RU2808788C1 - Milling cutter for cutting window in casing when drilling sidetrack - Google Patents

Abstract

FIELD: drilling.

SUBSTANCE: drilling and major repairs of oil and gas wells for milling the casing string during drilling a sidetrack. The device includes a body with a conical and cylindrical part, a coupling with a connecting thread, body blades made entirely milled and coated with a wear-resistant cutting-abrasion coating, an end part made in the form of a crown, a central channel and flushing holes in the body. The crown is made in steps, protruding from the periphery to the center and is equipped with grooves in which carbide plates are installed. The flushing holes of the crown are made between the incisors of each row. The working ends of the blades of the conical part are equipped with carbide inserts with a cutting-abrasion coating on top. The helical blades of the cylindrical part are made with the lower part of the blade shifted forward in the direction of rotation relative to the upper part of the blade and are additionally reinforced with carbide inserts.

EFFECT: reliability and durability of the structure is ensured with the ability to drill a pocket direction through the rock after cutting out the window, the passage of the bit for drilling a sidetrack is ensured, the speed of window milling is increased, and the wear of the cutting elements is reduced.

1 cl, 2 dwg

Description

The invention relates to the field of drilling and workover of oil and gas wells for milling the casing when drilling a lateral wellbore.

A milling tool is known (patent RU No. 123447, IPC E21B 29/06, publ. 12/27/2012, Bulletin No. 36), which is used for cutting a window in the casing string in a borehole, including a hollow body in which a flushing channel is made along cutter axes and flushing holes in the side, end and side blade working surfaces covered with a wear-resistant cutting-abrasion coating. The lower end part is made in the form of a cone with flushing holes and channels dividing the end into sectors, the lower conical end part passes into a conical bladed middle part with a smaller taper, and the upper part of the body has a cylindrical shape with spiral blades passing from the conical middle part.

The disadvantages of the device are:

- when drilling in the pocket direction, after cutting out the window, the milling cutter does not provide penetration, since there are no cutting elements for drilling through the rock, as a result, an additional tripping operation is required to lower the bit, which leads to additional material costs;

- failure of the bit to pass through the casing window for drilling a sidetrack, since due to wear of the cutting and abrasive coating on the blades of the cylindrical part, the diameter of the milling cutter is significantly reduced;

- due to insufficient washing of the end part during operation of the milling cutter, the end part heats up, becomes clogged with sludge and undergoes accelerated destruction, worsening the cutting process;

- the end cutting part of the milling cutter is less “aggressive” and does not provide a high speed of milling a window in the casing, which leads to increased wear of the working surface and a decrease in the overall penetration of the tool.

The closest in technical essence and achieved result is the starting milling cutter (patent RU No. 177284, IPC E21B 29/06, publ. 02/15/2018, Bulletin No. 5), including a housing with a lower end part, a bladed conical part, a bladed cylindrical the middle part and the coupling part with a connecting thread, in which there is a flushing channel along the axis of the tool and flushing holes in the end lower part and the blade conical part, wherein the blades are made entirely milled and covered with a wear-resistant cutting abrasion coating, and between the blades of the conical middle part there is a platform with a hole for a shear bolt for attaching the tool to the whipstock wedge. The end lower part is made in the form of a welded crown, consisting of particles of crushed tungsten carbide embedded in a matrix of nickel-containing brass, reinforced in the center with a trapezoidal protrusion, and the tangent to the outer surface of the bladed conical part makes an angle of 10±0.5° with the horizontal axis of the milling tool, while the blades of the conical part smoothly transition into the blades of the cylindrical middle part, and the blades are reinforced with composite material.

The disadvantages of the device are:

- when drilling in the pocket direction, after cutting out the window, the milling cutter does not provide penetration, since there are no cutting elements for drilling through the rock, as a result, an additional tripping operation is required to lower the bit, which leads to additional material costs;

- failure of the bit to pass through the casing window for drilling a sidetrack, since due to wear of the cutting and abrasive coating on the blades of the cylindrical part, the diameter of the milling cutter is significantly reduced;

- due to insufficient washing of the end part during operation of the milling cutter, the end part heats up, becomes clogged with sludge and undergoes accelerated destruction, worsening the cutting process.

The technical objectives of the proposed device are to create a reliable and durable milling cutter design that allows drilling a directional pocket through the rock after cutting out a window, ensuring the passage of a bit for drilling a sidetrack, as well as increasing the speed of milling a window in the well casing and reducing wear of cutting elements due to the supply of flushing to the end of the router.

