An underground anti-falling device and a positive displacement motor

Abstract

The present invention discloses a downhole anti-drop device and a positive displacement motor, which relate to the technical field of downhole oil drilling. The device includes: a hollow outer shell part, in which a limiting step is provided to divide the cavity of the outer shell part into a lower cavity and an upper cavity that communicate with each other. An overflow hole is provided on the limiting step. The lower cavity is used to be docked with the motor, and a static valve part is arranged in the upper cavity; a moving valve rod connected to the rotor of the motor, on which a moving valve plate located in the upper cavity is provided. The moving valve plate is arranged at an interval from one side of the static valve part close to the motor and cooperates with the static valve part to form an overflow channel; wherein, when the rotor is tripped and falls off, the moving valve plate moves away from the static valve part along with the rotor and fits against the end face of the limiting step to block the overflow hole of the limiting step, resulting in the overflow resistance of the overflow channel decreasing sharply first and then increasing sharply. The downhole anti-drop device in this application can not only prevent the rotor from falling off, but also provide a secondary reminder for the detachment of the rotor, giving the operator an operation space and avoiding secondary impacts.

Description

Technical Field

[0001] The present invention relates to the field of oil drilling, and particularly to a downhole anti-drop device and a positive displacement motor Background Art

[0002] In recent years, with the rapid development of China's economy, the demand for energy has been increasing day by day, and the exploitation volume of oil resources has also been gradually rising. As the shallow formations and easily exploitable oil and gas resources are gradually exhausted, the exploration and development of horizontal wells and extended reach wells in China are becoming more and more extensive. However, during the drilling process of horizontal wells and highly deviated wells, the drill string is in sliding drilling, so it often faces problems such as drag, sticking, and helical buckling caused by the self-weight of the drill string or the cuttings bed, etc., which affect the effective transmission of the drilling pressure, reduce the drilling efficiency or lead to downhole complex situations. However, the existing positive displacement motor is a volumetric downhole power drill that uses mud as the driving force. It can use the drilling mud as the power source to drive the rotation of the rotor of the motor, and then continuously transmit the torque and rotational speed to the drill bit, so as to achieve safe and efficient drilling, shorten the drilling time, and reduce the comprehensive drilling cost.

[0003] However, in the actual operation of the positive displacement motor, the rotor may fall off due to the uncoupling of the rotor of the motor and the rubber stator bushing. Once the rotor falls off, if there is no protection measure or the falling situation is not discovered in time, it will cause the fracture and damage of the positive displacement motor tool, and even lead to more serious downhole accidents. In the related art, an anti-drop mechanism is connected to the rotor. Once the rotor falls off, the anti-drop mechanism will cooperate with the internal flow-through hole of the positive displacement motor to prevent the rotor from completely falling off. At the same time, the anti-drop mechanism fits with the flow-through hole, resulting in a sudden change in the mud flow area inside the drill, which in turn causes an increase in the fluid pressure inside the drill string and an increase in the pump pressure. The user can obtain a "rotor fall" prompt based on the sudden change in the pump pressure. However, the applicant has found in actual work that the "rotor fall" prompt lasts for a short time and does not leave enough reaction time for the operator. It is easy for the operator to miss or ignore the "rotor fall" prompt during work. And because the anti-drop mechanism fits with the flow-through hole, the mud channel will be completely blocked. Once the operator does not discover it in time and stops the equipment, it will cause secondary effects such as the inability to start the pump of the drill. Summary of the Invention

[0004] Aiming at the problems that the "anti-drop warning" of the downhole anti-drop structure in the related art is not easy to detect and the reaction time left for the operator is insufficient, the present application provides a downhole anti-drop device for a positive displacement motor, which includes:

[0005] A hollow outer shell part, which is provided with a limiting step inside to divide the cavity of the outer shell part into a mutually connected lower cavity and an upper cavity. The limiting step is provided with a flow-through hole. The lower cavity is used to be docked with the motor, and a static valve part is arranged in the upper cavity;

[0006] A movable valve rod connected to the rotor of the motor, on which there is a movable valve plate located in the upper cavity. The movable valve plate is spaced from one side of the static valve portion close to the motor and cooperates with the static valve portion to form a flow passage; wherein,

[0007] When the rotor is tripped and drops, the movable valve plate is used to move away from the static valve portion along with the rotor and block the flow hole of the limiting step, so that the flow resistance of the flow passage first decreases sharply and then increases sharply.

[0008] In some embodiments, the movable valve plate and the static valve portion are radially eccentrically arranged in the housing portion, and the center of the movable valve plate is coaxially arranged with the movable valve rod; wherein,

[0009] When the rotor of the motor operates normally, the rotor drives the movable valve plate to rotate through the movable valve rod, so that the flow resistance of the flow passage between the movable valve plate and the static valve portion changes periodically.

