RU2687834C1 - Column shoe - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to construction of oil and gas wells, in particular to equipment for tooling of lower part of casing string. Shoe block includes a body with a central channel, one end of which is intended for connection to a pipe string, a bushing inserted into the other end of the body, a central channel from below with a constriction, above which side holes are made. Bushing is inserted inside the housing with fixation by shear elements for sealing of side holes with the possibility of movement downwards to narrowing of the central channel of the housing under action of a throw ball and opening of side holes. On external surface of housing there are identical screw recesses interconnected in lower part with corresponding side holes.

EFFECT: improving quality of cementing of casing string due to good washing of well bore through central flushing channel during string lowering, reliable shutting of holes in horizontal bore of shoe after completion of blasting.

1 cl, 4 dwg

Description

The invention relates to the field of construction of oil and gas wells, in particular to equipment for tooling the lower part of the casing.

The casing shoe is known (SU No. 1673725, IPC E21 B 17/14, published in Bull. No. 32 of August 30, 1991), which contains a metal cylindrical body with an axial channel and a concrete guide nozzle with a spherical outer surface rigidly connected to the lower part of the body. and with an axial channel, with the aim of improving reliability by improving the permeability and preventing clogging of the channel during the descent of the shoe, it is equipped with a fairing installed in front of the concrete guide nozzle and its associated elastic pins Concrete guide rail annular gap.

The disadvantages of this design:

- insufficient washing of the wellbore from the sludge located directly in front of the shoe in the process of lowering the casing;

- vibrations that occur during flushing, may further condense the sludge in front of the shoe, which will increase the likelihood of failure of the column;

- the fairing does not allow to create a turbulent flow of cement mortar.

The closest in technical essence is a column shoe (RU # 2574237, IPC Е21В 17/14, published in bul. № 4 dated 02/10/2016), including a body, one end of which is intended to be connected to a column pipe, a sleeve connected to another the end of the body, a guide nozzle with a central channel made of easily drilled material and placed in the lower part of the sleeve cavity, the free lower end of which with the guide nozzle is made obliquely, while the sleeve in front of the guide nozzle has side holes Flax on its outer surface, and has the ability to rotationally relative to the housing, the axial interaction of the device with an obstacle in the wellbore, or rotation relative to the housing when the well washed.

The disadvantages of this design:

- openings made tangentially to the outer surface of the body are designed for better flushing during the descent of the column, but do not allow for the cement mortar to be forced in the turbulent mode;

in a horizontal well, one of the holes may be closed by the well wall, which will have a bad effect on the quality of cementing;

- since the central channel has a diameter greater than the diameter of the side holes, in the process of pumping cement mortar, the main flow will pass through the central hole, which also does not allow for additional mixing of the solution.

The technical task of the invention is to improve the quality of cementing casing due to good washing of the wellbore during the descent of the column, the best replacement of drilling mud cement due to the creation of a turbulent flow of cement mortar and eliminate the overlap of the holes in the horizontal wellbore, as well as reliable overlapping of the holes of the Shoe at the end of pushing .

The technical problem is solved column shoe, including a housing with a Central channel, one end of which is designed to connect to the column pipe, a sleeve inserted into the other end of the housing, the Central channel from the bottom is provided with a constriction above which the side holes are made.

New is that the sleeve is inserted into the body with fixing shear elements to seal the side holes with the ability to move down to narrowing the center channel of the body under the action of the throw ball and the opening of the side holes, while on the outer surface of the body made the same screw sample, reported in the bottom with corresponding side holes.

FIG. 1 shows a column shoe during the descent of a column into a well with a partial section.

FIG. 2 shows a column shoe after the column has reached a predetermined installation interval and after a ball has been dropped with a partial cut.

FIG. 3 shows a column shoe after pushing cement mortar and planting a squeeze plug into the seat with a partial cut.

FIG. 4 shows a general view of the column shoe and screw samples made on it.

The column shoe consists of a body 1 (FIG. 1) with a central channel 2. The upper end of the body 1 is intended to be connected (for example, by thread) with a casing column (not shown in the figures.). A sleeve 3 is inserted into the lower end of the housing 1, the central channel 2 is provided with a constriction 4 below, above which the side openings 5 are made. The sleeve 3 is inserted inside the housing 1 with shear elements 6 fixed to seal the lateral openings 5 using sealing elements 7 and move down to tapering the central channel 4 (Fig. 2) of the housing 1 under the action of the ball 8 and opening the side holes 5. In addition, on the outer surface of the housing 1, identical helical samples 9 (Figs. 1 and 4) are provided, which are connected in the lower part with side holes 5. The cement mortar is pumped into the annulus by squeezing plug 10 (Fig. 3), which has a locking ring 11 in the lower part, and a corresponding groove 12 is in the central channel 2 (Fig. 1) of the housing 1 (Fig. 2 ) under the retaining ring 11 (Fig. 3). Column shoe works as follows.

The column shoe is mounted on the first casing pipe (not shown in the FIG.) And the column is lowered into the well. In the process of descending the column, intermediate flushing of the well is carried out to remove accumulated sediment in front of the shoe. At the same time, flushing is carried out through the central channel 2 (Fig. 1) and the constriction 4 of the housing 1. The sleeve 3 installed in the lower part of the central channel 2 of the housing 1 is fixed by shearing bis elements using sealing elements 7 reliably blocks the side openings 5. Upon reaching the casing the face is the final flush and at the same time the ball 8 is dropped into the casing string (Fig. 2). The ball 8 reaches the sleeve 3, closes the central hole, this increases the pressure, cuts elements 6 (Fig. 1), and the sleeve with the ball moves down to the narrowing 4 (Fig. 2). In this case, the central channel 2 (FIG. 1) overlaps, and the side openings 5 (FIG. 2) open. Next, pumped cement mortar. After injection of the calculated volume of cement mortar, a squeeze plug is inserted and the cork is pushed down with a buffer liquid. In the process of pushing into the annulus, the cement slurry passes through the side holes 5 (Fig. 4) and screw samples 9. At the same time, the cement slurry flow receives a turbulent motion, which leads to better mixing of the cement and replacement of the drilling mud. In addition, if one of the holes turned out to be closed by the lower part of the borehole wall due to the screw sample 9, it will still go out without difficulty.

When the stopper 10 (Fig. 3) reaches the column shoe, the locking ring 11 snaps into the corresponding groove 12 (Fig. 2) and the stopper 10 (Fig. 3) is fixed. This increases the pressure on the pump pressure gauge, which means the end of the pump. Next, turn off the pump, and the well is transferred to the operation of the cement hardening. The fixed flush plug 10 acts as a non-return valve, i.e. prevents cement from the annulus from falling back into the casing.

The proposed construction of the shoe allows you to improve the quality of casing cementing due to good washing of the wellbore through the central flushing channel during the descent of the column, improve the replacement of drilling mud cement by creating a turbulent flow of cement mortar and eliminate the overlapping holes in the horizontal wellbore, and also reliably block the holes Shoe at the end of delivery.

Claims (1)

Column shoe, comprising a housing with a central channel, one end of which is designed to connect to the column pipe, a sleeve inserted into the other end of the housing, the central channel from the bottom is provided with a taper, above which there are side openings, characterized in that the sleeve is inserted into the housing with shear fixation elements for sealing the side holes with the ability to move down to narrowing the center channel of the housing under the action of the rejection ball and opening the side holes, while on the outer surface of the core Pusa made the same screw samples, reported in the lower part with the corresponding side holes.

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