CN217028821U

CN217028821U - Floating guide shoe capable of completely closing fluid passage, central pipe string and well completion structure

Info

Publication number: CN217028821U
Application number: CN202220694658.7U
Authority: CN
Inventors: 裴柏林; 冯国江
Original assignee: Anton Bailin Oilfield Technology Beijing Co ltd
Current assignee: Anton Bailin Oilfield Technology Beijing Co ltd
Priority date: 2022-03-29
Filing date: 2022-03-29
Publication date: 2022-07-22
Anticipated expiration: 2032-03-29

Abstract

A floating guide shoe, a central pipe string and a completion structure capable of completely closing a fluid passage, wherein the floating guide shoe comprises an outer shell, a guide shoe and a check valve unit; the floating guide shoe further comprises a reverse sealing unit, and when the reverse pressure difference between the inner cavity of the outer shell and the external space of the floating guide shoe reaches or exceeds a second threshold value, the reverse sealing unit is closed. The utility model can completely close the fluid channel of the floating guide shoe by arranging the reverse sealing unit, avoids the automatic pressure relief of the check valve unit when the pressure in the inner cavity of the floating guide shoe is overlarge in the prior art, can be matched with a flow control sieve tube with the flow control capacity adjusted stage by stage, and realizes the step-by-step adjustment of the flow control capacity of the underground flow control sieve tube; secondly, the pressure for closing the floating guide shoe fluid channel can be accurately set by setting the elasticity of the clamping jaw and the inclination of the back of the clamping jaw; thirdly, the pressure resistance of the reverse closed unit after the fluid channel is completely closed can be improved by arranging the angles of the claw chamfers and the inclined plane grooves.

Description

Floating guide shoe capable of completely closing fluid passage, central pipe string and well completion structure

Technical Field

The utility model belongs to the technical field of oil exploitation, and relates to a floating guide shoe capable of completely closing a fluid passage, a central pipe column adopting the floating guide shoe and a well completion structure.

Background

The Guide shoe (Guide shoe) is a conical or spherical structure arranged at the front end of a central pipe column of an oil-gas well and is used for preventing the central pipe column from being scratched or inserted into a well wall when the central pipe column is lowered into the well and guiding the central pipe column to smoothly descend to the bottom of the well.

The floating guide shoe is a device with a check valve unit in the inner cavity and a guide shoe at the front end. The floating guide shoe has the function of guiding the central pipe column to go into the well and also has the function of one-way flow guiding in the forward direction (namely the direction from the inner cavity of the floating guide shoe to the outside). The floating guide shoe has the following functions that firstly, the conical spherical shape of the front end of the floating guide shoe is utilized to guide the central pipe column to smoothly go down to the bottom of the well; secondly, the well washing device is used for establishing a well washing channel; specifically, flushing fluid is injected into the inner cavity of the central tubular column in a pressurizing manner, when the difference between the fluid pressure in the inner cavity of the central tubular column and the fluid pressure in the annular space of the wellbore reaches or exceeds the opening pressure of the check valve unit, the check valve unit is opened, the flushing fluid sequentially passes through the inner cavity of the outer shell of the floating guide shoe, the check valve unit, the inner cavity of the guide shoe and the flow guide channel from the inner cavity of the central tubular column, finally enters the annular space of the wellbore, and is discharged from the wellhead with substances in the annular space of the wellbore, so that the well is positively flushed; and thirdly, sundries in the well casing ring are prevented from reversely entering the central pipe column through the floating guide shoe, and particularly, because the check valve unit is arranged in the inner cavity of the floating guide shoe, when the fluid pressure in the well casing ring is greater than that in the central pipe column, the check valve unit is closed, so that the fluid in the well casing ring can be prevented from entering the inner cavity of the central pipe column through the floating guide shoe.

In the prior art, the opening or closing of a check valve unit of a floating guide shoe is only controlled by the differential pressure at the bottom of a well and cannot be completely closed. Once the positive pressure difference at the bottom of the well is higher than the opening pressure of the check valve unit, the check valve unit is opened, and fluid in the inner cavity of the central pipe column flows out through the flow guide channel of the floating guide shoe and is decompressed, so that higher fluid pressure cannot be generated in the central pipe column.

SUMMERY OF THE UTILITY MODEL

The present invention is directed to overcoming some or all of the disadvantages of the prior art and to providing a floating guide that can completely close a flow passage, and a center string and a completion structure using the same, which can generate a higher fluid pressure inside the center string.

