Reverse circulation well cementing floating collar device and construction method

Abstract

The application provides a reverse circulation well cementing floating collar device, which comprises a floating collar body, a first flow-through hole arranged on the floating collar body, a protection sleeve concentrically arranged in the floating collar body, and a differential pressure sleeve arranged in the annulus between the floating collar body and the protection sleeve, wherein a second flow-through hole is arranged on the protection sleeve, and a third flow-through hole is arranged on the differential pressure sleeve and radially aligned with the first flow-through hole and the second flow-through hole and allows fluid to flow through.

Description

Technical Field

[0001] This invention relates to the field of oil and gas well engineering technology research, specifically to a reverse circulation cementing float device and a construction method. Background Technology

[0002] Cementing is a crucial step and method in the drilling and completion process of oil and gas wells. Conventional cementing involves sequentially injecting pre-filled fluid, cement slurry, and displacement fluid into the casing after it has been drilled. As the displacement fluid gradually fills the casing's internal space, the cement slurry gradually flows through the bottom of the casing into the annulus between the metal casing and the wellbore, sealing the annulus after solidification. However, for oil and gas wells in complex conditions such as those in formations prone to leakage or those with large temperature differences, conventional cementing techniques are insufficient to meet cementing quality requirements, leading to the development of reverse circulation cementing. At the end of the cementing operation, external fracturing is greater than internal fracturing. To prevent backflow of cement slurry from the external casing, a backpressure valve is installed at the bottom of the well.

[0003] Reverse circulation cementing involves sequentially injecting pre-flush fluid, cement slurry, and post-flush fluid into the annulus of the casing and wellbore at the wellhead. Once the cement slurry reaches the designed position, fluid injection is stopped, the wellhead is closed, and the cement slurry is allowed to solidify, completing the cementing operation. However, at the end of the cementing process, the fluid pressure outside the casing is higher than inside, making it prone to cement slurry entering the casing. Conventional float collars or inverted float collars cannot prevent this. The conventional approach is to close the casing wellhead and pressurize it at the end of grouting, utilizing the incompressibility of the fluid inside the casing to prevent further cement slurry entry. However, this method has a significant negative impact on cementing quality.

[0004] Therefore, it is desirable to provide a reverse circulation cementing float device to solve problems such as annular cement slurry entering the casing after reverse circulation cementing construction and poor cementing quality. Summary of the Invention

[0005] The purpose of this invention is to propose a reverse circulation cementing float device, which solves the problem of annular cement slurry entering the casing after reverse circulation cementing construction and poor cementing quality.

[0006] According to a first aspect of the present invention, a reverse circulation cementing float assembly is provided, comprising a float assembly body having a first flow hole on the float assembly body.

[0007] The protective sleeves concentrically arranged within the floating hoop body, and

[0008] A differential pressure sleeve is installed in the annulus between the float body and the protective sleeve.

[0009] The protective sleeve is provided with a second flow hole, and the differential pressure sleeve is provided with a third flow hole that is radially aligned with the first flow hole and the second flow hole and allows fluid flow.

[0010] In one embodiment, the protective sleeve is provided with a through-hole rupture disc for sealing the annulus.

[0011] In one embodiment, the differential pressure sleeve is initially fixed to the float hoop body by shear pins.

[0012] In one embodiment, connectors for connecting to the sleeve are provided at both ends of the float hoop body.

[0013] When the cement slurry reaches the designed position, drilling fluid is injected forward through the casing to create pressure buildup, which causes the fractured disc to break, thereby allowing the drilling fluid to flow into the annulus to shear the shear pins and push the differential sleeve downward to seal the first flow hole and the second flow hole.

[0014] In one embodiment, a radially outwardly extending snap ring groove is formed on the inner wall of the float hoop body, and a snap ring for engaging with the snap ring groove is filled on the outer wall of the differential pressure sleeve.

[0015] In one embodiment, the reverse circulation cementing float assembly further includes a ball seat mechanism, which includes a base and a ball seat spaced apart within a protective sleeve, a ball adapted to the ball seat, and a compression spring disposed between the base and the ball.

[0016] The ball is configured to form a sealed connection with the ball seat under the action of the compression spring.

[0017] In one embodiment, the base has multiple through holes that allow fluid to pass through.

