RU2401380C1 - Method of in-well casing string slit perforation and device to this end - Google Patents

Abstract

FIELD: oil-and-gas production.

SUBSTANCE: to make slits in casing strip wall, cement ring behind casing string and well productive strata, revolving disk mill axis in displaced in the slit formation plane along preset trajectory with simultaneous vertical reciprocation of perforator relative to casing string at preset speed. Note here that, with perforator moving from top extreme position to bottom extreme position, disk mill axis is simultaneously displaced from its trajectory top extreme point, first, at an angle to casing string wall generatrix, while smoothly cutting the mill into casing string wall, cement ring behind casing string and well productive strata, to trajectory point whereat mill is stopped and wherefrom mill axis is still displaced vertically to trajectory bottom extreme point. Note that casing string wall, cement ring behind casing string and well productive strata are milled at a time on produced slit depth. In lifting perforator from its bottom extreme position to top extreme position, revolving mill axis is displaced vertically from its trajectory bottom extreme point to top extreme point. Note here that remaining parts of casing string wall, cement ring behind casing string and well productive strata are milled at trajectory section whereat cut in aforesaid parts. To this end, perforator with hydraulic cylinder is used, hydraulic cylinder piston being mechanically coupled with revolving disk mill and hydraulically, on piston under side, being communicated with working pressure chamber and, on head end side, with tubular annulus via flow friction element designed to metre out fluid from head end side into hole clearance when fluid pressure acts on piston underside and rive hydraulic cylinder. Note here that said drive hydraulic cylinder makes perforator reciprocate vertically relative to casing string at design speed to distance limited by drive hydraulic cylinder stroke.

EFFECT: stable and reliable operation.

4 cl, 4 dwg

Description

The invention relates to the oil and gas industry during the opening of formations in cased wells.

A well-known perforator (see RF patent No. 20057549, 02/15/1994), which describes a method of forming a slotted channel in the casing, including the creation of pressure of the working fluid in the pipes to ensure the functioning of the mechanisms of fixation of the body of the drill, the drive of the cutting tool and the supply of the cutting unit and the formation of a gap by cutting through the column and the cement ring behind the column using a rotating chain cutter placed on the bed.

The disadvantages of the method include:

a) the fixed position of the punch on the casing significantly limits the possibility of obtaining a gap in the wall of the column of large sizes in length;

b) the design of the chain cutter, made in the form of interconnected cutting elements and a closed chain, is a rather complex structure. In addition, the chain as a flexible element cannot ensure the stability of the cutter.

Known other method and device for slotted perforation of the casing of oil and gas wells, adopted as a prototype (see RF patent No. 2315177, 01.20.2008)

In this method of borehole slotted perforation of the casing string, the formation of a gap in the casing wall, the cement ring behind the casing string and the reservoir is carried out by a rotating cutting tool in the form of a disk cutter by sequential movement of the latter, at the beginning in the radial direction relative to the casing string with a metered feed of the cutting tool, and then - in the vertical direction by moving the puncher with the estimated speed of its feed at a predetermined distance, for which a punch is used with a hydraulic cylinder, the piston of which is connected mechanically with a rotating cutting tool and hydraulically - with a working pressure cavity through hydraulic resistance, while the perforator has the ability to move in the vertical direction relative to the casing with a design speed for a given distance due to the wellhead lifting mechanism. A device for borehole slotted perforation comprises a composite housing in which a cutting unit is located, consisting of two flat rockers, movably mounted on the axis of the housing, a chain transmission and a kinematically associated disk cutter, drive and supply mechanisms of the cutting unit, supporting elements of the housing with the possibility interactions with the wall of the casing during punch operation.

The disadvantages of the method include:

a) the first stage of the sequential movement of the rotating disk cutter - dosed radial feed of the cutter in the direction of the casing wall - is unreliable, because it is proposed that the cutter is inserted into the wall of the casing when the casing body is stationary relative to the casing;

b) the use of a wellhead lifting mechanism to ensure a metered feed of a perforator during its reciprocating movement is impossible.

