One-way seal ring, sealing mechanism, tailpipe top packer and tailpipe cementing process

Abstract

The application provides a one-way sealing ring, a sealing mechanism, a tail pipe top packer and a tail pipe cementing process, wherein the one-way sealing mechanism comprises a center pipe, an upper deformed sleeve arranged on the outer wall of the center pipe, a lower deformed sleeve arranged on the outer wall of the center pipe, the upper deformed sleeve and the lower deformed sleeve being spaced apart in the axial direction, a sealing element arranged on the outer wall of the center pipe, the lower end of the sealing element being in abutment with the upper end of the lower deformed sleeve, an expansion cone arranged between the upper deformed sleeve and the sealing element, a sealing groove being arranged on the inner wall of the expansion cone in the circumferential direction, a sealing ring being arranged in the sealing groove, a flow-off groove being arranged on the inner wall of the expansion cone in the axial direction, the flow-off groove penetrating through the upper end and the lower end of the expansion cone, and fluid being allowed to flow only in one direction from the upper end of the expansion cone to the lower end of the expansion cone along the flow-off groove, while the fluid under the packer is allowed to flow upward, the wellhead annulus is allowed to be pressurized for cement setting, the pressure reduction caused by volume shrinkage is prevented to prevent the stratum fluid from flowing out, and the cementing quality is ensured.

Description

Technical Field

[0001] This invention relates to the field of oil and gas drilling and production downhole tool manufacturing technology, specifically to a one-way sealing ring, a sealing mechanism, a tailpipe top packer, and a tailpipe cementing process. Background Technology

[0002] The top packer for the tailpipe is mainly used for tailpipe cementing in the oil and gas industry. It is installed on top of the tailpipe hanger and is integrated with the tailpipe hanger. It can seal the annulus between the tailpipe and the upper casing, and solve the problem of gas leakage at the flare-mouth that may occur after tailpipe cementing in wells with low pressure loss, narrow pressure window, and simultaneous blowout and leakage.

[0003] For example, Chinese patent document with publication number "CN204266983U" discloses a packer structure for the top of the tailpipe, including a packer body and, from top to bottom, a rubber sleeve pusher, one or more rubber sleeves, and a fixing sleeve fitted around the body; an O-ring is provided between the rubber sleeve and the body; the fixing sleeve is fixedly connected to the body; a backstop ring is provided between the rubber sleeve pusher and the body; and a circumferential groove is machined on the surface of the rubber sleeve pusher. Using this packer structure in cementing operations can achieve the function of sealing the upper annulus, effectively solving the aforementioned technical problems. However, during use, because this structure forms a closed space between the packer and the pressure seat after setting, the cement slurry in this closed space will shrink in volume during the subsequent setting process and cannot be compensated for by external pressure. This will cause a decrease in the absolute pressure of the open hole annulus, while the fluid in the formation below the annulus remains under high pressure. The pressure difference between the annulus and the formation will push the fluid in the formation out of the formation along the open hole annulus, affecting the cementing quality. Summary of the Invention

[0004] The purpose of this invention is to address at least one of the aforementioned deficiencies in the prior art. For example, one objective of this invention is to provide a one-way sealing ring, a sealing mechanism, a packer at the top of the tailpipe, and a tailpipe cementing process to solve the problem of fluid surge caused by reduced open-hole annular pressure.

[0005] To achieve the above objectives, one aspect of the present invention provides a one-way sealing mechanism, which may include: a central tube; an upper deformable retaining sleeve fitted on the outer wall of the central tube; a lower deformable retaining sleeve fitted on the outer wall of the central tube and spaced apart from the upper deformable retaining sleeve in the axial direction of the central tube; a sealing element fitted on the outer wall of the central tube, the lower end of the sealing element abutting against the upper end of the lower deformable retaining sleeve; and an expansion cone fitted on the outer wall of the central tube, the expansion cone being positioned axially between the upper deformable retaining sleeve and the sealing element. Between the components, the lower end of the expansion cone can be inserted into the gap between the sealing element and the outer wall of the central tube, causing the sealing element to expand and thus fit tightly against the inner wall of the annular space to be sealed; a drainage groove is provided on the inner wall of the expansion cone along the axial direction of the expansion cone, and the drainage groove passes through the upper and lower ends of the expansion cone; a sealing groove is provided on the inner wall of the expansion cone along the circumferential direction of the inner wall of the expansion cone; a shearing fixing member is used to fix the sealing element relative to the expansion cone and can be sheared under the action of axial shear force; and a sealing ring is installed in the sealing groove so that the fluid can only flow unidirectionally from the upper end to the lower end of the expansion cone along the drainage groove.

[0006] Alternatively, the sealing ring may be inverted Y-shaped, and may include: an upper part, the inner diameter of which is larger than the outer diameter of the central tube, the upper end face of which has a radial groove along the radial direction of the sealing ring, the radial groove communicating with the gap between the inner wall of the upper part and the outer wall of the central tube to allow fluid to pass through; and a lower part, which includes an outer head and an inner head, the outer head being tightly fitted to the inner wall of the sealing groove, the inner head being tightly fitted to the outer wall of the central tube, the lower end of the inner head being spaced apart from the lower end of the outer head along the radial direction of the central tube, and the length of the outer head being greater than the length of the inner head.

[0007] Alternatively, an angle may be formed between the inner head and the outer head, and the angle may be 0 to 90 degrees.

[0008] Optionally, a step may be provided on the upper part of the sealing groove along the circumference of the sealing groove. The one-way sealing mechanism further includes: a limiting ring, which is installed on the step. The outer diameter of the limiting ring is larger than the bottom diameter of the drain groove and smaller than the bottom diameter of the step. The inner diameter of the limiting ring is larger than the outer diameter of the central tube. The outer edge of the limiting ring is spaced apart from the step, and the inner edge of the limiting ring is spaced apart from the outer wall of the central tube.

