RU2299303C2 - Expanding open well bore reamer - Google Patents

Abstract

FIELD: drilling equipment, particularly enlarging drilled holes, for instance by counterboring.

SUBSTANCE: well bore reamer comprises body with sub, pipe, expanding movable members pivotally arranged in longitudinal slots of the body and provided with limiting ledges, piston connected to sliding hollow rod and provided with blocking widened end part formed on outer surface thereof and jet nozzle. The body is provided with lower guiding pipe adapted to receive jet nozzle. Piston with longitudinal channels is installed in cylindrical bore of lower guiding pipe. The piston is provided with longitudinal channels made around piston outline and adapted to receive additional jet nozzles. The rod is spring-loaded with respect to sub. Blocking widened end part of the rod is made as a cone corresponding to mating inner surfaces of expanding movable members.

EFFECT: increased efficiency and reliability of reamer due to improved well bottom cleaning during well drilling and prevention of expanding member jamming during reamer shifting in transport position.

2 dwg

Description

The invention relates to the field of drilling equipment, in particular to devices for expanding a wellbore.

The design of deep wells for complex geological conditions involves the launching of several casing strings and, in some cases, liners.

Adequate annular clearance should be provided for high-quality cementing of the liner, which necessitates the expansion of the open hole bore below the shoe of the previously lowered string.

For expansion, bicentric chisels and sliding expanders are used.

Bicentric bits are simple in design and easy to operate, but provide a slight increase in the diameter of the open wellbore.

Sliding expanders have a more complex device, but they can increase the diameter of the barrel up to 30% or more, which is achieved due to the large radial exit of rock-cutting elements.

A known design of a sliding expander company Baker [1] type Lockomatic with forced locking of the blades in the position extended to the nominal diameter (analogue).

The reamer consists of a trunk attached to the bottomhole assembly of the drill pipe. The lower part of the barrel is made in the form of a guide pipe.

A movable hydraulic cylinder is installed on the outer surface of the barrel, the cavity of which is connected by a radial hole to the barrel channel.

At the bottom of the cylinder, in the longitudinal grooves, with the help of hinges, extendable elements of the expander are suspended: legs with cones on the pins or reinforced expander blades.

In the bored part of the bore at the level of the sliding blades, a sleeve is fixed with a blocking annular protrusion on the outer surface.

After the expander is lowered into the well below the casing shoe, rotation is transmitted to it and at the same time circulation of the flushing fluid is restored.

Under the action of excessive pressure, the cylinder body begins to move up the barrel of the device. In this case, the cams made on the inner surface of the blades are pushed onto the blocking ring of the sleeve, spreading the blades as the borehole is drilled.

Blocking of the blades in the fully extended position, as well as during subsequent drilling, occurs due to their abutment in the ledges made in the grooves of the cylinder.

To complete drilling, stop feeding the tool; the expander continues to rotate until the axial load is completely removed, after which the circulation is stopped and the tool is lifted. When entering the casing, the expander must be folded (move into transport position), abutting against the shoe with the lateral surface of the extended blades.

A significant design flaw is the unreliability, and sometimes the impossibility of translating the expander into the transport position when entering the column shoe, which is fraught with a complex accident. The reason is the unfavorable design feature of the expander — the presence of deep, deaf cavities under the extended blades.

In these cavities, when drilling mainly in soft rocks, due to insufficient washing, sludge accumulates, a tight oil seal is wound, which prevents folding of the blades when lifting.

A known design of a sliding expander [2], in which the noted disadvantages are partially eliminated (prototype).

Sliding elements are placed directly in the longitudinal grooves of the housing and are pivotally connected to the housing.

A cylindrical bore is made inside the housing, in which a spring-loaded piston is mounted, mounted on a movable hollow stem with a blocking ring on the outer surface and a jet nozzle.

After the rotation is transferred to the tool and the circulation is resumed, the blades extend with the borehole wall drilled to the stop in the ledges in the body grooves. The extension is due to the downward movement of the locking ring on the rod by excessive pressure on the piston.

Unlike the analogue in the prototype, after the circulation ceases at the end of drilling, the blocking ring together with the piston and rod are pulled up under the action of the spring, freeing the blades to move to the transport position.

However, in the prototype, as well as in the analogue, deaf cavities arise under the extended elements during drilling, due to insufficient washing in them, accumulation of sludge, winding of the stuffing box and, as a result, difficulties and even a jamming of the device when folding the elements are possible.

