U.S. patent application number 12/114537 was filed with the patent office on 2009-11-05 for modular hybrid drill bit.
This patent application is currently assigned to BAKER HUGHES INCORPORATED. Invention is credited to Karlos B. CEPEDA, Michael Steven DAMSCHEN, Matthew R. ISBELL, Tim King MARVEL, Ron D. McCORMICK, Don Q. NGUYEN, Rudolf Carl PESSIER, Steve M. WINNON, Anton F. ZAHRADNIK.
Application Number | 20090272582 12/114537 |
Document ID | / |
Family ID | 41255854 |
Filed Date | 2009-11-05 |
United States Patent
Application |
20090272582 |
Kind Code |
A1 |
McCORMICK; Ron D. ; et
al. |
November 5, 2009 |
MODULAR HYBRID DRILL BIT
Abstract
An earth-boring bit comprising a bit body is cofigured at its
upper end for connection into a drillstring. A fixed blade depends
axially downwardly from the bit body. An axially extending slot is
formed in the bit body adjacent the fixed blade. A bit leg is
received and retained in the slot by engagement between the slot
and correspondingly shaped bit leg, wherein the bit leg cannot be
removed from the slot except by axial movement relative to the bit
body. A rolling cutter is secured to the bit leg at its lower
extent. A fastener secures the bit leg against movement relative to
the bit body and extends through oblong apertures in the bit leg
and into the bit body, wherein the bit leg can be moved axially
relative to the bit body to adjust the projection of the rolling
cutter relative to the fixed blade. The slot defines a pair of
generally opposed sides connected by a third side, the generally
opposed sides being inclined toward one another to define a
dovetail that corresponds with the shape of the bit leg. The bit
body further comprises a shank that is configured for connection
into the drillstring at its upper extent and has a generally
cylindrical receptacle formed in its lower extent; and a bit body
portion having a generally cylindrical upper extent, the receptacle
being and dimensioned to receive the upper extent of the bit body,
wherein the shank and bit body portions are secured together by
welding.
Inventors: |
McCORMICK; Ron D.;
(Magnolia, TX) ; PESSIER; Rudolf Carl; (Galveston,
TX) ; NGUYEN; Don Q.; (Houston, TX) ; MARVEL;
Tim King; (The Woodlands, TX) ; ISBELL; Matthew
R.; (Houston, TX) ; ZAHRADNIK; Anton F.;
(Sugar Land, TX) ; CEPEDA; Karlos B.; (Houston,
TX) ; DAMSCHEN; Michael Steven; (Houston, TX)
; WINNON; Steve M.; (Conroe, TX) |
Correspondence
Address: |
LOCKE LORD BISSELL & LIDDELL LLP;ATTN: IP DOCKETING
600 TRAVIS, SUITE 3400
HOUSTON
TX
77002-3095
US
|
Assignee: |
BAKER HUGHES INCORPORATED
Houston
TX
|
Family ID: |
41255854 |
Appl. No.: |
12/114537 |
Filed: |
May 2, 2008 |
Current U.S.
Class: |
175/336 |
Current CPC
Class: |
E21B 10/14 20130101;
Y10T 29/49948 20150115; Y10T 29/49963 20150115; E21B 10/62
20130101; Y10T 29/49947 20150115; E21B 10/24 20130101 |
Class at
Publication: |
175/336 |
International
Class: |
E21B 10/08 20060101
E21B010/08 |
Claims
1. An earth-boring bit comprising: a bit body configured at its
upper end for connection into a drillstring; at least one fixed
blade depending axially downwardly from the bit body; an axially
extending slot formed in the bit body adjacent the fixed blade; a
bit leg received and retained in the slot by engagement between the
slot and correspondingly shaped bit leg, wherein the bit leg cannot
be removed from the slot except by axial movement relative to the
bit body; and at least one rolling cutter secured to the bit leg at
its lower extent.
2. The earth-boring bit according to claim 1, further comprising:
at least one fastener securing the bit leg against movement
relative to the bit body.