In order to achieve the purpose, the utility model adopts the following technical scheme:

in a first aspect, the embodiment of the present invention provides a floating guide shoe capable of completely closing a fluid channel, which includes an outer casing 1, a guide shoe 2 and a check valve unit 3; wherein, the outer shell 1 is a columnar hollow structure; the guide shoe 2 is arranged at the front end of the outer shell 1, and the interior of the guide shoe is of a hollow structure; the rear end of the guide shoe 2 is fixedly connected with the front end of the outer shell 1, so that the communication between the inner cavity of the guide shoe 2 and the inner cavity of the outer shell 1 is realized; the front end and/or the side wall of the guide shoe 2 is/are provided with a flow guide channel 21 for realizing the communication between the inner cavity of the guide shoe and the external space of the floating guide shoe; the check valve unit 3 is arranged in the inner cavity of the outer shell 1, and the initial state is a closed state so as to block the communication between the inner cavity of the outer shell 1 and the external space of the floating guide shoe through the flow guide channel 21 of the guide shoe 2; when the positive pressure difference between the inner cavity of the outer shell 1 and the external space of the floating guide shoe 2 reaches or exceeds a first threshold value, the check valve unit 3 is opened, so that the inner cavity of the outer shell 1 is communicated with the external space of the floating guide shoe through the flow guide channel 21; when the positive pressure difference between the inner cavity of the outer shell 1 and the external space of the floating guide shoe is smaller than a first threshold value, the check valve unit 3 is restored to a closed state; the floating guide shoe further comprises a reverse sealing unit 4; wherein, the reverse closing unit 4 is arranged in the inner cavity of the outer shell 1 and is connected with the check valve unit 3 in series in the inner cavity of the outer shell 1; the initial state of the reverse closing unit 4 is an open state; when the reverse pressure difference between the inner cavity of the outer shell 1 and the external space of the floating guide shoe reaches or exceeds a second threshold value, the reverse sealing unit 4 is closed, so that the communication between the inner cavity of the outer shell 1 and the external space of the floating guide shoe through the guide channel 21 of the guide shoe 2 is blocked; when the reverse closing unit 4 is closed, the opening state is recovered under the control of the forward or reverse pressure.

Optionally, the reverse closing unit 4 comprises a first sealing valve seat 41 and a first sealing sliding sleeve 42, wherein the first sealing valve seat 41 is of an annular structure as a whole, and the outer side of the first sealing valve seat is fixedly connected with the inner side of the outer housing 1 in a sealing manner; the first sealing sliding sleeve 42 is of a shaft-shaped structure as a whole and comprises a jaw end 421 and a closed end 422; wherein the claw end 421 includes a plurality of claw tips 423 arranged along the circumferential direction facing the claw 424 away from the axial center direction; the closed end 422 is of a closed structure; when the reverse closing unit 4 is in an open state, the jaw end 421 is located in the inner cavity of the first sealing valve seat 41, and the closed end 422 of the first sealing sliding sleeve 42 is located outside the front end of the first sealing valve seat 41; the inner cavity of the first sealing valve seat 41 and the space between the plurality of clamping claws 423 form a fluid channel inside the floating guide shoe; when the reverse closing unit 4 is in a closed state, the closed end 422 of the first sealing sliding sleeve 42 is located in the cavity of the first sealing valve seat 41, and is in sealing fit with the first sealing valve seat 41 to block the fluid passage inside the floating guide shoe.

Optionally, a first groove 411 is formed inside the first sealing valve seat 41 at a position matching the claw tips 423 of the plurality of claws 421, for receiving the claw tips 423 of the claws 421.

Optionally, the back 425 of the prongs 423 is of a beveled configuration; the side walls 412 of the first groove 411 and the back 425 of the claw tip 423 are inclined structures which are consistent with the inclination angle of the back 425 of the claw tip 423.

Optionally, a sliding duct 30 is arranged in the check valve unit 3 along the axis direction of the floating guide shoe, and a piston 5 and a push rod 6 are arranged in the sliding duct 30; one end of the piston 5 faces the direction of the floating guide shoe, and the other end of the piston is provided with a push rod 6; one end of the push rod 6 is connected or adjacent to the piston 5, and the other end is connected or adjacent to the first sealing sliding sleeve 42; when the reverse pressure difference between the inner cavity of the outer shell 1 and the external space of the floating guide shoe reaches or exceeds a second threshold value, the piston 5 moves towards the push rod 6 under the action of the fluid pressure difference, pushes the push rod 6 and the first sealing sliding sleeve 42 to move until the claw tips 423 of the claws 421 are separated from the first groove 411 and are clamped and fixed at the upper end part of the first sealing valve seat 41.

Optionally, the inner side of the claw tip 423 of the claw 421 is a chamfer structure; the upper end of the first sealing valve seat 41 is provided with an inclined groove 413 matched with the clamping and fixing position of the claw tip 423 of the claw 421, and the inclined angle of the inclined groove 413 is consistent with the chamfer angle of the inner side of the claw tip 423 of the claw 421.

Optionally, the closed end 422 of the first sealing sliding sleeve 42 is provided with a positioning block 426; the lower end surface of the first sealing valve seat 41 is provided with a positioning groove 414 matched with the positioning block 426.

Optionally, one or more sealing rings are disposed on the outer side of the closed end 422 of the first sealing sleeve 42 along the circumferential direction.

Optionally, the check valve unit 3 comprises a second sealing valve seat 33 and a second sealing valve sleeve 35, and a spring 36 in a compressed state is arranged between the second sealing valve seat 33 and the second sealing valve sleeve 35; in the initial state, the elastic force of the spring enables the second sealing valve seat 33 and the second sealing valve sleeve 35 to be combined to be in a sealing state; when the positive pressure difference between the inner cavity of the outer housing 1 and the space outside the floating guide shoe is greater than the first threshold value, the second sealing valve sleeve 35 separates from the second sealing valve seat 33 under the action of pressure, so that the check valve unit 3 is opened; when the positive pressure difference between the inner cavity of the outer shell 1 and the external space of the floating guide shoe is smaller than a first threshold value, the second sealing valve sleeve 35 is combined with the second sealing valve seat 33 under the action of the elastic force of the spring 36, and the check valve unit 3 is restored to the closed state.

