Well cementing device

Abstract

The invention provides a well cementation device which comprises a center pipe, an opening sleeve arranged on the outer surface of the center pipe in a sleeving mode and a sealing rubber sheet, a liquid inlet hole and a liquid flow channel are formed in the center pipe in the radial direction, the opening sleeve seals the liquid inlet hole and the liquid flow channel, and the opening sleeve is fixed to the outer surface of the center pipe through a fixing part. A liquid storage space is formed between the sealing rubber sheet and the center pipe, after the fixing part is cut off, the opening sleeve can move in the axial direction of the center pipe to open the liquid flow channel, and fluid in the center pipe can flow into the liquid storage space through the liquid flow channel. By implementing the two-stage well cementation construction, the stratum is prevented from being leaked due to the use of high-density cement, so that the well cementation quality is improved.

Description

Technical Field

[0001] The invention relates to the technical field of oil drilling, and in particular to a cementing device. Background Art

[0002] In the process of oil and gas production, in order to strengthen the well wall, isolate complex formations that are prone to collapse and leakage, ensure smooth drilling, isolate oil, gas and water layers, establish oil and gas outflow channels, prevent mutual channeling between production layers, ensure stratified oil testing during exploration and reasonable oil and gas production during the entire exploitation, it is necessary to cement the oil and gas wells. Cementing is the construction operation of inserting casing into the well and injecting cement into the annular space between the wellbore and the casing. It is an indispensable and important link in the drilling and completion process. Cementing mainly includes two links: casing and cementing. Among them, cementing refers to the operation of pumping cement slurry into the casing after the casing is lowered, and then using drilling fluid to displace the cement slurry into the annular space between the casing and the well wall and make the cement slurry reach the designed position. The height of the cement slurry reaching the annular space (cement slurry return height) is an important indicator for inspecting the quality of cementing operations. If the cement slurry cannot return to the designed position or the return height is insufficient, an empty casing will be formed at the wellhead or a free casing will be formed in the well. A large number of measures need to be taken to remedy it in the later stage, causing great economic losses.

[0003] For the secondary drilling of deep wells, when the whole well is sealed at one time with high-density cement slurry, the cement slurry is easy to leak out of the formation, which can easily cause the cement return height to fail to meet the standard, seriously affecting the cementing quality. For example, the existing literature "Western Mining Project" records the one-time sealing and cementing technology of deep wells in Daqing Oilfield, which involves the one-time sealing and cementing construction process of deep wells in the oilfield. The process includes pressure testing with drill pipes in the early stage of cementing construction, purifying the wellbore, optimizing the performance of drilling fluid, and using an ultra-low density cement slurry system during cementing to achieve one-time sealing of deep wells. However, the construction of this process is complex and the procedures are cumbersome, and the cost of the ultra-low density cement slurry system is relatively high. Summary of the invention

[0004] An object of the present invention is to provide a cementing device that can prevent formation leakage due to the use of high-density cement by implementing a two-stage cementing construction, thereby improving the cementing quality.

[0005] According to the present invention, a cementing device is provided, comprising a center tube, an opening sleeve sleeved on the outer surface of the center tube, and a sealing rubber. The center tube is radially provided with a liquid inlet hole and a liquid flow channel. The opening sleeve seals the liquid inlet hole and the liquid flow channel, and the opening sleeve is fixed to the outer surface of the center tube by a fixing portion. A liquid storage space is formed between the sealing rubber and the center tube. After the fixing portion is cut off, the opening sleeve can move axially along the center tube to open the liquid flow channel, and the fluid in the center tube can flow into the liquid storage space through the liquid flow channel.

[0006] In a preferred embodiment, the liquid storage space is formed by the outer surface of the central tube, the inner surface of the sealing rubber and the end surface of the opening sleeve.

[0007] In a preferred embodiment, the cementing device further comprises a hydraulic sleeve sleeved on the outer surface of the opening sleeve.