3. The earth-boring bit according to claim 2, wherein the fasteners
extend through oblong apertures in the bit leg and into the bit
body, wherein the bit leg can be moved axially relative to the bit
body to adjust the projection of the rolling cutter relative to the
fixed blade.
4. The earth-boring bit according to claim 1, wherein the slot is
formed by at least three sides, and at least one acute angle is
formed by two adjacent sides.
5. The earth-boring bit according to claim 1, wherein the slot
defines a pair of generally opposed sides connected by a third
side, the generally opposed sides being inclined toward one another
to define a dovetail that corresponds with the shape of the bit
leg.
6. The earth-boring bit according to claim 1, wherein the bit body
further comprises: a bit body portion having an upper extent; and a
shank that is configured for connection into the drillstring at its
upper extent and configured for connection to the bit body at its
lower extent, wherein the shank and bit body portions are secured
together by welding.
7. The earth-boring bit according to claim 1, further comprising: a
nozzle removably secured in the bit body, the nozzle receptacle
configured to receive a nozzle; a bearing formed integrally with
the bit leg, the rolling cutter mounted for rotation on the
bearing; and a lubricant compensator removably secured in the bit
leg, the lubricant compensator in fluid communication with the
bearing.
8. An earth-boring bit comprising: a shank configured at its upper
extent for connection into a drillstring and having a lower extent;
a body portion configured to connect to the lower extent of the
shank, the shank and body portions being removably secured together
to form a bit body; at least one fixed blade depending axially
downwardly from the bit body; an axially extending slot formed in
the bit body adjacent the fixed blade; a bit leg received and
retained in the slot by engagement between the slot and
correspondingly shaped bit leg; at least one rolling cutter secured
to the bit leg at its lower extent; and at least one fastener
securing the bit leg against movement relative to the bit body.
9. The earth-boring bit according to claim 8, wherein the fasteners
extend through oblong apertures in the bit leg and into the bit
body, wherein the bit leg can be moved axially relative to the bit
body to adjust the projection of the rolling cutter relative to the
fixed blade.
10. The earth-boring bit according to claim 8, wherein the slot is
formed by at least three sides and at least one acute angle is
formed by two adjacent sides.
11. The earth-boring bit according to claim 8, wherein the slot
defines a pair of generally opposed sides connected by a third
side, the generally opposed sides being inclined toward one another
to define a dovetail that corresponds with the shape of the bit
leg.
12. The earth-boring bit according to claim 8, wherein: the upper
extent of the bit body and the receptacle in the shank portion are
generally cylindrical and the receptacle is dimensioned to receive
the upper extent of the bit body, wherein the shank and bit body
portions are secured together by welding.
13. The earth-boring bit according to claim 8, further comprising:
a nozzle removably secured in the bit body, the nozzle receptacle
configured to receive a nozzle; a bearing formed integrally with
the bit leg, the rolling cutter mounted for rotation on the
bearing; and a lubricant compensator removably secured in the bit
leg, the lubricant compensator in fluid communication with the
bearing.
14. The earth-boring bit according to claim 8, wherein the
fasteners are bolts and the pin and body portions are secured
together by welding.
15. An earth-boring bit comprising: a shank configured at its upper
extent for connection into a drillstring and having a receptacle
formed in its lower extent; a body portion having an upper extent
shaped and dimensioned to be received in the receptacle in the
lower extent of the shank, the shank and body portions being
removably secured together; at least one fixed blade depending
axially downwardly from the body portion; an axially extending slot
formed in the body portion adjacent the fixed blade; a bit leg
received and retained in the slot by engagement between the slot
and correspondingly shaped bit leg, the bit leg having a removable
lubricant compensator assembly in fluid communication with a
bearing at a lower extent of the bit leg; at least one rolling
cutter mounted for rotation on the bearing of the bit leg; and at
least one fastener securing the bit leg against axial movement
relative to the bit body.
16. The earth-boring bit according to claim 15, wherein the
fasteners extend through oblong apertures in the bit leg and into
the bit body, wherein the bit leg can be moved axially relative to
the bit body to adjust the projection of the rolling cutter
relative to the fixed blade.