[0010] In some embodiments, at least one second drain hole is formed in the movable valve plate.

[0011] In some embodiments, the static valve portion includes:

[0012] A static valve seat, which is assembled in the upper cavity;

[0013] A static valve plate, which is assembled on the static valve seat, and at least one first drain hole is formed in the static valve plate. The flow area of the first drain hole is larger than that of the second drain hole.

[0014] In some embodiments, the shape of the second drain hole is fan-shaped.

[0015] In some embodiments, the shape of the movable valve plate is a Reuleaux triangle.

[0016] In some embodiments, three of the second drain holes are formed in a circumferential distribution on the movable valve plate.

[0017] In some embodiments, the second drain hole is a round hole with a diameter of 10 mm.

[0018] In some embodiments, the gap distance between the movable valve plate and the static valve portion is between 2 and 5 mm.

[0019] On the other hand, the present application provides a positive displacement motor drill, which includes: the downhole anti-falling device according to any one of the above.

[0020] Compared with the prior art, in the present invention, a static valve part is arranged at intervals above the moving valve plate, so that there is an overflow gap between the two. Once the rotor drops, the overflow gap between the moving valve plate and the static valve part becomes larger, thereby causing a sudden change in the pump pressure as the first drop warning. Subsequently, the moving valve plate fits with the overflow through-hole to block the mud channel, causing a second pump pressure change as the second drop reminder. The downhole anti-drop device of the present invention can not only prevent the rotor from dropping, but also provide a secondary reminder for the detachment of the rotor, giving the operator an operation space and avoiding secondary effects. Further, in the present invention, the moving valve plate rotates with the rotor, causing the overflow gap between the moving valve plate and the static valve part to continuously change, thereby causing a flow pulsation in the inner cavity. And the drilling fluid with pulsating pressure enters the annular space between the motor stator and the rotor from the inner cavity of the anti-drop joint, thereby providing greater hydraulic energy for the rotation of the rotor. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0022] Figure 1 It is a cross-sectional view of the downhole anti-drop device in the embodiment of the present invention;

[0023] Figure 2 It is a schematic diagram of the moving valve plate in the embodiment of the present invention;

[0024] Figure 3 is Figure 1 a schematic diagram of the A-A view in;

[0025] Figure 4 It is a schematic diagram of the state where the moving valve plate fits with the limiting step in the embodiment of the present invention.

[0026] In the figure: 1. Outer shell part; 11. Limiting step; 12. Lower cavity; 13. Upper cavity; 2. Motor; 21. Rotor; 4. Moving valve rod; 5. Moving valve plate; 51. Second drainage hole; 6. Static valve part; 61. Static valve seat; 62. Static valve plate; 63. First drainage hole. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. Apparently, the described embodiments are some but not all of the embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts fall within the scope of protection of this application.

[0028] The following further elaborates on the embodiments of the present invention with reference to the accompanying drawings. Aiming at the problems in the related art that the "fall prevention warning" of the downhole anti-falling structure is not easily noticeable and the reaction time left for the operator is insufficient, as Figure 1 shown, this application provides a downhole anti-falling device, which includes: a housing part 1, a moving valve plate 5, and a static valve part 6; wherein,

[0029] The hollow housing part 1 is provided with a limiting step 11 that divides the cavity of the housing part 1 into a mutually connected lower cavity 12 and upper cavity 13. The limiting step 11 is provided with a flow-through hole. The lower cavity 12 is used to be docked with the motor 2, and the static valve part 6 is arranged in the upper cavity 13;

[0030] A moving valve rod 4 connected to the rotor 21 of the motor 2 is provided with a moving valve plate 5 located in the upper cavity 13. The moving valve plate 5 is arranged at an interval with one side of the static valve part 6 close to the motor 2 and cooperates with the static valve part 6 to form a flow-through channel; wherein,

[0031] When the rotor 21 is tripped and falls, the moving valve plate 5 first moves away from the static valve part 6 along with the rotor 21, and then the moving valve plate 5 fits against the end face of the limiting step 11 to block the flow-through hole of the limiting step 11. During the whole process, the flow resistance of the flow-through channel first decreases sharply and then increases sharply.

[0032] In some embodiments, at least part of the moving valve plate 5 corresponds to the static valve part 6 in the axial position of the housing part 1.

