A cement slurry control tool for reverse circulation cementing

Abstract

The present invention discloses a cement slurry control tool for reverse circulation cementing, which mainly consists of a cylindrical structure composed of a ball seat, a housing, and a lower ball seat connected in sequence from top to bottom; wherein: the middle hole of the ball seat is a ball passage, and a ball blocking mechanism is arranged below the ball passage; the ball blocking mechanism cooperates with a pressure-bearing ball to form a structure where the ball passage is opened when the pressure-bearing ball is pressed downward, and the upward movement of the pressure-bearing ball is blocked; the housing is located below the ball blocking mechanism, and its interior is set as an expanded ball storage cavity; below the ball storage cavity is a conical lower ball seat, and a groove is arranged on the inner wall of the lower ball seat, and a spring baffle valve is installed in the groove. A sliding sleeve is arranged inside the groove of the lower ball seat, and the inner diameter of the sliding sleeve is slightly smaller than the through-diameter size of the ball passage. The sliding sleeve is fixed on the inner hole of the lower ball seat through a sliding sleeve pin. The spring baffle valve is limited by the sliding sleeve. After the sliding sleeve is removed, the spring baffle valve flips under the spring force to close the inner hole of the lower ball seat. After the reverse circulation cementing operation is completed, the cement slurry can be completely blocked in the space below the control tool.

Description

Technical Field

[0001] The present invention relates to a cementing tool in the field of drilling tools, and particularly to a cement slurry control tool for reverse circulation cementing. Background Art

[0002] Cementing, as an important link in the drilling cycle, determines the quality of completion construction and the safety and reliability of subsequent production operations. With the increasing complexity of oil exploration and development blocks, cementing construction faces severe challenges. Especially for leaky formations and large temperature difference formations, traditional cementing construction has great limitations and it is difficult to guarantee the cementing quality. To ensure the displacement efficiency of the cement slurry, cementing engineers often use turbulent displacement of the cement slurry, and the circulation friction is applied to the formation, which results in a contradiction between the formation pressure window and the cement slurry displacement efficiency.

[0003] In order to ensure the fluidity of the cement slurry during cementing of wells with large temperature differences, a large amount of retarder often needs to be added to the cement slurry. However, for the cement slurry returning to the upper low-temperature area, the dosage of the retarder is significantly excessive, resulting in super-retarding phenomenon, which affects the construction period and the cementing quality. Reverse circulation cementing can just solve these two prominent problems. On the one hand, the effect of the circulation friction is changed to reduce the pressure on the formation. On the other hand, the cement slurry only needs to circulate from the wellhead low-temperature area to the bottom high-temperature area through the annulus, and the requirement for the fluidity of the cement slurry is greatly reduced.

[0004] Chinese Patent CN210483629U discloses an "Anti-Circulation Cementing Casing Float Collar Device", which includes an inner pipe and a float collar casing. The float collar casing is sleeved on the outer wall of the inner pipe. In the middle of the inner wall of the inner pipe, there is a sealing frame. Several flow-through channels are formed at the top of the sealing frame to achieve the up-and-down communication inside the inner pipe. An annular sealing groove is formed on the outer edge of the lower part of the sealing frame, and a magnet is provided downward at the middle position inside the sealing frame. A supporting ring is provided below the sealing frame. The lower part of the supporting ring is closed, and a nylon ball is installed on the upper part. A magnet is provided on the top of the nylon ball. The magnet and the magnetic stone are arranged corresponding to each other up and down and adsorb each other. An annular sealing head protrudes upward from the outer edge of the upper part of the supporting ring. The sealing head and the sealing groove are arranged corresponding to each other up and down, and after the sealing head moves upward, it can be hermetically inserted into the sealing groove to block the flow-through channels on the sealing frame. Two sliding grooves are axially symmetrically formed on the inner wall of the float collar casing. A slider is respectively and correspondingly arranged on each sliding groove. A long circular hole is respectively opened on both sides of the inner pipe so that the slider can extend into the inner pipe and the slider can move up and down along the sliding groove. Each slider is fixedly connected with a fixing plate, and each fixing plate is connected to the bottom of the sealing head through a spring column. A slurry inlet is respectively opened on both sides of the inner pipe, and each slurry inlet is communicated with the corresponding sliding groove, and both slurry inlets are located below the slider. A float collar drain pipe is also provided on the outer wall of the float collar casing. The slurry outlet at the bottom of the float collar drain pipe is communicated with the lower part of the inner pipe, and the slurry outlet of the float collar drain pipe is located below the slurry inlet of the inner pipe. A sealing plug is inserted into the upper part of the inner wall of the inner pipe. A hair dryer and an air inlet pipe penetrating up and down are provided on the sealing plug, and the hair dryer blows air into the inner pipe through the air inlet pipe. The inner cavity of the inner pipe between the sealing plug and the sealing frame is communicated with a sealing chamber through a reserved pipe section. A pressure gauge and a thermometer are installed inside the sealing chamber, and the pressure gauge and the thermometer are respectively provided with a pressure transmitter and a temperature transmitter.

