Note: Descriptions are shown in the official language in which they were submitted.
CA 02438454 2008-11-03
REAMER HAVING TOROIDAL CRUSHER BODY
AND METHOD OF USE
BACKGROUND OF THE INVENTfON
Field of Invention
The present invention relates to a down hole tool for enlarging a drill
bore; and more specifically it relates to a reamer that enlarges a pilot hole.
State of the Art
It has long been known by those involved in drilling subterranean bore
holes for oil and gas exploration, mirieral recovery or in utility
construction
projects, to employ reamers to enlarge bore holes after a smaller pilot hole
has been drilled. Pilot holes can be drilied economically and more precisely.
Pilot holes can also be drilled with down hole motors that can be guided to
the
desired location from the point of ingress of the drill string.
Prior reamers have heretofore been manufactured in several distinct
styles. One type of reamer provides extensible arms and cutters that are
used to enlarge the hole to a larger diameter by rolling and crushing the face
and sides of the borehole with hardened buttons or dressed teeth. it is well
known in the drilling industry that these buttons or dressed teeth can be
fabricated from materials such as tungsten carbide or polycrystalline diamond
compact (PDC) or the like. The second type of reamer or hole opener
consisted of a tubular body with a plurality of arms supporting journals and
cutter bodies to extend to and crush the well bore. These arms, whether
extensible or fixed, and the smaller cutter cones carried on those arms, are
subject to failure in the hole as a result of their limited bearing surfaces
and
the smaller buttons, which wear out prematurely. As the number of arms
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
increases, the size of the bearings that can be used to provide rotational
movement of the cutter around each support arm diminishes, limiting the life
thereof. Further, because the extensible arms and cutter bodies were held
next to the body while going into the borehole, material was removed from the
tubular body further weakening the integrity of the entire tool. Other types
of
reamers or hole openers have been fashioned with three or more fixed cones
on journals mounted on integral posts on a tubular body. These hole openers
or reamers were similarly limited in the size of the cones and bearings
supported. The small cutter buttons and bearing surfaces cause short service
lives and can lead to premature failure of the tool. When failure occurred
down hole for either type of reamer (extensible arm or fixed arm), substantial
time and effort was required to fish the tool from the bore or to drill around
the
tool to complete the drilling program.
As noted above, prior art reamers generally provide a plurality of cutter
posts and journals onto each of which a cone having tungsten carbide buttons
is mounted. Because at least three cones are used on either type of reamer,
the cones were of limited size and typically provide small surfaces to contact
the borehole face to be reamed. Since smaller hardened buttons (or less
hard facing-which alternatively can be used to dress the surface of such
cutters) are used to cut the well bore surface, the service life of the
reamers is
shorter than it would be for tool providing a larger overall bearing surface
disposed with larger hardened button cutters. The life of these tools requires
that the cutters and journals be redressed to continue their useful life. This
redressing historically required the tool to be taken out of service and
returned
to the shop for repair and reconstruction.
2
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
Further, the normal operating problems of conventional hole openers is
exacerbated when drilling horizontal or near horizontal applications. In such
situations, the load and wear characteristics coming to bear on the support
arms can cause early and catastrophic failure of the arm structure and often
results in loss of cutters in the borehole itself. Additionally, in horizontal
or
near horizontal applications, the support arms of conventional openers create
additional torque on the tubular string that carries the reamer. The
additional
torque slows drilling progress and makes the cost per foot of opened hole
rise.
These problems can cause failure of both the support arms and loss of
cutters in the hole requiring expensive retrieval operations and delay the
completion of the operation.
A new type of reamer has long been sought which provides a longer
service life because it provides large bearing surfaces and large tungsten
carbide buttons or hard facing, which could be used in normal drilling
operations to open previously drilled pilot holes. Prior art reamers could not
be used under conditions which resulted in substantial longitudinal loading.
In
utility construction drilling projects, such as river crossings where bore
holes
are drilled under rivers to permit the installation of utility pipelines, it
is often
useful to drill from one side of the river to the other with a pilot drill,
then ream
the hole going from the pilot hole egress side to the ingress side. Utility
construction typically therefore requires a reamer that is pulled with
substantial force back through the pilot hole. In most drilling projects,
substantial or large amounts of longitudinal loading are generally avoided,
thereby preventing excessive torque from being introduced into the drill
string.
3
CA 02438454 2008-11-03
Summary of the Invention
In one broad aspect, the present invention seeks to provide a reamer for
enlarging a bore hole in conjunction with a drill string. The reamer comprises
at least one journal body comprising a tubular body having one journ.al
portion
and one toroidal crusher body rotatably attached thereto. There are means for
attaching the at least one journal body to the drill string. The toroidal
crusher
body, has a maximum diameter, an outer perimeter at the maximum diameter, a
crushing surface, and a plurality of crushing buttons on the crushing surface.
The toroidal crusher body is rotatably attached to the at least one journal
body.
The journal portion comprises an enlarged cylindrical surface removably, but
irrotatably, mounted on a central portion of an exterior of the tubular body.
The enlarged cylindrical surface has a central axis intersecting a
longitudinal
axis of the tubular body at an acute angle, and the toroidal crusher body has
an
inner surface rotatably engaging the enlarged cylindrical surface of the
tubular
body. When in an installed position, the axis of rotation of the toroidal
crusher
body intersects the longitudinal axis of the drill string at an acute angle
and the
outer perimeter encircles the longitudinal axis.