[0009] Optionally, a shear pin through hole may be provided on the upper part of the expansion cone along the circumference of the expansion cone. The shear pin through hole penetrates the side wall of the expansion cone. A blind hole is provided on the outer wall of the central tube at a position corresponding to the shear pin through hole. The shearing fastener is simultaneously inserted into the shear pin through hole and the blind hole. The number of shearing fasteners is the same as the number of shear pin through holes and the blind holes.

[0010] Alternatively, the axial length of the expansion cone may be greater than the axial length of the sealing element. The expansion cone can move along the axis of the central tube and be inserted between the sealing element and the outer wall of the central tube, so that the sealing element expands radially along the central tube and fits tightly against the inner wall of the annular space to be sealed.

[0011] Alternatively, the outer wall of the expansion cone may include an upper section, a middle section, and a lower section along the axial direction from top to bottom, wherein the diameter of the upper section is larger than the diameter of the middle section and the diameter of the middle section is larger than the diameter of the lower section.

[0012] Optionally, the outer wall of the lower deformable retaining sleeve may include an upper section and a lower section along the axial direction from top to bottom, wherein the diameter of the upper section is smaller than the diameter of the lower section, and the diameter of the upper section is the same as or slightly larger than the outer diameter of the sealing element; the inner wall of the lower deformable retaining sleeve may include an upper section, a middle section, and a lower section from top to bottom, wherein the diameter of the middle section is larger than the diameter of the upper section, and the diameter of the upper section is larger than the diameter of the lower section.

[0013] Optionally, an axial cut can be provided on the lower deformation retaining sleeve along the axial direction of the lower deformation retaining sleeve, penetrating the inner and outer walls of the lower deformation retaining sleeve.

[0014] Optionally, the lower part of the upper deformable retaining sleeve may be provided with a "double L-shaped" cut and a segmented sealing claw formed by the "double L-shaped" cut. The "double L-shaped" cut includes a first distance cut along the axis from the lower end face of the upper deformable retaining sleeve, a second distance cut along the circumferential direction, and a third distance cut along the axial direction. The first distance and the second distance are smaller than the third distance.

[0015] Another aspect of the present invention provides a one-way sealing ring, the sealing ring may include: an upper part, wherein the upper end face of the upper part is provided with a radial groove penetrating the inner and outer sides of the sealing ring along the radial direction of the sealing ring; and a lower part, the lower part including an outer head and an inner head, the lower end of the inner head being spaced apart from the lower end of the outer head along the radial direction of the sealing ring, and the length of the outer head being greater than the length of the inner head.

[0016] Another aspect of the present invention provides a tailpipe top packer, which may include: a one-way sealing mechanism as described above; and a setting mechanism fixedly connected to the upper end of the center tube of the one-way sealing mechanism.

[0017] Another aspect of the present invention provides a tailpipe cementing process, which may include: injecting cement slurry into the open hole annulus; connecting the hanger joint of the tailpipe top packer to the tailpipe hanger; pressing down the setting mechanism to fully insert the expansion cone of the tailpipe top packer into the sealing element, causing the sealing element to expand and block the annulus, thus completing the setting; after setting and before the cement slurry solidifies, pressurizing the wellhead annulus to allow fluid to be injected into the open hole and overlapping section annulus through the tailpipe top packer, pressurizing the cement slurry until it solidifies; after the cement slurry solidifies, using the one-way sealing mechanism of the tailpipe top packer to prevent post-cementing gas from rising from bottom to top into the upper annulus of the tailpipe top packer.

[0018] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0019] 1. This invention employs a structure consisting of an expanding cone, a sealing element, a limiting ring, and a sealing ring shaped similar to an inverted "Y". The packer sets by the expanding cone inserting into the inner hole of the sealing element to achieve expansion, thus adhering tightly to the inner wall of the annulus to be sealed, thereby achieving a seal between the packer and the annulus.

[0020] 2. The special structure of the sealing ring installed on the inner wall of the expansion cone of the present invention has a shape similar to an inverted "Y". It has only unidirectional sealing performance, which can prevent the fluid below it from going up through the packer, but allows the fluid above it to go down through the packer.

[0021] 3. This invention can be used, but is not limited to, tailpipe suspension cementing in the oil and gas field. It can not only prevent gas from leaking into the annulus above the packer after cementing, but also allow the cement slurry to be pressed up in the annulus at the wellhead before it solidifies. This ensures that the cement slurry is always under the pressure of the upper liquid column and the pressure at the wellhead during the cementing process, which compensates for the volume shrinkage of the cement slurry during solidification and prevents the formation fluid from leaking out due to the pressure drop caused by the volume shrinkage, thereby ensuring the cementing quality. Attached Figure Description

[0022] The above and other objects and / or features of the present invention will become clearer from the following description taken in conjunction with the accompanying drawings, in which:

[0023] Figure 1(a) shows a cross-sectional view of a one-way sealing mechanism according to an exemplary embodiment of the present invention.

[0024] Figure 1(b) is an enlarged view of part I in Figure 1(a).

[0025] Figure 2A cross-sectional view of the expansion cone in a one-way sealing mechanism according to an exemplary embodiment of the present invention is shown.

[0026] Figure 3 A cross-sectional view of the sealing ring in a one-way sealing mechanism according to an exemplary embodiment of the present invention is shown.

[0027] Figure 4 A cross-sectional view of the lower deformable retaining sleeve in a one-way sealing mechanism according to an exemplary embodiment of the present invention is shown.

[0028] Figure 5(a) shows a schematic diagram of the upper deformable retaining sleeve in the one-way sealing mechanism of an exemplary embodiment of the present invention.

[0029] Figure 5(b) shows an enlarged view of part II in Figure 5(a).

