RU2241822C1 - Device for slit perforation of cased wells - Google Patents

Abstract

FIELD: oil and gas extractive industry.

SUBSTANCE: device has hydraulic cylinder with spring-loaded piston and hollow rod connected to cutting assembly. The latter has cutting disk on axis placed in bushing groves. Axis ends are placed in guiding plates grooves, which plates are mounted in device body. Hydraulic-monitoring end piece is placed above disk and directed to longitudinal grove in body. Support screw-thread dies are placed oppositely to cutting disk. Hydraulic cylinder piston is provided with stop limiting its drive. Hydraulic-monitoring end piece is covered by bushing fixed by shear pin with socket for ball. Support dies are made projecting, mounted with possible displacement until stopped against column. Grooves in bushing for axis of cutting disk are made in form of broken line with different slant angle relatively to vertical axis of device.

EFFECT: higher reliability.

3 cl, 5 dwg

Description

The invention relates to the oil industry and can be used to create perforations in casing, cement stone and rock during the second opening of productive horizons in cased wells.

A device is known for creating perforation channels by cutting longitudinal slots with a sliding knob, the axis of which receives movement from the load of the hydraulic drive through the link and console system, and the nozzle is oriented to the working zone of the knob, RF patent 2039220, E 21 V 43/114 BI 19, 1995.

The disadvantage of this design of the perforator is the rapid wear of the friction surfaces of the parts and the difficulty of replacing them, as well as the high probability of sludge getting into the device and clogging of the nozzle.

The closest in technical essence to the claimed invention is a “Device for crevice perforation of cased wells” according to the patent of the Russian Federation No. 2161697, 7 E 21 B 43/114 from 04/07/99. BI PM No. 1, 2001, which is adopted as a prototype.

The device comprises a housing, a hydraulic cylinder, a spring-loaded hollow rod with a piston, a retractable cutting disc on the axis, a hydraulic nozzle and support rollers. On the basis of the open groove of the housing, a support plate is mounted with which a wedge made in the form of a fork-shaped slider contacts. Wedges cover the side plates with grooves. The axis of the sliding cutting disc is kinematically connected through the wedge to the hollow rod of the hydraulic cylinder and provides contact and indentation of the cutting disc into the casing wall, while pushing the device in the opposite direction until the supporting rollers touch the casing.

The disadvantage of the above design is that the hydraulic nozzle at this location is subject to clogging with sludge, and the support rollers are installed so that they increase the overall diameter of the device. All efforts from the hydraulic cylinder are transmitted to the axis - hence increased wear. The ball valve constantly keeps the channel closed, which makes it impossible to directly flush the tubing cavity from sludge. All this reduces the reliability of the device and complicates its maintenance.

The technical task of the invention is to limit the transmitted loads on the cutting unit, eliminating the risk of clogging of the jet nozzle with sludge, increasing the power of the jet exiting the nozzle, reducing the manufacturing cost and increasing the working life of the cutting disc.

The problem is solved by the proposed device for slotted perforation of cased wells containing a hydraulic cylinder with a spring-loaded piston and a hollow rod connected to a cutting unit having a cutting disk on an axis located in the grooves of the sleeve, the ends of the axis are located in the grooves of the guide plates installed in the device body, and the nozzle is mounted above the blade and oriented to the longitudinal groove in the housing, the support plates are located opposite the cutting disc.

New in the device is that the piston of the hydraulic cylinder is equipped with a stop restricting its stroke, and the hydraulic nozzle is blocked by a fixed shear pin sleeve with a socket for a ball, support plates are made retractable, installed to move them all the way to the column, and the grooves in the sleeve for the axis of the cutting disc is made in the form of a broken line with a different angle of inclination relative to the vertical axis of the device. The cutting edge of the cutting disk is made with a sharpening angle from 60 degrees to 90 degrees, and its diameter is equal to the diameter of the device body, the material for making the disk is tool steel for cold deformation of the metal, for example 6X 6V 3 MFS. The channel of the nozzle is made with a square cross section, and the nozzle is installed perpendicular to the axis of the device.

Figure 1 presents the proposed device in its original transport position; figure 2 is a section aa of the cutting unit; figure 3 - the device is in the working position at the time of maximum extension of the cutting disc beyond the column and erosion by a high-pressure jet from a hydraulic nozzle of cement stone; figure 4 - section bb - cutting unit in the working position; figure 5 - cross section and sharpening of the cutting disc.

The proposed device for slotted perforation of cased holes (Figs. 1 and 2) includes a housing 1, in which a cutting unit, consisting of a guide sleeve 2 with grooves 3, is placed to accommodate the axis 4 together with the cutting disk 5. The cutting edge of the disk 5 ( 5) is made with a sharpening angle from 60 degrees to 90 degrees, and its diameter is equal to the diameter of the device case, the material for the manufacture of the disk is tool steel for cold deformation of the metal, for example 6X 6B 3 MFS. The cutting disk 5 is located on the axis 4, which is installed in the grooves 3 of the sleeve 2, made in the form of a broken line with a different angle of inclination relative to the vertical axis of the device, and the ends of the axis 4 are located in the grooves 6 of the guide plates 7 installed in the housing 1. Axis 4 is installed in grooves with the ability to move in the radial direction.