[0033] It should be noted that the inner cavity of the drill tool (i.e., the cavity for the drilling fluid to pass through), the moving valve plate 5, the static valve part 6, and the limiting step 11 are all arranged in the inner cavity of the drill tool. The operator reads the pump pressure in the inner cavity of the drill tool through the fluid circulation of the drilling fluid on the ground pump pressure gauge, so that the operator can monitor the situation in the inner cavity of the drill tool in real time through the pump pressure gauge. In this application, at the beginning of the rotor 21 falling off, the rotor undergoes an axial displacement, and the moving valve plate 5 and the moving valve rod 4 move axially downward along with the rotor 21. The flow gap of the flow passage between the moving valve plate 5 and the static valve part 6 suddenly increases, and the flow resistance of the fluid flowing through the flow passage significantly decreases. Therefore, the pump pressure will suddenly decrease, and the operator can obtain the initial falling warning according to the display of the pump pressure gauge. Further, the moving valve plate 5 continues to fall with the rotor 21 until it comes into contact and cooperation with the end face of the limiting step 11. As Figure 4 shown, the moving valve plate 5 will block the flow hole of the limiting step 11, causing its flow area to suddenly decrease. Therefore, the flow resistance of the flow passage at this time will increase sharply, and then the pump pressure will increase significantly, thus causing a "pump jamming" prompt (the pressure shown on the pump pressure gauge becomes larger), so it can be used as the second prompt for the rotor 21 to fall. Through the double prompt for the falling of the rotor 21, the anti-falling device of this application avoids the situation that the screw tool is damaged or even more serious downhole accidents occur due to continuous drilling after the rotor falls off.

[0034] Preferably, the moving valve plate 5 and the static valve part 6 are radially eccentrically arranged in the housing part 1, and the center of the moving valve plate 5 is coaxially arranged with the moving valve rod 4; wherein,

[0035] When the rotor 21 of the motor 2 is running normally, the rotor 21 drives the moving valve plate 5 to rotate through the moving valve rod 4, so that the flow resistance of the flow passage between the moving valve plate 5 and the static valve part 6 changes periodically.

[0036] It can be understood that when the rotor 21 of the motor 2 is running normally (i.e., without tripping and falling off), the rotor 21 rotates to drive the moving valve plate 5 to rotate, so that the flow gap between the static valve part 6 and the moving valve plate 5 changes periodically, thus causing flow pulsation in the inner cavity. And the drilling fluid with pulsating pressure enters the annular space between the stator and the rotor of the motor from the inner cavity of the anti-falling joint, so as to provide greater hydraulic energy for the rotation of the rotor. On the premise of not introducing a new power device, by using the internal structure to generate flow pulsation and increasing the input energy of the motor rotor, the output power of the motor is prompted, which is beneficial to improving the drilling efficiency.

[0037] It should be noted that although the flow gap between the static valve part 6 and the dynamic valve plate 5 will also change periodically during normal operation, resulting in changes in the pump pressure. However, first, when the rotor 21 is operating normally, the above changes are periodic, and the change in the pump pressure is basically regular. Second, the change in the flow area of the flow passage of the static valve part 6 caused by the rotation of the dynamic valve plate 5 is not large. Compared with the sharp change in the pump pressure caused by the direct separation of the dynamic valve plate 5 from the static valve part 6 when the rotor 21 drops, the above periodic change in the pump pressure is small. Therefore, it is easy for the operator to distinguish between the two and make a correct judgment.

[0038] In some preferred embodiments, the anti-drop device further includes a pump pressure warning device. The operator can preset a threshold value in advance. Once the pump pressure reaches the set threshold value, an alarm will be triggered to remind the operator that the rotor 21 has dropped. Or, a pump pressure change threshold is preset in advance. When the change rate of the pump pressure is too large within a short period of time, the operator can be reminded through a warning light or an alarm sound.

[0039] In some embodiments, at least one second drain hole 51 is formed on the dynamic valve plate 5. It can be understood that when the dynamic valve plate 5 rotates, the corresponding position of the second drain hole 51 and the drain hole of the static valve part 6 changes, and thus the flow gap changes.

[0040] Furthermore, as Figure 2 and Figure 3 shown, the shape of the dynamic valve plate 5 is a Reuleaux triangle. Three second drain holes 51 are arranged on the dynamic valve plate 5 in a circumferential distribution. It can be understood that the second drain holes 51 of the dynamic valve plate 5 in this application are arranged in the middle of the dynamic valve plate 5. Since the dynamic valve plate 5 is provided with the second drain holes 51, even if the dynamic valve plate 5 drops onto the limit step 11, it will not immediately completely block the limit step 11 and cause a pump blockage quickly. And as Figure 4 shown, when the dynamic valve plate 5 falls onto the limit step 11, the contact area between the dynamic valve plate 5 and the limit step 11 is large, and the impact resistance is stronger. The dynamic valve plate 5 will not be unable to withstand the collision and the impact of high-pressure fluid due to the opening of the second drain holes 51.

[0041] Preferably, the second drain hole 51 is a round hole with a diameter of 10 mm. And the gap distance between the dynamic valve plate 5 and the static valve part 6 is between 2 and 5 mm.

