RU2580556C1 - Device for cementing casing string of large diameter - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil and gas industry, particularly, to cementing of large-diameter pipes casing strings through drill pipe on oil and gas wells. Device comprises shoe assembly, docking tool and top cementing plug. Shoe assembly includes housing with cement sleeve with the seating sleeve and check valve with throttle. Docking tool comprises rod with sealing elements. In middle part of rod there are circulation radial holes. Rod lower part is equipped with thrust for squeezing plug setting. Rod docking tool is equipped with casing and damper spring. Damping spring is located above casing. Casing is fixed on rod with shear screw in position, covering sealing elements. Inside rod there is suspended sleeve locked with a shear screw to shut off said circulation radial holes. Squeezing plug in lower part has sealing elements and grooves for fixation.

EFFECT: technical result is increasing of string cementing quality and simplification of process operations during cementing of strings.

1 cl, 3 dwg

Description

The invention relates to the oil and gas industry, in particular, to the technology of cementing casing strings of large diameter through a drill pipe in oil and gas wells.

A device for cementing a casing string in a well is known, including a “stop ring” in the form of a pipe muffled from below with longitudinal grooves and radial channels, with an annular ledge at the top and a conical surface at the bottom, telescopically to which a lower support ring is provided in the lower casing sleeve provided with shear elements, the free ends of which are included in the longitudinal grooves of the nozzle, and having a conical bore in the lower end that is adequate to the conical surface of the nozzle, while the device is equipped with an upper m ftoy with an upper support ring installed in it, made with an annular bore on the inner surface in the lower part, the inner diameter of which is equal to the outer diameter of the plug located at the lower end of the washing pipes and made in the form of two telescopically connected parts, the upper of which is rigidly connected with the washing pipes, and the lower one is connected to the upper part by shear elements and is equipped with a spring clip on the outer surface, above the plug there are radial channels connecting the inner lethargy flushing pipe annular space, wherein the lower and upper coupling pipe coupled [RF patent №2271437, E21B 33/14, publ. 03/10/2006].

The disadvantage of this device is the need to move the flushing pipes with a plug in the axial direction during cementing of the columns, as well as the greater likelihood of excessive axial loads when landing flushing pipes on the device nodes installed in the shoe part of the casing, and their damage; the possibility of damage to the sealing elements during descent or erosion during the circulation of process fluids through the device, which can lead to leaks and, as a result, the overflow of cement slurry into the casing in the initial waiting period for cement hardening (OZZ); increased consumption of cement slurry due to large mixing zones with the drilling fluid; the need to drill a large number of parts in the shoe part of the casing.

The closest in technical essence to the proposed technical solution is a device for cementing casing strings through a string of pipes of small diameter, comprising a housing with cement and socket sleeves housed in it, a nipple adapter with sealing elements, a check valve with a throttle and a flow plug with a core located on cuffs, the device is also equipped with a lower cementing plug, the core of which has end slots on the upper end, and the core of the squeezing plug and is made with a through channel, the lower end of which is blocked by an elastic element fixed from two opposite ends with a cap nut made with a transverse through channel, and the nipple adapter is made with an emphasis for the lower tube and windows located between the sealing elements and located at a height from the stop [ A.S. USSR No. 1002530, E21B 33/14, publ. 03/07/1983].

The disadvantage of this device is the need to move in the axial direction columns of pipes of small diameter with a nipple adapter in the process of cementing the columns, as well as the greater likelihood of excessive axial loads when planting the column of pipes of small diameter in the socket sleeve of the shoe part of the casing, which can lead to their destruction; the possibility of damage to the sealing elements during descent, which can lead to leaks in the connection of nodes.

The objective of the invention is to provide a device that would provide improved cementing quality of large diameter casing strings.

EFFECT: improved quality of cementing columns and simplification of technological operations during cementing of columns.

The task and technical result are achieved by the fact that in the proposed device for cementing large-diameter casing strings containing a shoe assembly, a docking tool and a squeezing plug, the shoe assembly comprises a housing with a cement cup placed therein with a bushing and a check valve with a throttle, a docking tool contains a stem with sealing elements, circulating radial holes are made in the middle part of the stem, the lower part of the stem is provided with an abutment for landing the squeeze plugs, unlike the prototype, the stem of the docking tool is equipped with a casing and a damper spring, the damper spring is located above the casing, while the casing is fixed to the stem with a shear screw in the position overlapping the sealing elements, a suspension sleeve is fixed inside the rod, fixed with a shear screw to block the specified radial circulation holes, and the squeeze plug in the lower part has sealing elements and grooves for fixing.