A technical problem is solved with a milling cutter for cutting a window in the casing when drilling a sidetrack, including a body with a conical and cylindrical part, a coupling with a connecting thread, body blades made entirely milled and coated with a wear-resistant cutting-abrasion coating, an end part in the form of a crown, a central channel and flushing holes in the body .

What is new is that the crown is made in a stepped manner protruding from the periphery to the center and is equipped with grooves in which carbide plates are installed, also the flushing holes of the crown are made between the cutters of each row, and the working ends of the blades of the conical part are equipped with carbide inserts with a cutting-abrasion coating on top, helical blades The cylindrical part is made with the lower part of the blade shifted forward along the direction of rotation relative to the upper part of the blade and additionally reinforced with carbide inserts.

In fig. Figure 1 shows a general view of a milling cutter for cutting a window in the casing when drilling a sidetrack.

In fig. 2 – view A.

A milling cutter for cutting a window in the casing when drilling a sidetrack includes a body 1 (Fig. 1) with a conical 2 and a cylindrical 3 part, a coupling 4 with a connecting thread 5, blades 6, 7 of the body 1 made entirely milled and covered with a wear-resistant cutting-abrasion coating 8 , end part in the form of a crown 9, central channel 10 and flushing holes 11 in body 1.

The crown 9 is made stepwise, protruding from the periphery to the center and is equipped with grooves 12 in which carbide plates 13 are installed. The flushing holes 14 of the crown 9 are made between the carbide plates 13 of each row 15. The working ends 16 of the blades 7 of the conical part 2 are equipped with carbide inserts 17 with cutting abrasive coating on top. The helical blades 6 of the cylindrical part 3 are made with a displacement of the lower part 18 of the blade 6 forward in the direction of rotation relative to the upper part 19 of the blade 6 and are additionally reinforced with carbide inserts 20.

A milling cutter for cutting a window in the casing when drilling a sidetrack works as follows.

A milling cutter for cutting a window in the casing when drilling a sidetrack is lowered into the well in a separate run or attached to a whipstock (not shown in Fig. 1, 2), then the entire assembly is lowered into the well until the window is cut out. After orienting and fixing the whipstock relative to the casing, milling of the casing begins with flushing with flushing fluid. As the milling cutter moves along the wedge, a hole is cut out with carbide plates 13 located on the crown 9, due to which a high speed of window cutting is achieved in comparison with abrasion by deposited chips as in the prototype. In this case, thanks to the flushing holes 14 of the crown 9 between the carbide plates 13 of each row 15, the carbide plates 13 are effectively cooled and chips are removed from the cutting zone. Then the hole is expanded with blades 7 before moving to a cylindrical part 3 with blades 6 of nominal diameter. In this case, the carbide inserts 17 on the working ends 16 of the blades 7 do not work, since they are covered on top with a cutting-abrasion coating 8, due to which the casing window further expands and exits to the cylindrical part 3. Due to the fact that the helical blades 6 of the cylindrical part 3 made with a displacement of the lower part 18 of the blade 6 forward in the direction of rotation relative to the upper part 19 of the blade 6 and additionally reinforced with carbide inserts 20, the window is calibrated and sludge is effectively removed, since the helical blades 6 work like a screw. Upon completion of milling of the casing and the milling cutter exits the window, thanks to the presence of carbide inserts 17, a pocket is drilled - direction from the casing window to the required depth.

The proposed milling cutter for cutting a window in the casing when drilling a sidetrack is a reliable and durable milling cutter design that allows you to drill a pocket-direction through the rock after cutting out the window, ensure the passage of the bit for drilling a sidetrack, and also increase the speed of milling the window in the well casing and reduce wear of cutting elements due to the supply of flushing to the end part of the router.

Claims (1)

A milling cutter for cutting a window in the casing when drilling a sidetrack, including a body with a conical and cylindrical part, a coupling with a connecting thread, body blades made entirely milled and coated with a wear-resistant cutting-abrasion coating, an end part made in the form of a crown, a central channel and flushing holes in the body, characterized in that the crown is made stepped protruding from the periphery to the center and is equipped with grooves in which carbide plates are installed, also the flushing holes of the crown are made between the cutters of each row, and the working ends of the blades of the conical part are equipped with carbide inserts with a cutting-abrasion coating on top, the helical blades of the cylindrical part are made with the lower part of the blade shifted forward in the direction of rotation relative to the upper part of the blade and are additionally reinforced with carbide inserts.