RU2223388C1 - Facility for stage cementing of casing string - Google Patents

Abstract

FIELD: oil and gas production, two-stage cementing of casing strings in oil and gas wells. SUBSTANCE: facility has body with rest and circulation holes, door placed inside body above circulation holes and joined to it with the aid of shear elements, location bushing installed inside door and linked to it by means of pins, fixing arm located between body and door and driving plug comprising rod and elastic member. Door and rest have opposing grooves and protrusions. In compliance with invention facility is fitted with housing placed over perimeter of body to form common space opposite to circulation holes. Gate connected to body with the use of shear elements is installed in mentioned space above holes. Inner diameter of location bushing accommodates outer diameter of lower part of driving plug in which conical bore additional fixing arm is placed. EFFECT: facility demonstrates high operational reliability, success and high quality of operations of injection of cement slurry of second stage. 3 cl, 1 dwg

Description

The invention relates to the oil industry and can be used for cementing casing in two stages in oil and gas wells.

A known clutch for stepped casing cementing, including a housing with circulation holes and plugs installed in them, an abutment for closing the housing sleeve, a landing sleeve under the separation plug (1).

The disadvantages of the device:

- the internal section of the coupling is less than the internal section of the casing due to the damper closing the circulation holes;

- when drilling cement stone inside the coupling, depressurization of the column is possible due to the destruction of the damper protruding into the inside of the column.

The closest in technical essence to the proposed one is a sleeve for stepwise cementing of the casing, comprising a housing with a stop and circulation holes, a shutter placed inside the housing above the circulation holes and connected to it by shear elements, a landing sleeve installed inside the shutter and connected to it by studs, a latch located between the housing and the shutter, the shutter and stop being made with reciprocal grooves and protrusions, and a cork plug including a rod and elastic element (2).

Significant disadvantages of the device are:

- there is no guarantee that the plugs 3 will fall out of the housing at the same time, otherwise, high pressure will be created during flushing;

- the possibility of creating caverns, due to the horizontal arrangement of the circulation holes and high pressure, which can subsequently fall off and block these holes and thereby exclude the possibility of pumping cement in the second stage;

- the need to create a lot of pressure when blocking the circulation openings can lead to the destruction of the sealing rings of the valve against the edges of the holes and cause depressurization of this assembly, which will lead to the overflow of cement into the inside of the casing and the lifting of the cork plug. In this case, there will be a need to leave the casing after the cement of the second stage is squeezed under pressure.

The objective of the invention is to provide a device with high reliability in the operation of its components and parts and guaranteeing the success and high quality of the operation for the injection of cement mortar of the second stage.

This problem is solved by the proposed device, comprising a housing with a stop and circulation holes, a shutter placed inside the housing above the circulation holes and connected with shear elements, a landing sleeve installed inside the shutter and connected to it by means of pins, a latch located between the housing and the shutter moreover, the shutter and emphasis are made with reciprocal grooves and protrusions, and a squeezing plug, including a rod and an elastic element.

New is that the device is equipped with a casing located around the perimeter of the housing and forming a cavity opposite to the circulation holes, in which a slide is installed above the holes connected to the housing by shear elements, and the inner diameter of the landing sleeve is selected for the outer diameter of the bottom of the cork plug , in the conical bore of which an additional clamp is installed.

Also new is that the additional lock is made in the form of a split, spring, conical ring, the tip of which is directed towards the bottom of the device; the landing sleeve in the lower part is equipped with an annular stop in the working position interacting with an additional clamp; the gate is made in the form of an annular sleeve.

The drawing shows the proposed device in longitudinal section.

It consists of a housing 1 with circulation openings 2, an emphasis 3, the functions of which are performed by a pipe connected to the casing. A casing 4 is put on the casing opposite the circulation openings 2 and forms a cavity 5 with it, in which a slide 6 is mounted connected to the casing by shear elements 7. Inside the casing there is a shutter 8, and inside the latter there is a landing sleeve 9, and the shutter is connected to the casing by shear elements 10, and with the landing sleeve - studs 11. In the body of the body from the inside in the conical bore is a latch 12, and from the outside there is an annular bore 13.