4
CA 02438454 2008-11-03
In a further aspect, the invention provides a reamer for enlarging a bore
hole in conjunction with a drill string. The reamer comprises at least one
journal body, means for attaching the at least one journal body to the drill
string, at least one toroidal crusher body, each having a maximum diameter, an
outer perimeter-at the maximum diameter, a crushing surface, and a plurality
of
crushing buttons on the crushing surface. The at least one toroidal crusher
body is rotatably attached to the at least one journal body and is
asymmetrical
relative to a plane in the maximum diameter of the journal body. When in an
installed position, an axis of rotation of each of the at least one toroidal
crasher
body intersects a longitudinal axis of the drill string at an acute angle and
the
outer perimeter encircles the longitudinal axis.
Still further, the invention comprehends a reamer for enlarging a bore
hole in conjunction with a drill string. The reamer comprises at least one
journal body, means for attaching the at least one journal body to the drill
string, at least one toroidal crusher body, each toroidal crusher body having
a
maximum diameter, an outer perimeter at the maximum diameter, a crushing
surface, and a plurality of mill teeth in a zig-zag pattern on the crushing
surface. The at least one toroidal crusher body is rotatably attached to the
at
least one journal body, and when in an installed position, an axis of rotation
of
CA 02438454 2008-11-03
each of the at least one toroidal crusher body intersects a longitudinal axis
of
the drill string at an acute angle and the outer perimeter encircles the
longitudinal axis.
Accordingly, several of the aspects and advantages of the present
invention can be readily appreciated from the disclosure of the present
invention.
Since the present invention has eliminated the support arms and
provides significantly larger bearings and surfaces supporting the cutters,
the
operational life is greatly extended. Conventional hole openers, because of
their mass, require special handling to install and replace at the
5a
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
job site. Several embodiments of the present invention are compact and
significantly lighter than the conventional devices permitting easy
installation,
removal and replacement.
Another feature of the present invention is that only selected cutters
engage the formation to be cut. Conventional cutters were supported by
support arms that supported the distal end of the cutter body. With the
present invention, the cutter is supported by the journal spindle
substantially
coaxial with the longitudinal axis of the drill string. The profile of the
cutter
within the annulus is more compact because there is no dragging of the
support arm past the formation opened by the cutter. This feature also
reduces the drag and torque on the body itself and on the whole drill string
thereby reducing mechanical wear on the drilling assembly from this
operation. The tubular member carrying the hole opener experiences less
torque than prior conventional hole openers and requires less mechanical
energy to open the hole to the desired inner diameter.
A still further benefit of the present invention is that it permits a smaller
pilot hole to be used to provide the initial pathway for the driller. Since
the
overall outer diameter profile of the reamer, approximating the diameter of
the
drill string for the pilot hole, is smaller than conventional openers, a
smaller
and therefore more economical pilot hole can be drilled. Drilling of a smaller
pilot hole can be accomplished more quickly than drilling a larger diameter
pilot hole and can be accomplished by a smaller drilling rig that is also more
economical.
Additionally, in one embodiment of the present invention, the cutter
body is symmetric in construction, front to back (that is, relative to its
6
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
maximum diameter. Accordingly, it can be reversed as cutter elements wear
down and the former back of the cutter body would then be used as the
primary cutter surface facing the direction of travel of the reamer.
Significantly, the present invention provides a reamer which can be
either pushed or pulled through the pilot hole with greater longitudinal
loading
than previously used with such tools without the danger of introducing such
excessive torque, while still providing a long service life because of its
large
bearing surfaces and cutter elements, for example, cutter buttons. The
combination of these benefits thereby satisfies a long felt but unanswered
need of the drilling industry in a new and unobvious way.
The reamer cutter body of the present invention is wholly consumable
and can be scrapped at the bore hole site when totally worn. There is no
need to return the body to the manufacturer. The cutter body can be replaced
and the reamer reused.
BRIEF DESCRIPTION OF THE DRAWING
Fig. 1 is a cross-sectional view of an embodiment of a reamer
according to the present invention adjacent a bore hole face.
Fig. 2 is a perspective view of another embodiment of a reamer
according to the present invention in a pilot hole with a centralizer (cutter
buttons).
Fig. 3 is a schematic representation of the reamer body according to
Fig. 2 in a representative bottom hole assembly.
Fig. 4 is a cross-sectional view of the reamer body according to Fig. 2
connected in a drill string.
7
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
Fig. 5 is a cross-sectional view of another embodiment of a reamer
according to the present invention providing a removable journal body on a
tubular body.
Fig. 6 is a perspective view of another embodiment of a reamer
according to the present invention in a pilot hole with a centralizer (mill
teeth
in a zig-zag pattern).
Fig. 7 is a cross sectional view of another embodiment of a reamer
opener according to the present invention.
Fig. 8 is a cross sectional view of another embodiment of a reamer
according to the present invention providing smaller cone bodies.
Fig. 9 is-a cross sectional view of another embodiment of a reamer
according to the present invention providing a large diameter hole opener.
