Tail pipe tripping-in pipe string and tripping-in method

Abstract

The invention provides a tail pipe running-in pipe string which comprises a flow dividing mechanism which comprises a shell, a first sleeve arranged in the shell and a first sectioning ball seat arranged in the first sleeve and abutting against the shell, and a sitting and hanging driving mechanism which is arranged on the downstream of the flow dividing mechanism and comprises a second sleeve. The first sleeve is fixed to the inner wall of the first sleeve through a first pin, the second split ball seat is fixed to the inner wall of the second sleeve through a first pin, the pressure building ball can be thrown into the tail pipe tripping-in pipe string, and the first split ball seat is constructed to be capable of expanding under building pressure formed by the pressure building ball, so that the pressure building ball is allowed to move downwards through a flow dividing mechanism; and the first pin is constructed to be capable of being cut off under the further pressure building effect, so that the second sectioning ball seat is expanded, and the pressure building ball is allowed to pass through the seat hanging driving mechanism.

Description

Technical Field

[0001] The invention relates to the field of downhole tools for petroleum solidification and completion, and in particular to a liner lowering pipe string and a method for lowering the liner lowering pipe string into a wellbore. Background Art

[0002] The liner cementing technology is to connect the liner string with the liner hanger, and lower the hanger and liner string to the designed position through the drilling tool, and then perform cementing operations. The operating pipe string generally includes: feeding drilling tools, liner hanger, ball seat, float collar, float shoe, etc.

[0003] When the liner string is lowered into the wellbore, the fluid in the wellbore needs to return along the liner annulus, generating excitation pressure on the formation, which is very likely to induce formation leakage; at the same time, it is necessary to intermittently grout from the wellhead during the lowering process to ensure the pressure balance inside and outside the string, which will greatly increase the operation time.

[0004] At present, the automatic grouting liner running technology uses a normally open float collar to achieve the simultaneous return of fluid through the liner and the annulus during the liner running process, thereby reducing the agitation pressure. However, since the inner diameter of the liner is generally larger than the inner diameter of the drill tool, a certain agitation pressure will still be generated when the internal fluid returns to the drill tool. For this reason, a drill pipe diversion short section (SPE135178) was developed, which is connected to the upper part of the liner hanger. The bottom of the liner is equipped with an automatic grouting float collar and a guide shoe, so that the internal fluid of the pipe string can return to the drill tool through the large channel of the drill tool annulus after returning to the drill tool, thereby greatly reducing the agitation pressure during the liner running process, and ensuring the safety, reliability and running speed of the liner in the formation prone to leakage. The diversion short section uses a reverse throttling mechanism to use the pressure difference generated by the upward return fluid at the throttling mechanism to open the diversion hole, and then uses a spring to realize the automatic closing of the diversion hole. The automatic grouting float collar is closed by dropping a ball. After the liner is lowered into place, the reverse sealing of the float collar is achieved by dropping a ball to hold the pressure.

[0005] However, the tail pipe lowering pipe string and system still have the following problems:

[0006] (1) The sliding parts inside the drill pipe diversion nipple and the sealing tube for closing the diversion hole need to be installed with multiple sets of sealing rings. The sliding resistance of opening and closing the diversion hole in the downhole environment is relatively large. There is a risk that the diversion hole cannot be completely closed only by the reset force of the spring, which may lead to problems such as failure to hang the tail pipe hanger and cementing in the later stage. If the closing reliability is ensured by increasing the spring reset force, the opening pressure of the diversion hole will increase, and the purpose of reducing the exciting pressure cannot be achieved.

[0007] (2) The liner hanger is set and the floating collar is closed by automatic grouting. It is necessary to insert pressure-holding balls of different sizes in sequence. First, a smaller pressure-holding ball is inserted to close the floating collar, and then a larger ball is inserted to set the liner hanger. This is not only complicated to operate, but also limits the diameter of the pipe, which may affect the pressure of the fluid in the pipe and affect the effect of reducing the agitation pressure.

[0008] Therefore, it is desired in the art to provide a tail pipe lowering pipe string to solve the above technical problems. Summary of the invention

[0009] The purpose of the present invention is to provide a liner running string, which can ensure the complete closure of the diversion hole on the diversion mechanism and realize the hanging operation of the liner hanger and the closing operation of the automatic grouting float collar by only one ball throwing. In this way, the safety and reliability of the liner running in ultra-deep wells prone to leakage and the effect of drill pipe diversion and leakage prevention are effectively improved.

[0010] According to the present invention, a tail pipe lowering pipe string is provided, comprising a flow dividing mechanism, which comprises a shell, a first sleeve arranged in the shell, and a first petal ball seat arranged in the first sleeve and abutting against the shell.

[0011] A seating drive mechanism is arranged downstream of the diverter mechanism, comprising a second sleeve, and a second petal ball seat fixed on the inner wall of the second sleeve by a first pin, and

[0012] A pressure-holding ball can be put into the lower inlet pipe string of the tail pipe.

[0013] Among them, the first petal ball seat is constructed to be able to expand after the pressure formed by the pressure-holding ball goes down, thereby allowing the pressure-holding ball to go down through the diversion mechanism; the first pin is constructed to be able to shear off under further pressure, thereby causing the second petal ball seat to expand after going down, so as to allow the pressure-holding ball to pass through the sitting and hanging drive mechanism.

[0014] In one embodiment, the housing comprises a first housing portion, and a second housing portion disposed downstream of the first housing portion, wherein a plurality of spaced-apart flow diversion holes for dispersing fluid are disposed along a circumference of the second housing portion.

[0015] In one embodiment, a plurality of alternately arranged seats and ball seat grooves are provided along the circumference of the first sleeve, and the first split-petal ball seat includes a plurality of first ball seat petals radially arranged in the ball seat grooves.