[0018] In one embodiment, a plurality of staggered sealing rings are provided along the axial direction of the differential pressure sleeve, and the differential pressure sleeve forms a sealed connection with the float hoop body and the protective sleeve respectively through the sealing rings.

[0019] According to a second aspect of the present invention, a construction method is provided that utilizes a reverse circulation cementing float device as described above, comprising the following steps:

[0020] S1. Lower this device to the predetermined position inside the well;

[0021] S2. Sequentially inject isolation fluid and cement grout into the outer annulus of the casing until the cement grout reaches the designed position;

[0022] S3. Drilling fluid is injected forward through the casing to pressurize and cause the fractured disc to break, thereby allowing the drilling fluid to flow into the annulus to shear the shear pins and push the differential sleeve downward until the retaining ring of the differential sleeve engages with the retaining ring groove.

[0023] In one embodiment, before step S2, drilling fluid circulation is required to remove rock cuttings deposits from the bottom of the well.

[0024] In one embodiment, in step S3, the third flow hole is arranged in a staggered manner with the first flow hole and the second flow hole.

[0025] Compared with the prior art, the advantages of the present invention are as follows:

[0026] This invention solves the problem of annular cement slurry entering the casing after reverse circulation cementing construction and resulting in poor cementing quality. At the same time, it can also prevent fluid in the annulus from entering the casing without closing the wellhead gate after cementing construction.

[0027] Specifically, during fluid injection, the first, second, and third flow holes are first radially aligned to serve as fluid flow channels. When the cement slurry reaches the designed position and grouting is stopped, drilling fluid can be injected forward through the casing to create a pressure-locked environment within the float collar body, thereby sequentially breaking the fracture plate and shearing the shear pins. This causes the differential sleeve to descend and seal the first and second flow holes, thus isolating the annulus from the casing and preventing the cement slurry in the annulus from entering the casing during the setting period, thereby further improving the cementing quality. Attached Figure Description

[0028] The invention will now be described in detail with reference to the accompanying drawings, in which:

[0029] Figure 1 The schematic diagram illustrates the structure of the reverse circulation cementing float assembly according to the present invention;

[0030] Figure 2 The sealing condition of the reverse circulation cementing float device according to the present invention is shown;

[0031] Figure 3 A cross-sectional view of the base in the reverse circulation cementing float assembly according to the present invention;

[0032] Figure 4 This is a cross-sectional view of the ball seat in the reverse circulation cementing float assembly according to the present invention.

[0033] In the accompanying drawings, the same parts use the same reference numerals. The drawings are not drawn to scale. Detailed Implementation

[0034] To make the technical solutions and advantages of the present invention clearer, exemplary embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not an exhaustive list of all embodiments. Furthermore, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0035] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0036] In this invention, unless otherwise explicitly specified and limited, the terms "installation", "connection", "linking", "fixing", etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components.

[0037] Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0038] The invention will now be further described with reference to the accompanying drawings.

[0039] Figure 1 The schematic diagram shows the structure of the reverse circulation cementing float device 100 according to the present invention.

[0040] Figure 2 The sealing state of the reverse circulation cementing float device 100 according to the present invention is shown.

[0041] like Figures 1-2 As shown, according to a first aspect of the present invention, a reverse circulation cementing float assembly 100 is provided, mainly comprising a float body 10, a protective sleeve 20 concentrically arranged within the float body 10, and a differential pressure sleeve 30 disposed within an annulus 11 between the float body 10 and the protective sleeve 20. Preferably, the float body 10 is provided with at least two spaced-apart first flow holes 101, the protective sleeve 20 is provided with at least two spaced-apart second flow holes 201, and the differential pressure sleeve 30 is provided with at least two spaced-apart third flow holes 301. In the initial state, the first flow holes 101, the second flow holes 201, and the third flow holes 301 are radially aligned, thereby allowing fluid to flow into the protective sleeve 20.

[0042] In this invention, the fluid comprises a separation fluid and a cementing slurry injected sequentially.

[0043] In one embodiment, such as Figure 1 As shown, connectors for connecting to casing (not shown) are provided at both ends of the float collar body 10. Preferably, the upper float collar connector 14 is located at the upper part of the float collar body 10, and the lower float collar connector 15 is located at the lower part of the float collar body 10. Preferably, the upper float collar connector 14 and the lower float collar connector 15 in this device are threadedly connected to the upper and lower casings respectively, which is beneficial to subsequent cementing operations.