Fig. 10 is a schematic bottom end view of the toroidal cutter bodies of
the large diameter hole opener of Fig.9 deployed within a bore hole.
Fig. 11 is partially schematic view of an embodiment of a reamer
according to the present invention connected to a drill pipe in a well bore
from
above and to a drill bit immediately below the hole opener.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings in which like numerals denote similar
elements, and more particularly to FIG. 1, there is shown by way of
illustration, but not of limitation, a reamer 100 providing a journal 110
having
an axis of rotation RA skewed at an acute angle a from the longitudinal axis
LA of the drill string to which the reamer 100 is attached. As drilling
proceeds, the reamer 100 is free to rotate slowly engaging the face BHF of
the hole BH to be reamed with adjacent radial rows of irregularly spaced
8
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
hardened buttons or impact elements that crush the rock against which they
come in contact.
The cutting elements, buttons 112,145, 146 and 149 in this
embodiment and such elements in the embodiments shown in Figs. 2 - 11,
are made from tungsten carbide. It may appreciated that such hardened
buttons can also be fabricated from polycrystalline diamond compact (PDC),
thermally stable polycrystalline diamond cutters (TSP), natural diamond, or
steel teeth with hard facing, all in a manner well known to those skilled in
the
art. Likewise, the shape of the cutter buttons can be of a variety of designs
or
shapes in accordance with the desired use for a given type of formation to be
reamed. For example, the buttons could be ovoid or ogive shaped, conical or
900 chisel shaped, or scooped or crested cutter buttons, in a manner well
known to those in the drilling industry, without departing from the spirit or
intent of this invention.
In the various embodiments disclosed herein, because the reamer
body or journal provides a much larger surface than the roller cones found on
most prior art reamers, the buttons can be fabricated larger than would
normally be used in the tool sized for use in this application. Consequently,
the wear life of the reamer is extended because these larger buttons or impact
elements have substantially longer service lives. Likewise, the reamer of the
present invention allows the toroidal cutter body to be mounted on a journal
that provides larger bearing surfaces or races for thrust and roller bearings
formed on its outer surface that likewise assure a longer service life for the
reamer.
9
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
The reamer 100 shown in Fig. 1 could be used wherever a pilot hole
had previously been drilled to enlarge the hole or bore to its desired gauge.
As may be readily appreciated, the reamer has a toroidal cutter body 116
around the longitudinal axis LA of the drill string, but is skewed to have, an
axis of rotation RA and provide a rolling movement of the cutter body 116
against the face BHF of the surface of the well bore being opened. Viewed
from the side, cutter body 116 will rotate slowly (at a rate slower than the
drill
string) clockwise around the axis of rotation of the drill string, that is,
the
longitudinal axis LA. The drill hole bore BH is engaged by the reamer buttons
112 as the cutter body 116 rotates about its axis of rotation RA and around
the longitudinal axis LA of the drill string, wherein the axis of rotation RA
intersects the longitudinal axis LA at an acute angle a. The outer perimeter
OP at the maximum diameter of the cutter body 116 encircles the longitudinal
axis LA. In the snap-shot in time shown in Fig. 1, the arrangement of the
buttons on the cutting surface 118 of the body 116 assures that only a portion
120 of the buttons 112 are fully engaged as adjacent buttons are moved
closer to full engagement. All of the buttons 112 on the opposing portion 121
are off the surface BHF of the borehole thereby preventing dragging or galling
of the cutter body 116 in the hole as this crushing movement occurs.
The reamer 100 provides threaded surfaces on each end of its
longitudinal axis to connect with the drill string 10 (not shown here) at 122
and
with the lower bottom hole assembly BHA (not shown here) at 124. Reamer
100 can be placed below a centralizer and above a drill bit or drilling motor
(not shown) in a manner well known to those engaged in the drilling industry.
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
As shown in Fig. 1, reamer 100 has a cutter body 116 that is fabricated
in a toroidal shape having an interior surface providing a bearing race 114.
Alternatively, the interior surface of the toroidal cutter body 116 can be
machined conically (not shown) to permit a tapered roller bearing to be used
to facilitate rotation of the cutter body 116.
The exterior surface of the toroidal cutter body 116 is machined to
accept a multiplicity of tungsten carbide buttons, such as those shown at 112,
145 and 149 that are inserted in each of the spaced holes. The spacing of the
holes on the cutting surface 118 is made to provide a maximum coverage of
cutting surface 118 of the cutter body 116 with buttons 112. Buttons 112 are
chosen to maximize the size of the buttons. The choice of buttons and their
spacing prevents any specific part of the body from receiving excessive wear.
The size of buttons which can be used in the present invention are much
larger than those which can be used on individual cones adapted for use on a
standard reamer which can be used in the similar sized well bore.
It is well known to those skilled in the art of manufacture of drilling and
reaming tools that mill tooth cutter bodies can also be used to accomplish
opening in certain types of formations. A mill tooth surface (not shown) can
also be fabricated on the cutter body. The mill tooth cutter surface would be
interrupted to allow passage of fluid and cuttings around the teeth, but in
all
other pertinent aspects would be like existing mill tooth cutter bodies. One
example of a mill tooth cutter surface is shown in Fig. 6 having a zig-zag
pattern.