Optionally, the second sealing valve sleeve 35 is a shaft-like structure, and the shaft center is provided with a through sliding hole 30.

Optionally, be equipped with first supporting sleeve 8 between check valve unit 3 and the reverse unit 4 of sealing, first supporting sleeve 8 is the tubular structure, the outside of first supporting sleeve 8 with the inboard laminating of shell body 1.

In a second aspect, embodiments of the present invention further provide a center pipe string, wherein a bottom end of the center pipe string is provided with a floating guide shoe capable of completely closing the fluid passage as described in the first aspect.

In a third aspect, embodiments of the present invention also provide a completion structure including a wellbore and a central string disposed in the wellbore; the bottom end of the central pipe string is provided with a floating guide shoe which can completely close the fluid passage as described in the first aspect.

The floating guide shoe capable of completely closing the fluid channel, provided by the utility model, has the advantages that firstly, the reverse sealing unit is arranged, so that the fluid channel of the floating guide shoe can be completely closed, the pressure relief caused by the opening of the check valve unit when the pressure in the inner cavity of the floating guide shoe is overlarge in the prior art is avoided, the floating guide shoe can be matched with a flow control sieve tube with the flow conductivity adjusted step by step, and the flow conductivity of the underground flow control sieve tube can be adjusted step by step; secondly, the fluid pressure for closing the floating guide shoe fluid channel can be accurately set by reasonably setting the elastic strength of the clamping jaw and the inclination of the inclined plane at the back of the clamping jaw; thirdly, the chamfer of the clamping jaw and the inclined groove matched with the chamfer are arranged, so that the pressure resistance of the reverse sealing unit after the fluid channel is completely closed can be improved, and the device cannot fail due to the positive high pressure difference.

Drawings

FIG. 1 is a schematic view of the overall structure of a floating guide shoe of the prior art;

FIG. 2 is a schematic diagram of a half-section of a floating guide shoe with a fluid passage completely closed according to an embodiment of the present invention;

FIG. 3 is an enlarged view of a portion of FIG. 2 at A;

FIG. 4 is an enlarged view of a portion of FIG. 2 at B;

FIG. 5 is a perspective sectional view of a floating guide with a fluid passage completely closed according to an embodiment of the present invention;

fig. 6 is a schematic half-sectional view of a floating guide shoe capable of completely closing a fluid passage in a closed state of a reverse sealing unit according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the specific embodiments of the present invention and the accompanying drawings. It is to be understood that the disclosed embodiments are merely exemplary of the utility model, and are not intended to be exhaustive or exhaustive. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are used merely for convenience of description and simplification of the description, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood according to specific situations by those of ordinary skill in the art.

To facilitate understanding of the embodiments of the present invention, description is first made on application scenarios of the prior art and the embodiments of the present invention.

As shown in fig. 1, it is a schematic diagram of a prior floating guide shoe, which comprises an outer shell 1-1, a check valve unit and a guide shoe 1-9. Wherein, the outer shell 1-1 is a columnar hollow structure or a cylindrical structure; the rear end (i.e. the end which is used for connecting a central pipe column when in use and the end which faces a well head) of the outer shell 1-1 is used for fixedly connecting the central pipe column through threads, buckles, positioning pins and the like; a guide shoe 1-9 is arranged at the front end (i.e. the end facing the deep part of the well bottom and the end deviating from the well mouth when in use) of the outer shell 1-1, the guide shoe 1-9 is of a hollow structure with an open rear end, and the rear end of the guide shoe 1-9 is fixedly connected with the front end of the outer shell 1-1 through a rotation stopping pin 1-10 (of course, other fixed connection modes can be adopted), so that the communication between the inner cavity of the guide shoe 1-9 and the inner cavity of the outer shell 1-1 is realized; the front end and/or the side wall of the guide shoe 1-9 is provided with a flow guide channel 1-7 for realizing the communication between the inner cavity of the guide shoe 1-9 and the outer space (such as a shaft annulus) of the floating guide shoe. A second support sleeve 1-11 is provided between the check valve unit and the guide shoe 1-9 for positioning the check valve unit in the inner cavity of the outer housing 1-1.

The check valve unit is arranged in an inner cavity of the outer shell 1-1 and comprises a third sealing valve seat 1-3 and a valve body 1-5; the third sealing valve seat 1-3 is of a circular ring structure, the outer side wall of the third sealing valve seat 1-3 is in fit sealing with the inner side wall of the outer shell 1-1, and the outer side wall and the inner side wall are fixedly connected; a sealing ring 1-8 is arranged between the third sealing valve seat 1-3 and the outer shell 1-1 to improve the sealing effect between the third sealing valve seat and the outer shell; one end of the valve body 1-5 is attached to the third sealing valve seat 1-3, so that an internal flow channel of the floating guide shoe is closed, the other end of the valve body 1-5 is fixedly connected with a spring sleeve 1-4 through a positioning pin 1-2, a spring 1-6 in a compression state is arranged between the spring sleeve 1-4 and the third sealing valve seat 1-3, the spring is in the compression state, so that internal stress is formed and acts on the valve body 1-5 and the third sealing valve seat 1-3, the valve body 1-5 and the third sealing valve seat 1-3 are in an attachment state when being free from external pressure or acting force, and the check valve unit is in a closed state.