[0030] Figure 6(a) shows an axial view of the limiting ring in a one-way sealing mechanism according to an exemplary embodiment of the present invention.

[0031] Figure 6(b) shows an enlarged view of part III in Figure 6(a).

[0032] Figure 6(c) shows a radial view of the limiting ring in a one-way sealing mechanism according to an exemplary embodiment of the present invention.

[0033] Figure 6(d) shows an enlarged view of part IV in Figure 6(c).

[0034] Explanation of reference numerals in the attached figures:

[0035] 1000 - Center tube, 1100 - External thread, 1200 - Blind hole;

[0036] 2000 - Upper deformable retaining sleeve, 2100 - Split-type setting pawl, 2110 - "Double L-shaped" cutout, 2111 - First distance, 2112 - Second distance, 2113 - Third distance;

[0037] 3000-Cut staples;

[0038] 4000-Expansion cone, 4100-Inner wall of expansion cone, 4110-Sealing groove, 4120-Step, 4130-Drainage groove, 4200-Outer wall of expansion cone, 4210-Upper section of outer wall of expansion cone, 4220-Middle section of outer wall of expansion cone, 4230-Lower section of outer wall of expansion cone, 4300-Shear pin through hole;

[0039] 5000 - Sealing element;

[0040] 6000 - Lower deformable retaining sleeve, 6100 - Outer wall of retaining sleeve, 6110 - Upper section of outer wall of retaining sleeve, 6120 - Lower section of outer wall of retaining sleeve, 6200 - Inner wall of retaining sleeve, 6210 - Upper section of inner wall of retaining sleeve, 6220 - Middle section of inner wall of retaining sleeve, 6230 - Lower section of inner wall of retaining sleeve, 6231 - Internal thread, 6300 - Axial cut;

[0041] 7000 - Hanger connector;

[0042] 8000 - Sealing ring, 8100 - Upper part, 8110 - Radial groove, 8120 - First end face, 8130 - Longitudinal face, 8140 - Second end face, 8200 - Lower part, 8210 - Outer head, 8220 - Inner head;

[0043] 9000 - Limiting ring, 9100 - Radial cut. Detailed Implementation

[0044] In the following description, a one-way sealing ring, a one-way sealing mechanism, a tailpipe top packer, and a tailpipe cementing process of the present invention will be explained in detail with reference to exemplary embodiments.

[0045] It should be noted that terms such as "first," "second," "third," and "fourth" are used merely for ease of description and distinction, and should not be construed as indicating or implying relative importance. Similarly, terms such as "upper," "lower," "inner," "outer," "front," "back," "left," and "right" are used merely for ease of description and to establish relative orientations or positional relationships, and do not indicate or imply that the referred component must possess that specific orientation or position. For those skilled in the art, some terms in this document, such as "pressure," are equivalent to pressure intensity.

[0046] The currently used top packer (referred to as packer) provides a bidirectional seal after setting, preventing fluid from flowing upwards from below the packer or downwards from above the packer.

[0047] The inventors discovered that in related technologies, the top packer of the tailpipe sets immediately after cementing and pressure injection. While this setting prevents fluid below the packer from flowing upwards through it (preventing oil and gas from rising), it also prevents fluid above the packer from flowing downwards through it. This creates a closed space in the annulus between the packer and the pressure seat, between the casing and the open hole. The cement slurry in this closed space undergoes volume shrinkage during the subsequent setting process. Without a packer, this shrinkage is compensated for by injecting fluid at the wellhead under pressure. However, with a packer, because it prevents fluid above the packer from flowing downwards through it, the wellhead pressure injection cannot compensate for the volume shrinkage during cement setting. This results in a decrease in the absolute pressure of the open hole annulus, causing high-pressure fluid to escape from the formation and affecting cementing quality.

[0048] This addresses the technical problem of wellhead pressure buildup caused by bidirectional sealing after packer setting failing to compensate for volume shrinkage during cement setting, resulting in a decrease in absolute pressure in the open hole annulus, causing high-pressure fluid to escape from the formation and affecting cementing quality.

[0049] One aspect of the present invention provides a one-way sealing mechanism, comprising: a central tube; an upper deformable retaining sleeve sleeved on the outer wall of the central tube; a lower deformable retaining sleeve sleeved on the outer wall of the central tube and spaced apart from the upper deformable retaining sleeve in the axial direction of the central tube; a sealing element sleeved on the outer wall of the central tube, the lower end of the sealing element abutting against the upper end of the lower deformable retaining sleeve; and an expansion cone sleeved on the outer wall of the central tube, the expansion cone being positioned axially between the upper deformable retaining sleeve and the sealing element, the expansion cone... The lower end can be cone-shaped into the gap between the sealing element and the outer wall of the central tube, causing the sealing element to expand and thus fit tightly against the inner wall of the annular space that needs to be sealed; the inner wall of the expansion cone is provided with a drainage groove along the axial direction of the expansion cone, the drainage groove passing through the upper and lower ends of the expansion cone, and the inner wall of the expansion cone is provided with a sealing groove along the circumference of the inner wall of the expansion cone; a shearing fixing element is used to fix the sealing element relative to the expansion cone and can be sheared under the action of axial shear force; and a sealing ring is installed in the sealing groove so that the fluid can only flow unidirectionally from the upper end to the lower end of the expansion cone along the drainage groove.

[0050] The top packer of the tailpipe according to the present invention has a one-way sealing function, which can prevent the fluid below the packer from flowing upward, but allows the fluid above the packer to flow downward. This invention effectively solves the technical defects of related technologies, achieving pressure build-up in the annulus from the wellhead after cementing. The pressure forces fluid through the packer into the open hole and overlapping section annulus, achieving the purpose of pressurizing and allowing the cement slurry to set, compensating for the reduction in shrinkage volume during the cement slurry setting process, thereby improving the setting quality. When fluid enters the annulus below the packer and reaches the packer position, the packer can also prevent it from continuing to rise, achieving the anti-gas channeling purpose of conventional top packers for tailpipes.

