain required temperature, with a temperature range of 20℃-90℃.

[0048] The first oil rod joint and the second oil rod joint are clamped on the upper clamping block 10 and the lower clamping block 11 of the fatigue testing machine, respectively. The fatigue testing machine is started to carry out the fatigue test. During the test, the water pump continuously pumps water so that water flows through the sealing cylinder 4, which can carry away the heat generated by the internal friction of the carbon fiber sucker rod 1 in time, and reduce the impact of the internal friction heat generation on the fatigue test of the carbon fiber sucker rod 1.

[0049] Accurate fatigue performance data of carbon fiber sucker rod 1 were obtained.

[0050] The fatigue performance of glass fiber sucker rods and hybrid fiber sucker rods were tested using the methods described above, and accurate fatigue performance data for glass fiber sucker rods and hybrid fiber sucker rods were obtained.

[0051] Example 3:

[0052] The fatigue performance test of carbon fiber sucker rod was conducted using the device described in Example 1. The difference between this example and Example 2 is that the water tank contains oil, which can be machine oil or kerosene.

[0053] Turn on the water pump. The water pump draws oil from the water storage tank and pressurizes it. The oil flows into the water cylinder through the inlet pipe, and the water flows back to the water storage tank through the outlet pipe after passing through the water cylinder.

[0054] The temperature range of the thermostat is 20℃-150℃.

[0055] All components not discussed in detail in this application, as well as the connection methods of these components, are well-known technologies in this field. They can be directly applied and will not be elaborated further.

[0056] In this utility model, the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; "linking" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0057] In the description of this utility model, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0058] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0059] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. An auxiliary device for testing the fatigue performance of sucker rods, comprising a sucker rod joint, characterized in that, It also includes a sealing cylinder; Oil rod connectors are slidably inserted at both ends of the sealing cylinder. The sealing cylinder and the oil rod connectors are sealed by a sealing element. An inlet and an outlet are provided on the cylinder wall between the oil rod connectors at both ends.

2. The auxiliary device for testing the fatigue performance of sucker rods according to claim 1, characterized in that, The oil rod connector includes a retaining ring, a retaining sleeve, and a clamping handle; The inner wall of the retaining ring is provided with a first conical surface, the outer wall of the retaining sleeve is provided with a second conical surface, the retaining sleeve is inserted into the retaining ring, the first conical surface and the second conical surface are engaged, and the retaining sleeve is provided with a slit opening; The clamping handle is connected to the clasp port, the first conical surface faces the clamping handle, and the outer diameter of the clamping handle is smaller than the outer diameter of the clasp.

3. The auxiliary device for testing the fatigue performance of sucker rods according to claim 2, characterized in that, One of the two oil rod joints has a limiting step on the outer wall of the retaining ring, and the limiting step contacts and limits the sealing cylinder.

4. The auxiliary device for testing the fatigue performance of sucker rods according to claim 2, characterized in that, The clamping handle is provided with a straight handle portion at the end away from the retaining ring.

5. The auxiliary device for testing the fatigue performance of sucker rods according to claim 2, characterized in that, The sealing element consists of a sealing groove and a sealing ring, and the sealing element is disposed on the inner wall of the sealing cylinder or the outer wall of the retaining ring.

6. The auxiliary device for testing the fatigue performance of sucker rods according to claim 2, characterized in that, The clamping handle is connected to the retaining ring port via an external threaded connector.

7. A fatigue performance testing system for sucker rods, comprising a fatigue testing machine, characterized in that, It also includes a water pump, a constant temperature water tank, and an auxiliary device for testing the fatigue performance of a sucker rod as described in claim 1; The water pump is connected to the liquid inlet on the sealing cylinder via an inlet pipe, and the constant temperature water tank is connected to the liquid outlet on the sealing cylinder via an outlet pipe. The constant temperature water tank contains a cooling medium.

8. The sucker rod fatigue performance testing system according to claim 7, characterized in that, The cooling medium is water or oil.

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