The aim of the invention is to remedy these disadvantages by creating a method and device for downhole slotted perforation of the casing, ensuring the reliability of the formation of the slit and the operation of the device.

This goal is achieved by the fact that in the known method of borehole slotted perforation of the casing string, cement ring behind the casing string and the productive formation of the well by a rotating cutting tool made in the form of a disk cutter and having the ability to move in the radial direction with a metered feed to the side of the casing string and with the estimated feed rate in the vertical direction relative to the casing at a given distance, in contrast to the prototype, the formation of a gap in the casing wall columns, the cement ring behind the casing string and the production layer of the well is carried out by moving the axis of the rotating disk cutter in the plane of slot formation along a predetermined path with the simultaneous reciprocating movement of the punch in the vertical direction relative to the casing with the estimated speed, while during the descent of the punch from its upper end position to the lower end position, the axis of the rotating disk cutter is simultaneously moved from its upper reference point of the path to n at the beginning - at an angle to the generatrix of the casing wall, while smoothly cutting the cutter sequentially into the casing wall, the cement ring behind the casing and the producing formation, to the point of the trajectory where the cutting is completed and from which the cutter axis continues to move in the vertical direction to the lower end point of the trajectory, while simultaneously milling the walls of the casing, the cement ring behind the casing and the reservoir on the resulting After the insertion, the depth of the slit, and while lifting the punch from its lower end position to the upper end position, the axis of the rotary cutter is simultaneously moved in the vertical direction from its lower end point of the path to the upper end point of the path, and on the path from the point of completion of the cutter to the top the end point continues to milling the remainder of the wall of the casing, cement ring behind the casing and the reservoir in this area, for which use a perforator with hyd a cylinder, the piston of which is connected mechanically with a rotating disk mill and hydraulically from the piston side to the working pressure cavity, from the supra-piston side to the annular space through the hydraulic resistance, which serves for dosed supply of fluid from the over-piston cavity of the hydraulic cylinder into the annulus during the action of the working fluid pressure on the piston from the piston side, and the drive hydraulic cylinder, due to which the reciprocating metered movement of the perforated operators in the vertical direction relative to the casing with the calculated rate of its supply to the distance of the drive stroke-limited hydraulic cylinder piston. In addition, the goal is achieved by the fact that in the known device for borehole slotted perforation of the casing, comprising a composite housing with a longitudinal cutout, a feed mechanism for the disk cutter, a drive of the cutter and the support rollers of the housing, while the transmission mechanism of the disk cutter is located in the longitudinal cutout between two flat rockers, pivotally mounted on the axis of the body with the possibility of rotational-vibrational motion, in contrast to the prototype, the gear mechanism of the disk cutter is made in the form of a three-stage bevel-cylindrical gear transmission, the gear block of which is mounted movably on the axis of the casing together with the flat rockers, and the gear of the last stage is connected coaxially with the disk cutter, mounted in turn movably on the common axis of the flat rockers, in the longitudinal cut of the casing are additionally placed squeezing a roller with the possibility of its interaction with the casing wall during the operation of the perforator, the feed mechanism of the squeeze roller in the form of a hydraulic cylinder mounted pivotally on the upper axis of the housing, with a spring-loaded piston with a rod, at the end of which is located the axis of the squeezing roller movably mounted on it, and a lever pivotally connected at one end to the axis of the squeezing roller and the other with the lower axis of the housing, a drive hydraulic cylinder is located above the punch housing a housing with upper and lower sub, a piston with a reversible switch integrated inside it and bi-directional with respect to the position of the piston and its associated hollow rod, to the lower end of which a perforated housing is connected a, and the upper end is located in the cavity of the tubing, while the lower sub is equipped with a latch with the possibility of interaction with the lower end of the hollow rod to fix the perforator in its original working position, and the upper sub is attached to the string of tubing, the diameter of the upper side of the hollow rod is smaller than the diameter of the lower side of the hollow rod, and the hydraulic cavities above the piston and under the piston communicate with the annular cavity through hydraulic resistances in the form of of groove channels, the squeezing roller is placed relative to the axis of the punch on the same side as the disk cutter, and the support rollers mounted movably each on its axis of the housing are located on the opposite side, while a pair of support rollers are located at the bottom of the housing uniformly spaced from each other predetermined angles from the plane of placement of the squeezing roller, and in the upper part of the housing there is one supporting roller in the same plane of placement of the squeezing roller.

