Spring type circulating valve

Abstract

The utility model discloses a spring type circulating valve which comprises an upper connector, a lower connector, a spline mandrel, a spline outer cylinder, a circulating outer cylinder and a circulating mandrel, a first circulating hole and a second circulating hole which are communicated with each other are formed in the corresponding positions of the circulating outer cylinder and the circulating mandrel, and the second circulating hole and the first circulating hole can be plugged in a staggered mode through a rubber piece and an auxiliary sealing piece. And a displacement buffer mechanism is arranged on the spline mandrel and the spline outer cylinder and has a function of preventing the circulating hole from being accidentally closed. By means of the circulation channel, on one hand, the upper pressure and the lower pressure of the packer rubber sleeve are balanced in the tripping process, on the other hand, after liquid of the drift diameter is discharged into the annular space through the circulation channel, the piston effect caused by negative pressure at the annular space at the upper end of the rubber sleeve is avoided, and the resistance effect during tripping and rubber sleeve setting is reduced. And downward pressure is effectively buffered through the buffer spring, so that the problem of gouges and damage to the circulating mandrel is avoided. In the drilling process, the counter-acting force of the buffer spring can prevent the packer or the tubular column from being slightly blocked.

Description

Technical Field

[0001] This application relates to the technical field of logging tools, and particularly to a spring-type circulation valve. Background Art

[0002] The spring-type circulation valve is a testing tool that assists the packer in setting and releasing during tripping operations. It is a supplement and extension to existing circulation tools. Its main functions are as follows: During the process of the packer being lowered into the well, due to the presence of a setting rubber barrel component, and the outer diameter of this setting rubber barrel component is usually relatively large, with a relatively small gap between it and the casing. Therefore, when the rubber barrel is in the casing, the up and down well fluids flow slowly, and the resistance formed makes it difficult for the packer to be tripped in and out and set. Thus, by means of the circulation valve, the liquid below the packer rubber barrel enters the through-hole of the packer and then circulates through the circulation valve to the annulus above the rubber barrel (when lifting, the well fluid flows in the reverse direction), reducing the impact of downhole fluid resistance on the packer.

[0003] There are mainly two commonly used types of traditional circulation valves for assisting packers: one is the mechanical RTTS circulation valve, and the other is the hydraulic circulation valve with a delay function. The RTTS circulation valve mainly controls the opening and closing of the circulation hole by designing a track groove that moves along a certain trajectory inside the tool, and the lug on the mandrel slides in the track groove. The hydraulic circulation valve mainly controls the opening and closing of the circulation hole by triggering the internal delay mechanism with pressure to control the length of the delay time. Each of these two types of circulation valves has its own insurmountable disadvantages during use, and their main limitations are as follows:

[0004] 1). Although the RTTS circulation valve has a simple structure, its operation is relatively complex. The opening and closing of the circulation hole can only be achieved through lifting, lowering, and rotating operations. In horizontal wells and highly deviated wells, it is very difficult to transmit the torque from the wellhead to the pipe string where the tool is located.

[0005] 2). Due to the limitation of its own track groove structure, there is a possibility that the lug will come out of the groove during the process of lowering the drill string, increasing the risk of accidentally closing the circulation hole. The above factors all increase the difficulty of the operation.

[0006] 3). The hydraulic circulation valve opens and closes the circulation hole by lifting and lowering, but it has a complex structure, and its internal delay structure is relatively precise. Once a failure occurs, the circulation hole cannot be closed, resulting in the failure of this operation. The operation requires a relatively high stability of the tool.

[0007] 4). The complex internal structure of the hydraulic circulation valve makes both the procurement cost and the maintenance cost much higher than those of other tools.

[0008] 5) The hydraulic circulation valve achieves delay by driving hydraulic oil. Therefore, the oil chamber must be cleaned thoroughly before adding hydraulic oil, and the requirements for the oil product are relatively high. Especially, the smaller the influence of temperature on the kinematic viscosity of the hydraulic oil, the better. Therefore, the preparation work before operation is rather cumbersome.

[0009] Therefore, according to the feedback from the on-site operators, it is very necessary and urgent to have a circulation tool that has the same functions as the traditional circulation valve, is easy to operate, has stable performance, is inexpensive, and is convenient for maintenance and servicing. Summary of the Invention

[0010] In view of the above problems, the present application aims to provide a spring-type circulation valve, which mainly reduces the liquid resistance during the process of running in and setting the packer, and effectively solves the functional deficiencies of the traditional circulation valve.