[0051] Figure 1(a) shows a cross-sectional view of a one-way sealing mechanism according to an exemplary embodiment of the present invention, and Figure 1(b) is an enlarged view of part I in Figure 1(a).

[0052] As shown in Figures 1(a) and 1(b), the one-way sealing mechanism according to an exemplary embodiment of the present invention includes: a central tube 1000, an upper deformable retaining sleeve 2000, a shear pin 3000, an expansion cone 4000, a sealing element 5000, a lower deformable retaining sleeve 6000, a sealing ring 8000, and a limiting ring 9000. The central tube 1000 is a hollow cylindrical structure. The upper end of the central tube 1000 is used to connect with the setting mechanism, and the lower end of the central tube 1000 is connected with the hanger connector 7000. In this embodiment, the hanger connector 7000 is sleeved on the lower end of the central tube 1000.

[0053] The upper deformable retaining sleeve 2000, shear pin 3000, expansion cone 4000, sealing element 5000, and lower deformable retaining sleeve 6000 are sequentially fitted onto the outer wall of the central tube 1000 from top to bottom. Specifically, the lower end of the lower deformable retaining sleeve 6000 abuts against the upper end of the hanger connector 7000, the lower end of the sealing element 5000 abuts against the upper end of the lower deformable retaining sleeve 6000, and the lower end of the expansion cone 4000 can be inserted into the gap between the sealing element 5000 and the central tube 1000. The upper part of the expansion cone 4000 has a shear pin through hole 4300, which penetrates both the inner and outer walls of the expansion cone 4000. A blind hole 1200 is provided on the outer wall of the central tube 1000 at a position corresponding to the shear pin through hole 4300. The shear pin 3000 is inserted into both the shear pin through hole 4300 and the blind hole 1200 to fix the expansion cone 4000 to the central tube 1000. The lower end of the upper deformable retaining sleeve 2000 abuts against the upper end of the expansion cone 4000. However, the present invention is not limited to this. In addition to shear pins, shear pins or the like can also be used. Any shearing fastener that can fix the expansion cone 4000 relative to the central tube 1000 and can be sheared under external force is acceptable.

[0054] Figure 2 A cross-sectional view of the expansion cone in a one-way sealing mechanism according to an exemplary embodiment of the present invention is shown. Figure 3 Figure 6(a) shows a cross-sectional view of the limiting ring in the one-way sealing mechanism of an exemplary embodiment of the present invention, Figure 6(b) shows an enlarged view of part III in Figure 6(a), Figure 6(c) shows a radial view of the limiting ring in the one-way sealing mechanism of an exemplary embodiment of the present invention, and Figure 6(d) shows an enlarged view of part IV in Figure 6(c).

[0055] like Figure 2 As shown, the expansion cone 4000 has a cylindrical structure. A drainage groove 4130 is formed on the inner wall of the expansion cone 4000 along the axial direction, penetrating both the upper and lower ends of the expansion cone 4000. Multiple drainage grooves 4130 are formed on the inner wall of the expansion cone 4000, and these grooves are spaced apart from each other circumferentially. Each drainage groove 4130 extends along the length of the expansion cone 4000. In this embodiment, four drainage grooves 4130 are formed on the inner wall of the expansion cone 4000, evenly spaced apart from each other circumferentially. However, the invention is not limited to this; the number of drainage grooves 4130 can also be one, two, three, five, or more.

[0056] A sealing groove 4110 is provided on the upper part of the inner wall of the expansion cone 4000 along the circumferential direction of the inner wall of the expansion cone 4000. The cross-section of the sealing groove 4110 can be rectangular. The upper and lower ends of the sealing groove 4110 are connected to the drain groove 4130 respectively. The bottom diameter of the sealing groove 4110 is larger than the bottom diameter of the drain groove 4130. The sealing groove 4110 is used to install the sealing ring 8000.

[0057] The upper part of the sealing groove 4110 is provided with a step 4120 along the circumferential direction of the inner wall of the expansion cone 4000. A limit ring 9000 is installed on the step 4120. The outer edge of the limit ring 9000 is in clearance fit with the step 4120, the inner edge of the limit ring 9000 is in clearance fit with the outer wall of the central tube 1000, and the lower end face of the limit ring 9000 is in contact with the upper end face of the sealing ring 8000. The outer diameter of the limit ring 9000 is larger than the bottom diameter of the drain groove 4130, and the outer diameter of the limit ring 9000 is smaller than the bottom diameter of the sealing groove 4110.

[0058] like Figures 6(a) to 6(d) As shown in Figure 6(b), the limiting ring 9000 can be a rigid annular ring. A radial cut 9100 is formed on the limiting ring 9000. As can be seen from Figure 6(b), the radial cut 9100 penetrates the inner and outer sides of the limiting ring 9000 radially. Figure 2 As can be seen from Figure 6(d), the radial cut 9100 is opened from the left end face of the retaining ring 9000 along the axial direction of the retaining ring 9000 for a certain distance, then along the circumference of the retaining ring 9000 for a certain distance, and then along the axial direction of the retaining ring 9000 for a certain distance until the radial cut 9100 reaches the right end face of the retaining ring 9000. The setting of the radial cut 9100 can shrink and reduce the inner diameter of the retaining ring 9000, which makes it easier for the retaining ring 9000 to be installed on the step 4120.

[0059] The sealing ring 8000 is installed in the sealing groove 4110. The lower end of the limiting ring 9000 is in contact with the upper end of the sealing ring 8000. The sealing ring 8000 is made of elastic material. When compressed by radial forces from the left and right sides, it will tend to bulge upward. The limiting ring 9000 is made of rigid material. When it is in contact with the upper end of the sealing ring 8000, it will restrict the upward bulge of the sealing ring 8000 and ensure the sealing effect of the sealing ring 8000.