[0005] In the present invention, the cement slurry is introduced into the bottom of the inner pipe through the float collar drain pipe. Since the density of the cement slurry is greater than that of the drilling fluid, the drilling fluid moves upward. Under the action of the impact force, the slider moves upward, driving the spring column to move upward, and then driving the sealing head to move towards the position of the sealing groove. During this process, after the spring column moves upward, due to its pulling force, it drives the supporting ring to move upward, and finally drives the nylon ball to contact the top inside the sealing frame. Due to the magnetism between the magnet and the magnetic stone, the nylon ball and the top inside the sealing frame are in closer contact. This attraction makes the connection between the sealing head and the sealing groove closer again, so that the sealing head tightly seals the sealing groove. A sealing flange is used to seal the sealing chamber and the reserved pipe section, and together with the sealing plug and the hair dryer, a simple leak detection device is formed. Then, according to the readings of the pressure gauge and the thermometer, it is used to detect whether the inner pipe is completely sealed, which brings great convenience to the work of the staff.

[0006] However, during the on-site application of reverse circulation cementing, due to the U-tube effect, the problem of a large amount of cement slurry entering the casing during the waiting-for-setting period is particularly serious, and the subsequent plug cleaning operation seriously affects the construction period. Therefore, there is an urgent need for effective processes and tools to control the cement slurry on-site. Summary of the Invention

[0007] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a cement slurry control tool for reverse circulation cementing to avoid the uncontrollable entry of cement slurry into the casing and cause "sausage filling" accidents.

[0008] To solve the above technical problems, the present invention is implemented by adopting the following technical solutions: A cement slurry control tool for reverse circulation cementing mainly consists of a cylindrical structure composed of a ball seat, a housing, and a lower ball seat connected in sequence from top to bottom; wherein: the middle hole of the ball seat is a ball path, and a ball blocking mechanism is arranged below the ball path; the ball blocking mechanism cooperates with a pressure-bearing ball to form a situation where the ball path is opened when the pressure-bearing ball is pressed downward, and the upward movement of the pressure-bearing ball is blocked; the housing is located below the ball blocking mechanism, and its internal part is an expanded ball storage cavity; below the ball storage cavity is a conical lower ball seat, a groove is arranged on the inner wall of the lower ball seat, and a spring baffle valve is installed in the groove. A sliding sleeve is arranged inside the groove of the lower ball seat, and the inner diameter of the sliding sleeve is slightly smaller than the through-diameter size of the ball path. The sliding sleeve is fixed on the inner hole of the lower ball seat through a sliding sleeve pin. The spring baffle valve is limited by the sliding sleeve. After the sliding sleeve is removed, the spring baffle valve flips under the spring force to close the inner hole of the lower ball seat.

[0009] The above solution further includes: at least two groups of the ball blocking mechanisms are evenly distributed on the ball seat below the ball path, and each group includes a ball basket spring baffle, a baffle pin, and a spring positioning pin; wherein, the ball basket spring baffle includes a rotating head and a rotating arm. The rotating head forms a rotational limiting fit with the groove of the ball seat. At the same time, a keyway is arranged on the rotating head of the ball basket spring baffle. The rotating head is initially fixed on the ball seat through a baffle pin, so that the inner diameter of the ball basket spring baffle is smaller than the inner diameter of the ball path; the spring positioning pin is arranged in the ball seat below the ball basket spring baffle, forms a rotational support fit with the rotating head of the ball basket spring baffle and then enters the keyway to limit the keyway again.

[0010] The number of the ball basket spring baffles is one pair and they are symmetrically arranged in the grooves on the inner wall of the lower ball seat.

[0011] The ball seat and the lower ball seat are respectively provided with threaded joints.

[0012] The bottom of the ball storage cavity is of a conical structure.

[0013] The top of the sliding sleeve is of a conical structure.

