HK1117210B - Roller reamer - Google Patents

Description

Roller reamer

Technical Field

The present invention relates generally to devices for enlarging or maintaining a borehole to a desired diameter using a reaming action. In particular, the invention relates to reamers with rollers.

Background

In drilling, it is often necessary to maintain or enlarge the diameter of the bore hole, followed secondarily and subsequently by the passage of the cutting member. This is necessary due to drill wear and the gradual reduction of the reference diameter of the hole. Furthermore, some materials to be drilled may expand, which will cause the borehole diameter to decrease after the drill bit passes.

Reamers may be used in conjunction with a drill bit to ensure that a borehole is drilled to a constant diameter. Roller-type reamers have rotatably mounted cutting members. Roller reamers are commonly used in the drilling industry, one purpose of which is to ream a hole just behind the drill bit to maintain the hole size. Roller reamers may also act as stabilizers above the drill bit to stabilize the drill bit and drill string against the tendency to wander encountered during drilling.

One problem with roller reamers is that under conditions encountered during drilling, rock chips and other debris may form behind the rollers, which may block or slow the rotation of the rollers, thereby reducing efficiency. Furthermore, even under normal operating conditions, rotation of the rollers can cause the temperature of the rollers to rise, which further increases the stress on the rotating parts. The increased stress may cause those rotating parts to wear more quickly. This poses a problem of high cost since the reamer must reach the surface, be removed and be reassembled.

The technique of reaming is an important measure to achieve the desired diameter of the drilled hole. Accordingly, there is a need for a reamer having an improved structure and a long service life. It is an object of the present invention to reduce or eliminate many or all of the disadvantages of roller reamers described above, or at least to provide an effective alternative.

Disclosure of Invention

In its broadest form, the present invention is directed to a reaming tool for coupling to a drill string, having:

a body having a connection means at either end for coupling to a drill string,

at least one roller reamer rotatably mounted to the body, an

At least one channel disposed to extend across the body crosswise to the roller reamer.

The roller reamer may be substantially cylindrical in shape and extend substantially along the body. Preferably, a plurality of roller reamers are radially spaced around the body. More preferably, the roller reamers are angled away from the longitudinal axis of the body and may have an outer surface that is generally curved along the longitudinal axis of the rollers to form a "barrel" shape.

The rollers may be formed with a series of helical grooves, with the outer surface of the ribs formed between the grooves contacting the surface of the hole to be drilled.

Preferably, the channel extends along the body and is inclined at an angle to the longitudinal axis.

More preferably, in use, the channels direct fluid flow over and around the roller substantially in the direction of the helical groove of the roller.

The outer surface of the ribs formed between the grooves of the rollers may have hardened elements coupled to provide wear resistance. For example, multiple carbide inserts may be embedded into each of these surfaces, or a hard face (wear resistant coating) may be used.

More preferably, the carbide inserts are arranged such that the trajectories of adjacent carbide inserts overlap when the roller is rotated, thereby providing optimal reaming efficiency.

Other variations and alternatives of the present invention will be readily apparent to those skilled in the art and are understood to be included within the scope of the present invention.

In order that the invention may be fully understood, preferred embodiments will now be described. It should be understood, however, that the scope of the present invention is not limited to the features of this embodiment.

Drawings

These embodiments are illustrated in the accompanying drawings, in which:

FIG. 1 shows a side view of a reaming tool;

FIG. 2 is a top view of the reamer of FIG. 1; and

fig. 3 shows a detailed view of a portion of fig. 1.

Detailed Description

Referring to fig. 1, a reaming tool 10 includes an elongate body 12, the elongate body 12 having threaded portions 14a and 14b at each end, the threaded portions 14a and 14b connecting the reaming tool to a drill rod of a drill string or to a drill bit (not shown) at the end of the drill string. Those skilled in the art will appreciate that any means of coupling the reaming tool 10 to a drill string may be used. This includes the combination of a drill bit and a roller reamer positioned behind the drill bit.

The elongate body 12 has an enlarged portion including roller reaming elements 16. In use, the enlarged portion is subjected to erosive wear, thereby producing a change in diameter. Accordingly, a hard face 17 may be provided at each end of the enlarged portion. The hard face 17 may be a plurality of carbide inserts or, alternatively, the hard face 17 may be a tungsten carbide coating metallurgically bonded to the enlarged portion of the elongated body 12, as described in the examples.

In this embodiment, the reaming tool 10 has three roller reamers 16 rotatably mounted about the circumference of the elongated body 12. In fig. 1, only two of the roller reamers 16 are visible, the third roller reamer not. It should be understood that any number of roller reamers 16 may be used, however three roller reamers 16 are preferred for small diameter cutters. Each roller reamer 16 is substantially cylindrical and may be tapered from each end to form a barrel shape, thereby improving the reaming process. The roller reamers 16 are disposed at an angle to the longitudinal axis of the elongate body 12. This inclination along the longitudinal axis of the roller reamers 16, together with the curvature, means that each roller reamer 16 has improved contact with the hole; the roller reamer 16 is in contact with the bore along the entire length of the roller reamer.

The elongated body 12 has a channel 18 extending along a surface thereof. The channel 18 is also preferably angled with respect to the longitudinal axis of the elongated body.

A top view of the enlarged portion of the elongated body 12 is shown in figure 2. The channels 18 of the elongated body 12 and a portion of each of the three roller reamers 16 can be seen. It is evident from this view that the channels 18 and roller reamers 16 are arranged continuously and evenly spaced around the circumference of the reaming tool. A flow annulus 19 is formed between the elongate body 12 and the side wall of the bore (not shown). The drilling fluid is forced below the drill string and above the cutting components of the drill bit, and then forced up the flow annulus 19 past the reaming tool 10.

