RU2441132C2 - Set of equipment for cutting opening in casing string - Google Patents

Abstract

FIELD: oil-and-gas production.

SUBSTANCE: proposed set comprises deflecting wedge with anchoring mechanism made up of shaped tube with stopped bottom end, hydraulic line communicating drill pipe inner space with that of said shaped tube, and milling tool fitted atop said deflecting wedge. Said milling tool comprises thrust ring fitted on its body and made up of plain bearing with outer diameter exceeding that of said tool by clearance that prevents contact between hard-alloyed milling tool cutting edges and deflecting wedge guide surface. Blades on milling tool extend at right angle above tool body. Besides, proposed set comprises two-position flushing assembly to shut off hydrodynamic channel of communication between hole clearance and tube side.

EFFECT: higher efficiency and reliability.

6 dwg

Description

The invention relates to the field of drilling oil and gas wells and is used to cut "windows" in the casing for further drilling of additional sidetracks.

A one-pass device with a whipstock for forming a “window” in a well casing is known (RF patent No. 2173761, IPC 7 E21B 29/06), including a deflecting wedge (whipstock) with a main deflecting surface, a milling tool with the possibility of separation, a packer made with the possibility of fixing for the walls of the casing.

A disadvantage of the known device is that 1) the packer device has a relatively small contact area with the casing, which does not provide a proper degree of adhesion, 2) when lowering the device to a predetermined depth, it is necessary to top up water (into the inner cavity of the drill pipe) , 3) the flushing holes on the milling cutter are located on its main cutting part, which in the process of casing milling can lead to a loss of flushing fluid circulation, since there is a high probability of clogging of the washing holes with metal slurry.

A device for cutting a "window" in the casing (RF patent No. 2278239, IPC E21B 29/06), comprising a deflector wedge with a guiding surface, a mechanical anchor, a milling tool consisting of a window milling cutter mounted on the upper end of the deflector wedge the possibility of separation, and two milling cutters located above the borehole relative to the window milling cutter, the window milling cutter in the upper part has a thickening, and the deflector wedge has a ledge made with the possibility of its interaction with the thickening of the window milling cutter at the time of cutting the casing wall.

A disadvantage of the known device is that 1) the anchor assembly has a relatively small contact area (dies) with the production casing, which does not provide adequate adhesion and can lead to the displacement (rotation) of the deflecting wedge during milling, 2) there is a need installing a cement bridge in the wellbore, as the anchor unit of the device requires emphasis on the face.

The closest to the claimed structural features and the achieved result is a device for drilling sidetracks from a cased hole (prototype - RF patent No. 2263196, IPC 7 E21B 7/08), containing a deflecting wedge with a fixing mechanism in the form of a corrugated pipe, one end of which is plugged , a channel for supplying fluid to the cavity of the profile pipe, a milling tool of the device is installed in the upper part of the deflecting wedge by means of a shear screw — window and expansion milling cutters.

The disadvantages of the prototype are:

1) A significant proportion of the work of the router is spent on unproductive work, because In the process of work, in addition to casing milling, the body (guide chute) of the diverter wedge is also milled, which, according to the calculations, consumes more than half the power of the work performed (up to 51%). This reduces the working life of the milling cutters, and also creates the danger of displacement (rotation) of the body of the wedge-deflector relative to the cut out "window";

2) Due to the structural features of the elements of the milling part of the device (watermelon-shaped form of the cutter) and its geometric dimensions, the process of milling the casing of this device is clearly indefinite - from abrasion-cutting to extrusion and rupture of the walls of the production string. This creates significant dynamic loads on the boring tool (hooks of the boring tool, etc.) and adversely affects the quality of the cut-out “window”;

3) During the descent of the device into the well, it is necessary to constantly fill the in-pipe and annular space of the drill pipes with flushing fluid (to top up). Failure to do so leads to premature deformation (opening or collapse) of the profile pipe due to a violation of the hydrodynamic pressure equilibrium in the in-pipe and annular spaces.

The objective of the invention is to remedy the above drawbacks and increase the efficiency of milling the "window" in the casing by eliminating the contact of carbide weapons of the body milling cutter (guide trough) of the deflector during operation and increasing the service life of the latter, as well as by reducing the overhead spent on refilling wells.

The specified result is achieved in the proposed set of equipment for cutting the "window".