[0011] To achieve the above object, the technical solution adopted in the present application is as follows: A spring-type circulation valve includes an upper joint and a lower joint, and is characterized in that: a spline mandrel, a spline outer cylinder and a circulation outer cylinder are sequentially connected between the upper joint and the lower joint. A circulation mandrel is further provided at the bottom end of the spline mandrel and inside the circulation outer cylinder. The circulation outer cylinder and the circulation mandrel are provided with a first circulation hole and a second circulation hole that are mutually penetrated at corresponding positions, and the second circulation hole and the first circulation hole can be misaligned and blocked, and a displacement buffer mechanism is connected to the upper part of the circulation mandrel.

[0012] Preferably, the displacement buffer mechanism includes a buffer chamber jointly formed between the spline mandrel and the spline outer cylinder, and a buffer spring provided in the buffer chamber.

[0013] Preferably, a locking piston is movably embedded between the end parts of the spline outer cylinder and the circulation mandrel. An outer ring hole is provided at the top end of the circulation outer cylinder where the locking piston is located, and an inner ring hole is provided on the spline mandrel opposite to the inner bottom of the locking piston.

[0014] Preferably, a drain hole communicating with the buffer chamber is circumferentially provided at the bottom of the spline outer cylinder.

[0015] The beneficial effects of the present application are: The spring-type circulation valve has a simple structure and high reliability in use. It can close and open the circulation channel by directly lifting and lowering the pipe string, and solves the following three problems:

[0016] First, the range of oil and gas wells used is wider. By using the method of lifting and lowering to switch the circulation channel, it can meet the requirements of vertical wells with good verticality, and can also meet the use requirements of highly deviated wells and horizontal wells;

[0017] Second, the damping mode of the spring is adopted. On the one hand, the pipe string can be directly pressed down to close the circulation hole. On the other hand, the resistance of the spring can prevent the circulation hole from being accidentally closed due to slight resistance during the process of running in the hole; during the process of closing the circulation hole, it plays a buffering role for the spline mandrel to prevent severe collision due to inertia;

[0018] Third, the preparatory work in the early stage of the tool is greatly reduced, the mechanism is simple, the operation is simple, and the reliability is higher. This tool has no delay mechanism. Before running into the well, there is no need to install hydraulic oil, only reliable sealing is required, no rotation operation is needed, and the maintenance and procurement costs are low. Brief Description of the Drawings

[0019] Figure 1 It is a schematic diagram of the overall structure of the spring-type circulation valve of this application.

[0020] Figure 2 For this application Figure 1 An enlarged schematic diagram of the structure at position A in it.

[0021] Figure 3 For this application Figure 1 An enlarged schematic diagram of the structure at position B in it.

[0022] Figure 4 For this application Figure 1 An enlarged schematic diagram of the structure at position C in it.

[0023] Figure 5 For this application Figure 1 A sectional view taken along the direction D in it.

[0024] In the figure: 2 - scraping cap; 7a - stepped surface; (11 - 15) - support seal; (16 - 21) - O-ring. Detailed Description of the Invention

[0025] In order to enable those of ordinary skill in the art to better understand the technical solution of this application, the technical solution of this application will be further described below in conjunction with the drawings and embodiments.

[0026] Referring to Figures 1 to 4 A spring-type circulation valve shown in the figure, including an upper sub 1 and a lower sub 10. The upper sub 1 is used to connect the circulation valve to the tool string, and the lower sub 10 is used to connect to the downhole packer. As Figures 2 - 4As shown, a spline mandrel 4, a spline outer cylinder 3, and a circulation outer cylinder 9 are sequentially connected between the upper sub 1 and the lower sub 10. A circulation mandrel 8 is further provided at the bottom end of the spline mandrel 4 and inside the circulation outer cylinder 9. A scraping cap 2 for upward step limiting of the spline mandrel 4 is provided at the top end of the spline outer cylinder 3. The spline mandrel 4 is in sliding contact downward relative to the scraping cap 2 and the spline outer cylinder 3. Preferably, the spline mandrel 4 and the spline outer cylinder 3 are in a key and keyway mating structure, so as to transmit the torque input from the wellhead to the spline mandrel 4 when the circulation valve needs to rotate, and then transmit it to the tools below the circulation valve through the spline outer cylinder 3. Preferably, the other connected components of the circulation valve are in a threaded fixed connection.