17. The earth-boring bit according to claim 15, wherein the slot is
formed by at least three sides and at least one acute angle is
formed by two adjacent sides.
18. The earth-boring bit according to claim 15, wherein the slot
defines a pair of generally opposed sides connected by a third
side, the generally opposed sides being inclined toward one another
to define a dovetail that corresponds with the shape of the bit
leg.
19. The earth-boring bit according to claim 15, wherein the
fasteners are bolts and the pin and body portions are secured
together by welding.
20. The earth-boring bit according to claim 15, wherein the
receptacle in the shank and the upper extent of the body portion
are generally cylindrical.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Technical Field
[0002] The present invention relates in general to earth-boring
drill bits and, in particular, to a bit having a combination of
rolling and fixed cutters and cutting elements and a method of
drilling with same.
[0003] 2. Description of the Related Art
[0004] The success of rotary drilling enabled the discovery of deep
oil and gas reservoirs and production of enormous quantities of
oil. The rotary rock bit was an important invention that made the
success of rotary drilling possible. Only soft earthen formations
could be penetrated commercially with the earlier drag bit and
cable tool, but the two-cone rock bit, invented by Howard R.
Hughes, U.S. Pat. No. 930,759, drilled the caprock at the
Spindletop field, near Beaumont, Tex. with relative ease. That
venerable invention, within the first decade of the last century,
could drill a scant fraction of the depth and speed of the modern
rotary rock bit. The original Hughes bit drilled for hours, the
modern bit drills for days. Modern bits sometimes drill for
thousands of feet instead of merely a few feet. Many advances have
contributed to the impressive improvements in rotary rock bits.
[0005] In drilling boreholes in earthen formations using
rolling-cone or rolling-cutter bits, rock bits having one, two, or
three rolling cutters rotatably mounted thereon are employed. The
bit is secured to the lower end of a drillstring that is rotated
from the surface or by a downhole motor or turbine. The cutters
mounted on the bit roll and slide upon the bottom of the borehole
as the drillstring is rotated, thereby engaging and disintegrating
the formation material to be removed. The rolling cutters are
provided with cutting elements or teeth that are forced to
penetrate and gouge the bottom of the borehole by weight from the
drillstring. The cuttings from the bottom and sides of the borehole
are washed away by drilling fluid that is pumped down from the
surface through the hollow, rotating drillstring, and are carried
in suspension in the drilling fluid to the surface.
[0006] Rolling-cutter bits dominated petroleum drilling for the
greater part of the 20.sup.th century. With improvements in
synthetic or manmade diamond technology that occurred in the 1970s
and 1980s, the fixed-cutter, or "drag" bit, became popular again in
the latter part of the 20.sup.th century. Modern fixed-cutter bits
are often referred to as "diamond" or "PDC" (polycrystalline
diamond compact) bits and are far removed from the original
fixed-cutter bits of the 19.sup.th and early 20.sup.th centuries.
Diamond or PDC bits carry cutting elements comprising
polycrystalline diamond compact layers or "tables" formed on and
bonded to a supporting substrate, conventionally of cemented
tungsten carbide, the cutting elements being arranged in selected
locations on blades or other structures on the bit body with the
diamond tables facing generally in the direction of bit rotation.
Diamond bits have an advantage over rolling-cutter bits in that
they generally have no moving parts. The drilling mechanics and
dynamics of diamond bits are different from those of rolling-cutter
bits precisely because they have no moving parts. During drilling
operation, diamond bits are used in a manner similar to that for
rolling cutter bits, the diamond bits also being rotated against a
formation being drilled under applied weight on bit to remove
formation material. Engagement between the diamond cutting elements
and the borehole bottom and sides shears or scrapes material from
the formation, instead of using a crushing action as is employed by
rolling-cutter bits. Rolling-cutter and diamond bits each have
particular applications for which they are more suitable than the
other; neither type of bit is likely to completely supplant the
other in the foreseeable future.
[0007] In the prior art, some earth-boring bits use a combination
of one or more rolling cutters and one or more fixed blades. Some
of these combination-type drill bits are referred to as hybrid
bits. Previous designs of hybrid bits, such as is described in U.S.