In Fig.1 shows a device for slotted perforation of the casing in the initial position, Fig.2 - support rollers along section AA; figure 3 - gear disk cutter from a hydraulic motor; figure 4 - the trajectory of the axis of the rotating disk cutter during operation of the punch relative to the casing from top to bottom and bottom to top.

The device comprises a composite housing 1 with a longitudinal cutout 2, a drive 3 of a disk cutter 4, a feed mechanism for a disk cutter located in the lower part of the housing 1 and consisting of a hydraulic cylinder 5 with a spring-loaded piston 6 with a rod 7 and a pair of rods 8 pivotally connected to the rod 7 and located in the longitudinal cutout 2 of the housing 1. In addition, in the longitudinal cutout 2 there is a gear of the disk cutter 4 from the drive 3 and a feed mechanism of the squeeze roller 9. The gear mechanism consists of two flat rocker arms 10 and a three-stage conical-cylinder gear wheel. The rocker arms 10 are articulated by the upper end and the gear block 11 of the gear train is movably mounted on the common axis 12 of the housing 1. The gear wheel 13 associated with the disk mill 4 is mounted movably on the axis 14 of the rocker arm 10. By the same axis 14 are pivotally connected to the plane rocker arm 10 traction 8 of the feed mechanism of the disk cutter 4.

The feed mechanism of the squeeze roller 9 consists of a hydraulic cylinder 15 mounted pivotally on the upper axis 16 of the housing 1, with a spring-loaded piston with a rod and a lever 17 pivotally connected with the upper end to the axis 19 of the squeezing roller 9, and the other end with the lower axis 18 of the housing 1.

In addition, on the housing 1, on the opposite side of the squeezing roller 9, three support rollers 20 are each located on their axes, while in the lower part of the housing 1 there is a pair of support rollers uniformly spaced from each other at predetermined angles from the plane of placement of the squeeze roller 9, and in the upper part of the housing 1 there is one supporting roller in the same plane of placement of the squeezing roller 9. The under-piston cavities of the hydraulic cylinders 5 and 15 are in fluid communication with the working cavity through the channel 21 made in the body of the housing 1. the evy cavity of the hydraulic cylinder 5 is in fluid communication with the annular space through the throttle hole 22.

Above the housing 1 of the punch, a driving hydraulic cylinder 23 is placed, comprising an upper sub 24, by which the device is connected to the pump and compressor pipes 25, a lower sub 26 with a retainer 27, a piston 28 with an internal reversing switch having an upper pusher 29 and a lower pusher 30 inside it, and bilateral with respect to the position of the piston 28 and the associated hollow rod 31, a perforator body 1 is connected to the lower end of the hollow rod 31, and the upper end is located in the cavity of the tubing 25. Moreover, the diameter of the upper Oron hollow rod diameter below the lower side of the hollow rod. Hydraulic cavities above the piston and under the piston of the drive hydraulic cylinder 23 are in communication with the annulus through the throttle channels 32 and 33, respectively.

The device operates as follows.

On the tubing string (tubing) 25, the device is lowered into the well to the perforation site. All mechanisms of the device are in the initial position, as shown in figure 1. A working fluid pressure is created in the tubing string, at which pressure is transmitted simultaneously to the hydraulic motor 3 and through the channel 21 to the sub-piston cavities of the hydraulic cylinders 5 and 15 and to the supra-piston cavity of the driving hydraulic cylinder 23 through the reversing piston switch 28. The hydraulic motor 3 simultaneously starts to work from the pressure of the fluid. feed mechanisms of the disk cutter 4 and the squeeze roller 9 and the drive hydraulic cylinder 23. As a result, the disk cutter 4, the piston 6, receives rotation through a bevel-cylindrical gear transmission acting through the rod 7, the pair of rods 8 and the axis 14 on the flat wings 10, provides a metered supply of a rotating disk cutter 4 to the side of the casing wall, the piston with the rod of the hydraulic cylinder 15 feeds the squeeze roller 9 towards the side of the casing string and the piston 28 with the hollow rod 31 of the drive hydraulic cylinder 23, freed from the latch 27, together with the perforator carry out dosed movement from top to bottom relative to the casing and, accordingly, the tubing string.