A hydraulic nozzle 8 is installed on the side surface of the guide sleeve 2 of the cutting unit so that the longitudinal axis of the channel of the hydraulic nozzle is directed perpendicular to the vertical axis of the device, and the channel, made with a square cross-section, is directed to the slot in the casing through the longitudinal groove 9 on the housing 1, in which the cutting disc 5 is located and moves.

On the opposite side of the specified longitudinal groove on the housing 1 there are two windows in which two support plates 10 are located. The support plates with their inner surface rest on the guide sleeve 2, which pushes them all the way to the column. In the upper part of the sleeve 2, a sliding sleeve 11 is installed together with the sealing rings 12, which overlap the flushing channel of the hydraulic nozzle 8. The sleeve 11 is fixed with a shear pin 13. Below the sleeve 11, a support fitting 14 is installed, which provides a differential pressure in the device’s hydraulic cylinder during cutting of the slit by cutting disk while flushing the well. A hollow rod 15 and a piston 16 are mounted to the upper part of the cutting unit, which are located in the hydraulic cylinder 17, which is connected to the housing 1 of the device. The housing 1 and the hydraulic cylinder 17 are separated by an intermediate support 18, on which the return spring 19 of the piston 16 is supported. Between the support 18 and the piston 16, a stop 20 is installed on the rod 15, which limits the stroke of the piston 16 and, consequently, the radial movement of the cutting disc 5. Restriction the piston stroke is necessary to relieve critical axial loads on the cutting unit of the device (cutting disc, bushing, guide plates) after the casing is cut by the cutting disc to a predetermined depth and the radial stroke of the cutting disc reaches Flashing maximum size.

Relief is achieved as follows. The rolling of the longitudinal gap in the casing device is carried out at an overpressure of up to 6.0 MPa. After cutting a gap, the cutting disc moves in the radial direction by the maximum value. After that, the cavity is washed out behind the casing through the slot with the help of a nozzle 8 at an excess pressure of 18-20 MPa, which will cause critical axial and radial loads exceeding more than 3 times the load that occurs when the gap is rolled. This will lead to increased wear of the parts of the cutting unit (cutting disc 5, axis 4, guide sleeve 2, guide plates 7), which are the main elements of the device.

If there is a stop 20, restricting the piston stroke at the moment of reaching the specified maximum radial output of the cutting disk 5, the piston 16 abuts against the stop 20, and a further increase in overpressure in the hydraulic cylinder of the device will not increase the load on the cutting unit. The stroke of the piston and the exit of the cutting disc beyond the casing is regulated depending on the wall thickness of the casing so that the hub of the cutting disc does not rest on the inner surface of the casing, axis 4 does not reach the extreme position in the grooves 3 and 6 (Fig. 3) . A circulation valve is installed in the upper part of the device, consisting of a sub 21, a housing 22, and a movable sleeve 23 with O-rings 24 and shear pins 25. A guide shoe 26 is installed on the lower part of the device casing 1. The proposed device is lowered into the casing 27. After completion the formation of a gap in the device discards a ball 28, which overlaps the channel 29 and wash cavities in the rock 30 behind the column. At the end of the washing up of the cavity, a ball 31 is thrown into the device, which opens the holes 32 of the circulation valve for draining the liquid.

The operation of the device for rolling the longitudinal slit in a cased hole is as follows. The device descends into the well in assembled and adjusted form on tubing (tubing) to the required interval of perforation. Then, using geophysical methods, by lowering the instruments into the tubing, the depth of descent of the device is mapped to a predetermined perforation interval. To remove various kinds of particles from the tubing that exfoliated from the walls of the tubing when lowering the geophysical instruments, and also got into the tubing cavity during the descent-lifting of pipes, direct or reverse flushing is restored in the well, and then, if necessary, fluid is replaced by injection into the well showdown fluids.

To carry out the perforation of the casing, the device is lowered to the lower position, by pumping liquid into the tubing, excessive pressure is created while flushing through the nozzle 14.

Excessive pressure is created and maintained stepwise from 0.5 MPa to 6.0 MPa. When creating pressure, the piston of the device together with the cutting unit moves down, the support plates 10 are moved in the radial direction until they stop against the column 27 (Figs. 3-4). At the same time, the cutting disc 5 extends in the radial direction along the grooves 3 and 6 until it contacts the casing. Then the device extends along the casing by the value of the specified interval of perforation up and again descends to its lowest position. Increasing the pressure stepwise and moving the device up and down, we act on the column with a cutting disc, due to which a gutter is formed in the pipe metal, and then a longitudinal gap is formed in the column wall (Fig. 3).

