RU2243359C1 - Sleeve for stepped cementation of casing column - Google Patents

Abstract

FIELD: oil and gas extractive industry.

SUBSTANCE: sleeve has body with radial cementing apertures, compacting rings, cover-bushing, placed on outer side of body and forming ring space with it. In the latter an additional bushing is placed, connected to body by shear elements. Lower portion of ring-shaped hollow is connected to inner space of body by radial channels. Cover-bushing is in rigid connection to body. Additional bushing is provided with radial channels, connecting through cementing apertures inner space of body to behind-column space of well at the moment of washing and forcing of cementing solution of second step. A damper is placed inside the body. The latter is connected to support bushing by shear elements, which bushing is stopped against upper end of body. The latter is made with ring shelf, placed on inner surface below cementing apertures.

EFFECT: simplified construction, higher effectiveness, higher reliability.

1 dwg

Description

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

A known coupling for step cementing, comprising a housing with radial cementing holes and radial channels, a movable sleeve and a pusher, and a spring-loaded annular partition (1).

The disadvantages of the device: design complexity due to the presence of a large number of parts; the presence of a large diameter spring necessitates an increase in the overall dimensions of the device; in addition, the spring does not work well in a cement medium; a large number of sealing elements and moving parts reduce the reliability of the seal and the operability of the device. There is a real possibility of contact of the movable sleeve with the wall of the well, which will lead the device to an inoperative state.

The closest in technical essence to the proposed one is a coupling for step cementing, including a housing with radial cementing holes, a casing sleeve located on the outside of the housing and forming an annular cavity with it, an additional sleeve located in this cavity and connected to the housing by shear elements, radial channels in the housing connecting the lower part of the annular cavity with the interior of the housing, and sealing elements.

Significant disadvantages of the device are the design complexity; many moving parts and sealing elements that reduce the performance and reliability of the seal; the external location of the differential sleeve 4 may lead to a) premature upward shift and the inability to carry out the operation of the injection of cement mortar of the first stage; b) the formation of an omentum above it and the inability to move it; c) contact with the wall of the well, which will lead the device to an inoperative state; large dimensions, and hence the large metal consumption.

The objective of the invention is to provide a cementing sleeve of a simplified design, having low metal consumption and having high performance and reliability of sealing.

This problem is solved by the proposed coupling, comprising a housing with radial cementing holes, a casing sleeve located on the outside of the housing and forming an annular cavity with it, an additional sleeve located in this cavity and connected to the housing by shear elements, radial channels in the housing connecting the lower part of the annular cavity with the internal space of the housing, and o-rings.

New is that the casing-sleeve is rigidly connected to the housing, and the additional sleeve is equipped with radial channels connecting the interior of the housing through the cementing holes with the annular space of the well at the time of washing and pumping the cement of the second stage; the coupling is equipped with a gate mounted inside the housing and connected by shear elements with a support sleeve abutting against the upper end of the housing, the latter being made with an annular ledge located on the inner surface below the cementing holes.

In FIG. The proposed device is shown in longitudinal section.

It consists of a housing 1 with radial cementing holes 2 and radial channels 3. On the housing there is a casing-sleeve 4 rigidly connected to it, forming an annular cavity 5 with the housing, in which there is an additional sleeve 6 connected to the housing by shear elements 7 and provided with radial channels 8. In the upper part of the housing 1, a gate 9 is installed, connected by shear elements 10 to the supporting sleeve 11. The mating surfaces of the coupling are provided with o-rings 12.

The coupling operates as follows.

The casing 13 with shoe 14, cementing valve 15 and stop ring 16, in which the proposed cementing sleeve is installed, is lowered into the well to the design depth so that the sleeve is approximately 150-200 m above the reservoir. Then, using conventional technology cement mortar of the first stage is pumped, proceeding from the fact that the coupling is blocked by a solution 40-50 m higher. At the end of cementing, the lower delivery plug 17 sits on the stop ring 16, the pressure in the column 13 rises sharply, under the influence of torogo shear elements 7 are destroyed and additional sleeve 6 rises up to the stop in the coupling face 18. This hole channels 2 and 8 are communicated with each other. After that, washing through the holes 2 and channels 8 remove the cement solution located above the cement clutch. After OZZ (waiting for the hardening of cement) pumped cement mortar of the second stage. At the end of the push, the upper cork stopper 19 sits on the gate 9, the pressure rises sharply, the shear elements 10 are destroyed, and the gate goes down all the way into the annular ledge 20, blocking the cementing holes 2 from the inside. The pressure rises again, which confirms the end of cementing. The pressure at the wellhead is reduced to zero, after which, under the influence of the differential pressure between the annulus and annulus, the sleeve 6 drops down and hermetically closes the cementing holes 2 from the outside of the housing.

After the OZZ, the gate 9 (made of cast iron) and the upper cementing plug 19 are drilled.

The proposed cementing sleeve has a simple structure and low metal consumption, has high performance and reliable sealing.

Information used

1. A.S. No. 1779742, MPKE 21 V 33/14, 1992 (analogue).

2. A.S. No. 1765367, IPC E 21 B 33/14, 1992 (prototype).

Claims (1)

Coupling for stepwise casing cementing, including a housing with radial cementing holes, a sleeve casing located on the outside of the housing and forming an annular cavity with it, an additional sleeve located in this cavity and connected to the housing by shear elements, radial channels in the housing connecting the lower part of the annular cavity with the inner space of the housing and o-rings, characterized in that the casing-sleeve is rigidly connected to the housing, and the additional sleeve is provided with rad by other channels connecting the internal space of the body through the cementing holes with the annular space of the well at the time of flushing and injection of the cement mortar of the second stage; equipped with a gate mounted inside the housing and connected by shear elements with a support sleeve abutting against the upper end of the housing, the latter being made with an annular ledge located on the inner surface below the cementing holes.