The metered movement of the piston 28 with the hollow stem 31 is ensured by the metered flow of fluid from the under-piston cavity of the hydraulic cylinder 23 into the annulus through the throttle channel 33. The total effort to move the arrangement from top to bottom is obtained from the effect of fluid pressure on the working area of the piston 28 from above and the cross-sectional area of the upper side of the hollow rod 31. The metered supply of a rotating disk cutter 4 to the side of the casing wall is provided by a metered fluid flow from the piston cavity of the hydraulic cylinder 5 into the annulus through the throttle hole 22.

Due to the lack of hydraulic resistance in the hydraulic system of the feed roll of the squeeze roller 9, the time taken to feed the squeeze roller to its interaction with the casing wall and subsequent fixation together with the support rollers 20 of the punch in the casing is small enough to ensure a stable and steady movement of the punch in casing before cutting.

During the dosed movement of the punch from the upper end to the lower end position in the vertical direction with the simultaneous dosed feed of the rotating disk cutter 4 towards the casing wall, the milling axis 14 moves along the path at an angle to the generatrix of the casing wall 34 from point A to point B (cm Fig. 4). In this case, the cutter is inserted sequentially into the casing wall, the cement ring behind the casing and the reservoir to a predetermined depth, and the metered feed of the disk cutter towards the casing wall is completed. At the next stage of moving the punch, the axis 14 of the disk cutter 4 moves along the trajectory from point B to point B with milling simultaneously the casing wall, cement ring behind the casing and the reservoir at the same depth, while additionally performing a rock erosion of the rock of the reservoir.

In the lower end position of the piston 28 with the hollow rod 31 of the hydraulic cylinder 23 and, accordingly, of the perforator, the lower pusher 30 of the reversing switch, interacting with the end face of the sub 26, switches the direction of movement of the layout from the bottom up. Liquid under pressure enters from the tubing cavity through a reversing piston switch 28 into the sub-piston cavity of the hydraulic cylinder 23. In this case, the liquid is displaced from the over-piston cavity through the throttle channel 32. Since the working area from the bottom of the piston 28 is larger than the cross-sectional area of the upper side of the hollow rod 31, the difference efforts from the influence of fluid pressure on these areas will be directed upwards.

During the movement of the punch from the lower end position to the upper end position, the axis 14 of the rotary cutter 4 is simultaneously moved upward from the lower point of the trajectory B to the upper point of the trajectory G with continued rock erosion of the rock, and the remainder is milled on the section of the trajectory from point B to point G casing wall, cement ring and reservoir.

In the upper final starting position of the punch after the interaction of the upper pusher 29 with the end face of the sub 24 and simultaneously fixing the hollow rod 31 of the hydraulic cylinder 23 with the retainer 27, the pressure in the tubing is relieved. Under the action of the return springs, the piston 6 and, accordingly, the disk mill 4 along the path from point G to the starting point A and the piston with the rod of the hydraulic cylinder 15 with the squeezing roller 9 are returned to their initial position. Then the assembly is lifted to the surface of the well.

Thus, the method and device for its implementation can provide stable and reliable operation during the formation of a gap in the casing of the well.