[0016] In one embodiment, an expansion groove extending radially outward and used to receive the first ball seat petal is formed on the inner wall of the second shell part, and the expansion groove is radially within the range of the second shell part.

[0017] The first ball seat petal is configured to expand and enter the expansion groove under the pressure formed by the pressure-holding ball and the first split-petal ball seat, thereby prompting the first sleeve to close the diversion hole and allow the pressure-holding ball to pass through.

[0018] In one embodiment, the first ball seat lobe includes a main body portion configured in a partial fan-shaped form, and a guide portion extending radially inward and downwardly inclined from the main body portion into the first sleeve, wherein a plurality of the guide portions enclose a round hole ball seat in the first sleeve for receiving a pressure-holding ball.

[0019] In one embodiment, the second split-petal ball seat includes a plurality of second ball seat petals that fit closely in the circumferential direction, and elastic ribs extending axially downward and obliquely outward from the second ball seat petals.

[0020] In one embodiment, a limiting groove extending radially outward and used to receive the second ball seat petal is formed on the inner wall of the second sleeve.

[0021] The second ball seat petal is configured to expand and enter the limiting groove under the pressure formed by the pressure-holding ball and the second split-petal ball seat to allow the pressure-holding ball to pass through.

[0022] In one embodiment, a step surface extending radially inward and downward is formed at the junction of the second ball seat petal and the pressure-holding ball, and a plurality of the step surfaces are enclosed in the second sleeve to form a round hole ball seat for receiving the pressure-holding ball.

[0023] In one embodiment, the liner lowering pipe string further includes an automatic grouting float collar arranged downstream of the seating drive mechanism, which includes a third sleeve, a supporting sleeve fixed in the third sleeve by a second pin, a gate valve arranged on the third sleeve, and a baffle arranged at the lower end surface of the third sleeve in the transverse direction.

[0024] Among them, in the initial state, the gate valve is in an open state under the action of the supporting sleeve. After the second pin is sheared off under the pressure formed by the holding pressure ball and the supporting sleeve, the supporting sleeve moves downward to the baffle, and the gate valve rebounds to form a reverse seal.

[0025] In one embodiment, the tail pipe lowering pipe string further comprises:

[0026] The tail pipe string has a guide shoe connected to its end, and

[0027] A liner hanger is arranged upstream of the liner string, wherein the liner hanger includes a lifting joint and a tie-back tube arranged in sequence from top to bottom, the tie-back tube is connected to the lifting joint through a third pin, the flow diversion mechanism is connected to the upper end of the liner hanger through the lifting joint, and the sitting and hanging driving mechanism is arranged in the tie-back tube.

[0028] A hydraulic cylinder is provided at the joint of the second sleeve and the tie-back tube, and the hydraulic cylinder can push the tie-back tube downward after the third pin is sheared off under the pressure formed by the pressure-holding ball and the second split ball seat.

[0029] In one embodiment, a plurality of through holes for guiding the fluid are arranged equidistantly along the circumferential direction and the axial direction of the guide shoe.

[0030] In one embodiment, the liner lowering pipe string further includes an emergency sleeve disposed between the automatic grouting float collar and the guide shoe, and at least one circulation hole disposed on the emergency sleeve.

[0031] Wherein, the circulation hole is configured to be able to open under the pent-up pressure formed when the through hole is blocked to allow the fluid to pass through.

[0032] According to a second aspect of the present invention, there is provided a method for lowering the liner running string as described above into a wellbore, comprising the following steps:

[0033] S1. During the lowering process of the liner lowering pipe string, the fluid in the wellbore returns to the diversion mechanism through the guide shoe, and the first sleeve is urged to move upward under the throttling pressure difference formed by the throttle valve to open the diversion hole, thereby allowing the upward returned fluid to be diverted; after the liner lowering pipe string reaches the designed position, the first sleeve is urged to move downward by the reset spring to close the diversion hole;

[0034] S2, if the diverter hole is not completely closed, the pressure-holding ball and the first petal ball seat form a pressure-holding in the diverter mechanism to cause the first ball seat petal to move downward and then expand and enter the expansion groove, thereby causing the first sleeve to close the diverter hole and allow the pressure-holding ball to pass through and move downstream to the seating drive mechanism;

[0035] S3, in the said sitting and hanging driving mechanism, firstly, after the said third pin is cut off under the pressure formed by the said holding pressure ball and the second petal ball seat, the said return tube moves downward under the action of the said hydraulic cylinder, and then under the further holding pressure, the said second ball seat petal is pushed downward and then expands and enters the said limiting groove, thereby allowing the said holding pressure ball to pass through and move downstream to the said automatic grouting floating collar;

[0036] S4. In the automatic grouting floating collar, after the second pin is sheared off under the pressure formed by the pressure-holding ball and the supporting sleeve, the supporting sleeve moves downward to the baffle, and the gate valve rebounds to form a reverse seal.

[0037] Compared with the prior art, the advantages of the present invention are:

[0038] First, the present invention provides expandable petal ball seats (first petal ball seat and second petal ball seat) in the diversion mechanism (drill pipe diversion short joint) and the sitting and hanging drive mechanism. Both petal ball seats can expand under pressure to allow the pressure-holding ball to pass through, so that only one ball throw is required to ensure that the diversion hole on the diversion mechanism is completely closed, and the suspension operation of the tail pipe hanger and the closing operation of the automatic grouting float collar can be achieved. In this way, the safety and reliability of the tail pipe lowering in ultra-deep and leak-prone wells and the effect of drill pipe diversion and leakage prevention are effectively improved.

[0039] Secondly, the present invention provides an expandable first split ball seat and a matching expansion slot in the splitter mechanism (drill pipe splitter sub). Therefore, when the splitter hole cannot be closed by the elastic force of the return spring, the present invention can achieve the purpose of completely closing the splitter hole and allowing the pressure-holding ball to pass through the drill pipe splitter sub by throwing the ball to hold the pressure.