[0027] In order to balance the liquid resistance above and below the rubber cylinder of the packer connected to the lower sub 10, and facilitate the lifting, lowering and setting of the packer, as Figure 3 shown, first circulation holes a1 and second circulation holes a2 that communicate with each other are provided at corresponding positions of the circulation outer cylinder 9 and the circulation mandrel 8, and the second circulation holes a2 and the first circulation holes a1 can be misaligned and blocked. When the circulation valve and the packer are in normal use, the well fluid in the annulus at the lower end of the packer rubber cylinder enters the through-hole and then ascends into the through-hole of the circulation valve, and circulates to the annulus outside the circulation outer cylinder 9 through the opposite first circulation holes a1 and second circulation holes a2, so as to balance the liquid resistance above and below the packer rubber cylinder (the well fluid flows in the reverse direction when lifting), thus facilitating the lowering and setting operations of the packer. At the same time, the circulation channel holes provide a passage for the well fluid in the annulus at the upper and lower ends of the rubber cylinder, avoiding the occurrence of negative pressure at one side of the packer annulus, causing the piston effect, and reducing the resistance during tripping and setting the packer.

[0028] When the packer needs to be set, the upper sub 1 of the circulation valve is pressed downward to drive the spline mandrel 4 and the circulation mandrel 8 to move downward, and the second circulation holes a2 on the circulation mandrel 8 are displaced to the lower side of the support seal and the O-ring provided on the upper side of the inner wall of the lower sub 10, realizing the misaligned blockage of the first circulation holes a1 and the second circulation holes a2, and closing the circulation channel.

[0029] During the process of running in the hole, the second circulation holes a2 of the circulation mandrel 8 may repeatedly pass through the support seal and the O-ring provided on the upper side of the inner wall of the lower sub 10, which increases the wear of the sealing rubber parts to a certain extent, and increases the possibility of scratching the sealing ring, increasing the risk of seal failure. Therefore, as Figure 4 shown, preferably, two sealing structures are provided to increase the probability of successful operation.

[0030] During the process of pressing the upper sub 1 downward to close the circulation channel, in order to prevent excessive downward pressure from knocking and damaging the circulation mandrel 8, as Figure 3As shown, a shift buffer mechanism is connected to the circulating mandrel 8. Through this shift buffer mechanism, during the process of pressing down the upper joint 1, the downward pressure can be effectively buffered, thus avoiding the problem of knocking and damaging the circulating mandrel 8.

[0031] Specifically, as Figure 3 shown, the shift buffer mechanism includes a buffer chamber b jointly formed between the spline mandrel 4 and the spline outer cylinder 3, and a buffer spring 6 arranged in the buffer chamber b. During the process of pressing down the upper joint 1, the downward pressure is effectively buffered by the buffer spring 6, thereby avoiding the problem of knocking and damaging the circulating mandrel 8. At the same time, during the process of drilling down, the reaction force of the buffer spring 6 can also avoid the risk that the circulating valve is slightly stuck, resulting in the accidental closing of the circulating channel due to the self - downward movement of the circulating mandrel 8.

[0032] After the packer is set, sometimes due to the negative pressure at the bottom of the well, there is an upward acting force on the packer and the entire string. This acting force will cause the packer to have a tendency to be released. When the anchoring ability of the slip of the hydraulic anchor is insufficient, it can even be released, as Figure 3 shown, a locking piston 7 is also movably embedded between the end of the spline outer cylinder 3 and the circulating mandrel 8. An outer ring hole c1 is provided at the top of the circulating outer cylinder 3 where the locking piston 7 is located. An inner ring hole c2 is provided on the spline mandrel 4 opposite to the inner bottom of the locking piston 7. And a step surface 7a corresponding to the inner ring hole c2 is provided at the inner bottom of the locking piston 7. Before the circulating channel of the circulating valve is closed, the annulus pressure and the through - bore pressure act on the locking piston 7 through the outer ring hole c1 and the inner ring hole c2. Since the pressure in the annulus and the through - bore is balanced before the circulating hole is closed, the locking piston is not stressed.