Body 110 is fabricated from steel tubular member that provides the
threaded surfaces for connection to the tubular members described above in
li
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
the drill string and in the bottom hole assembly. Body 110 also provides a
longitudinal passage 126 to permit fluid communication through the body 110.
Body 110 is machined to provide seals in seal grooves 128 and 130 to protect
the bearings 132, 134 and 136 and races 114, from hydraulic contamination
from the drilling fluid. The exterior surface of journal body 110 is obliquely
skewed at an angle of about 10 from the longitudinal axis LA of the body 110
to rotatably support the cutter body 116.
Body 110 also provides at least one port to permit the jetting of drilling
fluid against around the reamer to carry cuttings away from the reamer body
and to lubricate and cool the cutters. Port 138 points away from the face BHF
of the well bore being reamed. Retainer bearings 134 are inserted and
maintained in the race formed between the exterior surface of the body 110
and the interior surface of the cutter body 116 by a passage 140 in the body
110. A head cap screw 142 is inserted in the passage 140 to seal the retainer
bearings 134 in the race.
Moving the cutter body 116 over the seals 130 and roller bearings 136
assembles the reamer 100. Ball bearings 134 are then inserted and the plug
(head cap screw 142) is inserted into place.
It may also be appreciated that the body 110 can also provide the
support for different sized cutter bodies. The same size tubular body 110 can
also be used to support an 8-1/2 inch cutter body (not shown).
In operation, the cutter body 116 is free to revolve around its axis of
rotation RA at an acute angle a to the longitudinal axis LA of the drill
string
and body 110. The outer perimeter OP at the maximum diameter MD of the
cutter body 116 encircles the longitudinal axis LA. Another way of expressing
12
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
this is that the longitudinal axis LA intersects the plane defined by the
outer
perimeter OP. This skewed angle a permits the hardened buttons to crush
the face of the well bore being enlarged and roll slowly as the cutter body
116
moves around the longitudinal axis LA to engage adjacent surfaces. The
cooperating individual buttons 112 on the contact portion 120 of the cutting
surface 118 of the cutter body 116 engage the borehole BH. In operation, the
radially and irregularly positioned buttons or cutter elements selectively
crush
and stabilize the reamer as adjacent cutter elements are moved onto crushing
engagement with the surface of the bore.
The reamer 100 also permits the hardened buttons, such as
representative button 144, on the posterior side 146 of the body 110 of the
reamer 100 to continue cutting as reamer 100 is moved out of the hole BH.
This feature is useful in unconsolidated subterranean structures that collapse
on the drill string as the reamer passes. This feature also provides well
defined and smooth enlarged bore holes, the desired end result of the
reaming process.
Figs. 2, 4 and 5 show the reamer 200 providing an axis of rotation RA
skewed at an acute angle a from the longitudinal axis LA of the drill string
to
which the reamer is attached. As drilling proceeds, the reamer is free to
rotate slowly engaging the face of the hole to be reamed with a row of
hardened buttons that crush the rock against which they come in contact.
The reamer 200 shown in Fig. 2 could be used wherever a pilot hole
had previously been drilled to enlarge the hole or bore to its desired gauge.
Typically, the reamer 200 is connected to a drill string 10 above it. As shown
13
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
in Fig. 2, a centralizer 26 can be attached or connected adjacent the reamer
200 to centralize the reamer 200 in the hole BH.
Fig. 3 shows the reamer 200 in a perspective view mounted adjacent a
stylized drill bit assembly 28 which could be either a diamond bit system or a
standard cone drill bit, either of which are well known to persons having
ordinary skill in the art. As may be readily appreciated, the reamer has a
toroidal cutter body 216 around the longitudinal axis LA of the drill string,
but
the axis of rotation RA thereof is skewed at an acute angle a thereto (see
Figs. 3 and 4) to provide a rolling movement of the cutter body 216 against
the face BHF of the surface of the well bore being opened. Viewed from the
side in Figs. 4 and 5, reamer 200 will rotate slowly (at a rate slower than
the
drill string 10) clockwise about its axis of rotation RA around the
longitudinal
axis LA of the drill string 10. As stated earlier, another way of expressing
this
relationship is that the longitudinal axis LA intersects the plane defined by
the
outer perimeter OP of the toroidal cutter body 216 at its maximum diameter.
This plane is also intersected by the axis of rotation RA at the center
thereof.
In this embodiment, the longitudinal axis LA also intersects this plane at the
center thereof.
Fig. 4 is a cross sectional view of the reamer 200. The face BHF of
drill hole bore BH is engaged by the cutter body 216 buttons 112 on opposite
sides of the distal edge of the cutter body 216. The reamer 30 provides
threaded surfaces on each end of its longitudinal axis to connect with the
drill
string 10 and with the lower bottom hole assembly 20, for example, a
centralizer 26 (Fig. 2) or a stylized drill bit assembly'28 (Fig. 3). Reamer
200
can be placed below a centralizer and above a drill bit (not shown) or
drilling
14
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
motor (not shown) in a manner well known to those engaged in the drilling
industry. -
As shown in Fig. 4, reamer 200 has a cutter body 216 that is fabricated
in a toroidal shape that is symmetrical relative to its maximum diameter (that
is, the top and bottom halves are symmetrical) having an interior surface
providing a bearing race 214. Although the interior surface of Fig. 4
discloses
a right circular cylinder with a bearing race 214 approximately midway on said
face, other bearing types can warrant fabrication of the interior surface
having
different bearing races or geometric configurations. For example, a plurality
of ball bearing races (not shown) can be formed on the interior surface
without
departing from the spirit and purpose of the invention. Likewise, the interior
surface of the toroidal cutter body 216 can be machined conically (not shown)
to permit a tapered roller bearing to be used to facilitate rotation of the
cutter
body 216.