[0014] The present invention adopts a collar connection and can be connected to the casing string as a casing nipple. Ball seats are respectively provided at the upper and lower parts, and the copper ball can fall into the ball seat under the action of gravity. A ball-throwing control structure is adopted. There is a device for catching the copper ball at the upper part of the tool, which can limit the copper ball in the inner cavity of the tool. The lower ball seat and the sliding sleeve are integrally designed. The sliding sleeve is fixed to the tool body by shear pins. The ground can apply pressure to the casing to cut off the shear pins and push the sliding sleeve downward. After the sliding sleeve moves downward, it will release the spring baffle valve installed on the tool body to block the tool water eye and cut off the fluid passage.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) When waiting for setting after the reverse circulation cementing operation is completed, the reverse circulation path can be closed to solve the problem of a large amount of cement slurry entering the casing; (2) The baffle valve controlled by ball throwing can throw a copper ball at the wellhead, and the baffle valve can be manually closed to completely block the cement slurry in the space below the control tool. Description of the Drawings

[0016] Figure 1 It is a schematic structural diagram of the cement slurry control tool for reverse circulation cementing of the present invention.

[0017] Figure 2 It is a schematic structural diagram of the initial state of the ball basket spring baffle of the cement slurry control tool for reverse circulation cementing of the present invention.

[0018] Figure 3 It is a schematic structural diagram of the state after ball throwing of the ball basket spring baffle of the cement slurry control tool for reverse circulation cementing of the present invention.

[0019] In the figure: 1. upper ball seat; 2. ball path; 3. outer shell; 4. ball storage cavity; 5. lower ball seat; 6. sliding sleeve; 7. ball basket spring baffle; 8. baffle pin; 9. spring positioning pin; 10. sliding sleeve pin; 11. spring baffle valve. Detailed Embodiments

[0020] The following further describes the present invention in detail in conjunction with the drawings and specific embodiments.

[0021] Embodiment 1

[0022] A cement slurry control tool for reverse circulation cementing, mainly composed of a tubular structure formed by connecting a ball seat 1, a housing 3, and a lower ball seat 5 arranged in sequence from top to bottom; wherein: the middle hole of the ball seat 1 is a ball track 2, and a ball blocking mechanism is arranged below the ball track 2; the ball blocking mechanism cooperates with a pressure-bearing ball to form that when the pressure-bearing ball is pressed downward, the ball track 2 is opened, and the upward movement of the pressure-bearing ball is blocked; the housing 3 is located below the ball blocking mechanism, and its internal part is an expanded ball storage cavity 4; below the ball storage cavity 4 is a conical lower ball seat 5, a groove is arranged on the inner wall of the lower ball seat 5, and a spring baffle valve 11 is installed in the groove. A sliding sleeve 6 is arranged inside the lower ball seat 5 on the inner side of the groove of the lower ball seat 5. The inner diameter of the sliding sleeve 6 is slightly smaller than the through-diameter size of the ball track 2. The sliding sleeve 6 is fixed on the inner hole of the lower ball seat 5 through a sliding sleeve pin 10. The spring baffle valve 11 is limited by the sliding sleeve 6. After the sliding sleeve 6 is removed, the spring baffle valve 11 flips under the spring force to close the inner hole of the lower ball seat 5.

[0023] Embodiment 2

[0024] The above-mentioned Embodiment 1 further includes: at least two groups of the ball blocking mechanisms, and they are evenly distributed on the ball seat 1 below the ball track 2. Each group includes a ball basket spring baffle 7, a baffle pin 8, and a spring positioning pin 9; wherein, the ball basket spring baffle 7 includes a rotating head and a rotating arm. The rotating head forms a rotational limit fit with the groove of the ball seat 1. At the same time, a key groove 12 is arranged on the rotating head of the ball basket spring baffle 7. The rotating head is initially fixed on the ball seat 1 through the baffle pin 8, so that the inner diameter of the ball basket spring baffle 7 is smaller than the inner diameter of the ball track 2; the spring positioning pin 9 is arranged in the ball seat 1 below the ball basket spring baffle 7. After forming a rotational support fit with the rotating head of the ball basket spring baffle 7, it enters the key groove 12 to limit the key groove 12 again.

[0025] The number of the ball basket spring baffles 7 is a pair, and they are symmetrically arranged in the grooves on the inner wall of the lower ball seat 5.

[0026] The ball seat 1 and the lower ball seat 5 are respectively provided with threaded joints.

[0027] The bottom of the ball storage cavity 4 is of a conical structure.