[0040] On the one hand, the first petal ball seat can drive the second casing part to move downward synchronously under the action of holding pressure, and when the first ball seat petal expands and enters the expansion groove, it can prompt the second casing part to completely close the diversion hole, thereby eliminating the problems of being unable to sit the tail pipe hanger and cementing in the later stage due to the inability to close the diversion hole; on the other hand, since the first ball seat petal can expand and enter the expansion groove under the action of holding pressure, the inner diameter of the round hole ball seat is enlarged to allow the holding pressure ball to pass through the drill pipe diversion short section.

[0041] Thirdly, the present invention realizes the diversion of the upper fluid inside the tail pipe during the lowering process by providing the diversion hole in the diversion mechanism (drill pipe diversion short joint), thereby reducing the agitation pressure when lowering the tail pipe, and can ensure that the drilling fluid can be circulated in the forward direction at any time, thereby effectively improving the efficiency and safety of the tail pipe lowering. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The present invention will be described in detail below in conjunction with the accompanying drawings, in which:

[0043] Figure 1A The first part of the structure of the tail pipe lowering pipe string according to the present invention is schematically shown;

[0044] Figure 1B The second part structure of the tail pipe lowering pipe string according to the present invention is schematically shown;

[0045] Figure 1C The third part structure of the tail pipe lowering pipe string according to the present invention is schematically shown;

[0046] Figure 1D The fourth part structure of the tail pipe lowering pipe string according to the present invention is schematically shown;

[0047] Figure 2 The structure of the flow dividing mechanism in the tail pipe lower inlet pipe string according to the present invention is schematically shown;

[0048] Figure 2a is a partial schematic diagram of a flow splitting mechanism in a tail pipe lowering pipe string according to the present invention, which shows the structure of the second sleeve part;

[0049] Figure 2b It is a partial schematic diagram of the flow dividing mechanism in the tail pipe lower inlet pipe string according to the present invention, which shows the positional relationship between the support and the ball seat groove;

[0050] Figure 2c is a partial schematic diagram of a flow diversion mechanism in a tail pipe lower inlet pipe string according to the present invention, which shows the structure of the first ball seat petal;

[0051] Figure 3 The schematic diagram shows the working state of normal fluid circulation when the diversion hole of the diversion mechanism is closed;

[0052] Figure 4 The schematic diagram shows the working state of the fluid throttling return when the diverter hole of the diverter mechanism is opened;

[0053] Figure 5 The schematic diagram shows the state when the diverter hole of the diverter mechanism is not completely closed;

[0054] Figure 6 The schematic diagram shows the state when the diverter hole is completely closed by holding the pressure with a ball;

[0055] Figure 7 The schematic diagram shows the first stage of the pressure ball passing through the seat-and-hook drive mechanism;

[0056] Figure 8 The schematic diagram shows the second stage process of the pressure-holding ball passing through the sitting and hanging drive mechanism;

[0057] Fig. 9 The schematic diagram shows the first stage process of closing the automatic grouting float collar with a pressure holding ball;

[0058] Fig.10 The schematic diagram shows the second stage process of the pressure holding ball closing the automatic grouting floating collar.

[0059] In the drawings, the same reference numerals are used for the same components. The drawings are not drawn to scale. DETAILED DESCRIPTION

[0060] In order to make the technical solutions and advantages of the present invention more clearly understood, the exemplary embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than an exhaustive list of all the embodiments. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0061] The directional terms "upstream" or "above" or similar terms refer to the direction closer to the wellhead, i.e. Figure 1A The directional terms "downstream" or "below" or similar terms refer to the direction away from the wellhead, i.e. Figure 1A The bottom direction in .

[0062] In the description of the present invention, it should be understood 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, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0063] In the present invention, unless otherwise clearly stipulated and limited, terms such as "installed", "connected", "connected", "fixed" 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, or it can be the internal connection of two elements.

[0064] For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0065] The present invention will be further described below in conjunction with the accompanying drawings.

[0066] Figure 1A The first part of the structure of the liner lowering pipe string according to the present invention is schematically shown.

[0067] Figure 1B The second part of the structure of the tail pipe lowering pipe string according to the present invention is schematically shown.

[0068] Figure 1C The third part structure of the tail pipe lowering pipe string according to the present invention is schematically shown.

[0069] Figure 1D The fourth part structure of the tail pipe lowering pipe string according to the present invention is schematically shown.

[0070] As shown in FIGS. 1 to 4 , according to a first aspect of the present invention, a liner running string is provided, which mainly includes a flow diversion mechanism 10 , a seating and hanging drive mechanism 30 and an automatic grouting float collar 60 .

[0071] Figure 2 The structure of the flow dividing mechanism 10 in the tail pipe lowering pipe string according to the present invention is schematically shown.

[0072] Figure 2a FIG. 1 is a partial schematic diagram of the flow diversion mechanism 10 in the tail pipe lowering pipe string according to the present invention, which shows the structure of the second sleeve part 123 .

[0073] Figure 2b 1 is a partial schematic diagram of the flow diversion mechanism 10 in the tail pipe lower inlet pipe string according to the present invention, which shows the positional relationship between the support 19 and the ball seat groove 121.

[0074] Figure 2c FIG. 1 is a partial schematic diagram of a flow diversion mechanism in a tail pipe lowering pipe string according to the present invention, which shows the structure of the first ball seat petal 20 .

[0075] Figure 3 The schematic diagram shows the working state of the normal circulation of the fluid when the diverter hole 113 of the diverter mechanism 10 is closed.

[0076] Figure 4 The schematic diagram shows the working state of the fluid throttling back when the diverter hole 113 of the diverter mechanism 10 is opened.

[0077] Figure 5 The schematic diagram shows the state when the diverter hole 113 of the diverter mechanism 10 is not completely closed.