When the single-flow valve unit is in an initial state (closed state), the communication between the inner cavity of the outer shell 1-1 and the external space (such as a shaft annulus) of the floating guide shoe through the flow guide channel 1-7 of the guide shoe 1-9 can be blocked; when the positive pressure difference between the inner cavity of the outer housing 1-1 and the outer space of the floating guide shoe (the "positive pressure" is merely given for the sake of understanding and is not intended to limit the technical solution) reaches or exceeds a first threshold value, the valve body 1-5 moves downward against the spring force under the action of the fluid pressure, so that the lower end thereof is separated from the third sealing valve seat 1-3, the check valve unit is opened, so that the inner cavity of the outer housing is communicated with the outer space of the floating guide shoe through the diversion channel, and the fluid in the center string can flow through the check valve from top to bottom and finally enter the outer space (such as a shaft annulus) through the diversion channel 1-7 of the guide shoe 1-9. When the positive pressure difference between the inner cavity of the outer shell 1-1 and the space outside the floating guide shoe is smaller than a first threshold value (including a negative value), the check valve unit is restored to the closed state. The first threshold value can be set to be 0.1 to 1Mpa, and the actual application mostly does not exceed 0.5 Mpa. The first threshold value of the check valve unit can be set by changing parameters such as the spring force, the shut-off surface of the valve body 1-5, and the like.

In a practical application scenario, a floating guide shoe with a check valve unit is required to be adopted when the open hole new well completion operation is carried out. This is because the open hole section is to retain mud to prevent the open hole from collapsing, and the mud is cleaned after the string is run into the wellbore and is being displaced out of the wellbore using completion fluids.

On the other hand, the utility model discloses a but the stage-by-stage flow control screen pipe of adjusting the water conservancy diversion ability for oil gas well still develops, the flow control screen pipe includes one or more fluid valve, each of one or more fluid valve has the first side towards the flow control screen pipe inner chamber and towards the second side of the well bore annular space outside the flow control screen pipe; wherein the one or more fluid valves are closed in an initial state to block the corresponding fluid channels; and wherein each of the one or more fluid valves has a respective predetermined opening threshold and is configured to open a corresponding fluid passage when a difference in fluid pressure applied from the internal chamber of the base pipe to the first side of the fluid valve and the fluid pressure applied from the annular space to the second side of the fluid valve is greater than or equal to the respective predetermined opening threshold, such that fluid in the annular space is able to flow into the internal chamber of the base pipe via the corresponding fluid passage. The flow control device can utilize ground pressure equipment to apply liquid pressure to the completion pipe string provided with the sieve pipe after the operation of the continuous packing body is finished and put into production, and the formulated fluid valve of the sieve pipe is opened according to production requirements, so that the production liquid amount is increased. The flow control sieve tube can conveniently and easily realize staged and step-by-step adjustment of the flow conductivity of the flow control sieve tube, thereby ensuring the daily oil production of an oil well and prolonging the effective production time of the oil well in the whole exploitation period.

However, since the floating guide shoe is installed at the bottom of the water control completion pipe string provided with the adjustable water control sieve pipe, when ground equipment applies liquid pressure to the water control pipe string, the floating guide shoe is opened under a low forward pressure difference (for example, below 0.5 Mpa), the flow rate of the flow guide channel of the floating guide shoe is large, and a high liquid pressure (or pressure difference) is difficult to form inside the water control sieve pipe under the drainage effect of the flow guide channel; on the other hand, the minimum fluid pressure differential required to open the fluid valve of the flow control screen is also much greater than the opening pressure of the floating guide (typically between 3 and 15 Mpa), and therefore it is structurally and functionally difficult for a water control string to which the floating guide is installed to achieve the fluid pressure required by the flow control screen to open the next stage of fluid valve. For a completion string with the flow control screen having the flow control capability adjusted in stages, if the flow control screen is to be adjusted in stages, the flow passage of the floating guide shoe must be completely closed, so that the surface injection equipment can apply a high enough pressure to the inner cavity of the completion string to form a high enough pressure difference for opening the fluid valves of the stages on the flow control screen.

The technical solutions provided by the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

As shown in fig. 2 to 5, a floating guide shoe capable of completely closing a fluid passage includes an outer housing 1, a guide shoe 2, and a check valve unit 3. Wherein, the outer shell 1 is a cylindrical hollow structure, and the diameter of the outer shell is consistent with other pipe joints of the central pipe column. The guide shoe 2 is arranged at the front end (namely, the end close to the well bottom) of the outer shell 1, and the interior of the guide shoe 2 is of a hollow structure. The rear end of the guide shoe 2 is fixedly connected with the front end of the outer shell 1, so that the inner cavity of the guide shoe 2 is communicated with the inner cavity of the outer shell 1, and the guide shoe can be connected in various modes such as threaded connection and clamping connection. The front end and/or the side wall of the guide shoe 2 are/is provided with a flow guide channel 21 for realizing the communication between the inner cavity of the guide shoe and the external space of the floating guide shoe, and the flow guide channel is used as a channel through which fluid flows when a well is washed.

