U.S. patent number 3,840,080 [Application Number 05/345,094] was granted by the patent office on 1974-10-08 for fluid actuated down-hole drilling apparatus.
This patent grant is currently assigned to Baker Oil Tools, Inc.. Invention is credited to William O. Berryman.
United States Patent |
3,840,080 |
Berryman |
October 8, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
FLUID ACTUATED DOWN-HOLE DRILLING APPARATUS
Abstract
A hydraulic drilling motor connectable to a drilling string of
drill pipe thereabove and a drill bit therebelow for drilling a
bore hole in the earth, the motor having a hollow rotor connected
to a hollow drive shaft for attachment to the drill bit, the rotor
being rotatable in a stator or housing fixed to the drilling
string, the rotor passage being closed automatically by a valve
when liquid or other fluid is pumped through the motor to produce
rotor and shaft rotation, the valve automatically opening in the
absence of pumping fluid through the motor to permit fluid to drain
from the drilling string during its elevation with the motor in the
bore hole, or to automatically fill with fluid during its lowering
with the motor in the bore hole. Drilling weight is transferred
from the non-rotating drilling string and housing to the drive
shaft through an oil filled bearing section, the oil in such
section being maintained at a higher pressure than the pressure
externally of the section to retain the oil or other lubricant in a
clean state.
Inventors: |
Berryman; William O. (Houston,
TX) |
Assignee: |
Baker Oil Tools, Inc. (Los
Angeles, CA)
|
Family
ID: |
23353487 |
Appl.
No.: |
05/345,094 |
Filed: |
March 26, 1973 |
Current U.S.
Class: |
175/107;
74/458 |
Current CPC
Class: |
E21B
4/02 (20130101); Y10T 74/19953 (20150115) |
Current International
Class: |
E21B
4/02 (20060101); E21B 4/00 (20060101); E21b
003/12 () |
Field of
Search: |
;175/107 ;74/458 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Leppink; James A.
Attorney, Agent or Firm: Kriegel; Bernard
Claims
I claim:
1. Fluid motor apparatus for drilling a bore hole in a formation: a
housing structure having upper connector means for attachment to a
tubular drilling string extending to the top of the bore hole, said
structure including a stator; a rotor within said stator; said
stator and rotor having coacting helical lobes constantly in
contact with one another and in any transverse section, whereby
fluid pumped downwardly through the drilling string passes through
the helical passages between said stator and rotor lobes to rotate
said rotor in an orbital path around the axis of the stator; said
rotor being hollow throughout a major portion of its length and
having a plurality of helical lobes, said stator having one more
helical lobe than said rotor; a drive shaft rotatably supported in
said housing structure below said rotor and having lower connector
means for attachment to a drill bit, said shaft having passage
means for conducting fluid discharging from said stator to the
drill bit when attached to said lower connector means; and means
interconnecting said rotor and drive shaft for transmitting the
rotary motion of said rotor to said drive shaft; said hollow rotor
providing a central passage therein; said rotor having upper and
lower openings communicating with said passage for by-passing fluid
through said rotor passage between housing structure regions above
and below said stator; and means carried by and rotatable with said
rotor for selectively opening and closing said rotor passage.
2. Fluid motor apparatus for drilling a bore hole in a formation: a
housing structure having upper connector means for attachment to a
tubular drilling string extending to the top of the bore hole, said
structure including a stator; a rotor within said stator; said
stator and rotor having coacting helical lobes constantly in
contact with one another and in any transverse section, whereby
fluid pumped downwardly through the drilling string passes through
the helical passages between said stator and rotor lobes to rotate
said rotor in an orbital path around the axis of the stator; said
rotor being hollow throughout a major portion of its length and
having a plurality of helical lobes, said stator having one more
helical lobe than said rotor; a drive shaft rotatably supported in
said housing structure below said rotor and having lower connector
means for attachment to a drill bit, said shaft having passage
means for conducting fluid discharging from said stator to the
drill bit when attached to said lower connector means; and means
interconnecting said rotor and drive shaft for transmitting the
rotary motion of said rotor to said drive shaft; said hollow rotor
providing a central passage therein; said rotor having upper and
lower openings communicating with said passage for bypassing fluid
through said rotor passage between housing structure regions above
and below said stator; valve means carried by and rotatable with
said rotor responsive to the pressure of fluid pumped down the
drilling string for closing said rotor passage; and means on said
rotor for shifting said valve means to open position in the absence
of fluid pressure pumped down the drilling string.