[0078] Figure 6 The schematic diagram shows the state when the diverter hole 113 is completely closed by ball pitching and pressure holding.

[0079] Combine the following Figures 1A to 1D as well as Figures 2 to 6 Next, the flow dividing mechanism 10 in the lower inlet pipe string of the tail pipe is introduced.

[0080] In a specific embodiment, the flow diversion mechanism 10 is a drill pipe flow diversion nipple.

[0081] According to the present invention, the flow dividing mechanism 10 comprises a housing 11, a first sleeve 12 and a first petal ball seat.

[0082] In one embodiment, the housing 11 includes a first housing portion 111 and a second housing portion 112 disposed downstream of the first housing portion 111. Preferably, the first housing portion 111 and the second housing portion 112 are threadedly connected. A plurality of spaced-apart flow diversion holes 113 are disposed along the circumference of the second housing portion 112. The flow diversion holes 113 can effectively and reasonably divert the upward return fluid during the lowering of the tail pipe lowering pipe string 10, thereby reducing the agitation pressure when lowering the tail pipe.

[0083] In one embodiment, the first sleeve 12 is disposed in the housing 11, and includes a first sleeve portion 122, and a second sleeve portion 123 disposed downstream of the first sleeve portion 122. Preferably, the first sleeve portion 122 and the second sleeve portion 123 are fixedly connected by a fourth pin 4. An annulus 124 is formed between the first sleeve portion 122 and the first housing portion 111. The second sleeve portion 123 is sealedly connected to the inner circumferential surface of the second housing portion 112.

[0084] According to the present invention, the flow dividing mechanism 10 further comprises a reset mechanism disposed in the annulus 124. The reset mechanism comprises a reset spring 13 sleeved outside the first sleeve portion 122, and a spring seat 14 disposed at the junction of the first housing portion 111 and the reset spring 13. The first end of the reset spring 13 axially abuts against the spring seat 14, and the second end axially abuts against the upper end surface of the second sleeve portion 123.

[0085] In one embodiment, the first split ball seat is disposed in the second sleeve portion 123 and radially abuts against the second housing portion 112 in the housing 11 .

[0086] According to the present invention, the flow dividing mechanism 10 further comprises a throttle mechanism concentrically arranged in the housing 11 , which comprises a valve seat 15 arranged in the first housing portion 111 , and a throttle valve 16 arranged on the valve seat 15 .

[0087] During the lowering of the tail pipe string, the return fluid in the well can enter the diversion mechanism 10 (drill pipe diversion short joint), and the first sleeve 12 can squeeze the return spring 13 and move upward under the action of the throttling pressure difference formed by the throttle valve 16, thereby opening the diversion hole 113 to allow the fluid to be reasonably diverted to the external annulus through the diversion hole 113, thereby effectively reducing the exciting pressure when the tail pipe is lowered.

[0088] When the tail pipe lowering pipe string stops lowering and the fluid stops returning, the first sleeve 12 can move downward under the elastic force of the return spring 13 and re-block the diversion hole 113 through the second sleeve portion 123 .

[0089] In one embodiment, a plurality of alternately arranged seats 19 and ball seat grooves 121 are provided along the circumference of the second sleeve portion 123 in the first sleeve 12. In addition, the first split-petal ball seat includes a plurality of first ball seat petals 20 radially arranged in the ball seat grooves 121. In combination with the above, when the first sleeve 12 moves upward under the throttling pressure difference formed by the throttle valve 16, the first ball seat petals 20 can be contracted into the second sleeve portion 123 under the extrusion of the second housing portion 112.

[0090] In one embodiment, the first ball seat petal 20 includes a main body portion 21 configured in a partially fan-shaped form, and a guide portion 22 extending radially inward and downwardly from the main body portion 21 into the second sleeve portion 123 in the first sleeve 12. Among them, a plurality of guide portions 22 can enclose a round hole ball seat in the second sleeve portion 123 for receiving the pressure-holding ball 50. Preferably, the inner diameter of the round hole ball seat is smaller than the outer diameter of the pressure-holding ball 50, thereby, the first split ball seat can form a pressure-holding through the round hole ball seat abutting against the pressure-holding ball 50.

[0091] It is easy to understand that in the subsequent ball throwing and pressure holding operation, the pressure holding ball 50 forms an axial abutment with the round hole ball seat, thereby forming a pressure holding with the first petal ball seat in the first sleeve 12.

[0092] In one embodiment, a radially outwardly extending expansion groove 114 is formed on the inner wall of the second housing portion 112. Preferably, the expansion groove 114 is radially within the range of the second housing portion 112, and when the first split-petal ball seat is expanded, the expansion groove 114 can receive the first ball seat petal 20, thereby allowing the pressure-holding ball 50 to pass through the diversion mechanism 10 (drill pipe diversion nipple) and descend. The content is introduced below.

[0093] When the second sleeve portion 123 cannot rely on the elastic force of the reset spring 13 to re-seal the diverter hole 113, the present invention can not only determine whether the diverter hole 113 is completely closed by throwing a ball to hold the pressure, but also prompt the second sleeve portion 123 to completely close the diverter hole 113 and allow the holding pressure ball 50 to pass through.

[0094] It is easy to understand that when the diverter hole 113 is completely closed, the first petal ball seat has expanded and entered into the expanded groove 114. At this time, the pressure-holding ball 50 thrown in will directly pass through the diverter mechanism 10 and move downstream; when the diverter hole 113 is not completely closed, the first petal ball seat is contracted in the ball seat groove 121 of the second sleeve part 123. At this time, the pressure-holding ball 50 thrown in will not pass directly, but will abut against the first petal ball seat to form pressure holding.