The exterior surface of the toroidal cutter body 216 is machined to
accept a multiplicity of tungsten carbide buttons, such as those shown at 112,
that are inserted in each of the spaced holes. The spacing of the holes on the
exterior surface is made to provide a maximum coverage on the entire
exterior surface of the cutter body 216. Buttons 112 are chosen to maximize
the size of the buttons. The choice of buttons 112 and their spacing prevents
any specific part of the body 216 from receiving excessive wear. The size of
buttons which can be used in the present invention are much larger than
those which can be used on individual cones adapted for use on a standard
reamer which can be used in the similar sized well bore.
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
It is well known to those skilled in the art of manufacture of drilling and
reaming tools that mill tooth cutter bodies can also be used to accomplish
opening in certain types of formations. A mill tooth surface (not shown) can
also be fabricated on the cutter body. The mill tooth cutter surface would be
interrupted to allow passage of fluid and cuttings around the teeth, but in
all
other pertinent aspects would be like existing mill tooth cutter bodies. Fig.
6
depicts a reamer 400 like reamer 200 shown in Fig. 2 with the exception that
the cutter body 216 has mill teeth 412 in a zig-zag pattern instead of buttons
112.
Body 260 is fabricated from steel tubular member that provides the
threaded surfaces for connection to the tubular members described above in
the drill string 10 and in the bottom hole assembly 20. Body 260 also
provides a longitudinal passage 226 to permit fluid communication through the
body 260. Body 260 is machined to provide seals in seal grooves 230 and
roller bearings and races 248, around the exterior of the portion of the body
260. The exterior surface of body 260 is obliquely skewed at an angle of
about 100 from the longitudinal axis LA of the body 260 and of the drill
string
it will be attached to rotatably support the cutter body 216. This provides
the acute angle a at the intersection of the axis of rotation RA and the
longitudinal axis LA.
Body 260 also provides at least one port to permit the jetting of drilling
fluid against around the reamer to carry cuttings away from the reamer body
and to lubricate and cool the cutters. On Fig. 4, ports 238 point either
toward
or away from the face of the well bore being reamed. Ports 238 also provide a
means of securing the retainer plug 262 in the body 260 by the securing
16
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
engagement of sleeve 264 in port 266. The jetting ports 266 are sealed in the
body 260 by 0-ring 268 and retained in the body 260 by snap ring 270. The
opposing jetting port 238 is likewise fitted with snap ring and 0-rings to
secure
the jetting port in the passage.
Moving the cutter body 216 over the seals 230 and roller bearings 248
assembles the reamer 200. Ball bearings 232 are then inserted and the
grease plug 272 is inserted, then locked, into place by a pressure plug 262
which fits against an interior shoulder to retain, but not compress, the
grease
plug 272 against the ball bearing 232 in race 214. The pressure plug 262 that
seals the bearing race by 0-rings 274 from contamination by drilling fluid
from
the interior of the reamer body 260 is retained in place by locking sleeve
264.
Plug 262 seals a grease reservoir for lubricating the ball bearings 232 as
they
roll around the body. Grease reservoir 276 is machined into the cutter body
2.16 and filled through nipple 278 which is threadably engaged in floating
seal
280, which seats in a recess 282 machined into the surface of the cutter body
216 which is sealed to the drilling fluid with dynamic or floating seals 280
and
0-ring 284, after assembly to provide grease to.the bearing race during use
on demand.
It may also be appreciated that the body 260 can also provide the
support for different sized cutter bodies. Fig. 4 discloses the invention with
a
12-inch cutter body installed. The same size tubular body 260 as used in Fig.
4 can also be used to support an 8-'h inch cutter body (not shown).
Fig. 5 shows an alternative embodiment of the invention as reamer 300
that is like reamer 200, but has a removable journal body 360 mounted on the
tubular member 310 supporting the cutter body 216.
17
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
In operation, cutter body 216 of the reamer 300 is free to revolve about
its axis of rotation RA at an acute angle a to the longitudinal axis LA of the
drill string. The outer perimeter OP at the maximum diameter of the MD of the
cutter body 216 encircles the longitudinal axis LA. Another way of expressing
this is that the longitudinal axis LA intersects the plane defined by the
outer
perimeter OP, in this embodiment at its center. The axis of rotation RA also
intersects this plane at its center, which is also the point at which the
rotational axis RA and longitudinal axis LA intersect at the acute angle a.
This skewed angle permits the hardened buttons to crush the face of the well
bore being enlarged and roll slowly as the longitudinal axis moves to engage
adjacent surfaces. The buttons 112 on the distal edge or outer perimeter OP
of the reamer 200 and 300 in Figs. 4 and 5 engage the borehole BH to
provide a stable and centralizing support platform for the cutter buttons 112
that are on the portion 220 of the cutter body 216 crushing the borehole face
BHF.