A distinctive feature of the claimed invention is a design feature, which allows to obtain reliable sealing of the device for the entire period of cementing. To do this, on the stem of the docking tool there is a casing interacting with a damper spring, which ensures a soft fit of the docking tool in the shoe assembly, and a shear screw on the stem signals the beginning of landing due to the occurrence of axial force, which ensures cutting of the screws, the position of the casing overlapping the sealing elements protects them from damage during descent and from erosion during flushing, the hanging sleeve located inside the stem, fixed with a shear screw, closes the circulation radially openings in the middle part of the rod and allows you to redirect the flow of injected fluids without additional operations, and the squeeze plug in the lower part has sealing elements to seal the inner channel of the rod and the grooves for fixing it in the rod stop.

Figure 1 shows the inventive device in the initial position before landing of the docking tool in the shoe assembly, arrows indicate the direction of motion of the process fluids; figure 2 - in position after landing of the docking tool in the shoe assembly; figure 3 - in the position after squeezing the grouting mortar and landing squeezing plugs, arrows show the direction of movement of the process fluids.

A device for cementing large-diameter casing strings consists of a shoe assembly 1, a docking tool 2 and a squeeze plug 3. The shoe assembly 1 includes a housing 4 with a cement cup 5 and a seat sleeve 6 located therein, a check valve 7 with an orifice 8. Depending on the depth the descent of the columns the check valve may not be included in the shoe unit 1.

Docking tool 2 contains a rod 9 with sealing elements 10, and in the lower part of the rod 9 there is an abutment 12 for seating the squeeze plug 3.

A casing 13 is placed on the rod 9, interacting with the damper spring 14 and fixed on the rod 9 with a shear screw 15 in a position overlapping the sealing elements 10, a suspension sleeve 16 is fixed inside the rod 9, fixed with a shear screw 17, which closes the radial circulation holes 11 in the middle part stock 9.

Selling plug 3 in the lower part has sealing elements 18 for sealing the internal channel of the rod 9 and the groove 19 for fixing it in the support 12 of the rod 9.

The device operates as follows.

Before the casing is lowered into the well, a shoe assembly 1 is attached to its lower casing (not shown) and lowered into the well to the design depth. The casing is filled with process fluid through a non-return valve or through a central channel (not shown). Then, the docking tool 2 is attached to the pipe string of the drill pipe and lowered into the casing before landing in the shoe assembly 1. When the docking tool 2 is in the shoe assembly 1 to prevent a rigid docking at the moment of touching the casing 13 with the landing sleeve 6 with the estimated axial load on the shoe the knot is cut off by screw 15, which is indicated on the mouth by a weight indicator. After that, the start of the docking tool 2 is limited by a length not exceeding the stroke length of the casing 13 on the rod 9. In this case, the damper spring 14, interacting with the rod 9 and the casing 13, softens the fit of the docking tool 2 into the shoe assembly 1, and the sealing elements 10 enter the landing the sleeve 6 and seal the annulus from the annulus.

Then the casing is cemented according to the design technology, at the end of the cement slurry injection, the squeeze plug 3 is pressed and squeezed until it stops at stop 12. At the moment of passage inside the stem 9, the squeeze plug 3 shifts the suspension sleeve 16 fixed by the shear screw 17 and as a result opens the circulation radial holes 11 in the middle of the stem 9.

When the squeeze plug 3 is planted, the sealing elements 18 seal the inner channel of the rod 9, and the grooves 19 fix the squeeze plug 3 in the stop 12 of the rod 9, thereby sealing the annular space from the in-pipe. The circulation fluid is circulated through the circulating radial holes 11, this allows you to maintain the required positive temperature in the well due to the circulation of the flushing fluid after the completion of the flow during the entire period of the wet cleaning process, as well as to provide the calculated thermal regime of cementing hardening in the intervals of low and negative temperatures on the walls wells. In addition, the creation of a temperature regime with a constant value in the well during the period of the SSC prevents thermal deformation of the casing.