[0008] In a preferred embodiment, the cementing device further comprises a fixed baffle ring, which is arranged at the upper end of the sealing rubber, and the upper end of the sealing rubber is embedded in the fixed baffle ring.

[0009] In a preferred embodiment, the upper end of the sealing rubber is fixedly connected to the fixed baffle ring.

[0010] In a preferred embodiment, the cementing device further comprises a positioning sleeve, which is arranged at the lower end of the sealing rubber, and the lower end of the sealing rubber is pressed into the positioning sleeve and can be detached from the positioning sleeve.

[0011] In a preferred embodiment, the cementing device further comprises a first coupling disposed on the outer surface of the central pipe, and the lower end surface of the first coupling is embedded in the interior of the fixed retaining ring.

[0012] In a preferred embodiment, the lower end surface of the first coupling, the outer surface of the central tube, the inner surface of the sealing rubber and the end surface of the opening sleeve together surround the liquid storage space.

[0013] In a preferred embodiment, the cementing device further comprises a second coupling disposed on the outer surface of the central pipe, and the upper end surface of the second coupling is embedded in the interior of the hydraulic sleeve.

[0014] In a preferred embodiment, the upper end surface of the second coupling, the inner surface of the hydraulic sleeve and the outer surface of the central pipe form an accommodating space, and the opening sleeve can move axially along the central pipe inside the accommodating space.

[0015] The present invention also provides a downhole sealer, which is arranged near the second end of the central pipe, including the aforementioned cementing device, a first retaining ring sleeved on the outer surface of the central pipe, and a second retaining ring sleeved on the outer surface of the central pipe, and the rubber tube is sleeved on the outer surface of the central pipe and arranged between the first retaining ring and the second retaining ring.

[0016] In a preferred embodiment, the first retaining ring is located above the second retaining ring, the upper surface of the rubber cylinder abuts against the lower surface of the first retaining ring, and the lower surface of the rubber cylinder abuts against the upper surface of the second retaining ring.

[0017] The present invention comprises a central tube, an opening sleeve sleeved on the outer surface of the central tube and a sealing rubber, and the central tube 3 is radially provided with a liquid inlet hole and a liquid flow channel, the opening sleeve seals the liquid inlet hole and the liquid flow channel, and the opening sleeve is fixed to the outer surface of the central tube by a fixing part, and a liquid storage space is formed between the sealing rubber and the central tube. After the fixing part is cut off, the opening sleeve can move along the axial direction of the central tube to open the liquid flow channel, and the fluid in the central tube can flow into the liquid storage space through the liquid flow channel, thereby avoiding the situation where the cementing quality does not meet the standard due to leakage caused by the use of high-density cement for sealing, reducing the system cost, and effectively maintaining the late strength of cementing.

[0018] The present invention forms a liquid storage space surrounded by the outer surface of the central tube, the inner surface of the sealing rubber and the end surface of the opening sleeve. After the fixed portion is sheared off, the opening sleeve moves downward along the axial direction of the central tube to open the liquid flow channel. During the downward movement of the opening sleeve along the axial direction of the central tube, the liquid storage space can gradually become larger, thereby facilitating the accumulation of fluid therein for pushing the sealing rubber out.

[0019] The cementing device described in the present invention also includes a hydraulic sleeve sleeved on the outer surface of the opening sleeve. On the one hand, the hydraulic sleeve is used to constrain the radial displacement of the opening sleeve so that the opening sleeve can move axially. On the other hand, the hydraulic sleeve provides a flow space for the liquid between the outer surface of the central pipe and the inner surface of the hydraulic sleeve, which is convenient for the flowing liquid to shear the fixed part, thereby facilitating the release of the opening sleeve.

[0020] The present invention can fix the upper end of the sealing rubber to the fixed baffle ring, so that after the sealing rubber is pushed out by the mud and becomes ineffective, the sealing rubber can still be fixed to the fixed baffle ring, which is convenient for reuse. Specifically, after the pressure is pressed to the set pressure, the sealing rubber pressed on the lower end of the positioning sleeve falls off, the cement injection channel is opened, and the upper end of the sealing rubber and the fixed baffle ring are fixed at the connection, so that the sealing rubber itself is not damaged.