[0060] like Figure 3As shown, the sealing ring 8000 has an inverted "Y" shaped cross-section, which can be divided into an upper part 8100 and a lower part 8200. The upper part 8100 includes a first end face 8120, a longitudinal surface 8130, and a second end face 8140. The first end face 8120 is higher than the second end face 8140. Multiple radial grooves 8110 are formed on the first end face 8120 along the radial direction. The multiple radial grooves 8110 are evenly distributed on the first end face 8120. In this embodiment, there are 18 radial grooves 8110, but the invention is not limited to this; the number of radial grooves 8110 can be any one of 1 to 17 or greater than 18. The radial grooves 8110 penetrate the inner wall of the upper part 8100 and the longitudinal surface 8130 of the sealing ring 8000. The lower part 8200 includes an outer head 8210 and an inner head 8220. The included angle between the outer head 8210 and the inner head 8220 can be an acute angle between 0 and 90 degrees. The length of the outer head 8210 is greater than the length of the inner head 8220.

[0061] In other words, one side of the "Y"-shaped portion of the sealing ring 8000 is shorter and the other side is longer. After the sealing ring 8000 is installed in the sealing groove 4110 on the inner wall 4100 of the expansion cone, the shorter side is close to the outer wall of the central tube, and the longer side is close to the bottom surface of the sealing groove of the expansion cone.

[0062] After the sealing ring 8000 is installed in the sealing groove 4110, as Figure 2 and Figure 3 As shown, the outer edge of the sealing ring 8000 is in close contact with the bottom surface of the sealing groove 4110, the second end face 8140 is in close contact with the upper end face of the sealing groove 4110, the longitudinal surface 8130 and the step 4120 are in close contact, the second end face 8140 and the lower end face of the limiting ring 9000 are in close contact, and the lower end face of the outer head 8210 is in close contact with the lower end face of the sealing groove 4110.

[0063] After the expansion cone 4000 is assembled onto the center tube 1000, as shown in Figure 1(a) and Figure 1(b)... Figure 2 and Figure 3As shown, the inner wall 4100 of the expansion cone and the outer wall of the central tube 1000 are in clearance fit. The inner head 8220 contacts the outer wall of the central tube 1000 and generates radial pressure. The lower part of the inner head 8220 is tightly fitted to the outer wall of the central tube 1000. The inner diameter of the upper part 8100 of the sealing ring 8000 is larger than the outer diameter of the central tube 1000. There is a gap between the inner wall of the upper part 8100 of the sealing ring 8000 and the outer wall of the central tube 1000. The gap between the inner wall of the upper part 8100 of the sealing ring 8000 and the outer wall of the central tube 1000 is connected to the drain groove 4130 above the limiting ring 9000 through the radial groove 8110, the gap between the limiting ring 9000 and the step 4120 to form a fluid channel. The gap between the inner wall of the upper part 8100 of the sealing ring 8000 and the outer wall of the central tube 1000 can also be connected to the drain groove 4130 above the limiting ring 9000 through the gap between the limiting ring 9000 and the outer wall of the central tube 1000 to form a fluid channel.

[0064] When the packer is set, the setting mechanism presses down and pushes the expansion cone 4000, which then penetrates the inner hole of the sealing element 5000, expanding the sealing element 5000 and pressing it tightly against the inner wall of the annulus to be sealed, thereby achieving the sealing of the annulus by the packer.

[0065] In this embodiment, the outer wall 4200 of the expansion cone is divided into three sections from top to bottom: the upper section 4210, the middle section 4220, and the lower section 4230. The outer diameter of the upper section 4210 is larger than that of the middle section 4220, and the outer diameter of the middle section 4220 is larger than that of the lower section 4230. This makes it easier for the expansion cone 4000 to enter the gap between the sealing element 5000 and the outer wall of the central tube 1000 during its downward movement. However, the present invention is not limited to this. The outer wall 4200 of the expansion cone may also include more sections, as long as the outer diameter decreases sequentially from top to bottom. Alternatively, the outer wall 4200 of the expansion cone may be designed as an inverted cone or similar structure.

[0066] The axial length of the expansion cone 4000 is greater than the axial length of the sealing element 5000. During the downward movement of the expansion cone 4000 along the axis of the central tube 1000, it can completely pass through the gap between the sealing element 5000 and the outer wall of the central tube 1000. The sealing element 5000 can be completely wrapped around the outer wall 4200 of the expansion cone. The lower section 4230 of the outer wall of the expansion cone can enter between the lower deformation sleeve 6000 and the outer wall of the central tube 1000.

[0067] Figure 4 A cross-sectional view of the lower deformable retaining sleeve in a one-way sealing mechanism according to an exemplary embodiment of the present invention is shown.

[0068] like Figure 4As shown, the lower deformable retaining sleeve 6000 can be a cylindrical structure. The lower deformable retaining sleeve 6000 includes an outer retaining sleeve wall 6100 and an inner retaining sleeve wall 6200. The outer retaining sleeve wall 6100 is divided into an upper section 6110 and a lower section 6120, with the outer diameter of the upper section 6110 being smaller than the outer diameter of the lower section 6120. The inner retaining sleeve wall 6200 is divided into an upper section 6210, a middle section 6220, and a lower section 6230, with the inner diameter of the middle section 6220 being larger than the inner diameter of the upper section 6210, and the inner diameter of the upper section 6210 being larger than the inner diameter of the lower section 6230.

[0069] When the current deformable retaining sleeve 6000 is fitted onto the central tube 1000, as shown in Figure 1(a) and Figure 4 As shown, the inner diameters of the upper section 6210, the middle section 6220, and the lower section 6230 of the inner wall of the retaining sleeve are all larger than the outer diameter of the central tube 1000, thus creating a gap between the inner wall 6200 of the retaining sleeve and the central tube 1000. The diameter of the upper section 6110 of the outer wall of the retaining sleeve is the same as or slightly larger than the outer diameter of the sealing element 5000.