[0042] In some specific embodiments, the static valve part 6 includes: a static valve seat 61 and a static valve plate 62; wherein,

[0043] The static valve seat 61 is assembled in the upper cavity 13. The static valve plate 62 is assembled on the static valve seat 61, and at least one first drain hole 63 is provided on the static valve plate 62, and the flow area of the first drain hole 63 is larger than that of the second drain hole 51.

[0044] It can be understood that the drilling fluid enters the second drainage hole 51 through the first drainage hole 63. The flow-through area of the first drainage hole 63 is much larger than that of the second drainage hole 51. Therefore, when the moving valve plate 5 rotates, the change in the flow-through area corresponding to the second drainage hole 51 and the first drainage hole 63 is relatively small compared to the situation where the rotor 21 drops.

[0045] Preferably, the shape of the second drainage hole 51 is a fan-shaped structure.

[0046] In some other preferred embodiments, the end face mating clearance between the moving valve plate 5 and the static valve plate 62 is 2 - 5 mm. When the moving valve plate 5 rotates eccentrically around the axis of the static valve plate 62, due to the periodic change in the flow-through area among the moving valve body structure, the three second drainage holes 51 of the moving valve plate, and the two fan-shaped through holes in the static valve plate 62, the drilling fluid will generate a flow pulsation in the inner cavity of the anti-drop joint.

[0047] On the other hand, the present application provides a positive displacement motor, which includes any one of the above-mentioned downhole anti-drop devices.

[0048] In summary, in the present invention, a static valve part is arranged at an interval above the moving valve plate, so that there is a flow-through gap between the two. Once the rotor drops, the flow-through gap between the moving valve plate and the static valve part becomes larger, thereby causing a sudden change in the pump pressure as the first drop warning. Subsequently, the moving valve plate fits with the flow-through hole to block the mud channel, causing a second pump pressure change as the second drop reminder. The downhole anti-drop device of the present invention can not only prevent the rotor from dropping, but also provide a secondary reminder for the detachment of the rotor, giving the operator an operating space and avoiding secondary impacts. Further, in the present invention, the moving valve plate rotates with the rotor, causing the flow-through gap between the moving valve plate and the static valve part to change continuously, thereby causing a flow pulsation in the inner cavity. The drilling fluid with pulsating pressure enters the annular space between the motor stator and the rotor from the inner cavity of the anti-drop joint, thereby providing greater hydraulic energy for the rotation of the rotor.

[0049] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "upper" and "lower" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present application. Unless otherwise clearly specified and defined, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0050] It should be noted that in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0051] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. An underground anti-falling device, characterized in that, Comprising: A hollow outer shell portion (1) provided with a limiting step (11) that divides the cavity of the outer shell portion (1) into a mutually communicating lower cavity (12) and an upper cavity (13). An overflow hole is provided on the limiting step (11). The lower cavity (12) is used to dock with a motor (2), and a static valve portion (6) is provided in the upper cavity (13); A moving valve rod (4) connected to the rotor (21) of the motor (2), on which a moving valve plate (5) is provided in the upper cavity (13). The moving valve plate (5) is spaced from one side of the static valve portion (6) close to the motor (2) and cooperates with the static valve portion (6) to form a flow passage. The moving valve plate (5) and the static valve portion (6) are eccentrically arranged in the radial direction of the outer shell portion (1). The center of the moving valve plate (5) is coaxially arranged with the moving valve rod (4). At least one second drainage hole (51) is provided on the moving valve plate (5). The shape of the moving valve plate (5) is a Reuleaux triangle. The gap distance between the moving valve plate (5) and the static valve portion (6) is between 2 and 5 mm; wherein, When the rotor (21) becomes disengaged and drops, the moving valve plate (5) is used to move away from the static valve portion (6) with the rotor (21) and partially block the overflow hole of the limiting step (11), so that the flow resistance of the flow passage first decreases sharply and then increases sharply; When the rotor (21) of the motor (2) operates normally, the rotor (21) drives the moving valve plate (5) to rotate through the moving valve rod (4), so that the flow resistance of the flow passage between the moving valve plate (5) and the static valve portion (6) changes periodically.

2. The downhole anti-drop device according to claim 1, characterized in that, The static valve portion (6) includes: A static valve seat (61) assembled in the upper cavity (13); A static valve plate (62) assembled on the static valve seat (61), and at least one first drainage hole (63) is provided on the static valve plate (62). The flow area of the first drainage hole (63) is larger than that of the second drainage hole (51).

3. The downhole anti-drop device according to claim 2, characterized in that: The shape of the first drainage hole (63) is fan-shaped.

4. The downhole anti-falling device according to claim 2, wherein: Three of the second drainage holes (51) are provided on the moving valve plate (5) in a circumferential distribution.

5. The downhole anti-drop device according to claim 4, characterized in that: The second drainage hole (51) is a round hole with a diameter of 10 mm.

6. A positive displacement motor, characterized in that, It includes: The downhole anti-drop device according to claims 1-5.

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