[0044] In one embodiment of the invention, the top end of the protective sleeve 20 is sealed to the bottom end of the upper connector 14 of the float hoop, thereby effectively sealing the annular gap 11 between the float hoop body 10 and the protective sleeve 20. However, as Figure 1 As shown, the device is also provided with a through-type rupture disc 21 on the protective sleeve 20. In the initial state, the rupture disc 21 can effectively seal the annulus 11. When the cement slurry reaches the design position, the rupture disc 21 is broken under the pressure environment after the drilling fluid is injected in the forward direction, so that the differential pressure sleeve 30 moves downward under the driving force of the drilling fluid to achieve the effect of sealing the first flow hole 101 and the second flow hole 201. The details are described below.

[0045] Preferably, the fracturing pressure of the fracturing disk 21 is designed according to the downhole cementing process.

[0046] In one embodiment, such as Figure 1 As shown, the differential pressure sleeve 30 is initially fixed to the float hoop body 10 by shear pins 31. Therefore, this method can effectively limit the relative position between the float hoop body 10 and the differential pressure sleeve 30 during the lowering process, so as to avoid premature release of the differential pressure sleeve 30.

[0047] Furthermore, this method not only ensures that the differential pressure sleeve 30 can be fixed in position with the float body 10 in the initial state, but also ensures that the first flow hole 101, the second flow hole 201 and the third flow hole 301 are radially aligned in the initial state, thereby enabling the outer annulus (i.e., the annular cavity between the casing and the well wall) of the float body 10 to communicate with the internal cavity, allowing fluid to flow inside and outside the pipe through the flow holes (i.e., the first flow hole 101, the second flow hole 201 and the third flow hole 301).

[0048] Preferably, the shear fracture load of the shear pin 31 is designed based on the bottom hole pressure and process.

[0049] In one embodiment of the present invention, such as Figure 1As shown, a radially outwardly extending retaining groove 12 is formed on the inner wall of the float collar body 10, and a retaining spring 32 is filled on the outer wall of the differential pressure sleeve 30. Preferably, a pressure difference is generated after drilling fluid is injected into the annulus 11 between the float collar body 10 and the protective sleeve 20, which can push the differential pressure sleeve 30 downward until the retaining spring 32 of the differential pressure sleeve 30 engages with the retaining groove 11. At this time, the third flow hole 301 is misaligned with the first flow hole 101 and the second flow hole 201, so that the differential pressure sleeve 30 can achieve the sealing effect of the first flow hole 101 and the second flow hole 201.

[0050] In this invention, when the cement slurry reaches the designed position, drilling fluid can be injected forward through the upper casing to create a pressurized environment within the float body 10, thereby causing the rupture disc 21 to break so that the drilling fluid can continue to flow into the annulus 11.

[0051] However, as the drilling fluid in the annulus 11 increases, the differential pressure sleeve 30 will bear the downward pressure exerted by the drilling fluid. Therefore, when the design value is reached, the shear pin 31 is sheared, and the differential pressure sleeve 30 moves downward under the action of the drilling fluid until the retaining ring 32 of the differential pressure sleeve 30 engages with the retaining ring groove 11. From this point on, the first flow hole 101 and the second flow hole 201 can be blocked by the differential pressure sleeve 30 to further prevent the cement slurry in the annulus 11 from entering the casing during the setting period, thereby improving the cementing quality.

[0052] Figure 3 This is a cross-sectional view of the base 41 in the reverse circulation cementing float device 100 according to the present invention. Figure 4 This is a cross-sectional view of the ball seat 42 in the reverse circulation cementing float device 100 according to the present invention.

[0053] In one embodiment, such as Figure 1 , 3 As shown in Figure 4, the reverse circulation cementing float assembly 100 also includes a ball seat mechanism. Preferably, the ball seat mechanism includes a base 41 and a ball seat 42 spaced apart within the protective sleeve 20, a ball 43 adapted to the ball seat 42, and a compression spring 44 disposed between the base 41 and the ball 43. In the initial state, the ball 43 can form a sealed connection with the ball seat 42 under the action of the compression spring 44, which facilitates the formation of a pressure-locked environment within the float assembly 10 during subsequent forward injection of drilling fluid.