[0095] Specifically, a pressure-holding ball 50 is put into the drill pipe diverter nipple. The pressure-holding ball 50 forms an axial abutment with the round hole ball seat surrounded by a plurality of guide parts 22, thereby forming a pressure holding with the first petal ball seat in the sleeve 12. The first petal ball seat drives the second sleeve part 123 to move downward synchronously under the pressure holding, and when the first petal ball seat is aligned with the expansion groove 114 in the radial direction, the first ball seat petal 20 can expand and enter the expansion groove 114, thereby prompting the second sleeve part 123 to completely close the diverter hole 113, so as to improve the safety of the diverter mechanism 10 (drill pipe diverter nipple).

[0096] It is easy to understand that when the first ball seat petal 20 enters into the expansion groove 114, the first petal ball seat will obtain a larger diameter to allow the pressure-holding ball 50 to smoothly pass through the diversion mechanism 10 (drill pipe diversion short joint).

[0097] It is easy to understand that when the first ball seat petal 20 is contracted in the second sleeve portion 123 under the action of the second shell portion 112, the first petal ball seat will have a smaller inner diameter. Therefore, when the pressure-holding ball 50 is put into the diversion mechanism 10 (drill pipe diversion short joint), the pressure-holding ball 50 can abut against the first petal ball seat to form pressure holding. When the first ball seat petal 20 enters the expansion groove 114, the first petal ball seat will have a larger inner diameter, thereby allowing the pressure-holding ball 50 and the drill pipe rubber plug (not shown) to pass through.

[0098] In a preferred embodiment, the first ball seat petal 20 further includes a first engaging portion 23 and a second engaging portion 24 extending axially outward from both sides of the main body portion 21. In addition, a recessed portion extending radially inward is formed on the outer wall surface of the ball seat groove 121. It is easy to understand that the recessed portion can form an effective matching relationship with the first engaging portion 23 and the second engaging portion 24, respectively, so as to prevent the first ball seat petal 20 from falling off from the ball seat groove 121.

[0099] In a preferred embodiment, a guide slope 115 extending radially outward is formed at the junction of the expansion groove 114 and the first engaging portion 23. It is easy to understand that the guide slope 115 can allow the first ball seat petal 20 to move upward and exit the expansion groove 114 under the throttling pressure difference formed by the throttle valve 16, and can also allow the first ball seat petal 20 to expand and enter the expansion groove 114 under the pressure formed by the pressure ball 50 and the first split-petal ball seat.

[0100] In a preferred embodiment, a groove 18 is formed on the outer wall of the first sleeve portion 122, which extends radially inward and is used to accommodate the expandable snap ring 17. In the initial state, the snap ring 17 is contracted in the groove 18 under the action of the first housing portion 111. In addition, the spring seat 14 and the lower end surface of the first housing portion 111 form a spring cavity 141, which can be used to receive the snap ring 17.

[0101] During the process of ball pitching and pressure holding, if the pressure holding pressure formed by the pressure holding ball 50 and the first petal ball seat is greater than the shear stress of the fourth pin 4, the first sleeve portion 122 and the second sleeve portion 123 will separate, and the retaining ring 17 will follow the first sleeve portion 122 downward until it is radially aligned with the spring cavity 141, and the retaining ring 17 pops out of the retaining groove 18 and enters into the spring cavity 141 to achieve axial locking of the first sleeve portion 122, thereby permanently closing the diversion hole 113.

[0102] During the ball pitching and pressure holding process, if the pressure holding pressure formed by the pressure holding ball 50 and the first petal ball seat is not enough to shear off the fourth pin 4, it can also be sheared off during the subsequent pressure holding process of the hanging drive mechanism 30, thereby achieving the purpose of permanently closing the diversion hole 113.

[0103] Figure 7 The first stage process of the pressure holding ball 50 passing through the suspension drive mechanism 30 is schematically shown.

[0104] Figure 8 The second stage process of the pressure holding ball 50 passing through the suspension drive mechanism 30 is schematically shown.

[0105] Combine the following Figures 1A to 1D as well as Figures 7-8 Next, the seating and hanging driving mechanism 30 in the tail pipe lower inlet pipe string is introduced.

[0106] According to the present invention, the tail pipe lowering pipe string further comprises a seating drive mechanism 30 arranged downstream of the flow diversion mechanism 10. The seating drive mechanism 30 comprises a second sleeve 31 and a second petal ball seat fixed on the inner wall of the second sleeve 31 by a first pin 1.

[0107] In one embodiment, the second split ball seat comprises a plurality of second ball seat petals 40 that fit closely in the circumferential direction, and elastic ribs 42 extending axially downward and outwardly obliquely from the second ball seat petals 40. Preferably, the second ball seat petals 40 are fixed to the inner wall of the second sleeve 31 by the first pins 1.

[0108] In one embodiment, a step surface 411 extending radially inward and downward is formed at the junction of the second ball seat petal 40 and the pressure holding ball 50. A plurality of step surfaces 411 can enclose a round hole ball seat in the second sleeve 31. Preferably, the inner diameter of the round hole ball seat is smaller than the diameter of the pressure holding ball 50, so that the second petal ball seat can abut against the pressure holding ball 50 through the round hole ball seat to form pressure holding.

[0109] In one embodiment, a radially outwardly extending limiting groove 211 is formed on the inner wall of the second sleeve 31. Preferably, when the second split-petal ball seat expands, the limiting groove 211 can receive the second ball seat petal 40, thereby increasing the inner diameter of the second split-petal ball seat to allow the pressure-holding ball 50 to pass through the seat drive mechanism 30, which is described below.

[0110] According to the present invention, the liner lowering string further includes a tie-back tube 104. The seat-and-hang drive mechanism 30 is disposed in the tie-back tube 104. Preferably, the tie-back tube 104 and the lifting joint 103 (described below) are connected via a third pin 3 (the tie-back tube 104 is slidably connected to the lifting joint 103 via a plug cap 107). In addition, a hydraulic cylinder 212 is disposed at the joint between the second sleeve 31 and the tie-back tube 104.