Information sources

1. RF patent No.2007549, cl. E21B 43/114.

2. RF patent No. 2315177, cl. E21B 43/114.

Claims (4)

1. The method of borehole slotted perforation of the casing string, cement ring behind the casing string and the productive formation of the well by a rotating cutting tool made in the form of a disk cutter and having the ability to move in the radial direction with a dosed feed to the side of the casing string and with a design feed rate in vertical direction relative to the casing string for a predetermined distance, characterized in that the formation of a gap in the wall of the casing string, cement ring behind the casing string and the production layer of the well is carried out by moving the axis of the rotating disk cutter in the slotting plane along a predetermined path with the simultaneous reciprocating movement of the punch in the vertical direction relative to the casing string with the estimated speed, while during the descent of the punch from its upper end position to the lower end position, the axis of the rotating disk the cutters are simultaneously moved from its upper starting point of the trajectory at the beginning - at an angle to the generatrix of the casing wall while smoothly cutting the cutter sequentially into the casing wall, the cement ring behind the casing and the producing wellbore to the point of the trajectory at which the cutting end is completed and from which the axis of the cutter continues to be moved in the vertical direction to the lower end point of the trajectory, while milling simultaneously the walls of the casing string, the cement ring behind the casing string and the reservoir at the depth of the slit obtained after cutting, and while lifting the perforation the rotor from its lower end position to its upper end position, the axis of the rotating cutter is simultaneously moved in a vertical direction from its lower end point of the path to the upper end point of the path, and on the portion of the path from the point of completion of the cutter to the upper end point, the remainder of the casing string wall is continued to be milled, cement ring behind the casing and the reservoir in this area, which uses a hammer drill with a hydraulic cylinder, the piston of which is mechanically connected to a rotating rotary milling cutter and hydraulically from the piston side with a working pressure cavity, from the piston side with an annular space through a hydraulic resistance serving for dosed supply of fluid from the piston cavity of the hydraulic cylinder into the annulus during the action of the working fluid pressure on the piston from the piston side, and drive hydraulic cylinder, due to which the reciprocating dosed movement of the punch in the vertical direction relative to casing string with the estimated feed rate to a distance limited by the piston stroke of the drive hydraulic cylinder. 2. A device for borehole slotted perforation of a casing string, comprising a composite body with a longitudinal cutout, a disk cutter feed mechanism, a cutter drive and support rollers of the housing, while in the longitudinal cutout there is a gear of the disk cutter located between two flat rockers pivotally mounted on the axis housing with the possibility of rotational-oscillatory movement, characterized in that the gear mechanism of the disk cutter is made in the form of a three-stage bevel-cylindrical gear ne riders, the gear block of which is mounted movably on the axis of the housing together with the flat rockers, and the gear of the last stage is connected coaxially with the disk cutter, installed, in turn, movably on the common axis of the flat rockers, in the longitudinal cut of the housing there is an additional squeezing roller with the possibility of interaction with the casing wall during the operation of the punch, the feed mechanism of the squeeze roller in the form of a hydraulic cylinder pivotally mounted on the upper axis of the housing, with a spring-loaded piston with a rod, on Onze axis of which is placed movably mounted thereon squeezing roller, and a lever pivotally connected at one end with the axis of the nip roller and the other - with the lower axle housing. 3. The device according to claim 2, characterized in that a drive hydraulic cylinder is located above the perforator body, comprising a body with upper and lower sub, a piston with a reversible switch integrated inside it and bi-directional relative to the position of the piston and its associated hollow rod, to the lower end of which a perforator housing is attached, and the upper end is located in the cavity of the tubing, while the lower sub is equipped with a latch with the possibility of its interaction with the lower end of the hollow rod for fixing the perfo the radiator in its initial operating position, and the device is connected to the tubing string by the upper sub, the diameter of the upper side of the hollow stem being smaller than the diameter of the lower side of the hollow stem, and the hydraulic cavities above the piston and under the piston are in communication with the annulus through hydraulic resistances in the form of throttle channels. 4. The device according to claim 2, characterized in that the squeeze roller is placed relative to the axis of the punch on the same side as the disk cutter, and the support rollers mounted movably each on its axis of the housing are placed on the opposite side, with a pair of steam located in the lower part of the housing support rollers uniformly spaced from each other at predetermined angles from the plane of placement of the squeeze roller, and in the upper part of the housing there is one support roller in the same plane of placement of the squeeze roller.

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