The latter has been repeatedly observed, in particular, with the expansion of an open hole below the shoe of the technical string in sandstone deposits with clay layers in the wells of Kubangazprom LLC.

The task set in the invention is to increase the efficiency and reliability of the expander by improving the quality of cleaning the bottom while drilling and preventing jamming of the sliding elements when moving into transport position.

The objective is achieved by the fact that the expanding borehole extender comprises a housing including a sub, a nozzle, sliding movable elements pivotally mounted in the longitudinal grooves of the housing with restrictive ledges, a piston on a movable hollow rod with a blocking annular thickening on the outer surface, and an jet nozzle.

What is new in the expander is that the housing is equipped with a lower guide nozzle, in the bottom of which there is a jet nozzle, while a piston is installed in the cylindrical bore of the lower guide nozzle along the perimeter with longitudinal channels in which additional jet nozzles are placed, while the rod is spring-loaded relative to the adapter and the blocking annular thickening on the rod is made in the form of a cone corresponding to the mating inner surface of the sliding movable elements.

The expander is illustrated by the drawings shown in figures 1 and 2. Figure 1 shows a General view of the expander in the transport position, figure 2 - in the working position.

The design of the expanding expander includes (Fig. 1) a prefabricated housing consisting of a sub 1, a sleeve 2, a pipe 3 with longitudinal grooves 4 having restrictive ledges 5, and a lower guide pipe 6 with a bottom 7 and a jet nozzle 8. In the grooves of the housing are hinged sliding movable elements, for example, blades 9. A movable assembly is placed in the housing, including a rod consisting of bushings 10 and 11 interconnected by a thrust clutch 12, a piston 13 and a conical blocking annular thickening 14. The piston 13 is mounted in a cylindrical the bore of the guide pipe 6, has longitudinal channels located around the perimeter, in which additional jet nozzles 15 are installed.

In the sub 1, a stuffing box seal 16. A cylindrical spring 17 is placed between the end face of the sub 1 and the step of the thrust clutch 12

The expander descends into the well behind the casing shoe into the open hole.

The rotation of the tool is turned on, the circulation of fluid in the well is restored.

Under the action of excess pressure in the device (Fig. 2), the piston 13, moving upward, blocking an annular thickening 14, spreads the blades 9, drilling the walls of the open barrel until the nominal diameter is limited by the stop of the blades 9 in the limiting ledges 5 made in the longitudinal grooves 4 of the housing. After this, an axial load is created, the wellbore is expanded.

The washing liquid, divided into two streams, through additional jet nozzles 15 enters the cavity under the blades 9 and flushes sludge from under them and, simultaneously, exiting through the jet nozzles 8, flushes the barrel.

When drilling is completed, bit feed is sequentially stopped until the axial load is reduced to zero; rotation stops and then flushing; a cylindrical spring 17 is pushed down the rod with a blocking annular thickening 14; the blades 9 are folded into the transport position.

The design of the expander is distinguished by the following positive features:

- the forms of the blocking annular thickening and the reciprocal inner surface of the blades ensure their separation without the appearance of deaf internal cavities, in which sludge can accumulate and an omentum may appear (figure 2);

- the placement of additional nozzles in the movable piston allows you to maximize bring and direct a hard upward fluid flow directly into the zone of destruction of the rock and the cavity of the possible accumulation of sludge;

- part of the fluid flow through the lower nozzle provides sufficient flushing of the guide barrel of the expandable well.

Tests of an experimental expander in sandstone deposits with clay strata in the wells of Kubangazprom LLC showed that the bit is easily transferred from the transport position to the working position and vice versa; drilling takes place without clogging the bottom, with the complete removal of the drilled rock from the well.

Information sources

1. Baker oil tools, Fishing services Lockomatic Expanding hole opener and section mill product No. 150-79, product No. 150-95.

2. Composite Catalog, 1984-85 Voiume 4, Servco pp. 6696, 6702.

Claims (1)

A sliding borehole extender comprising a housing comprising a sub, a nozzle, sliding movable elements pivotally mounted in longitudinal grooves of the housing with restrictive steps, a piston on a movable hollow stem with a blocking annular thickening on the outer surface, and a jet nozzle, characterized in that the housing is provided a lower guide pipe, in the bottom of which there is a jet nozzle, while in the cylindrical bore of the lower guide pipe there is a piston with along the perimeter of the longitudinal channels in which additional jet nozzles are placed, the rod is spring-loaded relative to the adapter, and the blocking annular thickening on the rod is made in the form of a cone corresponding to the mating inner surface of sliding movable elements.

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