The check valve unit 3 may have any structure known in the art. In this embodiment, the check valve unit 3 is disposed in the inner cavity of the outer housing 1, and the initial state is a closed state, so as to block the communication between the inner cavity of the outer housing 1 and the external space of the floating guide shoe through the flow guide channel 21 of the guide shoe 2. When the positive pressure difference between the inner cavity of the outer shell 1 and the external space of the floating guide shoe 2 reaches or exceeds a first threshold value, the check valve unit 3 is opened, so that the inner cavity of the outer shell 1 is communicated with the external space of the floating guide shoe through the flow guide channel 21. When the positive pressure difference between the inner cavity of the outer shell 1 and the external space of the floating guide shoe is smaller than a first threshold value, the check valve unit 3 is restored to a closed state. The check valve unit 3 can thus be controlled to open and close by the pressure difference between the centre string and the wellbore annulus. Preferably, the first threshold value is 0.1-0.5 Mpa.

The floating guide also comprises a reverse closing unit 4. The reverse closing unit 4 is arranged in the inner cavity of the outer shell 1 and is connected with the check valve unit 3 in series in the inner cavity of the outer shell 1, namely, as long as one unit is in a closed state, the fluid channel of the floating guide shoe can be closed. In the series structure, the sequence of the front and rear positions of the check valve unit 3 and the reverse blocking unit 4 is not limited. The initial state of the reverse closing unit 4 is an open state; when the reverse pressure difference between the inner cavity of the outer shell 1 and the external space of the floating guide shoe (namely the fluid pressure in the shaft annular space is greater than the fluid pressure in the inner cavity of the outer shell 1) reaches or exceeds a second threshold value, the reverse sealing unit 4 is closed, so that the communication between the inner cavity of the outer shell 1 and the external space of the floating guide shoe through the guide channel 21 of the guide shoe 2 is blocked; when the reverse sealing unit 4 is closed, the opening state is recovered under the control of forward or reverse pressure, so that the floating guide shoe can not be decompressed when high-pressure fluid is filled in the central pipe column. Preferably, the second threshold value is 1-20 Mpa.

In one embodiment of the present application, the reverse closing unit 4 comprises a first sealing valve seat 41 and a first sealing sliding sleeve 42. The first sealing valve seat 41 is of a circular ring structure as a whole, and the outer side of the first sealing valve seat is fixedly connected with the inner side of the outer shell 1 in a sealing manner; preferably, a first rotation stopping pin 7 is arranged between the first sealing valve seat 41 and the outer housing 1, and is used for realizing connection and fixation between the first sealing valve seat 41 and the outer housing 1. The first sealing sliding sleeve 42 is a shaft-shaped structure as a whole, and includes a jaw end 421 and a closed end 422, and the jaw end 421 and the closed end 422 can move axially in the inner cavity of the first sealing sliding sleeve 42. Wherein, the claw end 421 includes a plurality of claw tips 423 arranged along the circumferential direction facing to the claw 424 facing away from the axial direction, and the claw 424 is used for realizing the positioning of the first sealing sliding sleeve 42 relative to the first sealing valve seat 41. The closed end 422 is a closed structure for closing the fluid passage. When the reverse closing unit 4 is in an open state, the jaw end 421 is located in the inner cavity of the first sealing valve seat 41, the closed end 422 of the first sealing sliding sleeve 42 is located outside the front end of the first sealing valve seat 41, and the inner cavity of the first sealing valve seat 41 and the spaces between the jaws 423 form a fluid passage inside the floating guide shoe, so that the fluid passage inside the floating guide shoe is ensured to be unblocked. When the reverse closing unit 4 is in a closed state, the closed end 422 of the first sealing sliding sleeve 42 is positioned in the cavity of the first sealing valve seat 41 and is in sealing fit with the first sealing valve seat 41, so that a fluid passage inside the floating guide shoe is blocked; moreover, the blocking is permanent, and when the reverse blocking unit 4 is closed, it is no longer controlled by the forward or reverse pressure to return to the open state.

In one embodiment of the present application, a first groove 411 is provided inside the first sealing valve seat 41 at a position matching the claw tips 423 of the plurality of claws 421, for receiving the claw tips 423 of the claws 421. Preferably, the first groove 411 is an annular groove, so that the pawl 421 can be locked into the first groove 411 at any angle in the circumferential direction. The claw 421 has a certain elasticity, and when the claw 421 is clamped into the first groove 411, the first groove 411 has a limiting effect on the claw 421, so that the first sealing valve seat 41 limits the first sealing sliding sleeve 42.

In one embodiment of the present application, the back 425 of the prongs 423 is a beveled structure; the side walls 412 of the first groove 411 and the back 425 of the claw tip 423 are inclined in a slope structure corresponding to the inclination angle of the back 425 of the claw tip 423. By reasonably setting parameters such as the inclined angle of the back 425 of the claw tip 423 and the length, the width, the elasticity and the like of the claw 421, the force required for pushing the first sealing sliding sleeve 42 to move upwards to the closed position can be accurately obtained, so as to meet the requirements of users on setting different trigger pressures or perfusion pressures. Preferably, the trigger pressure may be set to 1-20Mpa, and when the reverse blocking unit 4 is closed, it is ensured that a differential pressure of 40Mpa is applied regardless of the forward or reverse direction without breaking the locking state.