[0028] The top of the sliding sleeve 5 is of a conical structure.

[0029] Embodiment 3

[0030] Referring to the attached Figures 1 to 3 , a cement slurry control tool for reverse circulation cementing according to the present invention is generally of a tubular structure, the middle hole is a fluid passage, and from top to bottom are a ball seat 1, a housing 3, and a lower ball seat 5 in sequence. The middle hole of the ball seat 1 is provided with a ball track 2, below the ball track 2 is a ball basket spring baffle 7, there are a pair of ball basket spring baffles 7, the ball basket spring baffles 7 can rotate downward, the ball basket spring baffles 7 are fixed on the ball seat 1 by baffle pins 8, referring to the attached Figure 1。The ball basket spring baffle 7 is provided with a keyway 12, and a spring positioning pin 9 is fixed below the ball basket spring baffle 7. After the ball basket spring baffle 7 rotates counterclockwise by a certain angle, the spring positioning pin 9 enters the keyway 12 to limit the keyway 12 again. Below the ball basket spring baffle 7 is a ball storage cavity 4, and below the ball storage cavity 4 is a conical lower ball seat 5. The sliding sleeve 6 is fixed on the inner hole of the lower ball seat 5 by a sliding sleeve pin 10. Refer to the appendix Figure 1 。A spring baffle valve 11 is installed between the lower ball seat 5 and the sliding sleeve 6. The spring baffle valve 11 is installed in a groove on the inner wall of the lower ball seat 5 and is limited by the sliding sleeve 6. After the sliding sleeve 6 is removed, the spring baffle valve 11 can flip under the spring force to close the inner hole of the lower ball seat 5. The through-diameter size of the ball path 2 is slightly larger than the inner diameter of the sliding sleeve 6 and the device inner diameter at the ball basket spring baffle 7.

[0031] It is used for the copper ball of the cement slurry control tool for reverse circulation cementing. The size of the copper ball is smaller than the ball path 2 and slightly larger than the inner diameter of the sliding sleeve 6 and the device inner diameter at the ball basket spring baffle 7.

[0032] The uppermost end of the cement slurry control tool for reverse circulation cementing is connected to the casing string by threads and lowered into the well. The uppermost end is a conical upper ball seat 1 that receives the copper ball to facilitate the copper ball being pressed into the ball path 2. The diameter of the ball path 2 is similar to that of the copper ball. When the copper ball reaches the upper ball seat 1, the impact pressure can be observed at the wellhead. When the copper ball passes through the ball basket spring baffle 7, the baffle pin 8 is cut off, and the ball basket spring baffle 7 bounces upward and is locked by the spring positioning pin 9. The copper ball is restricted below the ball basket spring baffle 7. Below the ball basket spring baffle 7 is the ball storage cavity 4. During the reverse circulation cement injection process, the copper ball is stored in the ball storage cavity 4. To prevent the copper ball from being immediately pressed downward into the lower ball seat 5 and cutting off the sliding sleeve pin 10 after being pressed into the ball path 2 and passing through the ball basket spring baffle 7, resulting in the failure of the cement slurry control tool for reverse circulation cementing, the radial length of the ball storage cavity 4 should be greater than the diameter of the copper ball. Below the ball storage cavity 4 is a conical lower ball seat 5 that receives the copper ball, making it easy for the copper ball to be pressed into the sliding sleeve 6 with a ball seat. The sliding sleeve 6 is fixed at the position shown in the appendix Figure 1 , restricting the spring baffle valve 11 at the position shown in the appendix Figure 1 to provide a drilling fluid circulation path. The sliding sleeve 6 can be pushed by the copper ball and discarded into the casing string below the cement slurry control tool for reverse circulation cementing, releasing the spring baffle valve 11. The spring baffle valve 11 flips over to close the drilling fluid circulation path.