Together with the device in the kit, a stop assembly, lower and upper cork plugs are used.

The stop assembly consists of a saddle 14, a housing 15, couplings 16 and 17, and a shoe 18.

The lower cork plug includes a rod 19, an elastic cuff 20 and a latch 21. The upper cork plug includes a rod 22, an elastic cuff 23 and a latch 24.

The latches 21 and 24 are installed respectively in the conical bores of the rods 19 and 22 and have the same design, incl. and the latch 12, namely, they are made in the form of a split, spring, conical ring.

The mating parts are provided with seals 25.

The landing sleeve 9, the studs 11 and the shaft 22 are made of easily drilled material.

The device operates as follows.

It, complete with a stop assembly as a part of the casing string, is lowered into the well to the design depth so that the device is above the reservoir at a calculated distance. After that, cement cement of the first stage is pumped into the casing according to the usual technology using the lower cork plug in the volume necessary to shut off the device by 40-50 m. At the end of cementing, the cork sits on seat 14, and the seal 25 of the cork enters the inside of the seat on section with a smaller diameter and tightly pressed against its surface, and the latch 21 reliably holds the cork from the forces acting on it from the bottom up. With a further increase in pressure inside the column to 15.0 MPa, shear elements 7 are destroyed, the gate 6 rises up and leaves the casing 4. The annular space is flushed through the circulation openings 2.

After the OZC (waiting for the hardening of the cement), the calculated volume of the cement mortar of the second stage is pumped using the upper cork through the circulation holes 2.

At the end of cementing, the cork sits on the landing sleeve 9, while the portion of the larger diameter rod 22 with seals enters the inside of the sleeve and is firmly pressed to its surface, and the retainer 24 reliably fixes it in the sleeve 9. The pressure inside the column rises, and when it is about 15.0 MPa, shear elements 10 are destroyed, the shutter 8 together with the sleeve 9 are moved down, the latch 12 is activated and the holes 2 are closed, providing sealing of the device from the inside. The gate 6 is lowered down and provides sealing of the device from the outside.

Let’s assume the worst case scenario: let gate 6 pass through and shutter 8, i.e. the pressure of the column of cement in the annulus, acting on the plug, tends to bring it out of contact with the sleeve 9. However, the split spring retainer ring 24, moving in the axial direction, abuts the annular stop 26 and is jammed by the surface of the conical bore of the rod 22, reliably holding the squeeze traffic jam. In this case, the more pressure acts on the cork, the stronger its fixation.

After the OZZ of the cement mortar of the second stage, the top cork, the landing sleeve 9 and the studs 11 are drilled, after which the well is ready for further technological operations.

The proposed device has high reliability in the operation of components and assemblies, provides a high degree of sealing (slide gate, damper) and reliable fixation of the upper cork plug (additional lock), which ultimately guarantees the success and high quality of the cement mortar injection operation of the second stage.

Information used

1. The analogue. A.S. USSR No. 1694861, MKI E 21 B 33/14, 1991.

2. The prototype. RF patent No. 2074311, MKI 6 E 21 B 33/14, 1997.

Claims (4)

1. A device for stepwise cementing of a casing string, comprising a housing with a stop and circulation holes, a shutter placed inside the housing above the circulation holes and connected with shear elements, a landing sleeve installed inside the shutter and connected to it by means of studs, a latch located between case and damper, and the damper and stop are made with reciprocal grooves and protrusions, and a squeezing plug, including a rod and an elastic element, characterized in that the device is equipped with It is provided with a casing located around the perimeter of the casing and forming a cavity opposite the circulation openings, in which a slide is installed above the openings and connected to the casing by shear elements, and the inner diameter of the fitment sleeve is selected to be the outer diameter of the lower part of the cork plug, in which there is a conical bore additional clamp. 2. The device according to claim 1, characterized in that the additional latch is made in the form of a split, spring, conical ring, the tip of which is directed towards the bottom of the device. 3. The device according to claim 1, characterized in that the landing sleeve in the lower part is equipped with an annular stop in the working position interacting with an additional latch. 4. The device according to claim 1, characterized in that the gate is made in the form of an annular sleeve.

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