In one embodiment of the present application, a sliding hole 30 is formed inside the check valve unit 3 along the axial direction of the floating guide shoe, and a piston 5 and a push rod 6 are arranged inside the sliding hole 30. The purpose of the piston 5 and the push rod 6 is to convert the reverse pressure difference of the fluid into an acting force through the piston 5 when the fluid reverse pressure reaches a second threshold value, and to act on the first sealing sliding sleeve 42 through the push rod 6, so that the first sealing sliding sleeve 42 enters a locking state. Specifically, one end of the piston 5 faces the direction of the floating guide shoe and is in contact with fluid for receiving fluid pressure in a well casing annular space; the other end is provided with a push rod 6, the lower end of the push rod 6 is connected or adjacent to the piston 5, and the other end is connected or adjacent to the first sealing sliding sleeve 42 (a fixed connection mode can be adopted, and a distance can also be kept at one end). When the reverse pressure difference between the inner cavity of the outer shell 1 and the external space of the floating guide shoe reaches or exceeds a second threshold value, the piston 5 moves towards the push rod 6 under the action of the fluid pressure difference to push the push rod 6 and the first sealing sliding sleeve 42 to move until the claw tip 423 of the claw 421 is separated from the first groove 411 and is clamped and fixed at the upper end of the first sealing valve seat 41, and then enters a locking state. Preferably, the second threshold value is 1-20 Mpa.

In one embodiment of the present application, the inside of the claw tip 423 of the claw 421 is a chamfered structure; the upper end of the first sealing valve seat 41 is provided with an inclined groove 413 matched with the clamping and fixing position of the claw tip 423 of the claw 421, and the inclined angle of the inclined groove 413 is consistent with the chamfer angle of the inner side of the claw tip 423 of the claw 421. Preferably, the inclined groove 413 is an annular groove so that the claw 421 can be caught in the inclined groove 413 regardless of the angle of entry. The provision of chamfers and ramp grooves ensures that the prongs 423 snap into the ramp grooves 413 more effectively and do not slip off under external forces, thereby ensuring that the counter closure unit 4 remains locked more effectively.

In one embodiment of the present application, the closed end 422 of the first sealing sliding sleeve 42 is provided with a positioning block 426; the lower end surface of the first sealing valve seat 41 is provided with a positioning groove 414 matched with the positioning block 426. The positioning groove 414 is a circular ring structure, and the positioning block 426 may be a block or a circular ring with a matching shape. The positioning block 426 and the positioning slot 414 are provided to position the first sealing valve seat 41 when the reverse closing unit 4 is closed, so as to prevent the first sealing valve seat 41 from passing upward. On the other hand, the positioning block 426 and the positioning groove 414 are combined to have a sealing effect.

In one embodiment of the present application, one or more sealing rings (not shown) are provided circumferentially on the outside of the closed end 422 of the first sealing runner 42. The purpose of the sealing ring is to further increase the positioning effect between the first sealing sliding sleeve 42 and the first sealing valve seat 41.

In one embodiment of the present application, the check valve unit 3 is similar in structure to the prior art described herein, and includes a second sealing valve seat 33 and a second sealing valve sleeve 35, and a spring 36 is disposed between the second sealing valve seat 33 and the second sealing valve sleeve 35 in a compressed state. The specific structure of the check valve unit 3 is described above with reference to the floating guide shoe of the prior art. A second rotation stopping pin 38 is arranged between the second sealing valve seat 33 and the outer shell 1 to improve the fixing effect between the two; the lower end of the second sealing valve sleeve 35 is matched with the second sealing valve seat 33 to open or close the check valve unit 3, and the upper end of the second sealing valve sleeve is fixedly connected with a spring sleeve 34 through a positioning pin 32; the upper part of the second sealing valve seat 33 is also provided with a plurality of parallel axial through holes 37 as fluid passages.

In the initial state, the elastic force of the spring makes the second sealing valve seat 33 and the second sealing valve sleeve 35 combine to be in the sealing state; when the positive pressure difference between the inner cavity of the outer shell 1 and the outer space of the floating guide shoe is larger than the first threshold value, the second sealing valve sleeve 35 is separated from the second sealing valve seat 33 under the action of pressure, so that the check valve unit 3 is opened, and fluid flows through the through hole 37, the gap separated between the second sealing valve sleeve 35 and the second sealing valve seat 33, enters the cavity of the guide shoe 2 and flows into the shaft annulus through the diversion channel 21. When the positive pressure difference between the inner cavity of the outer housing 1 and the external space of the floating guide shoe is smaller than a first threshold value, the second sealing valve sleeve 35 is restored to be combined with the second sealing valve seat 33 under the elastic force of the spring 36, and the check valve unit 3 is restored to the closed state. Thus, during the forward well washing operation, the check valve unit 3 realizes the one-way conduction of the fluid.

In one embodiment of the present application, the second sealing valve sleeve 35 is a shaft-like structure, and the shaft center is provided with a through sliding hole 30. The sliding hole 30 is used for arranging the piston 5 and the push rod 6.