The reamer 200 and 300 also permit the hardened buttons 112 on the
posterior side 246 of the reamer to continue cutting as reamer 200 and 300
are moved out of the hole. This feature is useful in unconsolidated
subterranean structures that collapse on the drill string as the reamer
passes.
This feature also provides well defined and smooth enlarged bore holes, the
desired end result of the reaming process.
The operation of the reamer 300 in Fig. 5 is identical to that of reamer
200 shown in Fig. 4. Fig. 5 shows the removable journal 360 mounted on
tubular body 310 with seals in seal grooves 230 on the exterior surface and
seals with seal groove 390 on the interior surface of the removable journal
18
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
360. This body 360 is prevented from rotation on the tubular member 310 by
a dog 388 formed to fit in a recess or notch on the exterior surface of the
tubular body 310. Other means to prevent rotation could be used, such as
splines, key and key seat, hexagonal shaping or the like, without departing
from the spirit of the invention.
Fig. 7 is a cross-sectional view of one embodiment of a reamer 500
according to the present invention in a borehole BH abutting borehole hole
face BHF. The direction of longitudinal travel 50 of the tool is accomplished
by rotational and longitudinal force exerted on tubular members, for example,
drill string 10, (not shown) attached to the box end connection of a coupling
adapter 122 in a manner well known to those in the drilling industry. The
operator attaches the reamer or hole enlarger 500 immediately adjacent a drill
bit 28 (not shown in this view, but generally described in Fig. 11) or within
the
bottom hole assembly (BHA) adjacent drill collars (not shown) and can
proceed to place substantially greater loading or additional longitudinal
force
on the drill string because of the larger bearing surfaces allowed by the
design
of the present invention. Alternatively, the hole enlarger can be connected
immediately adjacent a bull plug or guide which connected to the end of the
body and guides the hole enlarger through a previously drilled pilot hole (not
shown, but well known to those in the industry). In utility drilling programs,
such as long horizontal drilling under rivers or streets for the installation
of
utility lines, the hole enlarger can be either pushed into the hole or drawn
back
through a previously drilled pilot hole to the ingress side of the original
drilling.
The direction of travel 50 can be either into or out of a previously drilled
pilot
hole. Additionally, since the bearing surfaces of the present invention are
19
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
substantially larger than the smaller bearings required on prior art multi-
cone
hole openers, an operator drills using the same longitudinal force for
substantially longer periods of time without damage to the bearing surface.
Furthermore, the hole enlarger 500 operates symmetrically in either
direction. If the cutting elements 112 on the cutter body 516 on one side of
the hole opener 500 become excessively worn from abrasion with a hardened
rock formation, the operator, can reverse the connection of the hole opener
500 to put the opposite cutter body 517 with its unworn cutters 112 toward the
bore hole face BHF and continue drilling. This feature permits a reamer to be
used for an extended period of drilling without replacement of the cutter
body.
In Fig. 7, coupling adapters or subs, 122 and 124, provide means for
threaded engagement of each to a threaded tubular member such as a drill
pipe on each (not shown), a drill pipe and a bull plug on the other (not
shown),
or a drill string and a drill bit (not shown in this view), all in a manner
well
known in this industry. Coupling adapter 122 provides a threaded pin 523 to
engage a threaded box 525 on journal 510. Journal 510 provides on its
opposing longitudinal end another threaded box end 527 for engagement with
an adapter 124 having engaging threads 529.
Journal 510 provides two opposing thrust bearing race 'surfaces 114
and 115 supporting thrust bearings 132. In the present embodiment, journal
510 also provides a central passage 126 to permit fluid communication from
coupling adapter 122 to coupling adapter 124. A central passage runs
through the entirety of the reamer 500 to provide drilling fluid communication
through the jets 138 or 139, depending on which cutter body 516 or 517 is
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
performing the cutting, to the bore to cool and lubricate the hole opener 500
and to carry away the cuttings from the borehole face BHF.
Journa1510 supports two longitudinally spaced toroidal cutter bodies
516 and 517 that are asymmetric relative to their respective maximum
diameter, that is, the top portion is different from the bottom portion. Each
of
the cutter bodies 516 and 517 rotate on an axis RA1 and RA2, respectively,
skewed at an acute angle a from the longitudinal axis LA of the coupling
adapters and the drill string (not shown) to which the reamer is to be
attached.
The outer perimeter OP1 and OP2 at the maximum diameter of the respective
cutter bodies 516 and 517 encircles the longitudinal axis LA. In this
embodiment, the axes RA1 and RA2 are each skewed 100 from the
longitudinal axis LA. The skew angle is 'at an acute angle a that assures that
the cutter teeth 112 on portion 120 of the cutter body 516 are fully engaged
to
crush the borehole face BHF while the diametrically and laterally spaced
cutter teeth 112 on portion 121 stand entirely off the face of the borehole
BHF. Further, the skew angle also keeps the lateral edge or outside
perimeter OP1 of the cutter body 516 engaging the borehole face with
centering cutter elements 545 which are opposed by the centering cutter
elements 547 on the outside perimeter OP2 of the cutter body 517 contacting
the borehole BH.