[0070] As shown in Figure 1(a) and Figure 4 As shown, the lower deformable retaining sleeve 6000 has an axial cut 6300 along the axial direction. The axial cut 6300 penetrates both sides of the inner and outer walls of the lower deformable retaining sleeve 6000, thereby communicating with the gap between the inner wall 6200 of the retaining sleeve and the central tube 1000. The axial cut 6300 is only provided on the upper section 6210 and the middle section 6220 of the inner wall of the retaining sleeve, and is not provided on the lower section 6230 of the inner wall of the retaining sleeve. When the lower deformable retaining sleeve 6000 is subjected to a radial force acting on the upper section 6210 and / or the middle section 6220 of the inner wall of the retaining sleeve, the side wall of the lower deformable retaining sleeve 6000 can undergo elastic deformation in the radial direction. At this time, a gap appears at the axial cut 6300, connecting the outer wall 6100 and the inner wall 6200 of the retaining sleeve, allowing fluid to flow from the inner wall 6200 to the outer wall 6100 of the retaining sleeve along the gap.

[0071] In one embodiment of the present invention, an internal thread 6231 is provided on the lower section 6230 of the inner wall of the retaining sleeve, and an external thread 1100 is provided on the outer wall of the central tube 1000 at a position corresponding to the internal thread 6231. The internal thread 6231 and the external thread 1100 cooperate with each other to fix the lower deformable retaining sleeve 6000 to the central tube 1000. In another embodiment of the present invention, the lower section 6230 of the inner wall of the retaining sleeve is a smooth surface, and the inner diameter of the lower section 6230 of the inner wall of the retaining sleeve is larger than the outer diameter of the central tube 1000. An annular step is provided on the outer wall of the central tube 1000, and the upper end of the lower section 6230 of the inner wall of the retaining sleeve can abut against the annular step, thereby fitting the lower deformable retaining sleeve 6000 onto the central tube 1000 and fixing it axially. However, the present invention is not limited to this, and the lower deformable retaining sleeve 6000 can also be fixedly connected to the central tube 1000 by other connection methods.

[0072] Figure 5(a) shows a schematic diagram of the upper deformable retaining sleeve in the one-way sealing mechanism of an exemplary embodiment of the present invention; Figure 5(b) shows an enlarged view of part II in Figure 5(a).

[0073] As shown in Figures 5(a) and 5(b), the lower part of the upper deformable retaining sleeve 2000 is provided with a segmented setting spring claw 2100. Several protrusions are provided on the upper outer wall, the function of which is to ensure that the direction of the setting and pressing down is always vertical. The segmented setting spring claw 2100 is formed by cutting a first distance 2111 along the axis from the lower end face of the elastic anti-push-off retaining sleeve body, then cutting a second distance 2112 circumferentially, and finally cutting a third distance 2113 axially. The first distance 2111 and the second distance 2112 are both smaller than the third distance 2113. The first, second, and third distances can be set according to the size of the sealing device. The cutting trajectory lines of the first distance 2111 and the second distance 2112 form a first "L" shape, and the cutting trajectory lines of the second distance 2112 and the third distance 2113 form a second "L" shape. Therefore, as shown in Figure 5(b), the first "L" shape and the second "L" shape form a "double L" shaped cut 2110. The split-type setting spring claw 2100 with a "double L-shaped" notch 2110 ensures that no gap is generated at the end face when the split-type setting spring claw 2100 expands radially outward, and can adhere tightly to the outer wall of the setting annulus, forming a "metal wall" that blocks the annulus. The "metal wall" can prevent the sealing element 5000 from being compressed and squeezed out of the annulus gap when it expands radially. The upper deformable retainer 2000 with the above structure expands radially outward after being subjected to the setting pressure. The lower end of the upper deformable retainer 2000 adheres tightly to the outer wall of the setting annulus and does not require the seal to push it. This is different from the traditional method of relying on the seal to expand and adhere to the outer wall of the setting annulus after being compressed, and there is no problem of insufficient pushing force of the seal. Furthermore, the split-type setting spring claw 2100 with a "double L-shaped" notch 2110 will not create a gap between the upper deformable retainer 2000 and the outer wall of the setting annulus, so that the sealing element 5000 will not be squeezed out of the gap under high pressure.

[0074] In addition to the “double L-shaped” cut 2110 shown in Figures 5(a) and 5(b), the cut structure of the upper deformable retaining sleeve 2000 can also be set as other structures. For example, in another embodiment, the “double L-shaped” structure can be omitted and set as a straight cut that extends to the lower end face of the upper deformable retaining sleeve 2000.

[0075] The hanger connector 7000 is fitted onto the lower end of the center tube 1000. The upper end of the hanger connector 7000 is abutted against the lower end of the lower deformation sleeve 6000. The lower end of the hanger connector 7000 is connected to the hanger, thereby connecting the top packer of the tailpipe to the hanger.

[0076] When the packer at the top of the tailpipe is set, the setting mechanism pushes down and pushes the expansion cone 4000. At this time, the shear pin 3000, which fixes the expansion cone 4000 in the axial direction, is sheared by the downward shearing force. The expansion cone 4000 is thus able to move downward and gradually enter the space between the sealing element 5000 and the outer wall of the central tube 1000. The sealing element 5000 is expanded in the radial direction of the central tube 1000 until the outer wall of the sealing element 5000 is close to the inner wall of the annulus to be sealed, thereby achieving the sealing of the annulus.

[0077] As the expansion cone 4000 moves downward until the sealing element 5000 is completely fitted onto the outer wall of the expansion cone 4000, the lower end of the expansion cone 4000 is inserted into the gap between the inner wall of the lower deformation retainer 6000 and the outer wall of the central tube 1000. Under the action of radial force, the lower deformation retainer 6000 expands radially outward and forms a gap at the axial cut 6300.