[0111] When the pressure-holding ball 50 enters the seating drive mechanism 30, the pressure-holding ball 50 will fall on the round hole ball seat surrounded by multiple step surfaces 411 in the second sleeve 31. At this time, the pressure-holding ball 50 forms an axial abutment with the round hole ball seat, thereby continuing to form pressure holding with the second petal ball seat in the second sleeve 31 until the pressure holding reaches the seating pressure of the liner hanger 102 to cut off the third pin 3, thereby, the hydraulic cylinder 212 will drive the tie-back tube 104 downward to achieve the seating of the external liner hanger 102.

[0112] The pressure is kept on until the pressure is greater than the shearing pressure of the first pin 1 to shear off the first pin 1, and the second split ball seat moves downward, and when the second ball seat petal 40 is aligned with the limiting groove 211 in the radial direction, the second ball seat petal 40 expands under the action of the elastic rib 42 and enters the limiting groove 211. At this time, the second split ball seat has a larger inner diameter, so that the pressure-holding ball 50 can pass through and move downward.

[0113] It is easy to understand that when the second ball seat petal 40 is fixed on the inner wall of the second sleeve 31 under the action of the first pin 1, the second petal ball seat has a smaller inner diameter, so that it can abut against the pressure-holding ball 50 through the round hole ball seat to form pressure holding; and when the second ball seat petal 40 enters into the limiting groove 211, the second petal ball seat has a larger inner diameter, so that it can allow the pressure-holding ball 50 to pass through.

[0114] Referring to the above, it can be seen that if the pressure formed by the pressure-holding ball 50 and the first split ball seat is not enough to shear off the fourth pin 4, the fourth pin 4 can be sheared off when the pressure-holding ball 50 causes the second split ball seat to expand, thereby realizing the separation of the first sleeve portion 122 and the second sleeve portion 123. Accordingly, the snap ring 17 will follow the first sleeve portion 122 downward until it is aligned with the spring cavity 141 in the radial direction, and the snap ring 17 will pop out from the slot 18 and enter the spring cavity 141 to realize the axial locking of the first sleeve portion 122, thereby realizing the permanent closure of the diverter hole 113. Other contents that are the same as above will not be repeated.

[0115] Fig. 9 The first stage process of closing the automatic grouting floating collar 60 by the pressure holding ball 50 is schematically shown.

[0116] Fig.10 The second stage process of closing the automatic grouting floating collar 60 by the pressure holding ball 50 is schematically shown.

[0117] Combine the following Figures 1A to 1D as well as Figures 9-10 Let's introduce the self-grouted floating collar 60 in the tail pipe lowering string.

[0118] According to the present invention, the tail pipe lowering pipe string further includes an automatic grouting float collar 60 arranged downstream of the sitting and hanging drive mechanism 30. The automatic grouting float collar 60 includes a third sleeve 61, a support sleeve 62 and a gate valve 64. The support sleeve 62 is fixed to the third sleeve 61 by a second pin 2, and the gate valve 64 is installed at the side end of the support sleeve 62. In one embodiment, the automatic grouting float collar 60 further includes a baffle 63 arranged at the lower end surface of the third sleeve 61 in the transverse direction. Preferably, the gate valve 64 is in an open state under the action of the support sleeve 62 in the initial state.

[0119] When the pressure ball 50 enters the automatic grouting float collar 60, the pressure ball 50 will fall on the support sleeve 62. At this time, the pressure ball 50 abuts against the support sleeve 62 and continues to form pressure until the pressure reaches the closing pressure of the automatic grouting float collar 60 to shear off the second pin 2. After that, the support sleeve 62 will move down to the baffle 63, and the gate valve 64 will also lose support and rebound to achieve reverse sealing. At this time, the tail pipe lowering string can circulate forward and complete the subsequent cementing operation.

[0120] In a preferred embodiment, the automatic grouting floating collar 60 is preferably of a gate type, and the gate valve 64 is urged to be in an open state by supporting the sliding sleeve 62, so that the effect of automatic grouting can be achieved.

[0121] According to the present invention, Figures 1A to 1DAs shown, the liner lowering string also includes a liner string 101 and a liner hanger 102. The liner hanger 102 is arranged upstream of the liner string 101, and includes a lifting joint 103 and a tie-back tube 104 arranged in sequence from top to bottom. The tie-back tube 104 is connected to the lifting joint 103 through a third pin 3, and the diversion mechanism 10 (drill pipe diversion short joint) is connected to the upper end of the liner hanger 102 through the lifting joint 103.

[0122] In one embodiment, Figure 1D As shown, the liner lower inlet pipe string further comprises a guide shoe 70 disposed at the end of the liner lower inlet pipe string 101. Preferably, a plurality of equally spaced through holes 701 are disposed along the circumference and axial direction of the guide shoe 70, so as to guide the fluid into the liner lower inlet pipe string.

[0123] During the lowering process of the liner, the fluid in the well can enter the liner string through the through hole 701 on the guide shoe 70, and then return to the diversion mechanism 10 (drill pipe diversion short joint) through the automatic grouting float collar 60 and the liner hanger 102 in sequence. Thereafter, the returning fluid pushes the throttle valve 16 in the diversion mechanism 10 upward to open the diversion hole 113, thereby continuing to return to the external annulus through the diversion hole 113 to reduce the excitation pressure when the liner is lowered.

[0124] In one embodiment, Figure 1D As shown, the liner lowering pipe string further includes an emergency sleeve 80 disposed between the automatic grouting float collar 60 and the guide shoe 70. Preferably, at least one circulation hole 801 is disposed on the emergency sleeve 80.

[0125] Preferably, the emergency sleeve 80 is a pressure differential emergency sleeve.

