RU2316644C2 - Mechanical-hydraulic perforator - Google Patents

Abstract

FIELD: oil and gas industry, particularly perforators using direct fluid action, for instance abrasive jets.

SUBSTANCE: perforator comprises hollow body with cylindrical groove in central part thereof, perforation piston with throttling channel and upper sub. Additional channel provided with piston is created in perforation piston. Piston is fixedly connected to the body and may block communication between throttling channel and body interior in initial position.

EFFECT: increased efficiency.

3 dwg

Description

The invention relates to the mining industry and can be used in oil and gas wells for opening a productive reservoir using a punch and a directional jet.

Known perforator, lowered into the well by cable.

The hammer includes a housing with a working chamber in the upper part, filled with liquid. In the lower part of the housing is a discharge chamber. In the middle part of the body are located, perpendicular to its axis, cylindrical bores in which the punches consisting of the piston and cutting parts are placed. The housing contains a pressure generating unit, separated from the working chamber by a separation piston, and a node for creating a hydraulic connection between the discharge chamber and the under-piston space.

To return the punches to their original position, leaf springs are placed on the outside of the housing.

In the explosion of the powder charge, the pressure is communicated to the separation piston and the working fluid in the working chamber. Overpressure of the working fluid, the punches sharply move to the wall of the production string with the creation of perforations in the latter. The punches are returned to their initial position by the force of pre-compressed leaf springs.

However, this design of the punch has drawbacks, namely for one descent, you can get several perforations - the number of punches in the punch. The depth of the perforation channel is small and is determined by the diameter of the body and the course of the punch, which in some cases is not enough to create a reliable hydrodynamic connection between the productive formation and the well, since during the initial opening of the formation, the zone of its mudding by the drilling fluid is much greater than the length of the perforation channel created by the punch.

A device is known for mechanical perforation of wells (see RF Pat. No. 2069741, M. cl. 6 ЕВВ 43/112, publ. 11/27/96 Bul. No. 33), designed for the secondary opening of oil and gas wells. The device consists of a housing with working pistons on one side of the housing, equipped with piercing units and channels for supplying the working fluid, a spring-loaded piston connected to the rod, through circulation channels in the piercing nodes, piston, rod and the corresponding channels in the housing. The working pistons are connected by a flexible hydraulic connection with the rod. A valve is installed in the inlet channel of the working piston.

The operation of the device. The device on the tubing is lowered into the well to a predetermined depth and the working fluid is supplied under pressure, which enters the cavity above the additional piston with increasing pressure in the chamber under the rod and transferring it to the working pistons with a tool for perforation. After performing mechanical perforation and the formation of a hydraulic connection between the high-pressure cavity and the axial channel of the nozzle, the working fluid acts on the rock of the productive formation with return through the channel in the second piercing unit to the annular space of the well.

The return of the additional and working pistons to their original position is carried out by the force of a pre-compressed spring after depressurizing the pipe lift string.

However, in some cases, the force of interaction of the piercing units with the casing metal and the rock of the formation, on the one hand, is uncontrollable, and on the other hand, can far exceed the force of the return spring. This can lead to complications when removing the device from the installation site.

It should be noted that in this case, under the rod, as noted in the description, a vacuum is created, due to which the piercing nodes are returned to their original position.

The presence of a flexible connection between the working pistons and the rod also can not always provide a simultaneous and simultaneous return of the working pistons to the cylindrical bores of the housing, since it is difficult to manufacture and mount a flexible connection with high accuracy.

In the description of the invention it is also noted that after the completion of the perforation, the device cavity above the additional piston is connected to the well cavity, that is, the action of the working fluid stream on the reservoir rock through the channels in the working pistons is short-term due to the small volume of the working fluid, which reduces the efficiency of use .

A device for perforating wells (see US Pat. RF No. 2043486, M. class. 6 EV 43/114, publ. 09/10/95 Bull. No. 25), comprising a housing, a piston and a punch with a flushing channel, is rigidly connected with the last one.

The punch is made in the shape of a rectangle and contains a flushing channel along its axis, hydraulically connected to the internal cavity of the housing. The piston stroke with a punch in the housing bore is limited by a stopper.

The disadvantage of the design of the device is:

1. The constant supply of working fluid through the channel in the piston and punch until the formation of a perforation hole in the casing leads to irrational losses of the working fluid and the time spent on the process. In the presence of abnormally low reservoir pressures, it is undesirable to fill the well with a working fluid, since the reservoir is flooded, which in some cases causes complications in well development.

2. The device is made in a monoblock design and cannot be connected to a similar second device to obtain several perforation holes simultaneously in one run.

The analysis of the inventive step showed the following: it is known to use a punch with a nozzle (see AS No. 757692, M. cl. ³ ЕВВ 43/114), the channel of which is constantly hydraulically connected to the axial channel of the body and the lift pipe string. The punch is rigidly fixed to the outside of the housing on the opposite side of the cylindrical bore in it.