Turning now to fig. 3, a detailed view of the enlarged portion of the elongated body 12 of fig. 1 is shown. The roller reamer 16 can be viewed in more detail. In particular, it can be observed that the plurality of helical flutes 20 have intervening ribs 22. The outer surface of the rib 22 has a bulbous head tungsten carbide insert 24 embedded therein. This provides a hard and wear resistant surface. Optionally, carbide inserts 24 are positioned such that when roller reaming element 16 is rotated, the trajectories of adjacent carbide inserts 24 on each rib 22 overlap, thereby providing optimal reaming efficiency. Furthermore, the helical configuration of the intervening ribs 22 results in increased contact between the roller reamer 16 and the borehole wall, which further improves the stability of the tool.

It should be understood that any shape of carbide inserts 24 having a reaming drilling action, as well as any configuration of carbide inserts 24 on ribs 22, may be used. For example, carbide inserts may be planar or pointed. Alternatively, the carbide inserts may be replaced with hard faces (wear resistant coatings).

The channels 18 of the elongate body 12 each extend from the periphery of the roller reamer 16, with the result that each channel 18 intersects the roller reamer 16. It will be appreciated that due to the location of the channels 18, a portion of the drilling fluid moving up the flow annulus 19 will flow through the channels 18 and over and around each roller reamer 16. The drilling fluid will carry away the debris and other debris around the roller reamer 16 that would otherwise be trapped around the roller reamer 16. The helical flutes 20 of the roller reamer 16 are preferably arranged so that as drilling fluid passes through the roller reamer 16, the helical flutes assist the drilling fluid to flow upwardly through the channel 18. The flow of drilling fluid will relieve the stress on the roller reamer 16 and reduce the temperature of the roller reamer 16 and the temperature of the carbide inserts 24, which otherwise may increase during operation. In addition, frictional heat generated on the carbides 24 is reduced due to improved flow of drilling fluid.

Although preferred embodiments of the apparatus of the present invention have been described in the foregoing detailed description, it will be understood that the invention is not limited to the embodiments disclosed, but is capable of numerous rearrangements, modifications, and substitutions without departing from the scope of the invention. Such modifications and variations that may be apparent to a person skilled in the art are considered to be within the scope of the present invention.

For example, more or fewer roller reamers may be included in the elongate body of the reaming tool. In such an arrangement there would be a corresponding number of channels. These examples are not intended as an exhaustive list, but are merely intended to represent other embodiments in accordance with the present invention.

Claims (12)

1. A reaming tool for coupling to a drill string, having:

a body rotatable in a rotational direction and having connection means at either end for coupling to a drill string, the body defining a longitudinal axis,

at least one roller reamer rotatably mounted to the body, the at least one roller reamer defining an axis of rotation that is inclined relative to a longitudinal axis of the body in a direction away from a direction of rotation of the body, and

at least one channel defining a channel axis, arranged to extend on the body and to be inclined relative to the longitudinal axis of the body in a direction towards the direction of rotation of the body, such that the channel intersects the roller reamer and such that the axis of the roller reamer intersects the channel axis.

2. The reaming tool of claim 1, comprising three radially spaced roller reamers and three channels.

3. The reaming tool of claim 2, wherein each roller reamer is mounted with its axis of rotation inclined relative to the longitudinal axis of the body.

4. The reaming tool of claim 2, wherein a longitudinal axis of each of the channels is oblique relative to a longitudinal axis of the body.

5. The reaming tool of claim 4, wherein a width of each channel at an intersection with each roller reamer is substantially the same as a width of the roller reamer.

6. The reaming tool of claim 4, wherein the longitudinal axis of each of the channels on each side of the roller reamer is not aligned.

7. The reaming tool of claim 1, wherein the body further includes a larger diameter portion disposed intermediate the distal ends of the body, the roller reamer and the channel being located on the larger diameter portion.

8. The reaming tool of claim 1, wherein each of the roller reamers has one or more helical channels extending along its length.

9. The reaming tool of claim 1, comprising a plurality of channels intersecting each roller reamer.

10. A drilling tool having:

a body rotatable in a rotational direction and defining a longitudinal axis; and a reaming portion having at least one roller reamer rotatably mounted to the body of the drilling tool, the at least one roller reamer defining an axis of rotation and being inclined in a direction away from the direction of rotation of the body, the axis of rotation also being inclined relative to the longitudinal axis of the body; and at least one channel extending on the body disposed across the roller reamer, the at least one channel being inclined relative to the longitudinal axis of the body in a direction toward the direction of rotation of the body.

11. The drilling tool of claim 10, wherein the longitudinal axis of each of the channels on each side of the roller reamer is not aligned.

12. A reaming tool for coupling to a drill string, the reaming tool comprising:

a body rotatable in a rotational direction and defining a longitudinal axis and having at one end at least one connector for coupling to a drill string, an

A reamer portion defining at least one recess extending along an axis that is inclined in a direction away from a direction of rotation of the body, the reamer portion comprising:

at least one roller reamer rotatably mounted within the at least one recess, the at least one roller reamer defining an axis of rotation that is radially offset from and skewed relative to the longitudinal axis of the main body, the at least one roller reamer further comprising a helical groove extending along a length of the at least one roller reamer and a plurality of wear members disposed adjacent the helical groove; and

at least one channel on the reamer portion extending at an angle from the at least one recess, the channel extending on the body and being inclined relative to a longitudinal axis of the body in a direction toward a direction of rotation of the body and defining a fluid passageway for directing fluid toward the at least one roller reamer.