[0054] Preferably, such as Figure 1As shown, the base 41 is provided with multiple through holes 411 that allow fluid to pass through. In other words, during the grouting process, the fluid can flow into the interior of the protective sleeve 20 through the first flow hole 101, the third flow hole 301, and the second flow hole 201 in sequence. However, since the ball seat mechanism has a unidirectional flow function, it not only allows the fluid to flow upward, but also prevents the drilling fluid from flowing downward, which is beneficial for generating a pressurized effect by subsequently injecting drilling fluid in the forward direction.

[0055] In one embodiment, such as Figure 1 As shown, multiple staggered sealing rings 33 are arranged along the axial direction of the differential pressure sleeve 30. Preferably, the differential pressure sleeve 30 forms a sealed connection with the float collar body 10 and the protective sleeve 20 respectively through the sealing rings 33. Therefore, this method ensures that the annulus 11 remains in a sealed state throughout the entire cementing operation, further ensuring that the differential pressure sleeve 30 can smoothly complete its descent and seal the first flow hole 101 and the second flow hole 201.

[0056] According to a second aspect of the present invention, a construction method is provided that utilizes a reverse circulation cementing float device as described above, comprising the following steps:

[0057] First, connect the upper float joint 14 and the lower float joint 15 of this device to the upper and lower casings respectively, and lower them to the predetermined position at the bottom of the well.

[0058] Then, fluid is injected into the outer annulus of the sleeve (i.e., the isolation fluid and cement slurry are injected in sequence). The fluid will flow into the interior of the protective sleeve 20 through the first flow hole 101, the third flow hole 301 and the second flow hole 201 in sequence, and then rise through the ball seat mechanism.

[0059] Then, when the cement grout reaches the designed position, the grouting stops, and at this time, the ball 43 forms a sealed connection with the ball seat 42 under the action of the compression spring 44.

[0060] Subsequently, drilling fluid is injected forward through the casing to create a pressurized environment within the float body 10, thereby causing the rupture disc 21 to break up and allowing the drilling fluid to continue flowing into the annulus 11.

[0061] However, as the drilling fluid in the annulus 11 increases, the differential pressure sleeve 30 will bear the downward pressure exerted by the drilling fluid. Therefore, when the design value is reached, the shear pin 31 is sheared, and the differential pressure sleeve 30 moves downward under the action of the drilling fluid until the retaining ring 32 of the differential pressure sleeve 30 engages with the retaining ring groove 11. From this point on, the first flow hole 101 and the second flow hole 201 can be blocked by the differential pressure sleeve 30, thereby isolating the annulus 11 from the casing and preventing the cement slurry in the annulus 11 from entering the casing during the setting period, so as to further improve the cementing quality.

[0062] Finally, the pressure inside the wellhead casing is released, and the cement slurry is allowed to solidify in the annulus, thus completing the cementing operation.

[0063] In one embodiment of the present invention, when the retaining ring 32 of the differential pressure sleeve 30 is engaged with the retaining ring groove 11, the third flow hole 301 is misaligned with the first flow hole 101 and the second flow hole 201, thereby enabling the differential pressure sleeve 30 to block the first flow hole 101 and the second flow hole 201.

[0064] In this invention, the device is connected to the well casing string via the upper float joint 14 and the lower float joint 15. The bottom of the casing has a float shoe without a one-way valve. The float joint is 1 to 2 casing pipes away from the float shoe. At this time, the fluid in the pipe and the annulus 11 can flow to each other.

[0065] However, after this device is lowered to the bottom of the well, the drilling fluid circulation pump (not shown) needs to be turned on first. The drilling fluid passes through the casing to the bottom of the casing and enters the annulus to circulate out of the well, cleaning the rock cuttings deposits at the bottom of the well. After the rock cuttings are cleaned up, the wellhead cementing device is installed, and the drilling fluid is changed to enter the annulus directly from the wellhead to the bottom of the well and circulate out of the well through the bottom of the casing and inside the casing.

[0066] Preferably, cementing operations begin after drilling fluid circulation is completed, by sequentially injecting isolation fluid and cement slurry through the annulus 11, wherein the injection volume of isolation fluid and cement slurry is pumped in according to design requirements.