[0126] During the construction process, if the through hole 701 of the guide shoe 70 is blocked, pressure will be formed in the tail pipe string. When the pressure reaches the pressure difference required by the emergency sleeve 80, the circulation hole 801 can be opened to allow fluid to pass through, thereby realizing the positive circulation of the tail pipe string to ensure subsequent cementing operations.

[0127] According to a second aspect of the present invention, there is provided a method for lowering the liner running string as described above into a wellbore, comprising the following steps:

[0128] First, during the lowering of the liner string, the fluid in the wellbore returns to the diverter mechanism 10 through the guide shoe 70. The first sleeve 12 moves upward by squeezing the return spring 13 under the action of the throttling pressure difference formed by the throttle valve 16, thereby opening the diverter hole 113 to allow the fluid to be reasonably diverted to the external annulus through the diverter hole 113.

[0129] Then, after the tail pipe is lowered into the pipe string to the designed position, the first sleeve 12 moves downward under the action of the return spring 13 and closes the diverter hole 113 .

[0130] Afterwards, if the diverter hole 113 is not completely closed, the pressure-holding ball 50 and the first petal ball seat form a pressure-holding in the diverter mechanism 10 to prompt the first ball seat petal 20 to move downward and then expand into the expansion groove 114, thereby prompting the first sleeve 12 to close the diverter hole 113 and allow the pressure-holding ball 50 to pass through and move downstream to the hanging drive mechanism 30.

[0131] Afterwards, in the sitting and hanging drive mechanism 30, first, after the third pin 3 is sheared off under the pressure formed by the pressure-holding ball 50 and the second petal ball seat, the return tube 104 descends under the action of the hydraulic cylinder 212, and then under further pressure, the second ball seat petal 40 is forced to move downward and then expand into the limiting groove 211, thereby allowing the pressure-holding ball 50 to pass through and move downstream to the automatic grouting floating hoop 60.

[0132] Finally, in the automatic grouting floating collar 60, after the second pin 2 is sheared off under the pressure formed by the pressure ball 50 and the supporting sleeve 62, the supporting sleeve 62 moves downward to the baffle 63, and the gate valve 64 rebounds to form a reverse seal.

[0133] Compared with the prior art, the advantages of the present invention are:

[0134] First, the present invention provides expandable petal ball seats (first petal ball seat and second petal ball seat) in the diverter mechanism 10 (drill pipe diverter nipple) and the seat-and-hang drive mechanism 30, respectively. Both petal ball seats can expand under pressure to allow the pressure-holding ball 50 to pass through, so that only one ball throw is required to ensure that the diverter hole 113 on the diverter mechanism 10 is completely closed, and the liner hanger 102 can be suspended and the automatic grouting float collar 60 can be closed. In this way, the safety and reliability of the liner lowering in ultra-deep wells prone to leakage and the effect of drill pipe diversion and leakage prevention are effectively improved.

[0135] Secondly, the present invention provides an expandable first split ball seat and a matching expansion slot 114 in the splitting mechanism 10 (drill pipe splitting nipple). Therefore, when the splitting hole 113 cannot be closed by the elastic force of the return spring 13, the present invention can achieve the purpose of completely closing the splitting hole 113 and allowing the pressure-holding ball 50 to pass through the drill pipe splitting nipple by throwing a ball to hold the pressure.

[0136] On the one hand, the first split-petal ball seat can drive the second casing part 123 to move downward synchronously under the action of holding pressure, and when the first ball seat petal 20 expands and enters the expansion groove 114, it can prompt the second casing part 123 to completely close the diversion hole 113, thereby eliminating the problems of being unable to sit the tail pipe hanger 102 and cementing in the later stage due to the inability to close the diversion hole 113; on the other hand, since the first ball seat petal 20 can expand and enter the expansion groove 114 under the action of holding pressure, the inner diameter of the round hole ball seat is enlarged to allow the holding pressure ball 50 to pass through the drill pipe diversion short section.

[0137] Thirdly, the present invention provides the diversion hole 113 in the diversion mechanism 10 (drill pipe diversion nipple), which not only realizes the diversion of the internal fluid during the liner lowering process to reduce the agitation pressure when the liner is lowered, but also ensures that the drilling fluid can be circulated in the forward direction at any time, thereby effectively improving the liner lowering efficiency and safety.

[0138] The above are only preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art can easily make changes or modifications within the disclosure scope of the present invention, and such changes or modifications should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A tail pipe lowering pipe string, comprising: A flow dividing mechanism (10) comprises a housing (11), a first sleeve (12) arranged in the housing (11), and a first petal ball seat arranged in the first sleeve (12) and abutting against the housing (11). A seating drive mechanism (30) disposed downstream of the diverter mechanism (10) comprises a second sleeve (31), and a second petal ball seat fixed to the inner wall of the second sleeve (31) by a first pin (1), and A pressure-holding ball (50) can be put into the lower inlet pipe string of the tail pipe, The first petal ball seat is configured to expand after the pressure formed by the pressure-holding ball (50) moves downward, thereby allowing the pressure-holding ball (50) to move downward through the diversion mechanism (10); the first pin (1) is configured to be sheared off under further pressure, thereby causing the second petal ball seat to expand after moving downward, thereby allowing the pressure-holding ball (50) to move downward through the seating drive mechanism (30).

2. The liner lowering pipe string according to claim 1, characterized in that: The housing (11) comprises a first housing portion (111) and a second housing portion (112) arranged downstream of the first housing portion (111), wherein a plurality of spaced-apart flow diversion holes (113) for dispersing fluid are arranged along the circumference of the second housing portion (112).

3. The liner lowering pipe string according to claim 2, characterized in that: A plurality of alternately arranged supports (19) and ball seat grooves (121) are provided along the circumference of the first sleeve (12), and the first split ball seat comprises a plurality of first ball seat lobes (20) radially arranged in the ball seat grooves (121).