A set of equipment for cutting a “window” in the casing, including a deflector wedge with an anchor mechanism made in the form of a profile pipe with a damped lower end, between which there is a hinged sub, a hydraulic pipe connecting the cavity of the drill pipe with the cavity of the profile pipe; a milling tool mounted in the upper part of the deflecting wedge by means of a shear screw with the possibility of disconnecting it from the deflecting wedge, according to the invention, the window cutter comprises a support ring, which is a sliding bearing mounted on the case of the window cutter, with an outer diameter exceeding the diameter of the latter by an amount the gap preventing contact of carbide weapons of the milling cutters of the guide surface (trough) of the deflector wedge, the support ring itself is made of easily cut Shai material (e.g., duralumin), form cutter blades sidetracking carbide arms formed protruding at right angles to the milling cutter body, the equipment kit further comprises a wash-off assembly, made to overlap the hydrodynamic channel-pipe communication between the annulus and through the junk ball.

The invention is illustrated by drawings, where

figure 1 presents a longitudinal section of a set of equipment in the transport position (in the process of lowering the equipment into the well);

figure 2 - the location of the set of equipment in the well;

figure 3 is a longitudinal section of a window and mortise milling assemblies;

figure 4 is a longitudinal section of a two-position washing unit a, b with an open and closed side hole, respectively;

in FIG. 5 is a longitudinal section of the equipment at the appropriate stages of equipment operation:

a - in the process of anchoring the deflecting wedge;

b - disconnecting the milling part of the equipment from the wedge-deflector;

in - in the process of milling the production casing.

The invention contains the following elements (see figure 1 ... 6):

(figure 1): 1 - wedge-diverter; 2 - hydraulic conduit; 3 - guide surface (trough) of the diverter wedge; 4 - window cutter; 5 - weapons cutting tool; 6 - cutting mill; 7 - on-off washing unit; 8 - a plunger; 9 - throw ball; 10 - weapons expanding mill; 11 - expanding cutter; 12 - axial hydraulic channel;

(figure 2) 13 - profile pipe; 14 - hinge assembly; 15 - a basic ring; 16 - connecting shear element; 17 - drill pipe; 18 - production casing;

(figure 3) 19 - the Central flushing hole; 20 - armament of the window mill; 21 - plugs for washing holes; 22 - sealing sleeve hydraulic conduit;

(figure 4) 23 is an expanded cavity of the washing unit; 24 - side flushing hole; 25 - flushing holes of the plunger; 26 - plunger shear screw;

(Fig.6) 27 - flushing hole.

A set of equipment for cutting the "window" in the production casing works as follows.

Before starting work on cutting the “window” in the casing, the well is filled with drilling mud or process water. Assemble the equipment layout in the following sequence (see figure 2).

Profile pipe 13 (filled with water) together with the wedge-deflector 1 falls below the table of the rotor of the drill. To the upper part of the deflecting wedge 1 and using a connecting shear element 16, a milling part of the equipment is mounted, consisting of three milling cutters: window 4, cut-out 6 and expanding 11. Next, the set of equipment is lowered into the well on drill pipes 17 to the cut-out interval of the “window”. During the descent, through the lateral flushing hole 24 of the on-off flushing unit 7 (Fig. 1), the internal cavity of the drill pipe string is self-filling, which ensures hydrodynamic balance in the well and pipes. After lowering the equipment to the design depth, the wedge deflector 1 is anchored (fixed) in the well. To do this, a thrown ball 9 is dropped inside the drill pipe 17, which, under the action of gravity and hydraulic pressure from the side of the mud pump, reaches the on-off flushing unit 7 and fits tightly into the seat seat of the plunger 8. Due to the overlap of the hole, fluid circulation through the side flush hole 24 stops and the in-pipe pressure increases, which when a certain value is reached (when the pressure drop is about 3 MPa) leads to a shear shear screw of the plunger 26 (Fig. 4), I fix the plunger 8. Under the aforementioned hydraulic pressure, the plunger 8 moves downward, blocking the side flushing hole 24 with the housing, and enters the expanded cavity of the flushing unit 23 of the on-off flushing unit 7 (Fig. 1). In this case, through the washing holes 25 of the plunger 8 and the hydraulic line 2, a hydraulic message appears between the axial hydraulic channel 12 and the cavity of the profile pipe 13 (Figs. 4 and 5a). Using a mud pump, the pressure is gradually increased to 10 MPa. Due to the closure of the inner cavity of the profile pipe 13 (the lower end of which is plugged), it begins to open (inflate) in the radial direction, pressing against the inner wall of the production string 18. The outer diameter of the profile pipe 13 in the open position corresponds to the internal diameter of the production string 18, therefore, tight compression is ensured . According to the results of bench tests, the adhesion strength reaches significant values (up to 30 t / m), which is sufficient for reliable fixation of the deflecting wedge in a cased well.

Profile pipe 13 is produced by the domestic industry in the form of thin-walled pipes (wall thickness 3 ... 6 mm) and can have various profiles, including and in the form of a multipath star, the outer diameter of the circumscribed circle of which should be less than the inner diameter of the column.