In an embodiment of the present application, a first supporting sleeve 8 is disposed between the check valve unit 3 and the reverse sealing unit 4, the first supporting sleeve 8 is a cylindrical structure, and the outer side of the first supporting sleeve 8 is attached to the inner side of the outer shell 1. The first support sleeve 8 is used to position and fix the position of the check valve unit 3 and the reverse blocking unit 4 in the inner cavity of the outer housing 1.

The assembly process of the device is as follows: firstly, a reverse closed unit 4, a first supporting sleeve 8 and a check valve unit 3 are assembled in an inner cavity of an outer shell 1 from bottom to top, and finally guide shoes are installed. The upward force of the guide shoe acts on the check valve unit 3, the first support sleeve 8 and the reverse closing unit 4 in turn, thereby fixing the above components.

The embodiment also provides a central pipe column, wherein the bottom end of the central pipe column is provided with the floating guide shoe capable of completely closing the fluid channel; the central pipe column adopts the flow control sieve pipe which is used for the oil-gas well and can adjust the flow conductivity stage by stage, so that the flow conductivity of the underground flow control sieve pipe can be adjusted stage by stage.

The present embodiments also provide a completion configuration including a wellbore and a center string disposed in the wellbore; the bottom end of the central pipe column is provided with the floating guide shoe which can completely close the fluid channel; the central pipe column adopts the flow control sieve pipe which can adjust the flow conductivity stage by stage for the oil-gas well, thereby realizing the step-by-step adjustment of the flow conductivity of the underground flow control sieve pipe.

Obviously, the central string and the completion structure have the technical effects as described above by using the floating guide shoe which can completely close the fluid passage as described above.

The steps of operation of the floating guide shoe, the central string and the completion structure with the fluid passage completely closed as given in the above embodiments are as follows: in the well descending stage of the central pipe string, the reverse closing unit 4 is opened, and the check valve unit 3 is closed, so that mud energy substances in the well bore are prevented from entering the central pipe string; after the central pipe column is lowered into the well, the ground equipment fills well-flushing liquid into the well through the central pipe column, the reverse sealing unit 4 is still in an open state, the check valve unit 3 is automatically opened under the action of filling pressure, the well is positively flushed, and substances such as slurry in the annular space of the well barrel are discharged through a well opening; in the production stage, oil and gas exploitation is realized under the action of a small reverse bottom hole pressure difference; when the flow guiding capacity of the flow control sieve tube needs to be increased, firstly, fluid is filled into the shaft annulus through surface equipment, so that a large reverse differential pressure is generated at the well bottom, the reverse sealing unit 4 is completely closed under the action of the reverse differential pressure, then, the fluid is filled into the central pipe column through the surface equipment, so that a large forward differential pressure is generated at the well bottom, and the flow guiding device of the flow control sieve tube is opened step by step through the forward differential pressure according to needs, so that the flow guiding capacity of the flow control sieve tube is increased step by step.

The foregoing is a further detailed description of the utility model in connection with specific preferred embodiments and it is not intended to limit the utility model to the specific embodiments described. For those skilled in the art to which the utility model pertains, several simple deductions or substitutions can be made without departing from the spirit of the utility model, and all shall be considered as belonging to the protection scope of the utility model.

Claims

1. A floating guide shoe capable of completely closing a fluid channel comprises an outer shell, a guide shoe and a check valve unit; wherein the content of the first and second substances,

the outer shell is of a cylindrical hollow structure;

the guide shoe is arranged at the front end of the outer shell, and the inner part of the guide shoe is of a hollow structure; the rear end of the guide shoe is fixedly connected with the front end of the outer shell, so that the inner cavity of the guide shoe is communicated with the inner cavity of the outer shell; the front end and/or the side wall of the guide shoe are/is provided with a flow guide channel for realizing the communication between the inner cavity of the guide shoe and the external space of the floating guide shoe;

the check valve unit is arranged in the inner cavity of the outer shell, and the initial state is a closed state so as to block the communication between the inner cavity of the outer shell and the external space of the floating guide shoe through the flow guide channel of the guide shoe; when the positive pressure difference between the inner cavity of the outer shell and the external space of the floating guide shoe reaches or exceeds a first threshold value, the check valve unit is opened, so that the inner cavity of the outer shell is communicated with the external space of the floating guide shoe through the flow guide channel; when the positive pressure difference between the inner cavity of the outer shell and the external space of the floating guide shoe is smaller than a first threshold value, the check valve unit is restored to a closed state;

the method is characterized in that: the floating guide shoe further comprises a reverse sealing unit; wherein, the first and the second end of the pipe are connected with each other,

the reverse sealing unit is arranged in the inner cavity of the outer shell and is connected with the check valve unit in series in the inner cavity of the outer shell; the initial state of the reverse closing unit is an opening state; when the reverse pressure difference between the inner cavity of the outer shell and the external space of the floating guide shoe reaches or exceeds a second threshold value, the reverse sealing unit is closed, so that the communication between the inner cavity of the outer shell and the external space of the floating guide shoe through the guide shoe flow guide channel is blocked; when the reverse closing unit is closed, the reverse closing unit is not controlled by forward or reverse pressure any more and returns to an open state.