3. Fluid motor apparatus for drilling a bore hole in a formation: a
housing structure having upper connector means for attachment to a
tubular drilling string extending to the top of the bore hole, said
structure including a stator; a rotor within said stator; said
stator and rotor having coacting helical lobes constantly in
contact with one another and in any transverse section, whereby
fluid pumped downwardly through the drilling string passes through
the helical passages between said stator and rotor lobes to rotate
said rotor in an orbital path around the axis of the stator; said
rotor being hollow throughout a major portion of its length and
having a plurality of helical lobes, said stator having one more
helical lobe than said rotor; a drive shaft rotatably supported in
said housing structure below said rotor and having lower connector
means for attachment to a drill bit, said shaft having passage
means for conducting fluid discharging from said stator to the
drill bit when attached to said lower connector means; and means
interconnecting said rotor and drive shaft for transmitting the
rotary motion of said rotor to said drive shaft; wherein said
stator has four lobes, said rotor having three lobes; said hollow
rotor providing a central passage therein; said rotor having upper
and lower openings communicating with said passage for by-passing
fluid through said rotor passage between housing structure regions
above and below said stator; and means carried by and rotatable
with said rotor for selectively opening and closing said rotor
passage.
4. Fluid motor apparatus for drilling a bore hole in a formation: a
housing structure having upper connector means for attachment to a
tubular drilling string extending to the top of the bore hole, said
structure including a stator; a rotor within said stator; said
stator and rotor having coacting helical lobes constantly in
contact with one another and in any transverse section, whereby
fluid pumped downwardly through the drilling string passes through
the helical passages between said stator and rotor lobes to rotate
said rotor in an orbital path around the axis of the stator; said
rotor being hollow throughout a major portion of its length and
having a plurality of helical lobes, said stator having one more
helical lobe than said rotor; a drive shaft rotatably supported in
said housing structure below said rotor and having lower connector
means for attachment to a drill bit, said shaft having passage
means for conducting fluid discharging from said stator to the
drill bit when attached to said lower connector means; and means
interconnecting said rotor and drive shaft for transmitting the
rotary motion of said rotor to said drive shaft; wherein said
stator has four lobes, said rotor having three lobes; said hollow
rotor providing a central passage therein; said rotor having upper
and lower openings communicating with said passage for by-passing
fluid through said rotor passage between housing structure regions
above and below said stator; valve means carried by and rotatable
with said rotor responsive to the pressure of fluid pumped down the
drilling string for closing said rotor passage; and means on said
rotor for shifting said valve means to open position in the absence
of fluid pressure pumped down the drilling string.
5. Fluid motor apparatus for drilling a bore hole in a formation: a
housing structure having upper connector means for attachment to a
tubular drilling string extending to the top of the bore hole, said
structure including a stator; a rotor within said stator; shaft
means connected to said rotor for attachment to a drill bit to
rotate the same; radial bearing means between said shaft means and
housing structure for transmitting radial forces between said shaft
means and housing structure; axial bearing means between said shaft
means and housing structure for transmitting axial loads between
said housing structure and shaft means; means providing a confined
space adapted to contain a liquid lubricant and in which said
radial bearing means and axial bearing means are contained, and
booster piston means for subjecting the liquid lubricant to a
greater unit pressure than the unit pressure externally of said
confined space, said booster piston means having a first effective
transverse area responsive to the pressure of fluid externally of
said confined space, said booster piston means also having a second
effective transverse area bearing against the lubricant in said
confined space which is less than said first transverse area.
6. Apparatus as defined in claim 5; said confined space being an
annular space between said shaft means and housing structure, said
booster piston means defining an end of said annular space and
comprising an annular piston having said second effective
transverse area bearing against the lubricant and said first
effective transverse area subject to the pressure of the fluid
externally of said annular space.
7. Apparatus as defined in claim 5; said stator and rotor having
coengaging means to provide a positive displacement hydraulic motor
wherein said rotor is rotated in response to fluid under pressure
pumped down the drilling string and between said rotor and stator;
said rotor having passage means including upper and lower openings
for by-passing fluid through said passage menas between housing
structure regions above and below said stator; means on said rotor
for selectively opening and closing said passage means; said shaft
means having a fluid passage adapted to receive fluid from said
lower opening for discharge into the drill bit.
8. Apparatus as defined in claim 5; said stator and rotor having
coengaging means to provide a positive displacement hydraulic motor
wherein said rotor is rotated in response to fluid under pressure
pumped down the drilling string and between said rotor and stator;
said rotor having passage means including upper and lower openings
for by-passing fluid through said passage means between housing
structure regions above and below said stator; means on said rotor
for selectively opening and closing said passage means; said shaft
means having a fluid passage adapted to receive fluid from said
lower opening for discharge into the drill bit; said means on said
rotor comprising valve means responsive to the pressure of fluid
pumped down the drilling string for closing said passage means, and
spring means acting between said rotor and valve means for shifting
said valve means to open position in the absence of fluid pressure
pumped down the drilling string.