The second cutter body 517 carried on the journal 510 centers the tool
500 in the borehole BH by centering cutter elements 547. The skew angle on
the second cutter body 517 provides clearance of the cutter teeth 112 thereon
and centering cutting elements 547 located away from the borehole wall
thereby eliminating the dragging associated with other types of hole
enlargers.
21
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
Each cutter body 516 and 517 is provided with inner seals in seal
groove 528 and outer seals in seal groove 530 to prevent fluid from entering
the bearing races defined between the cutter bodies 516 and 517 and the
journal 510. Cutter bodies 516 and 517 are each retained on the journal 510
by bearings 134 inserted in a sealed raceway formed between the inner
surface of the cutter body and the outer surface of the journal through a hole
535 drilled in the journal body 510. Upon assembly of the reamer 500, the
assembler will put the cutter body 516 or 517 over the journal 510 after
seating the bearings 132, then insert the retainer bearings 134 into the hole
535, all in a manner well known to those in this industry. The assembler will
complete the assembly by inserting ball retainer 562. The process will be
repeated for both cutter bodies and the hole opener will then be ready for
connection as previously described in a drilling operation.
Fig. 8 is a cross sectional view of a smaller diameter hole opener 600.
As may be readily appreciated from viewing this figure, the journal and
connector adapters can be used for smaller diameter hole openers. Smaller
cutter bodies on the same journal 610 can be substituted and used on the
same coupling adapters 122 and 124. The smaller cutter bodies 616 and 617
are assembled in the same manner as described above for reamer 500 and
the tool 600 can provide proportionately greater bearing surface to cutter
surface thereby allowing a long service life for this smaller cutter body hole
opener. The angle of the cutter body against the bore hole face has
increased and the centering cutter elements on the lateral edge of each cutter
body have been reduced, but the function is the same. The skew angle of the
journal to the longitudinal axis of the drill journal body and the connected
22
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
coupling adapters is the same as the angle of the larger diameter hole
opener. In Fig. 8, this angle a is approximately 100.
The embodiment in Fig. 8 contains coupling adapters 122 and 124,
journal 610, cutter bodies 616 and 617 which are mounted on the journal 610
and rotate about their respective axis of rotation RA1 and RA2, each of which
intersects the longitudinal axis LA of the drill string (not shown) that
coincides
with the longitudinal axis of the reamer. Thrust bearings 132 allow
longitudinal loading of the cutters on the bore hole face BHF in a manner
equivalent to the hole opener 500 described in Fig. 7. The cutter bodies 616
and 617 are retained on the journal 610 by retainer bearings 134 which are
retained in the body by ball retainer 562. Coupling adapters provide jets 138
and 139 to clear cutting debris from the bore hole BH.
The action of the smaller diameter dual toroidal cutter body reamer 600
mirrors that of the larger diameter reamer 500. The cutter elements 612 on
portion 120 engage on one side of the bore hole face BHF while the opposing
cutter elements 612 on portion 121 are lifted off the face BHF by the skew
angle a of the journal 610. The reamer or hole opener assembly is centered
in the bore hole by the centering cutter elements 645 and 647 found on the
lateral face or outer perimeter OP1 and OP2 of the toroidal cutter bodies 616
and 617, respectively, that are engaging the borehole BH. Since this reamer
can operate in either direction, the worn cutters which can slow the rate of
penetration of the reamer can be remedied by merely flipping the obverse
reamer in the drill string so that the primary direction of travel is provided
with
the fresh cutter elements previously found on the reverse side of the reamer
in the same manner as the larger reamer.
23
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
Fig. 9 discloses an alternative embodiment of the dual toroidal cutter
body reamer previously discussed. For illustrative purposes only, the existing
hole size in the lower well bore LWB is 20 inches at the lower bore hole
before opening and 36 inches after use of the hole opener in the upper well
bore UWB. Reamer 700 varies from the smaller hole opener described
above, but the operation of the hole opener 700 is equivalent. In this
embodiment, each journal body 710 and 711 is bolted to the connector
adapters or subs 124 and 122, respectively, by a large socket head cap screw
792 which serves to anchor an intermediate journal support plate 794, and the
journals 710 and 711 to the opposing connector adapter 124 and 122,
respectively, while providing rotational support for the cutter bodies 716 and
717. As may be also appreciated, each journal 710 and 711 overhangs the
journal support plate 794 with shoulder 796 which provides a flat milled
surface which prevents the journals 710 and 711 from turning as the reamer
700 is rotated in the borehole.
As may be readily appreciated after reviewing Figs. 1 through 11, a
reamer or hole opener can be fabricated in a number of differing sizes and
configurations without departing from scope or intent of the invention
disclosed herein. Similar to the smaller embodiments, each journal of the
reamer supports a plurality of large thrust bearings which carry the
longitudinal force and assure the relatively free rotation of the cutter
bodies on
each journal. Retainer bearings are provided for and mounted in a raceway
formed between the outer surface of the journal and the inner surface of the
cutter body in the same manner previously described herein for the smaller
diameter hole openers.
