RU2129650C1 - Disconnecting device - Google Patents

Abstract

FIELD: oil production industry. SUBSTANCE: disconnecting device can be used in lowering and cementation of casing pipe strings. Device has following components: body, funnel-shaped sleeve, locking unit, adapter, washing holes arranged in the form of separate unit. Located between body of device and funnel-shaped sleeve is load bearing housing. Locking unit is made in the form of resilient collets which are fixed by bush and are provided with successively arranged catchers. Washing holes can be located in adapter or in body of disconnecting device. Solids of revolution can be located in slots made in external surface of movable bush for fixing of collets. Application of aforesaid embodiment of disconnecting device improves operational reliability in processes of lowering, cementation, and disconnection of casing strings. EFFECT: higher efficiency. 4 cl, 2 dwg

Description

 The invention relates to techniques and is intended for lowering and cementing casing strings.

 A device for lowering secret casing strings is provided, comprising a housing and a locking assembly with a collet hook and a movable sleeve for fixing the collets (AS USSR E 21 B 33/14 N 1028836 1980, publ. 15.07.83 g).

 However, the known device does not provide a sufficient degree of reliability.

 The closest analogue to the purpose and combination of essential features is a disconnector adopted as a prototype (AS USSR E 21 B 33/14 1601346, 10.23.90).

 The known disconnector comprises a housing with radial flushing holes, a funnel clutch and a locking assembly with locking elements in the form of elastic collets with hooks fixed by a movable sleeve. However, the known disconnector has a complex structure: it has four coaxial bushings, it requires the complete discharge of two balls and a cut of three sets of shear devices. After actuation of the disconnector and removing it to the surface, drilling of the sleeve is required. All this complicates maintenance and reduces the reliability of the device, and its dimensions do not allow the operation in small boreholes.

 Thus, the problem that the invention should solve can be formulated as follows: the creation of a device that reliably performs all operations associated with the descent of a countersunk casing, including in trunks of small diameter. This problem is solved in that the disconnector comprising a housing with washing holes, a funnel coupling, a locking assembly with locking elements in the form of elastic collets with hooks, a movable sleeve for fixing the collets, is equipped with an adapter connected to the funnel coupling with washing holes in which are located bushings with plugs secured by shear elements, coaxial to the collets between the housing and the funnel clutch, a power casing with a locking device is installed, while the collets are equipped with successive spacing Pami.

 According to another embodiment, in the disconnector comprising a housing with flushing holes, a funnel coupling, a locking assembly with locking elements in the form of elastic collets with hooks, a movable sleeve for fixing the collets, washing holes are made in the recess of the outer surface of the housing, in which bushings with plugs are placed, fixed shear elements, coaxial collets between the body and the coupling funnel mounted power casing with a locking device, while the collet is equipped with sequentially located hooks.

 Also, for both versions, grooves with rolling bodies located in them can be made on the outer surface of the movable sleeve for fixing the collets.

 Equipping the disconnector with a sub with flushing holes equipped with bushings with plugs and shear elements increases the reliability of opening the washing holes. Each hole with a set of parts is an autonomous system. Therefore, the probability of failure is reduced in proportion to the number of flushing holes. Also, the possibility of jamming when opening the washing windows is reduced due to the small stroke of the plugs. The placement of the holes on the adapter of a smaller diameter and in the "shadow" of the housing leaves space for the plugs to fall out freely.

 The presence of two or more hooks arranged in series on each collet increases the load-carrying capacity of the closed unit, while maintaining its minimum dimensions (since the allowable stress of shearing of steel is several times less than the allowable tensile stress).

 The presence of a power casing between the housing and the funnel-clutch unloads the collets from the compressive loads arising during the descent. The compression force will be transmitted from the funnel coupling to the housing along the power casing, bypassing the collets.

 The implementation of the washing holes in the recess of the outer surface of the housing reduces operating costs, since the unit is used repeatedly, unlike the first option. When lowering the countersunk column, the disconnector is loaded with tensile force. Through the bevels on the hooks of the collets, the load is transferred in the radial direction so that the collets clamp the movable sleeve. In order to increase the reliability of operation, it is proposed to reduce the friction force by the introduction of rolling elements.