[0021] The present invention arranges a positioning sleeve at the lower end of the sealing rubber and the lower end of the sealing rubber is pressed into the positioning sleeve and can be detached from the positioning sleeve. After cement is squeezed into the annulus between the surface layer and the oil layer casing through the sealing rubber and the cementing construction is completed, due to the high density of the annular cement slurry and the large static liquid column pressure, the sealing rubber can be returned to its position under the action of the pressure difference, and the cement injection channel can be closed, thereby preventing the cement slurry from returning. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The figure schematically shows an overall structural diagram of the cementing device of the present invention.

[0023] In the present application, all drawings are schematic drawings, which are only used to illustrate the principles of the present invention and are not drawn according to the actual scale. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other arbitrarily.

[0025] In the description of the present invention, it is necessary to understand that the terms "inside", "outside", "axial", "radial", "upper", "lower", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention 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, and therefore cannot be understood as a limitation on the present invention.

[0026] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0027] In the description of the present invention, “plurality” means two or more than two, unless otherwise clearly and specifically defined.

[0028] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation" and the like 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 a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] Figure 1 The figure schematically shows an overall structural diagram of the cementing device 100 of the present invention. Figure 1As shown, the cementing device 100 of the present invention comprises: a central tube 3, an opening sleeve 4 sleeved on the outer surface of the central tube 3, and a sealing rubber 6. The central tube 3 is provided with a liquid inlet hole 8 and a liquid flow channel 9 in the radial direction. Before the pressure is applied, the opening sleeve 4 seals the liquid inlet hole 8 and the liquid flow channel 9, and the opening sleeve 4 is fixed to the outer surface of the central tube 3 by a fixing part (not shown in the figure). The fixing part is, for example, a pin. A liquid storage space s is formed between the sealing rubber 6 and the central tube 3. During the pressure application inside the surface casing, cement slurry can enter the area where the opening sleeve 4 is located through the liquid inlet hole 8 and the fixing part can be sheared by the liquid. After the fixing part is sheared, the opening sleeve 4 can be opened inside. Under the action of the external pressure difference, it moves axially along the center tube 3, so that the liquid flow channel 9 can be exposed to open the liquid flow channel 9, and the cement slurry in the center tube 3 can flow into the liquid storage space s through the liquid flow channel. Since the liquid storage space s is formed between the sealing rubber 6 and the center tube 3, the fluid in the liquid storage space s can continuously squeeze the sealing rubber 6 to squeeze and push the sealing rubber 6 out, so that the fluid can squeeze into the annulus between the surface layer and the oil layer casing, and squeeze the mud between the surface casing and the oil layer casing into the formation, so that the cement injection channel can be opened, and the cement flows out from the cementing device into the annulus between the surface casing and the oil layer casing, which is used to seal the well section above the surface casing shoe. It should be noted that the fixing part can be a pin. The sealing rubber 6 described in the present invention has anti-extrusion ability and can keep the sealing performance unchanged during the lowering of the surface casing and cementing process.

[0030] The cementing device 100 described in the present invention can control the cement return height to the lower part of the cementing device 100 (the casing shoe of the surface casing) after each conventional cementing construction is completed, that is, when implementing oil layer casing cementing, so as to avoid leaking. After the waiting solidification is completed, the cementing device 100 described in the present invention is used to carry out the second-stage cementing construction. Specifically, the cement slurry is pressurized to enter the area where the opening sleeve 4 is located through the liquid inlet hole 8, and the fixed part is cut off. The opening sleeve 4 then moves axially along the central pipe 3 under the action of the internal and external pressure difference, so that the liquid flow channel 9 can be exposed to open the liquid flow channel 9, and the cement slurry in the central pipe 3 can flow into the liquid storage space s through the liquid flow channel, and the cement slurry then squeezes and pushes the sealing rubber 6 out, and squeezes the cement slurry into the formation to fill the upper part of the casing shoe of the surface casing with cement. Since the cementing device 100 of the present invention can perform two-stage cementing, it is possible to avoid the situation where the cementing quality does not meet the standards due to leakage caused by the use of high-density cement for sealing, reduce the system cost, and effectively maintain the late strength of cementing.