Pat. No. 4,343,371 to Baker, III, have provided for the rolling
cutters to do most of the formation cutting, especially in the
center of the hole or bit. Other types of combination bits are
known as "core bits," such as U.S. Pat. No. 4,006,788 to Garner.
Core bits typically have truncated rolling cutters that do not
extend to the center of the bit and are designed to remove a core
sample of formation by drilling down, but around, a solid cylinder
of the formation to be removed from the borehole generally
intact.
[0008] Rolling-cutter bits tend to fail when the bearing or seal
fails and one or more cutters stop rotating or rotating easily.
Bearing failure is most often caused by loss of lubricant from the
bit or damage to the bearing as a result of severe operating
conditions. In some cases, the bearing failure is so catastrophic
that a cutter falls off of the bearing, which can lead to costly
and time-consuming fishing operations to recover the lost cutter.
Typically, rolling-cutter bits cannot successfully be refurbished
because of irreparable bearing damage. Diamond bits rarely have
such a catastrophic failure. Instead, individual diamond cutters
tend to be lost and the bit body is slowly worn away such that it
is no longer within drilling specifications. Diamond bits can be
refurbished by replacing lost cutters until the bit body is too
worn.
[0009] Another type of hybrid bit is described in U.S. Pat. No.
5,695,019 to Shamburger, Jr., wherein the rolling cutters extend
almost entirely to the center. Fixed cutter inserts 50 (FIGS. 2 and
3) are located in the dome area 2 or "crotch" of the bit to
complete the removal of the drilled formation. Still another type
of hybrid bit is sometimes referred to as a "hole opener," an
example of which is described in U.S. Pat. No. 6,527,066. A hole
opener has a fixed threaded protuberance that extends axially
beyond the rolling cutters for the attachment of a pilot bit that
can be a rolling cutter or fixed cutter bit. In these latter two
cases the center is cut with fixed cutter elements but the fixed
cutter elements do not form a continuous, uninterrupted cutting
profile from the center to the perimeter of the bit.
[0010] Although each of these bits is workable for certain limited
applications, an improved hybrid earth-boring bit with enhanced
drilling performance would be desirable.
SUMMARY OF THE INVENTION
[0011] It is a general object of the present invention to provide
an improved earth-boring bit of the hybrid variety. This and other
objects are achieved by providing an earth-boring bit comprising a
bit body configured at its upper end for connection into a
drillstring. At least one fixed blade depends axially downwardly
from the bit body. An axially extending slot is formed in the bit
body adjacent the fixed blade. A bit leg is received and retained
in the slot by engagement between the slot and correspondingly
shaped bit leg. At least one rolling cutter is secured to the bit
leg at its lower extent.
[0012] According to an illustrative embodiment of the invention, at
least one fastener secures the bit leg against movement relative to
the bit body and the fastener extends through oblong apertures in
the bit leg and into the bit body, wherein the bit leg can be moved
axially relative to the bit body to adjust the projection of the
rolling cutter relative to the fixed blade.
[0013] According to an illustrative embodiment of the invention,
the slot is formed by at least three sides, and at least one acute
angle is formed by two adjacent sides. The slot defines a pair of
generally opposed sides connected by a third side, the generally
opposed sides being inclined toward one another to define a
dovetail that corresponds with the shape of the bit leg.
[0014] According to an illustrative embodiment of the invention,
the bit body further comprises a shank that is configured for
connection into the drillstring at its upper extent and has a
generally cylindrical receptacle formed in its lower extent; and a
bit body portion having a generally cylindrical upper extent, the
receptacle being and dimensioned to receive the upper extent of the
bit body, wherein the shank and bit body portions are secured
together by welding.