2. The floating guide shoe with complete closure of the fluid passageway as set forth in claim 1, wherein: the reverse closing unit comprises a first sealing valve seat and a first sealing sliding sleeve, wherein,

the first sealing valve seat is integrally of a circular ring structure, and the outer side of the first sealing valve seat is fixedly connected with the inner side of the outer shell in a sealing manner;

the first sealing sliding sleeve is integrally of a shaft-shaped structure and comprises a jaw end and a closed end; the clamping jaw end comprises a plurality of clamping jaws, wherein the plurality of clamping jaws are arranged along the circumferential direction, and the clamping jaws face away from the axis direction; the closed end is of a closed structure;

when the reverse closing unit is in an open state, the end of the clamping jaw is positioned in the inner cavity of the first sealing valve seat, and the closed end of the first sealing sliding sleeve is positioned outside the front end of the first sealing valve seat; the inner cavity of the first sealing valve seat and the spaces among the clamping jaws form a fluid channel inside the floating guide shoe;

when the reverse closing unit is in a closed state, the closed end of the first sealing sliding sleeve is positioned in the cavity of the first sealing valve seat and is in sealing fit with the first sealing valve seat to block a fluid passage in the floating guide shoe.

3. The floating guide shoe with complete closure of the fluid passageway as set forth in claim 2, wherein: and a first groove is formed in the position, matched with the claw tips of the plurality of claws, of the inner side of the first sealing valve seat and used for accommodating the claw tips of the claws.

4. The floating guide shoe with a completely closed fluid passage as set forth in claim 3, wherein:

the back of the claw tip is of an inclined plane structure;

the side walls of the first groove corresponding to the back of the claw point are inclined plane structures with the same inclination angles with the back of the claw point.

5. The floating guide shoe with a completely closed fluid passage as set forth in claim 3, wherein:

a sliding pore channel is arranged in the check valve unit along the axis direction of the floating guide shoe, and a piston and a push rod are arranged in the sliding pore channel; one end of the piston faces the direction of the floating guide shoe, and the other end of the piston is provided with a push rod; one end of the push rod is connected or adjacent to the piston, and the other end of the push rod is connected or adjacent to the first sealing sliding sleeve;

when the reverse pressure difference between the inner cavity of the outer shell and the external space of the floating guide shoe reaches or exceeds a second threshold value, the piston moves towards the direction of the push rod under the action of the difference of fluid pressures to push the push rod and the first sealing sliding sleeve to move until the claw tips of the claws are separated from the first grooves and are clamped and fixed at the upper end part of the first sealing valve seat.

6. The floating guide shoe with a completely closed fluid passage as set forth in claim 3, wherein:

the inner sides of the claw tips of the clamping jaws are of a chamfer structure;

the first sealed disk seat upper end be equipped with the claw point joint fixed position of jack catch matches the inclined plane recess, the inclined plane inclination of inclined plane recess with the inboard chamfer angle of jack catch claw point is unanimous.

7. The floating guide shoe with complete closure of the fluid passageway as set forth in claim 2, wherein:

a positioning block is arranged at the closed end of the first sealing sliding sleeve;

and the lower end surface of the first sealing valve seat is provided with a positioning groove matched with the positioning block.

8. The floating guide shoe with complete closure of the fluid passageway as set forth in claim 2, wherein: one or more sealing rings are arranged on the outer side of the closed end of the first sealing sliding sleeve along the circumferential direction.

9. The floating guide shoe with the fluid passage completely closed according to claim 1, wherein:

the check valve unit comprises a second sealing valve seat and a second sealing valve sleeve, and a spring in a compression state is arranged between the second sealing valve seat and the second sealing valve sleeve; in an initial state, the elasticity of the spring enables the second sealing valve seat and the second sealing valve sleeve to be combined to be in a sealing state;

when the positive pressure difference between the inner cavity of the outer shell and the external space of the floating guide shoe is larger than the first threshold value, the second sealing valve sleeve is separated from the second sealing valve seat under the action of pressure, so that the check valve unit is opened;

when the positive pressure difference between the inner cavity of the outer shell and the external space of the floating guide shoe is smaller than a first threshold value, the second sealing valve is sleeved with the second sealing valve seat under the action of the elastic force of the spring, and the check valve unit is restored to a closed state.

10. The floating guide shoe with complete closure of the fluid passageway as claimed in claim 9, wherein: the whole second sealing valve sleeve is of a shaft-shaped structure, and a through sliding hole channel is formed in the axis of the second sealing valve sleeve.

11. The floating guide shoe with complete closure of the fluid passageway as set forth in claim 1, wherein: be equipped with first supporting sleeve between check valve unit and the reverse unit of sealing, first supporting sleeve is the tubular structure, the outside of first supporting sleeve with the inboard laminating of shell body.

12. A center tube string, comprising: the bottom end of the center pipe string is provided with a floating guide shoe capable of completely closing a fluid passage as claimed in any one of claims 1 to 11.

13. A completion structure comprising a wellbore and a center string disposed in the wellbore, wherein: the bottom end of the center pipe string is provided with a floating guide shoe capable of completely closing a fluid passage as claimed in any one of claims 1 to 11.