24
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
Again referring to Fig.9, on the side opposite the head cap screw
pathway, each opposing connector adapter 124 and 122 is integrally
connected to the journal support plate 794 by bosses or tabs 797 which flank
the head cap screw pathways and offer structural support to the entire
assembly. As may be appreciated from Fig. 9, upon installation of the head
cap screws 792, through the journal support plate 794 and each journal 710
and 711, into the trussed plates 798 and 799 on the adapter 124 and 122,
respectively, the large diameter reamer 700 can be used in either direction
and can be flipped end over end and used going in either direction. The
adapters or subs 124 and 122 also provide jetting ports 138 and 139,
respectively, to direct drilling fluid toward the cutting surfaces.
Fig. 10 shows the cross sectional end view of the large reamer. The
opposing toroidal cutter bodies balance each other to form a round and
symmetric hole throughout the operation of the opener. There is more than
adequate room to evacuate the cuttings through the ample passageway
formed on each side of the reamer with the interior bore of the opened hole.
Cutter elements 112 are inserted in lower cutter body 716. Tabs or bosses
797 are affixed to the journal support plate 794 and straddle the pathways for
insertion of the head cap screws.792. The socket head cap screw 792 is
tightened through the pathway provided in the plate 798. The back side of the
upper cutter body 717 can be viewed from below and its cutter elements act
to centralize the hole opener 700 throughout its rolling engagement with the
well bore BH.
Fig. 11 discloses a partially schematic view of an embodiment of a
reamer according to the present invention, for example, reamer 500 shown in
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
Fig.7, though any of the other embodiments can be substituted therefor,
connected to a drill string at the upper end and a drill bit at its lower end
in a
manner familiar to all those involved in this industry. Other operational
configurations could be obtained using the present reamer without departing
from the spirit or intent of the invention disclosed herein. As may be
appreciated from the foregoing description and the attached drawings, the
large bearing surfaces and the balanced opposed toroidal cutter bodies allow
significant compression to be applied to the hole opener without damage or
excessive wear. Drilling can proceed quickly and for longer periods of time
without the need for replacement or fishing of broken hole opener arms from
the borehole.
The large bearing surfaces and strength of the reamer embodiments
according to the present invention permit larger loads to be placed on the
body than has heretofore been available to drilling personnel. Since the
reamer can be pulled back through a pilot hole, substantial progress can be
made by increasing the pulling power of the drilling rig being used and does
not, unlike conventional cutter movement, depend upon hydrostatic pressure
from a pump system or the rotational speed of the drill string.
Since the reamer embodiments according to the present invention offer
little resistance to the rotational movement of the drill string, cutting is
accomplished by the crushing effect of the cutter buttons being either pushed
or pulled against face of the the well bore surface. The reamer offers no
inherent torque into the drill string since it is free to rotate. Torque
remains
relatively constant throughout the reaming process. The crushing of the wall
26
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
of the borehole can be readily accomplished by the longitudinal loading of the
drill string.
Since only one or a few of the cutter buttons on the anterior face of the
reamer (or those facing the direction of travel of the reamer in the borehole)
will be in contact with the formation face at one point, the full longitudinal
force
will be focused on the few buttons in contact. The crushing effect of these
few
buttons having the full longitudinal force of the drill string will increase
the rate
of penetration and reaming that can be accomplished over traditional multi-
coned cutter assemblies because the forces in those bodies are spread
among several distinct points of contact required to maintain and centralize
the cutter in the hole thereby permitting prior art cutters to rotate.
In operation, it is expected that a piiot hole will first be drilled in a
manner well known to those skilled in the art. After the pilot hole is
drilled, the
drill string can be fitted with the reamer. If going into the hole, a guide
shoe
can be placed ahead of the reamer into the pilot hole to guide the reamer. In
utility construction, since the point of egress of the pilot hole drill can be
on the
surface, the driller will install the reamer to be pulled back through the
pilot
hole. Very often, the utility construction drilling rigs lack the pump
capacity of
large oil and gas drilling rigs to drive downhole drilling mud motors.
Consequently, utility construction rigs often can exert more force on the
reamer of the present invention when pulling the reamer back through the
pilot hole than was previously permitted with the smaller and more fragile
cutter bodies. It is believed that the greater longitudinal force exerted
against
this toroidal reamer will increase the rate of hole opening in all formations
and
27
CA 02438454 2003-08-13
WO 02/064939 PCT/US02/04365
provide a longer service life for the tool. The saving in time of reaming and
repair will substantially reduce overall drilling costs.
The cutter body in each of these embodiments has a cutting surface
which has cutting elements thereon. The cutter body is free to rotate about is
axis of rotation RA. The acute angle a between the axis of rotation RA and
the longitudinal axis LA of the drill string is such that only a portion of
the
cutting surface of the cutter body, preferably not more than one-half of the
cutting surface, is moved into engagement with the face of the well bore
adjacent the pilot hole. As the drill string rotates, the reamer engages the
well
bore at the borehole face with a cutting or impact element on a portion of the
rotatable cutter body, while holding the adjacent cutting or impact elements
away from the bore face. In each of the specific embodiments disclosed
herein, the acute angle a was about 10 degrees. However, other acute angle
magnitudes can be used that satisfy the functional limitation given above.
The acute angle a can, for example, range from about 5 to about 20 degrees,
more preferably from about 8 to about 15 degrees.
Although the description above contains many specifics, these should
not be construed as limiting the scope of the invention but as merely
providing
illustrations of some of the presently preferred embodiments of this
invention.
28