[0067] Compared with existing technologies, the advantages of this invention are:

[0068] This invention solves the problem of annular cement slurry entering the casing after reverse circulation cementing construction and resulting in poor cementing quality. At the same time, it can also prevent fluid in the annulus from entering the casing without closing the wellhead gate after cementing construction.

[0069] Specifically, when injecting fluid, the first flow hole 101, the second flow hole 201, and the third flow hole 301 are first radially aligned to serve as flow channels for the fluid. When the cement slurry reaches the designed position and grouting is stopped, drilling fluid can be injected forward through the casing to create a pressure-locked environment within the float body 10, thereby causing the fracture plate 21 to break and the shear pins 31 to be sheared in sequence. This causes the differential sleeve 30 to descend and block the first flow hole 101 and the second flow hole 201, thus achieving a seal between the annulus 11 and the casing, thereby preventing the cement slurry in the annulus 11 from entering the casing during the setting period, and further improving the cementing quality.

[0070] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art can easily make changes or modifications within the scope of the present invention, and such changes or modifications should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A reverse circulation cementing float device, comprising: The float body (10) has a first flow hole (101) on it. The protective sleeve (20) is concentrically arranged within the floating hoop body (10), and A differential pressure sleeve (30) is installed in the annulus (11) between the float body (10) and the protective sleeve (20). The protective sleeve (20) is provided with a second flow hole (201), and the differential pressure sleeve (30) is provided with a third flow hole (301) that is radially aligned with the first flow hole (101) and the second flow hole (201) and allows fluid flow.

2. The reverse circulation cementing float device according to claim 1, characterized in that, The protective sleeve (20) is provided with a rupture disc (21) that is arranged through the annulus (11) and is used to seal the annulus (11).

3. The reverse circulation cementing float device according to claim 2, characterized in that, The differential pressure sleeve (30) is initially fixed to the floating hoop body (10) by shear pins (31).

4. The reverse circulation cementing float device according to claim 3, characterized in that, At both ends of the floating hoop body (10) are respectively provided joints for connecting with the sleeve. When the cement slurry reaches the design position, drilling fluid is injected forward through the casing to create pressure and cause the fracture plate (21) to break, thereby allowing the drilling fluid to flow to the annulus (11) to shear the shear pin (31) and push the differential sleeve (30) downward to seal the first flow hole (101) and the second flow hole (201).

5. The reverse circulation cementing float device according to claim 4, characterized in that, A radially outwardly extending snap ring groove (12) is formed on the inner wall of the float body (10), and a snap ring (32) for engaging with the snap ring groove (12) is filled on the outer wall of the differential pressure sleeve (30).

6. The reverse circulation cementing float device according to any one of claims 1 to 5, characterized in that, The reverse circulation cementing float assembly also includes a ball seat mechanism, which includes a base (41) and a ball seat (42) spaced apart within the protective sleeve (20), a ball (43) adapted to the ball seat (42), and a compression spring (44) disposed between the base (41) and the ball (43). The ball (43) is configured to form a sealed connection with the ball seat (42) under the action of the compression spring (44).

7. The reverse circulation cementing float device according to claim 6, characterized in that, The base (41) is provided with a plurality of through holes (411) that allow fluid to pass through.

8. The reverse circulation cementing float device according to any one of claims 1 to 5, characterized in that, Multiple staggered sealing rings (33) are provided along the axial direction of the differential pressure sleeve (30), and the differential pressure sleeve (30) forms a sealed connection with the float body (10) and the protective sleeve (20) respectively through the sealing rings (33).

9. A construction method utilizing the reverse circulation cementing float device according to any one of claims 1 to 8, comprising the following steps: S1. Lower this device to the predetermined position at the bottom of the well; S2. Sequentially inject isolation fluid and cement grout into the outer annulus of the casing until the cement grout reaches the designed position; S3. Drilling fluid is injected forward through the casing to pressurize and cause the fracture plate (21) to break, thereby allowing the drilling fluid to flow to the annulus (11) to shear the shear pin (31) and push the differential sleeve (30) downward until the retaining ring (32) of the differential sleeve (30) engages with the retaining ring groove (11).

10. The construction method according to claim 9, characterized in that, Before step S2, drilling fluid circulation is required to remove rock cuttings deposits from the bottom of the well.

11. The construction method according to claim 9, characterized in that, In step S3, the third flow hole (301) is arranged in a staggered manner with the first flow hole (101) and the second flow hole (201).

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