[0078] After the packer at the top of the tailpipe is set, when the pressure at the bottom of the packer is higher than that at the top, the gap between the expansion cone 4000 and the inner wall of the annulus is sealed by the sealing element 5000 after expansion, and the gap between the expansion cone 4000 and the central tube 1000 is sealed by the sealing ring 8000. Specifically, the process of the sealing ring 8000 blocking the upward flow of the lower fluid is as follows: When the lower fluid of the expansion cone 4000 flows upward through the drain groove 4130 on the inner wall 4100 of the expansion cone and reaches below the sealing ring 8000, that is, between the outer head 8210 and the inner head 8220, at this time, the outer head 8210 and the inner head 8220 are pressed against the bottom of the sealing groove 4110 and the outer wall of the central tube 1000 respectively by the upward pressure of the fluid, preventing the fluid from flowing upward through the limiting ring, and thus preventing the fluid from continuing to rise to the top of the expansion cone 4000, thereby achieving the purpose of preventing the lower fluid from reaching the top through the packer.

[0079] After the packer at the top of the tailpipe is set, when the pressure at the top of the packer is higher than that at the bottom, the gap between the expansion cone 4000 and the inner wall of the annulus is sealed by the sealing element 5000 after expansion. The gap between the expansion cone 4000 and the central tube 1000 allows fluid to pass from top to bottom. The process by which fluid can pass through the sealing ring 8000 from top to bottom is as follows: When the pressure at the top of the packer is higher than that at the bottom, the fluid passes from top to bottom through the drain groove 4130 at the top of the inner wall 4100 of the expansion cone, then through the gap between the limiting ring 9000 and the step 4120, and then through the radial groove 8110 on the first end face 8120 on the upper part 8100 of the sealing ring 8000, entering the gap between the sealing ring 8000 and the outer wall of the central tube 1000. At this time, the inner head 8220, which is in contact with the outer wall of the central tube 1000, contracts radially under the downward pressure of the fluid, causing the inner head 8220 to move away from the central tube 1000. The fluid passes through the gap between the sealing ring 8000 and the outer wall of the central tube 1000, enters the venting groove 4130 below the sealing ring 8000, passes through the expansion cone 4000, enters the gap between the lower deformation sleeve 6000 and the outer wall of the central tube 1000, and then enters the annular space at the bottom of the packer through the gap at the axial cut 6300 on the lower deformation sleeve 6000. This achieves the purpose of allowing the upper fluid to pass through the sealing ring 8000 to reach the lower annulus, and also allows the cement slurry to be pressurized and allowed to set in the annulus above the packer after the packer is set.

[0080] Another aspect of the present invention provides a one-way sealing ring, such as Figure 3 As shown, the sealing ring has an inverted "Y" shaped cross-section, which can be divided into an upper part 8100 and a lower part 8200. The upper part 8100 includes a first end face 8120, a longitudinal surface 8130, and a second end face 8140. The first end face 8120 is higher than the second end face 8140. A plurality of radial grooves 8110 are formed on the first end face 8120 along the radial direction. In this embodiment, there are 18 radial grooves 8110, but the present invention is not limited to this. The number of radial grooves 8110 can also be any one of 1-17 or greater than 18. The radial grooves 8110 penetrate the inner wall of the upper part 8100 and the longitudinal surface 8130 of the sealing ring 8000. The lower part 8200 includes an outer head 8210 and an inner head 8220. The included angle between the outer head 8210 and the inner head 8220 can be 30 to 60 degrees. The length of the outer head 8210 is greater than, less than, or equal to the length of the inner head 8220.

[0081] Another aspect of the present invention provides a tailpipe top packer, the tailpipe top packer comprising: as shown in the figure Figures 1(a) to 6(d) The one-way sealing mechanism shown is fixedly connected to Figures 1(a) to 6(d) The setting mechanism at the upper end of the one-way sealing mechanism shown in the figure.

[0082] Another aspect of the present invention provides a tailpipe cementing process, the tailpipe cementing process comprising:

[0083] S100, Inject cement grout into the naked eye ring.

[0084] S200, connect the tailpipe top packer hanger connector 7000 to the tailpipe hanger as one unit.

[0085] S300, the lower setting mechanism, fully inserts the expansion cone 4000 of the packer at the top of the tailpipe into the sealing element 5000, causing the sealing element 5000 to expand and block the annular space, thus completing the setting.

[0086] S400: After setting and before the cement slurry solidifies, the fluid is injected into the open hole and overlapping section annulus through the packer at the top of the tailpipe by pressurizing the annulus at the wellhead to pressurize the cement slurry for solidification.

[0087] After S500 cement slurry solidifies, the one-way sealing mechanism of the top packer of the tailpipe prevents post-cementation gas from leaking upwards into the upper annulus of the top packer of the tailpipe.

[0088] In summary, the one-way sealing mechanism and tailpipe top packer of the present invention adopt a novel inverted "Y" shaped one-way sealing ring structure. On the one hand, it can prevent gas from leaking into the upper annulus of the packer after cementing. On the other hand, it can also allow the cement slurry to solidify through the annulus at the wellhead by pressurizing it after cementing and before the cement slurry solidifies. This ensures that the cement slurry is always under the action of the upper liquid column pressure and the wellhead pressurization pressure during the cement slurry solidification process, compensating for the volume shrinkage during the cement slurry solidification period, preventing the formation fluid from leaking out due to the pressure drop caused by the volume shrinkage, and achieving a good cementing effect.