[0015] According to an illustrative embodiment of the invention,
the earth-boring bit further comprises a nozzle removably secured
in the bit body, the nozzle receptacle configured to receive a
nozzle; a bearing formed integrally with the bit leg, the rolling
cutter mounted for rotation on the bearing; and a lubricant
compensator removably secured in the bit leg, the lubricant
compensator in fluid communication with the bearing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] So that the manner in which the features and advantages of
the present invention, which will become apparent, are attained and
can be understood in more detail, more particular description of
embodiments of the invention as briefly summarized above may be had
by reference to the embodiments thereof that are illustrated in the
appended drawings which form a part of this specification. It is to
be noted, however, that the drawings illustrate only some
embodiments of the invention and therefore are not to be considered
limiting of its scope as the invention may admit to other equally
effective embodiments.
[0017] FIG. 1 is a side elevation view of the embodiment of the
hybrid earth-boring bit constructed in accordance with the present
invention;
[0018] FIG. 2 is a bottom plan view of an embodiment of the hybrid
earth-boring bit of FIG. 1 constructed in accordance with the
present invention;
[0019] FIG. 3 is an exploded view of another embodiment of the
hybrid earth-boring bit of FIG. 1 constructed in accordance with
the present invention; and
[0020] FIG. 4 is a fragmentary view of a portion of the
earth-boring bit of FIG. 3, illustrating the configuration of the
axial slot in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0021] Referring to FIGS. 1-2, an illustrative embodiment of a
modular hybrid earth-boring drill bit is disclosed. The bit 11
comprises a bit body 13 having an axis 15 that defines an axial
center of the bit body 13. A plurality (e.g., two shown) of bit
legs or heads 17 extend from the bit body 13 in the axial
direction. The bit body 13 also has a plurality (e.g., also two
shown) of fixed blades 19 that extend in the axial direction. The
number of each of legs 17 and fixed blades 19 is at least one but
may be more than two (as in the case of the embodiment illustrated
in FIG. 3). In one embodiment, the centers of the legs 17 and fixed
blades 19 are symmetrically spaced apart from each other about the
axis 15 in an alternating configuration.
[0022] Rolling cutters 21 are mounted to respective ones of the bit
legs 17. Each of the rolling cutters 21 is shaped and located such
that every surface of the rolling cutters 21 is radially spaced
apart from the axial center 15 (FIG. 2) by a minimal radial
distance 23. A plurality of rolling-cutter cutting inserts or
elements 25 are mounted to the rolling cutters 21 and radially
spaced apart from the axial center 15 by a minimal radial distance
27. The minimal radial distances 23, 27 may vary according to the
application, and may vary from cutter to cutter, and/or cutting
element to cutting element.
[0023] In addition, a plurality of fixed cutting elements 31 are
mounted to the fixed blades 19. At least one of the fixed cutting
elements 31 is located at the axial center 15 of the bit body 13
and adapted to cut a formation at the axial center. In one
embodiment, the at least one of the fixed cutting elements 31 is
within approximately 0.040 inches of the axial center. Examples of
rolling-cutter cutting elements 25 and fixed cutting elements 31
include tungsten carbide inserts, cutters made of super-hard
material such as polycrystalline diamond, and others known to those
skilled in the art.
[0024] FIGS. 3 and 4 illustrate the modular aspect of the bit
constructed according to the present invention. FIG. 3 is an
exploded view of the various parts of the bit 111 disassembled. The
illustrative embodiment of FIG. 3 is a three-cutter, three-blade
bit. The modular construction principles of the present invention
are equally applicable to the two-cutter, two-blade bit 11 of FIGS.
1 and 2, and hybrid bits with any combination of fixed blades and
rolling cutters.
[0025] As illustrated, bit 111 comprises a shank portion or section
113, which is threaded or otherwise configured at its upper extent
for connection into a drillstring. At the lower extent of shank
portion 113, a generally cylindrical receptacle 115 is formed.
Receptacle 115 receives a correspondingly shaped and dimensioned
cylindrical portion 117 at the upper extent of a bit body portion
119. Shank 113 and body 119 portions are joined together by
inserting the cylindrical portion 117 at the upper extent of body
portion 119 into the cylindrical receptacle 115 in the lower extent
of shank 113. For the 121/4 inch bit shown, the receptacle is a
Class 2 female thread that engages with a mating male thread at the
upper extent of the body. The circular seam or joint is then
continuously bead welded to secure the two portions or sections
together. Receptacle 115 and upper extent 117 need not be
cylindrical, but could be other shapes that mate together, or could
be a sliding or running fit relying on the weld for strength.