[0031] In one or more embodiments, the liquid storage space s is formed by the outer surface of the central tube 3 , the inner surface of the sealing rubber 6 , and the end surface of the opening sleeve 4 .

[0032] In the present invention, the liquid storage space s is formed by the outer surface of the central tube 3, the inner surface of the sealing rubber 6 and the end surface of the opening sleeve 4. After the fixed portion is sheared off, the opening sleeve 4 moves axially downward along the central tube 3 to open the liquid flow channel 9. During the axial downward movement of the opening sleeve 4 along the central tube 3, the liquid storage space s can gradually become larger, thereby facilitating the accumulation of fluid therein for pushing the sealing rubber 6 out.

[0033] In one or more embodiments, the opening sleeve 4 is placed on the outer surface of the central tube 3 and seals the liquid inlet 8 and the liquid flow channel 9 respectively by rubber rings. It should be noted that the sealing connection between the opening sleeve 4 and the liquid inlet 8 can be broken by pressing.

[0034] In one or more embodiments, the cementing device 100 described in the present invention also includes a hydraulic sleeve 2 sleeved on the outer surface of the opening sleeve 4. On the one hand, the hydraulic sleeve 2 is used to constrain the radial displacement of the opening sleeve so that the opening sleeve 4 can move axially. On the other hand, the hydraulic sleeve 2 provides a flow space for the liquid between the outer surface of the center pipe 3 and the inner surface of the hydraulic sleeve 2, which is convenient for the flowing liquid to shear the fixed part, thereby facilitating the release of the opening sleeve 4.

[0035] In one or more embodiments, the cementing device 100 of the present invention further includes a fixed retaining ring 7, which is disposed at the upper end of the sealing rubber 6, and the upper end of the sealing rubber 6 is embedded in the fixed retaining ring 7. Optionally, the fixed retaining ring 7 is connected to the central pipe 3 by a thread to support other parts.

[0036] In one or more embodiments, the upper end of the sealing rubber 6 is fixedly connected to the fixed baffle ring 7. Optionally, the upper end of the sealing rubber 6 and the fixed baffle ring 7 can be fixed by a toothed fixing member.

[0037] The present invention can make the upper end of the sealing rubber 6 fixedly connected to the fixed baffle ring 7, so that after the sealing rubber 6 is pushed by the mud and becomes ineffective, the sealing rubber 6 can still be fixed to the fixed baffle ring 7, so as to be reused. Specifically, after the pressure is pressed to the set pressure, the sealing rubber 6 is pressed against the lower end of the positioning sleeve 5 and falls off, opening the cement injection channel, and the upper end of the sealing rubber 6 and the fixed baffle ring 7 are kept fixed at the connection, so that the sealing rubber 6 itself is not damaged.

[0038] In one or more embodiments, the cementing device 100 of the present invention further includes a positioning sleeve 5 , which is disposed at the lower end of the sealing rubber 6 . The lower end of the sealing rubber 6 is pressed into the positioning sleeve 5 and can be detached from the positioning sleeve 5 .

[0039] In the present invention, the positioning sleeve 5 is arranged at the lower end of the sealing rubber sheet 6, and the lower end of the sealing rubber sheet 6 is pressed into the positioning sleeve 5 and can be disengaged from the positioning sleeve 5. After the cement is squeezed into the annulus between the surface casing and the production casing through the sealing rubber sheet 6 and the cementing operation is completed, due to the high density of the annulus cement slurry and the large hydrostatic pressure, the sealing rubber sheet 6 can be returned under the action of the pressure difference to close the cement injection channel, thereby preventing the cement slurry from flowing back. After the sealing rubber sheet 6 is returned, the cement injection channel can be closed, and the liquid flow channel 9 and the liquid storage space s are filled with cement. After the cement solidifies, all the channels are completely sealed, ensuring the sealing and pressure-bearing performance inside the pipe.