4. The liner lowering pipe string according to claim 3, characterized in that: An expansion groove (114) extending radially outward and used to receive the first ball seat petal (20) is formed on the inner wall of the second shell part (112). The expansion groove (114) is located within the range of the second shell part (112) in the radial direction. The first ball seat flap (20) is configured to expand and enter the expansion groove (114) under the pressure formed by the pressure-holding ball (50) and the first split-flap ball seat, thereby prompting the first sleeve (12) to close the diversion hole (113) and allow the pressure-holding ball (50) to pass through.

5. The liner lowering pipe string according to claim 4, characterized in that: The first ball seat flap (20) includes a main body portion (21) configured in a partially fan-shaped form, and a guide portion (22) extending radially inward and downwardly from the main body portion (21) into the first sleeve (12), wherein a plurality of the guide portions (22) are arranged in the first sleeve (12) to form a round hole ball seat for receiving a pressure-holding ball (50).

6. The liner lowering pipe string according to any one of claims 1 to 5, characterized in that: The second split-lobed ball seat comprises a plurality of second ball seat lobes (40) that are tightly fitted in the circumferential direction, and elastic ribs (42) extending axially downward and outwardly obliquely from the second ball seat lobes (40).

7. The liner lowering pipe string according to claim 6, characterized in that: A limiting groove (211) is formed on the inner wall of the second sleeve (31) and extends radially outward and is used to receive the second ball seat petal (40). The second ball seat petal (40) is configured to expand and enter the limiting groove (211) under the pressure formed by the pressure-holding ball (50) and the second split-petal ball seat, so as to allow the pressure-holding ball (50) to pass through.

8. The liner lowering pipe string according to claim 7, characterized in that: A step surface (411) extending radially inward and downward is formed at the junction of the second ball seat petal (40) and the pressure-holding ball (50), and a plurality of the step surfaces (411) are enclosed in the second sleeve (31) to form a round hole ball seat for receiving the pressure-holding ball (50).

9. The liner lowering pipe string according to any one of claims 1 to 5, characterized in that: The liner lowering pipe string further comprises an automatic grouting float collar (60) arranged downstream of the seating drive mechanism (30), comprising a third sleeve (61), a supporting sleeve (62) fixed in the third sleeve (61) by a second pin (2), a gate valve (64) arranged on the third sleeve (61), and a baffle (63) arranged at the lower end surface of the third sleeve (61) in a transverse direction. In the initial state, the gate valve (64) is in an open state under the action of the supporting sleeve (62), and after the second pin (2) is sheared off under the pressure formed by the pressure-holding ball (50) and the supporting sleeve (62), the supporting sleeve (62) moves downward to the baffle (63), and the gate valve (64) rebounds to form a reverse seal.

10. The liner lowering pipe string according to claim 9, characterized in that: The tail pipe lowering pipe string further comprises: The tail pipe string (101) has a guide shoe (70) connected to its end, and A liner hanger (102) is arranged upstream of the liner string (101), wherein the liner hanger (102) comprises a lifting joint (103) and a tie-back tube (104) arranged in sequence from top to bottom, the tie-back tube (104) is connected to the lifting joint (103) via a third pin (3), the flow diversion mechanism (10) is connected to the upper end of the liner hanger (102) via the lifting joint (103), and the sitting and hanging drive mechanism (30) is arranged in the tie-back tube (104). A hydraulic cylinder (212) is provided at the joint between the second sleeve (31) and the tie-back tube (104), and after the third pin (3) is sheared off under the pressure formed by the pressure-holding ball (50) and the second split ball seat, the hydraulic cylinder (212) can cause the tie-back tube (104) to move downward.

11. The liner lowering pipe string according to claim 10, characterized in that: A plurality of through holes (701) for guiding fluid are arranged at equal intervals along the circumference and axial direction of the guide shoe (70).

12. The liner lowering pipe string according to claim 11, characterized in that: The liner lowering pipe string further comprises an emergency sleeve (80) arranged between the automatic grouting float collar (60) and the guide shoe (70), and at least one circulation hole (801) arranged on the emergency sleeve (80). The circulation hole (801) is configured to be able to open under the pressure generated when the through hole (701) is blocked to allow the fluid to pass through.

13. A method for lowering a liner running string according to any one of claims 1 to 12 into a wellbore, comprising the following steps: S1. During the lowering process of the liner lowering pipe string, the fluid in the wellbore returns to the diversion mechanism (10) through the guide shoe (70), and the first sleeve (12) is urged to move upward under the throttling pressure difference formed by the throttle valve (16) to open the diversion hole (113), thereby allowing the upward returned fluid to be diverted; after the liner lowering pipe string reaches the designed position, the first sleeve (12) is urged to move downward by the return spring (13) to close the diversion hole (113); S2. If the diverter hole (113) is not completely closed, the pressure-holding ball (50) and the first split-petal ball seat form a pressure-holding in the diverter mechanism (10) to cause the first ball seat petal (20) to move downward and then expand and enter the expansion groove (114), thereby causing the first sleeve (12) to close the diverter hole (113) and allow the pressure-holding ball (50) to pass through and move downstream to the seating drive mechanism (30); S3, in the sitting and hanging driving mechanism (30), first, after the pressure-holding ball (50) and the second split ball seat form a pressure-holding state and cut off the third pin (3), the return tube (104) moves downward under the action of the liquid cylinder (212), and then, under further pressure-holding, the second ball seat petal (40) is forced to move downward and then expand and enter the limiting groove (211), thereby allowing the pressure-holding ball (50) to pass through and move downstream to the automatic grouting floating collar (60); S4. In the automatic grouting floating collar (60), after the second pin (2) is sheared off under the pressure formed by the pressure-holding ball (50) and the supporting sleeve (62), the supporting sleeve (62) moves downward to the baffle (63), and the gate valve (64) rebounds to form a reverse seal.

Images