9. Fluid motor apparatus for drilling a bore hole in a formation: a
housing structure having upper connector means for attachment to a
tubular drilling string extending to the top of the bore hole, said
structure including a stator; a rotor within said stator; shaft
means connected to said rotor for attachment to a drill bit to
rotate the same; radial bearing means between said shaft means and
housing structure for transmitting radial forces between said shaft
means and housing structure; axial bearing means between said shaft
means and housing structure for transmitting axial loads between
said housing structure and shaft means; means providing a confined
space adapted to contain a liquid lubricant and in which said
radial bearing means and axial bearing means are contained; and
booster piston means for subjecting the liquid lubricant to a
greater unit pressure than the unit pressure externally of said
confined space; said confined space being an annular space between
said shaft means and housing structure, said booster piston means
defining an end of said annular space and comprising an annular
piston having a first portion bearing against the lubricant and a
second portion subject to the pressure of the fluid externally of
said annular space, said second portion having a greater transverse
pressure responsive annular area than the transverse annular area
of said first portion.
10. Fluid motor apparatus for drilling a bore hole in a formation:
a housing structure having upper connector means for attachment to
a tubular drilling string extending to the top of the bore hole,
said structure including a stator; a rotor within said stator;
shaft means connected to said rotor for attachment to a drill bit
to rotate the same; radial bearing means between said shaft means
and housing structure for transmitting radial forces between said
shaft means and housing structure; said shaft means having a lower
thrust shoulder; a first thrust shoulder on said housing structure;
first thrust bearing means engaging said first shoulder; a second
thrust shoulder on said housing structure; second thrust bearing
means engaging said second shoulder; yieldable means engaging said
first bearing means; load transmitting means engaging said
yieldable means and lower shoulder to transmit drilling weight from
said housing structure through said first shoulder, first bearing
means and yieldable means to said lower shoulder; said second
bearing means being initially ineffective to transmit drilling
weight to said load transmitting means and becoming effective to
transmit drilling weight to said load transmitting means upon
predetermined yielding of said yieldable means when subjected to a
load exceeding a predetermined value.
11. Apparatus as defined in claim 10; and a third thrust bearing
between said housing structure and shaft means for axially
supporting said shaft means from said housing structure.
12. Apparatus as defined in claim 10; said yieldable means
comprising a yieldable ring adapted to deflect when subjected to
axial loads.
13. Apparatus as defined in claim 10; and a third thrust bearing
between said housing structure and shaft means for axially
supporting said shaft means from said housing structure; said
yieldable means comprising a yieldable ring adapted to deflect when
subjected to axial loads.
14. Apparatus as defined in claim 10; means providing a confined
space adapted to contain a liquid lubricant and in which said
radial bearing means and axial bearing means are contained; and
booster means for subjecting the liquid lubricant to a greater unit
pressure than the unit pressure externally of said confined
space.
15. Apparatus as defined in claim 10; means providing a confined
space adapted to contain a liquid lubricant and in which said
radial bearing means and axial bearing means are contained; and
booster means for subjecting the liquid lubricant to a greater unit
pressure than the unit pressure externally of said confined space;
said confined space being an annular space between said shaft means
and housing structure, said booster means defining an end of said
annular space and comprising an annular piston having a first
portion bearing against the lubricant and a second portion subject
to the pressure of the fluid externally of said annular space.
16. Apparatus as defined in claim 10; means providing a confined
space adapted to contain a liquid lubricant and in which said
radial bearing means and axial bearing means are contained; and
booster means for subjecting the liquid lubricant to a greater unit
pressure than the unit pressure externally of said confined space;
said confined space being an annular space between said shaft means
and housing structure, said booster means defining an end of said
annular space and comprising an annular piston having a first
portion bearing against the lubricant and a second portion subject
to the pressure of the fluid externally of said annular space, said
second portion having a greater transverse pressure responsive
annular area than the annular area of said first portion.
Description
The present invention relates to downhole drilling motor apparatus,
and more particularly to hydraulic motor apparatus of the positive
displacement type for attachment to a tubular drilling string for
drilling straight or deviated bore holes in earth formations.
Downhole drilling motors of the positive displacement type are
known, embodying a rotor and stator arrangement of the Moineau type
illustrated and described in U.S. Pat. No. 1,892,217. The rotor in
prior drilling motors has one lobe operating within a companion two
lobe stator made of rubber or corresponding elastomer material, the
rotor itself being a solid steel member. The rotor partakes of an
eccentric or orbital pass around the axis of the stator, producing
an excessive amount of vibration as a result of the orbiting speed
of the rotor, combined with its relatively high mass due to its
solid construction, resulting in a decreased life of the rotor and
of the parts of the motor associated therewith.