After the anchor of the deflector 1 is anchored, it is disconnected by pulling the drill pipe string 17 upward to create a critical tensile load of about 9 tons. At this point, the connecting shear element 16 is cut off and the milling part of the equipment is disconnected from the drill pipe string 17. In this case, the upper part hydraulic pipe 2 (copper tube) exits the sealing sleeve of hydraulic pipe 22 and opens a central flushing hole 19 of the window mill 4, through which the well is flushed (Figs. 4 and 5b).

The rotor of the drill through the string of drill pipes 17 give the rotation of the milling part of the layout, consisting of window 4, mortise 6 and expanding 11 milling machines with a rotation speed of 60 ... 100 rpm and slowly bring the drilling tool down. The plugs for closing the washing holes 21 (Fig. 3) are made of brittle metal (cast iron), which, when rotated, break from impact on the guide surface (trough) of the diverter wedge 3 and open the washing holes 27 of the window mill 4. The window mill 4, being the extreme when lowering the drilling tool downward, the first one touches the inclined surface of the deflector 1 and, making a rotational-translational motion (like the whole layout), slides along the guide surface (groove) of the deflector, relying on supporting ring 15. The presence of the supporting ring allows you to provide the necessary technological clearance between the armament elements of the window 4 and the milling cutters 6, as well as the guiding surface (trough) of the diverter wedge 3 (Fig.6), while avoiding touching the latter and protecting it from exposure shock loads arming milling machines (pigv).

The axial load created by the weight of the drill string on the support ring 15 of the window mill 4, is distributed through the touch points to the wedge deflector (at the beginning of milling) and, according to calculations, after about 250 ... 300 mm (from the start of milling) to the inner wall of the production casing 18 . The contact load attributable to the wedge deflector 1 and the inner wall of the production casing 18 is distributed almost equally (51% and 49% of the generated axial load, respectively). For example, when creating an axial load of 2000 kg, the magnitude of the contact load falling on the support ring 15 of the window mill 4 will be distributed as follows: 1020 kg on the deflector, 980 kg on the production casing wall. Based on the magnitude of the contact loads, the design parameters are calculated and the material of the support ring 15 is selected. In the proposed set of equipment, the support ring 15 is made of easily destructible material (for example, duralumin) that can withstand the above contact loads and collapses when they are exceeded. The design of the support ring 15 is made similar to a plain bearing, namely with the possibility of rotation independent of the housing. Moreover, according to the calculations, its outer diameter exceeds the diameter of the case of the window mill and is, depending on the size of the equipment used, 1.5 ... 3.0 mm (Fig. 3).

At the end of the milling process and the exit of the milling tool from the casing to the rock, the rotor is turned off and the rotation of the drill string is stopped. Check the quality of the cut out “window” on the cross by double descent of the layout to the bottom and its rise. Next, the drill pipe 17 with the milling tool is removed to the surface, and the wedge-deflector 1 and the profile pipe 13 remain in the well and serve as a direction for drilling the sidetrack, as well as for attaching the sidetrack to the well-string.

Information sources

1. SMITH INTERNATIONAL, INC. “One-pass device with whipstock for forming a window in the well casing”. RF patent No. 2173761, publ. 09.09.20.

2. Limited Liability Company Scientific and Production Enterprise Burintekh “System for cutting a window in a casing string”. RF patent No. 2278239, publ. 2006.06.20, bull. Number 17.

3. Gibadullin N.Z., Gilyazov P.M., Nizamov D.I. and others. "A device for drilling sidetracks from a cased well." RF patent No. 2263196, publ. 2005.10.27, bull. No. 30.

Claims (1)

A set of equipment for cutting a “window” in the casing, including a deflector wedge with an anchor mechanism made in the form of a profile pipe with a damped lower end, between which there is a hinged sub, a hydraulic pipe connecting the cavity of the drill pipe with the cavity of the profile pipe; a milling tool installed in the upper part of the deflecting wedge by means of a shear screw with the possibility of disconnecting it from the deflecting wedge, characterized in that the window cutter contains a support ring, which is a sliding bearing mounted on the case of the window cutter, with an outer diameter exceeding the diameter of the latter by the size of the gap that prevents the carbide weapon elements from touching the milling cutters of the guide surface (trough) of the deflector wedge, the support ring itself is made of easily cut Shai material (duralumin), form cutter blades sidetracking carbide arms formed protruding at right angles to the milling cutter body, the equipment kit further comprises a wash-off assembly, made to overlap the hydrodynamic channel-pipe communication between the annulus and through the junk ball.

Images