The technical result that can be obtained by implementing the invention is reduced to the following:

- the possibility of the formation of perforations in the casing with exposure to the rock of the reservoir by a highly kinetic jet of working fluid and the formation of a deep perforation channel;

- excluding the ingress of working fluid into the well until the formation of perforations in the casing;

- the possibility of repeated repetition of the perforation process without lifting the perforator to the surface.

The technical result is achieved using a known hydromechanical perforator containing a hollow body, in the middle part of which a cylindrical bore is made perpendicular to its axis, in which there is a piston-punch with a channel equipped with a nozzle. A plunger is mounted axisymmetrically to the piston-punch in the bottom of the body, in its cylindrical bore, which in the initial position shuts off the hydraulic connection of the body cavity with the nozzle channel until a perforation channel is formed in the casing. The stroke of the piston punch in a cylindrical bore is limited to a glass.

However, the combination of structural elements, the form of their interaction in the distinctive part of the claims, will give the above technical result and not identified by available sources of scientific, technical and patent literature.

Together with the known features of the present invention allows to solve the problem - to create a deep perforation channel in the reservoir with a minimum flow rate of the working fluid.

This in turn gives reason to conclude that the invention meets the criterion of "inventive step".

The invention is industrially applicable, since the main structural elements - a punch with a nozzle - have passed comprehensive bench tests and well tests with positive results.

Figure 1 shows a sectional view of the design of a hydromechanical rotary hammer in its initial position.

Figure 2 - design of the hydromechanical perforator in the position of the formation of the perforation hole in the casing and the formation of a jet of working fluid deep perforation channel in the rock of the reservoir.

Figure 3 is a General view of the hydromechanical perforators, connected in series with each other and facing the punches in opposite directions.

The hydromechanical hammer drill consists of a housing 1, in which a cylindrical bore 2 is made perpendicular to its axis with a piston-punch 3 installed therein. The stroke of a piston-punch 3 in a cylindrical bore 2 is limited by a nozzle 4 rigidly connected to the housing 1. In the body of the piston-punch 3, an axisymmetric channel 5 is made, into which a plunger 6 is inserted, which is rigidly connected to the body of the housing 1, and a channel 7, which passes into the throttle 8, facing its outer side. In the initial position, the plunger 6 overlaps the live section of the channel 5 and channel 7, which prevents the flow of working fluid beyond the casing until the formation of a perforation in the casing. The gap between the housing 1 and the body of the piston-punch 3 is closed by a high-tight movable seal 9. The cylindrical bore 2 under the piston-punch 3 is constantly hydraulically connected to the axial channel 10 of the housing 1 and the cavity 11 below the place of execution of the cylindrical bore 2, which is sealed from the well by a cover 12. The upper end of the housing 1 is provided with an internal thread, to which a sub 13 is connected. The annular gaps between the housing 1, the sub 13 and the cover 12 are sealed by the sealing elements 14. The presence of the cover 12 on the lower the end of the housing 1 allows the assembly of several perforators in series with each other with the location of the piston punches in opposite directions with the transfer of the sub 13 to the housing 1 of the upper perforator.

The layout of hydromechanical perforators, for example, in the amount of three pieces is connected to the pipe string and lowered into the well to a predetermined depth. The working fluid is fed into the pipe string and the pressure is raised to the required value. The working fluid under pressure enters the axial channel 10 of the housing 1 and is communicated to the cross-sectional area of the piston-punch 3, which moves in the cylindrical bore 2 and the nozzle 4 until the cutting part contacts the wall of the casing pipe while maintaining the plunger 6 in channel 5. At a given pressure the working fluid is the opening of the perforation in the casing with the exit of the cutting part beyond. At the same time, the plunger 6 opens the supply of the working fluid to the channel 7, passing into the throttle 8, with the action of a highly kinetic jet of working fluid on the rock of the productive reservoir and the formation of a deep perforation channel. The time of exposure to a rock with a jet of working fluid is determined based on the strength of the rock and the required depth of the perforation channel.

From the practice of using sandblasting perforation, it is known that it is economically feasible to obtain perforation channels with a depth of L = 300 ÷ 350 mm for a time t = 5 min.

After the perforation process is completed, the supply of working fluid to the pipe string is shut off and the layout of the perforators is lifted up to the next interval. Punch piston 3 due to the interaction of its outer surface with the bent metal of the casing at the place of formation of the perforation returns to the cylindrical bore 2 of the housing 1 with the inlet of the plunger 6 in the axial channel 5 and the termination of the hydraulic connection of the cavity of the pipe string with the cavity of the hole through channel 7.

In a number of field wells, there are conditions when the reservoir pressure is much less than hydrostatic, which makes it undesirable to supply a large amount of working fluid to the reservoir. To exclude the free flow of the working fluid from the pipe string into the well, a shut-off valve is installed above the hydromechanical perforator assembly, designed to close at hydrostatic pressure at the depth of the reservoir.

Claims (1)

A hydromechanical hammer drill containing a hollow body with a cylindrical bore in the middle part, a punch piston with a throttling channel, an upper sub, characterized in that an additional channel is provided in the piston punch, equipped with a plunger rigidly connected to the body and installed with the possibility of overlapping hydraulic connection between throttling channel and body cavity in the initial position.

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