[0033] At the same time, when the packer is set and the circulating channel is closed, if the annulus pressure is greater than the formation pressure, a downward pressure is generated on the locking piston 7 through the outer ring hole c1 and acts on the string, preventing the formation pressure from generating an upward acting force on the packer, thus avoiding the risk that the packer has a tendency to be released or is directly released, which is beneficial to the setting of the packer.

[0034] When pressing down the upper joint of the circulating valve when the packer needs to be set, the spline mandrel 4 moves downward to compress the buffer spring 6, the inner cavity of the buffer chamber b shrinks, resulting in an increase in the pressure in the buffer chamber b and correspondingly increasing the setting resistance of the packer, thus affecting the smooth setting of the packer. Therefore, to solve this problem, as Figure 3 shown, a drain hole d communicating with the buffer chamber b is circumferentially provided at the bottom of the spline outer cylinder 3, which can discharge the formation fluid in the buffer chamber b, reduce the downward pressure resistance, and facilitate the quick setting of the packer.

[0035] The principle of this application is as follows: The circulation valve is connected to the top of the packer through the lower joint 10 and lowered simultaneously with the packer. In the current state, the first circulation hole a1 and the second circulation hole a2 of the circulation valve are in alignment and communicate with each other. The well fluid below the packer rubber barrel enters the through-hole, rises continuously, and then enters the annulus outside the circulation valve through the second circulation hole a2 and the first circulation hole a1, realizing that the pressure below the packer is circulated to the annulus through its through-hole and the circulation valve, and reducing the resistance caused by the pressure below the packer to the setting of the packer when it is lowered.

[0036] During the circulation process, when there is a pressure difference between the through-hole pressure and the annulus pressure, the annulus pressure and the through-hole pressure act on the locking piston 7 through the outer annulus hole c1 and the inner annulus hole c2. The locking piston 7 balances the annulus pressure and the through-hole pressure, so that the circulation valve is not affected by force before the circulation channel is closed.

[0037] After the setting is completed, press down the upper joint of the circulation valve, and the buffer spring 6 is compressed to buffer the downward pressure to a certain extent. At the same time, the formation fluid in the buffer chamber b can be discharged through the drain hole d, reducing the resistance of the downward pressure and facilitating the quick setting of the packer. The circulation mandrel 8 moves downward relative to the circulation outer barrel 9, so that the second circulation hole a2 moves downward to the position below the support seal and the O-ring on the inner wall of the lower joint 10, causing the second circulation hole a2 and the first circulation hole a1 to be misaligned and blocked, realizing the closing of the circulation channel.

[0038] The above shows and describes the basic principle, main features and advantages of this application. Without departing from the spirit and scope of this application, this application will have various changes and improvements, and these changes and improvements all fall within the scope of this application claimed.

Claims

1. A spring-type circulation valve, comprising an upper joint (1) and a lower joint (10), characterized in that: A spline core shaft (4), a spline outer cylinder (3) and a circulation outer cylinder (9) are connected in sequence between the upper joint (1) and the lower joint (10). A circulation core shaft (8) is also provided at the bottom end of the spline core shaft (4) and inside the circulation outer cylinder (9). A first circulation hole (a1) and a second circulation hole (a2) which are interconnected are provided at corresponding positions of the circulation outer cylinder (9) and the circulation core shaft (8). The second circulation hole (a2) and the first circulation hole (a1) can be offset and blocked, and a displacement buffer mechanism is connected to the circulation core shaft (8).

2. The spring-loaded circulation valve according to claim 1, characterized in that: The displacement buffer mechanism comprises a buffer chamber (b) which is jointly arranged between a spline core shaft (4) and a spline outer cylinder (3), and a buffer spring (6) arranged in the buffer chamber (b).

3. The spring-loaded circulation valve according to claim 2, characterized in that: A locking piston (7) is movably embedded between the ends of the spline outer cylinder (3) and the circulating core shaft (8); an outer ring hole (c1) is provided on the circulating outer cylinder (9) at the top end of the locking piston (7); and an inner ring hole (c2) is provided on the spline core shaft (4) opposite to the inner bottom of the locking piston (7).

4. The spring-loaded circulation valve according to claim 3, characterized in that: A drainage hole (d) communicating with the buffer chamber (b) is circumferentially provided at the bottom of the spline outer cylinder (3).

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