An example of the implementation of the inventive device for cementing casing large diameter through drill pipes is considered when cementing directions with a diameter of 530 mm with a depth of descent of 40 m

Before running the casing, which consists of pipes 530x8,0-K52 - TU 14-3-1970-97, a shoe unit 1 is connected to the well on its lower casing and lowered into the well to the design depth. The casing is filled through the central channel of the shoe assembly 1. In this case, the check valve is not included in the shoe assembly 1. Then, the connecting tool 2 is connected to the lower pipe of the drill pipe string with a diameter of 127 mm (TBPV 127x9.2) and lowered into the casing before landing to the shoe unit 1.

The drill string is selected in such a way that the docking tool 2 fully enters the shoe assembly 1 and ensures complete unloading of the drill string, and the upper drill pipe lock is located above the rotor of the drilling rig in such a way as to allow cementing and start-up of the cork plug 3. Complete unloading of the drill the columns are carried out in order to prevent it from being pushed out of the well during cementing, especially at the end of the grouting supply.

At the moment the docking tool 2 is inserted into the shoe assembly 1, the screws 15 are cut off, which is indicated on the mouth by a weight indicator, to reduce the speed of descent of the column and to prevent the docking casing 13 from joining rigidly 6. The start of the docking tool is limited to a length not exceeding the casing stroke 13 on the rod 9. At the same time, the damper spring 14, interacting with the rod 9 and the casing 13, softens the final landing of the docking tool 2 in the shoe assembly 1, and the sealing elements 10 enter the landing sleeve 6 and germ They innerize the annulus from the annulus. As a result, the circulation of process fluids is carried out through the drill pipe through the shoe unit 1 and annular space. After the descent of the working drill string is completed, the well is flushed and the casing is prepared for cementing.

Cementing casing is carried out according to standard technology. In accordance with the work plan, in the process of cementing the columns, the buffer fluid and grout are injected. In order to obtain the rise of cement behind the casing to the mouth, the cement slurry is pumped until it reaches the mouth, after which the squeeze plug 3 is launched and pressed to the stop 12 until it is planted.

At the moment when the squeeze plug 3 passes inside the stem 9, the circulating radial holes 11 open. Further circulation of the squeezing fluid is carried out through the drill pipes, said radial holes 11 and the annular space between the casing and the drill pipes. This allows you to maintain the required value of the positive temperature in the well during the period of OZZ.

When landing the squeeze plug 3, the sealing elements 18 seal the inner channel of the rod 9, and the grooves 19 fix the squeeze plug 3 in the stop 12 of the stem 9, which prevents the backflow of grout from the annular space through the shoe assembly 1 into the columns.

After carrying out all the operations stipulated by the work plan for fixing the column from the well, the docking tool 2 is removed with the cork plug 3.

The use of a device for cementing large-diameter casing strings provides the following advantages compared to the traditionally used technology for cementing casing strings:

- provides a cementing process with a maximum flow rate of the injected fluid and ensuring a high upward flow rate;

- improves the degree of substitution of the drilling fluid with grouting and ensures the rise of the grouting fluid behind the casing to the mouth;

- significantly or completely decreases the mixing zone of the cement slurry with the drilling fluid;

- allows the cementing process to be carried out using mud pumps and one cementing unit for pumping the last portion of the squeezing fluid and receiving a stop signal;

- eliminates the need for large-sized cementing plugs and cementing heads.

Claims (1)

A device for cementing large-diameter casing strings containing a shoe assembly, a docking tool and a squeezing plug, the shoe assembly includes a housing with a cement cup placed therein with a bushing and a check valve with a throttle, the docking tool contains a stem with sealing elements, in the middle part of the stem circular radial holes, the lower part of the stem is provided with an abutment for seating the squeeze plug, characterized in that the stem of the docking tool is equipped with a housing and a spring, the damper spring is located above the casing, while the casing is fixed on the stem with a shear screw in a position overlapping the sealing elements, a suspension sleeve is fixed inside the stem fixed with a shear screw to cover the said radial circulation holes, and the cork plug in the lower part has sealing elements and grooves for fixing.

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