[0089] Although the present invention has been described above in conjunction with exemplary embodiments and accompanying drawings, those skilled in the art should understand that various modifications can be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. A one-way sealing mechanism, characterized in that, The one-way sealing mechanism includes: Central tube; An upper deformable retaining sleeve is fitted onto the outer wall of the central tube; A lower deformation sleeve is sleeved on the outer wall of the central tube and spaced apart from the upper deformation sleeve in the axial direction of the central tube. A sealing element is sleeved on the outer wall of the central tube, and the lower end of the sealing element abuts against the upper end of the lower deformation retainer. An expansion cone is fitted onto the outer wall of the central tube. The expansion cone is positioned axially between the upper deformable retaining sleeve and the sealing element. The lower end of the expansion cone can penetrate the gap between the sealing element and the outer wall of the central tube, causing the sealing element to expand and thus adhere tightly to the inner wall of the annular space to be sealed. A drainage groove is provided on the inner wall of the expansion cone along its axial direction, extending through both the upper and lower ends of the expansion cone. A sealing groove is also provided on the inner wall of the expansion cone circumferentially. A shearing fastener that fixes the sealing element relative to the expansion cone and is capable of being sheared off under axial shear force; and A sealing ring is installed in the sealing groove so that the fluid can only flow unidirectionally from the upper end to the lower end of the expansion cone along the drainage groove; The sealing ring includes: The upper part has an inner diameter larger than the outer diameter of the central tube. A radial groove is formed on the upper end face of the upper part along the radial direction of the sealing ring. This radial groove communicates with the gap between the inner wall of the upper part and the outer wall of the central tube to allow fluid passage. The lower part includes an outer head and an inner head. The outer head is in close contact with the inner wall of the sealing groove, and the inner head is in close contact with the outer wall of the central tube. The lower end of the inner head is spaced apart from the lower end of the outer head along the radial direction of the central tube, and the length of the outer head is greater than the length of the inner head.

2. The one-way sealing mechanism according to claim 1, characterized in that, An angle is formed between the inner head and the outer head, and the angle is 0 to 90 degrees.

3. The one-way sealing mechanism according to claim 2, characterized in that, The upper part of the sealing groove is further provided with a step along the circumference of the sealing groove, and the one-way sealing mechanism further includes: A limiting ring is installed on the step. The outer diameter of the limiting ring is larger than the bottom diameter of the drain groove and smaller than the bottom diameter of the step. The inner diameter of the limiting ring is larger than the outer diameter of the central pipe. The outer edge of the limiting ring is spaced apart from the step, and the inner edge of the limiting ring is spaced apart from the outer wall of the central pipe.

4. The one-way sealing mechanism according to claim 3, characterized in that, The upper part of the expansion cone has a shear pin through hole along the circumference of the expansion cone. The shear pin through hole penetrates the side wall of the expansion cone. A blind hole is opened on the outer wall of the central tube at a position corresponding to the shear pin through hole. The shearing fastener is inserted in both the shear pin through hole and the blind hole. The number of shearing fasteners is the same as the number of shear pin through holes and blind holes.

5. The one-way sealing mechanism according to claim 4, characterized in that, The axial length of the expansion cone is greater than the axial length of the sealing element. The expansion cone can move along the axis of the central tube and be inserted between the sealing element and the outer wall of the central tube, so that the sealing element expands radially along the central tube and fits tightly against the inner wall of the annular space that needs to be sealed.

6. The one-way sealing mechanism according to claim 5, characterized in that, The outer wall of the expansion cone is divided into an upper section, a middle section, and a lower section. The diameter of the upper section is larger than that of the middle section, and the diameter of the middle section is larger than that of the lower section.

7. The one-way sealing mechanism according to claim 6, characterized in that, The outer wall of the lower deformable retaining sleeve includes an upper section and a lower section of the outer wall along the axial direction from top to bottom. The diameter of the upper section of the outer wall is smaller than the diameter of the lower section of the outer wall, and the diameter of the upper section of the outer wall is equal to or slightly larger than the outer diameter of the sealing element. The inner wall of the lower deformable retaining sleeve includes an upper section, a middle section, and a lower section along the axial direction from top to bottom. The diameter of the middle section is larger than the diameter of the upper section, and the diameter of the upper section is larger than the diameter of the lower section.

8. The one-way sealing mechanism according to claim 7, characterized in that, An axial cut is provided on the lower deformation retaining sleeve along the axial direction of the lower deformation retaining sleeve, penetrating the inner and outer walls of the lower deformation retaining sleeve.

9. The one-way sealing mechanism according to any one of claims 1 to 8, characterized in that, The lower part of the upper deformable retaining sleeve is provided with a "double L-shaped" cut and a split-type setting spring claw formed by the "double L-shaped" cut. The "double L-shaped" cut includes a first distance cut along the axis from the lower end face of the upper deformable retaining sleeve, a second distance cut along the circumferential direction, and a third distance cut along the axial direction. The first distance and the second distance are smaller than the third distance.

10. A tailpipe top packer, characterized in that, The tailpipe top packer includes: The one-way sealing mechanism as described in any one of claims 1 to 9; and The setting and sealing mechanism is fixedly connected to the upper end of the central tube of the one-way sealing mechanism.

11. A tailpipe cementing process, characterized in that, The tailpipe cementing process includes: Cement grout was injected into the air gap of the naked eye ring; The hanger connector of the tailpipe top packer as described in claim 10 is connected to the tailpipe hanger as a whole; The lowering setting mechanism inserts the expansion cone of the packer at the top of the tailpipe into the sealing element, causing the sealing element to expand and block the annular space, thus completing the setting process. After setting and before the cement slurry solidifies, the fluid is injected into the open hole and overlapping section annulus through the packer at the top of the tailpipe by pressurizing the annulus at the wellhead to pressurize the cement slurry and wait for it to solidify. After the cement slurry solidifies, the one-way sealing mechanism of the packer at the top of the tailpipe prevents gas from rising from the bottom to the upper annulus of the packer after cementing.

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