After the final formation of the slit, the ball 28 is discarded into the device, which overlaps the opening of the sliding sleeve 11 and channel 29, and with increasing pressure, the pin 13 fixing the sleeve 11 is cut off, the sliding sleeve 11 moves down to the support fitting 14 and blocks the hole (Fig. 1 and 3). In this case, the flushing channel of the hydraulic nozzle 8 opens and the liquid through the hydraulic nozzle is fed into the slot in the casing, eroding the cement stone and rock 30 behind the column until a cavity is formed. In this case, the excess pressure in the device rises to 18-20 MPa and the device moves along the entire gap using the tubing up and down.

Monitoring the process of rolling the slit in the casing, as well as the formation of the slit is carried out on the surface according to the indications of the weight indicator.

After the formation of a gap in the casing, the cutting disc 5 takes an extreme radial position, the piston abuts against the stop 20 and the forces created by the fluid pressure are not transmitted to the cutting unit of the device (Fig. 3).

The duration of washing the cavity behind the column is determined by the technical and technological conditions, the condition of the well. After the formation of the cavity through the slotted hole behind the casing, the device must be rotated in the well by 120 degrees using tubing and the operation of rolling the gutter, the formation of a gap in the casing and the washing of the cavity is repeated.

After performing slotted perforation of the column in one interval in the same way, you can perform slotted perforation in the other interval by moving the device up or down using tubing. At the end of the work, the pressure in the tubing decreases to zero, the return spring 19 returns the piston 16 to the upper position. The entire cutting unit also moves up. The cutting disk 5 and the support plate 10 are returned to the transport position (figure 1). A ball 31 is dropped into the tubing string, after it is seated in the saddle of the movable sleeve 23, the pressure in the tubing is created, shear pins 25 are cut off, the movable sleeve 23 is moved down and opens the holes 32 of the circulation valve for draining the fluid from the tubing during their lifting from the well.

The use of the proposed device for slotted perforation of casing strings provides the following advantages.

If there is a stop 20, restricting the stroke of the piston 16 and, therefore, the cutting disk 5, the transmission of critical loads to the details of the cutting unit after cutting a gap in the column is excluded, when the cavity is replenished, when the overpressure in the device increases by a factor of 2–3 to create a hydromonitor effect from the hydraulic nozzle 8.

The presence of grooves in the sleeve in the form of a broken line with a different angle of inclination relative to the vertical axis of the device and in the guide plates for the ends of the axis of the cutting disc provides a change in the radial forces transmitted by the cutting disc to the column and reduces the idle stroke of the piston 16 when the cutting disk 5 is connected to the column wall .

The presence of supporting dies 10 allows you to increase the diameter of the housing of the device by placing a cutting disk 5 of maximum diameter in it, to bring the cutting disk 5 closer to the casing and the hydraulic nozzle 8 to the slot to be cut.

The use of a fixed shear pin of the sleeve 11 provides the possibility of both direct and reverse flushing of the well during tripping operations, improved hydraulic patency, eliminates the ingress of foreign objects into the hole of the hydraulic nozzle 8 before the erosion of the cavity.

The nozzle 8 has a channel with a square cross-section, the longitudinal axis of the channel is directed radially to the housing and perpendicular to the vertical axis of the device, which reduces the energy consumption of the fluid stream for swirling and twisting.

In general, the proposed device can improve the reliability and efficiency of its management, increase the working life of device parts and the quality of work.

Claims (3)

1. Device for slotted perforation of cased holes by cutting longitudinal slots in the casing followed by washing with a high-pressure jet of cement stone and rock, containing a hydraulic cylinder with a spring-loaded piston and a hollow rod connected to a cutting unit having a cutting unit on an axis located in the grooves of the sleeve , the ends of the axis are located in the grooves of the guide plates installed in the device case, and the hydraulic nozzle is installed above the disk and is oriented to the longitudinal groove in the case, the supporting plates the ki are located opposite the cutting disc, characterized in that the piston of the hydraulic cylinder is equipped with an abutment restricting its stroke, and the hydraulic nozzle is blocked by a fixed shear pin with a sleeve with a socket for the ball, support plates are made retractable, installed with the possibility of their movement against the stop on the column, and grooves in the sleeve for the axis of the cutting disc is made in the form of a broken line with different angles of inclination relative to the vertical axis of the device. 2. The device according to claim 1, characterized in that the cutting disk is made with a diameter equal to the diameter of the device body, and its cutting edge has a sharpening from 60 to 90 °, the material for the manufacture of the cutting disk is tool steel for cold deformation of the metal - 6X 6V 3 IFS. 3. The device according to claim 1, characterized in that the channel of the nozzle is made with a square cross section, and the nozzle is installed perpendicular to the axis of the device.

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