[0033] Construction process and working principle: After drilling is completed, the casing is run in, and a positive circulation is established to flush the debris in the wellbore. To ensure the smoothness of the positive circulation, the copper ball is to be inserted after running in the casing and completing the circulation flushing. The wellhead is pressured to press it into the upper ball seat 2 and into the ball track 2. The wellhead is continuously pressured, and the copper ball descends in the ball track 2, pushing the ball basket spring baffle 7, shearing the baffle pin 8, and entering the ball storage cavity 4 through the ball basket spring baffle 7. This is done to make the copper ball closer to the lower ball seat 5 when the cementing operation is completed, facilitating further operations. At this time, drilling fluid is injected into the annulus at the wellhead to establish a reverse circulation. After the reverse circulation is established, cleaning fluid, spacer fluid, and cement slurry are successively injected into the annulus at the wellhead. During the reverse circulation process, the ball basket spring baffle 7 confines the copper ball in the ball storage cavity 4. After judging that the cement slurry has reached the predetermined position based on the injection and displacement time and various surface signals, the reverse circulation is stopped. Pressure is applied to the casing at the wellhead to press the copper ball into the lower ball seat 5 and push the sliding sleeve 6 downward, shearing the sliding sleeve pin 10, causing the sliding sleeve 6 to fall below the cement slurry control tool for reverse circulation cementing, releasing the spring baffle valve 11, and the spring baffle valve 11 closes the reverse circulation passage. At this time, part of the casing pressure at the wellhead is removed, and waiting for cement setting.

[0034] Working principle of the ball basket spring baffle 7: Taking the spring baffle on the left side in the appendix Figure 1 as an example, the enlarged view is as shown in the appendix Figure 2 . In the free state, the ball basket spring baffle 7 has a tendency to rotate counterclockwise. When running in the well, the ball basket spring baffle 7 is fixed at the Figure 2 position shown by the baffle pin 8. When the copper ball is pressed into the ball track, it descends and pushes the spring baffle 7 to rotate clockwise, and the baffle pin 8 is sheared. After the copper ball passes through the ball basket baffle and enters the ball storage cavity 4, the ball basket spring baffle 7 immediately rotates counterclockwise. After rotating a certain angle, the spring positioning pin 9 enters the keyway 12, restricting the spring baffle 7 at the Figure 3 position shown in the appendix, which can confine the copper ball in the ball storage cavity 4 and allow the drilling fluid to pass through.

Claims

1. A cement slurry control tool for reverse circulation cementing, mainly composed of a tubular structure formed by connecting a ball seat (1), a housing (3), and a lower ball seat (5) arranged successively from top to bottom; It is characterized in that: The middle hole of the ball seat (1) is a ball path (2), and a ball blocking mechanism is arranged below the ball path (2); the ball blocking mechanism cooperates with a pressure-bearing ball to form a situation where the ball path (2) is opened when the pressure-bearing ball is pressed downward, and the upward movement of the pressure-bearing ball is blocked; the housing (3) is located below the ball blocking mechanism, and its internal part is set as an enlarged ball storage cavity (4); below the ball storage cavity (4) is a conical lower ball seat (5). A groove is arranged on the inner wall of the lower ball seat (5), and a spring baffle valve (11) is installed in the groove. A sliding sleeve (6) is arranged inside the groove of the lower ball seat (5). The inner diameter of the sliding sleeve (6) is slightly smaller than the through-diameter size of the ball path (2). The sliding sleeve (6) is fixed on the inner hole of the lower ball seat (5) through a sliding sleeve pin (10). The spring baffle valve (11) is limited by the sliding sleeve (6). After the sliding sleeve (6) is removed, the spring baffle valve (11) flips under the spring force to close the inner hole of the lower ball seat (5); There are at least two groups of the ball blocking mechanisms, and they are evenly distributed on the ball seat (1) below the ball path (2). Each group includes a ball basket spring baffle (7), a baffle pin (8), and a spring positioning pin (9); Among them, the ball basket spring baffle (7) includes a rotating head and a rotating arm. The rotating head forms a rotational limit fit with the groove of the ball seat (1). At the same time, a keyway (12) is arranged on the rotating head of the ball basket spring baffle (7). The rotating head is initially fixed on the ball seat (1) through a baffle pin (8), so that the inner diameter of the ball basket spring baffle (7) is smaller than the inner diameter of the ball path (2); The spring positioning pin (9) is arranged inside the ball seat (1) below the ball basket spring baffle (7). After forming a rotational support fit with the rotating head of the ball basket spring baffle (7), it enters the keyway (12) to limit the keyway (12) again; The ball seat (1) and the lower ball seat (5) are respectively provided with threaded joints; The bottom of the ball storage cavity (4) is of a conical structure.

2. The cement slurry control tool for reverse circulation cementing according to claim 1, It is characterized in that: The number of the ball basket spring baffles (7) is one pair, and they are symmetrically arranged in the grooves on the inner wall of the lower ball seat (5).

3. The cement slurry control tool for reverse circulation cementing according to claim 2, It is characterized in that: The top of the sliding sleeve (6) is of a conical structure.

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