[0040] In one or more embodiments, the cementing device 100 of the present invention further includes a first coupling 1 arranged on the outer surface of the central pipe 3, and the lower end surface of the first coupling 1 is embedded and fixed inside the retaining ring 7.

[0041] In one or more embodiments, the lower end surface of the first coupling 1, the outer surface of the central pipe 3, the inner surface of the sealing rubber sheet 6, and the end surface of the opening sleeve 4 together enclose to form a liquid storage space s.

[0042] The following briefly describes the specific implementation process of the cementing device 100 of the present invention: When completing the surface casing well completion, the cementing tool 100 of the present invention is installed on the string of the surface casing, and the cementing tool 100 is in a closed state during the surface casing cementing. When implementing the production casing cementing, the cementing tool 100 is used to control the cement return height to be located below the cementing tool 100. After the cement condensation is completed, pressure is applied in the production casing annulus to open the cementing tool 100 of the present invention. At this time, the squeeze cement operation can be implemented to complete the upper part cementing of the production casing.

[0043] Although the present invention has been described with reference to the preferred embodiments, various improvements can be made to it and the components therein can be replaced with equivalents without departing from the scope of the present invention. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A cementing device, comprising a center tube, an opening sleeve sleeved on the outer surface of the center tube, and a sealing rubber, wherein the center tube is radially provided with a liquid inlet hole and a liquid flow channel, the opening sleeve seals the liquid inlet hole and the liquid flow channel, and the opening sleeve is fixed to the outer surface of the center tube through a fixing portion, a liquid storage space is formed between the sealing rubber and the center tube, after the fixing portion is cut off, the opening sleeve can move axially along the center tube to open the liquid flow channel, and the fluid in the center tube can flow into the liquid storage space through the liquid flow channel.

2. The cementing device according to claim 1, It is characterized in that The liquid storage space is formed by being surrounded by the outer surface of the central tube, the inner surface of the sealing rubber and the end surface of the opening sleeve.

3. The cementing device according to claim 1, It is characterized in that It also includes a hydraulic sleeve which is sleeved on the outer surface of the opening sleeve.

4. The cementing device according to claim 2, It is characterized in that It also includes a fixed baffle ring, which is arranged on the upper end of the sealing rubber, and the upper end of the sealing rubber is embedded in the fixed baffle ring.

5. The cementing device according to claim 4, It is characterized in that The upper end of the sealing rubber is fixedly connected to the fixed baffle ring.

6. The cementing device according to claim 6, It is characterized in that It also includes a positioning sleeve, which is arranged at the lower end of the sealing rubber. The lower end of the sealing rubber is pressed into the positioning sleeve and can be separated from the positioning sleeve.

7. The cementing device according to claim 4, It is characterized in that It also includes a first coupling hoop arranged on the outer surface of the central pipe, and the lower end surface of the first coupling hoop is embedded in the fixed retaining ring.

8. The cementing device according to claim 7, It is characterized in that The lower end surface of the first coupling, the outer surface of the central tube, the inner surface of the sealing rubber and the end surface of the opening sleeve together surround and form the liquid storage space.

9. The cementing device according to claim 4, It is characterized in that It also includes a second coupling hoop arranged on the outer surface of the central pipe, and the upper end surface of the second coupling hoop is embedded in the interior of the hydraulic sleeve.

10. The cementing device according to claim 9, It is characterized in that The upper end surface of the second coupling, the inner surface of the hydraulic sleeve and the outer surface of the central pipe form an accommodating space, and the opening sleeve can move axially along the central pipe inside the accommodating space.

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