 In FIG. 1 shows a longitudinal section through a disconnector; FIG. 2 is a longitudinal section through flushing holes located in a recess of the housing.

 The disconnector includes a housing 1 with elastic collets 2, at the end of which there are hooks 3 included in the reciprocal grooves in the funnel 4, into which an adapter 5 with screw holes 6 is screwed. In the holes 6 there are bushings 7 closed by plugs 8, fixed shear elements 9. Inside the housing 1 with flushing holes (not shown) is located the piston 10 of the movable sleeve 11 mounted in the funnel 4 on the shear pins 12. On the outer surface of the sleeve 11 in the area where the hooks 3 are mounted, grooves 13 are made in which rolling members 14 (balls, rollers). The washing holes 6 can be located in the recess 15 of the housing 1, and additional holes 16 are made in the movable sleeve 11. A power casing 17 with a locking device 18 is installed between the housing 1 and the funnel-coupling 4.

 The device operates as follows.

 Secret column lowered on a pipe string. A disconnector is installed between the columns. After the descent, they begin cementing. After washing, the cement slurry is pumped and its cement plug is pushed through, which passes through the disconnector until it fits onto the stop ring at the bottom of the countersunk column. After landing, the pressure inside the column rises. The plugs 8 cut off the elements 9 and fall into the annulus. The washing holes 6 are open, through which the circulation of the washing liquid passes. In this case, the removal (cutting) of excess cement mortar above the disconnector occurs, which protects the extracted column from sticking. After the hardening of the cement mortar, a separation operation is performed. To do this, restore circulation of the flushing fluid and throw a ball into the well (or let the plug in), which sits on the piston 10 of the movable sleeve 11 and blocks the passage. The pressure in the column increases, under its action the pins 12 are cut off. The movable sleeve 11 slides down, releasing the hooks 3 of the collets 2. The piston 10 extends all the way into the discharge groove. The fluid flowing around it enters the annulus through the channels inside the disconnector. By the burst of pressure, and then by its drop, the moment of operation of the device is recorded. The column is being raised. The elastic collets 2, sliding the hooks 3 along the bevels in the coupling funnel 4, are released. The funnel 4 and adapter 5 remain in the well. Everything else, including the ball (cork), rises to the mouth. When this liquid is poured out of the column through the disconnector.

 The small dimensions of the device allow it to be used when working in small diameter wells, as well as in sidetracks. At the same time, high reliability of the descent, cementing, flushing and separation processes is maintained.

 The device is convenient in operation, which increases labor productivity because it does not require subsequent drilling, and the lifting of the column occurs without the so-called. siphon.

 All these positive characteristics were confirmed during successfully completed trials of the disconnector in well No. 4101 of the Listvenskoye field of JSC Udmurtneft.

Claims (4)

 1. A disconnector comprising a housing with washing holes, a funnel coupling, a locking assembly with locking elements in the form of elastic collets with hooks, a movable sleeve for fixing the collets, characterized in that it is equipped with an adapter connected to the coupling funnel with washing holes in which bushings with plugs fixed by shear elements are placed, a power casing with a locking device is installed coaxially to the collets between the housing and the funnel coupling, while the collets are equipped with successively arranged hooks.  2. The disconnector according to claim 1, characterized in that on the outer surface of the movable sleeve for fixing the collets are made grooves with rolling bodies located in them.  3. A disconnector comprising a housing with washing holes, a funnel coupling, a locking assembly with locking elements in the form of elastic collets with hooks, a movable sleeve for fixing the collets, characterized in that washing holes are made in the recess of the outer surface of the housing, in which bushings with plugs secured by shear elements, coaxial to the collets between the housing and the funnel coupling, a power casing with a locking device is installed, while the collets are equipped with successively arranged hooks.  4. The disconnector according to claim 3, characterized in that on the outer surface of the movable sleeve for fixing the collets are made grooves with rolling bodies located in them.

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