Alternatively, the joint could be strengthened by a close
interference fit between upper extent 119 and receptacle 115. Tack
welding around the seam could also be used.
[0026] A bit leg or head 121 (three are shown for the three-cutter
embodiment of FIG. 3) is received in an axially extending slot 123
(again, there is a slot 123 for each leg or head 121). As shown in
greater detail in FIG. 4, slot 123 is dovetailed (and leg 121
correspondingly shaped) so that only axial sliding of leg 121 is
permitted and leg 121 resists radial removal from slot 123. A
plurality (four) of bolts 127 and washers secure each leg 121 in
slot 123 so that leg 121 is secured against axial motion in and
removal from slot 123. A rolling cutter 125 is secured on a bearing
associated with each leg 121 by a ball lock and seal assembly 129.
The apertures in leg 121 through which bolts 127 extend are oblong,
which permits the axial positioning of leg 121 within slot 123,
which in turn permits selection of the relative projection of the
cutting elements on each rolling cutter. A lubricant compensator
assembly 131 is also carried in each leg 121 and supplies lubricant
to the bearing assembly and compensates for pressure variations in
the lubricant during drilling operations. A preferred compensator
is disclosed in commonly assigned U.S. Pat. No. 4,727,942 to Galle
and Zahradnik. At least one nozzle 133 is received and retained in
the bit body portion 119 to direct a stream of drilling fluid from
the interior of bit 111 to selected locations proximate the cutters
and blades of the bit.
[0027] FIG. 4 is a fragmentary section view of bit body 119
illustrating the configuration of slot 123. As previously noted,
slot 123 has a pair of adjacent opposing sides 135 that are
inclined toward one another at an acute included angle (from
vertical) to define a dovetail. A third side, which may be curved
or flat, connects the two opposing sides 135. A rectilinear 137
recess is formed within the third side for additional engagement
between the bit leg and bit body. As stated, bit leg 121 is
provided with a corresponding shape so that once assembled
together, bit leg 121 resists removal from slot 123 except by axial
force. Preferably, for the 121/4 inch bit illustrated, slot 123 is
approximately 3.880 inches wide at its widest point, opposing sides
135 are inclined at an angle of approximately 15 degrees and
converge to define an included angle of approximately 30 degrees.
Recess 137 is approximately 1.880 inches wide and approximately
0.385 inches deep. The corresponding surfaces of bit leg 121 are
similarly dimensioned, but between 0.005 and 0.010 inch smaller to
provide a sliding or running fit within the slot. A close
interference fit could also be used to enhance strength, at the
cost of ease of assembly. A blind threaded hole or aperture 139 is
formed in bit body 119 to receive each of the fasteners or bolts
127 (FIG. 3). Alternatively, the opposed sides 135 of slot 123
could be "straight," but such a construction will not be as strong
as the "dovetailed" construction and may unduly strain bolts
127.
[0028] Thus, in accordance with the present invention, the threaded
shank is separable from the bit body and each bit leg and
associated rolling cutter is also separable from the bit body
(along with the associated lubricant compensator, bearing and seal
assembly). Thus, as the bit wears, various parts may be replaced as
appropriate. If the bearing associated with a cutter loses
lubricant and fails, the entire bit leg assembly can be replaced as
needed. If the bit body wears to the degree that it will no longer
support fixed cutters (or other parts of the bit assembly), it can
be replaced. If the shank is damaged, it can be replaced. Although
the welded joint is not typically considered a replaceable joint,
in this instance, the weld can be removed, a new shank or body
portion fitted, and there will be ample material remaining to
permit re-welding of the two together.
[0029] While the invention has been shown or described in only some
of its forms, it should be apparent to those skilled in the art
that it is not so limited, but is susceptible to various changes
without departing from the scope of the invention as hereinafter
claimed, and legal equivalents thereof.
* * * * *