The drilling weight of prior motor apparatus is transmitted through
a bearing assembly to the motor shaft, this bearing assembly being
lubricated by the drilling mud or other fluid pumped down through
the string of drill pipe and through the motor itself. Since
drilling mud is very often sand laden, the bearings are operating
in an abrasive liquid, resulting in their relatively short life,
limiting the time that the apparatus can be used in drilling a bore
hole, with consequent requirements for moving the entire motor
apparatus from the bore hole and replacement of a substantial
number of its parts, or, for that matter, replacement of the entire
motor unit. Because of the use of the solid rotor, a dump valve
assembly is incorporated in the drilling string above the motor to
allow the drilling fluid to fill the drill pipe as the apparatus is
run in the bore hole and to drain from the drill pipe while coming
out of the hole.
The use of a single lobe rotor results in the rotor, drive shaft
and bit connected thereto operating at a relatively high speed, the
motor being capable of producing a low maximum torque. Such high
speed reduces considerably the drilling life of a drill bit,
shortens the life of the bearings, and increases the aforementioned
vibration difficulties. With a single lobe rotor, a limited fluid
pressure differential can only be used to prevent excessive fluid
slippage between the rotor and stator during orbital movement of
the rotor around the stator axis, with consequent reduction in the
horsepower developed by the drilling motor.
By virtue of the present invention, a downhold drilling motor is
provided having a multiple lobe rotor operating within a companion
multiple lobe stator. In a Moineau type of apparatus, the stator
has one lobe more than the rotor. With a drilling motor embodying a
multiple lobe rotor, the pressure differential that can be used
without an undesirable percentage of fluid slippage is far greater
than with a single lobe rotor. Accordingly, for a given pressure
differential, more drilling weight can be applied to the drilling
bit, or, conversely, a given drilling weight can be applied to the
bit with a less pressure drop across the drilling motor. Since the
torque developed for a given pressure is much greater than in the
prior drilling motors, and since the pressure differential across
the motor is greater, the combination of these factors results in
the capability of the motor to generate a far greater torque than
in the prior drilling motors. By way of example, since the torque
generated at any pressure differential in applicant's apparatus is
about one and three-fourths times that developed by prior devices,
the motor being operable at about twice the pressure differential
of the prior devices, the motor of the present invention is capable
of generating at least three and one-half times the torque of the
prior devices. Accordingly, while drilling, the present apparatus
has the capability of operating with about three and one-half times
as much drilling weight imposed on the drill bit.
With the present invention, the motor can develop the proper
horsepower while operating at much slower speeds than prior fluid
motors, permitting roller type drilling bits to be used without
increased damage to their parts, so that the drilling bits are
capable of drilling greater footages before requiring withdrawal
from the bore hole and replacement. The result is a considerable
saving in drilling cost per foot of hole, a lesser number of
drilling bits being required for drilling a required length of bore
hole, which is produced at greater drilling rates. Moreover, there
is a substantial reduction in the time required for making round
trips of the apparatus into and out of the bore hole for the
purpose of changing drilling bits.
By virtue of the present invention, the vibration of the rotor is
considerably reduced by making it hollow, which reduces its mass,
thereby contributing to long life of the motor and of the parts
associated therewith. The vibration is also reduced by the ability
to operate the drilling motor at reduced r.p.m.
Because of the use of a hollow rotor, with the advantages noted
above, a dump valve assembly can be incorporated in the rotor
itself, which is closed while drilling fluid is being pumped down
through the drilling string and the drilling motor, but which
automatically opens to permit the drilling mud or other fluid to
drain from the drill pipe, through the hollow rotor, motor shaft
and bit while the apparatus is being removed from a bore hole
filled with drilling mud or other fluid, the string of drill pipe
automatically filling with the drilling mud or other fluid in the
bore hole while the drill pipe and apparatus are being run in the
bore hole.
A further objective of the invention is to provide a bearing
assembly in the drilling motor that is sealed against entry of
external fluids and substances, such as the drilling mud, the
bearing assembly being filled with oil maintained at a higher
pressure than the pressure externally of the bearing assembly,
thereby insuring clean oil acting upon the bearings themselves
which contributes to the long life of the bearing assembly,
enhancing its ability to transmit drilling weight from the drilling
string and stator or housing portion secured thereto and to the
drill bit, as well as its ability to resist radial or lateral
motion of the motor shaft within the stator or housing.
A further object of the invention is to provide a bearing assembly
in a fluid drilling motor which is capable of safely transmitting
greater drilling weights from the drill string and stator or
housing to the drill bit. More particularly, a plurality of thrust
bearings are used in which one of the bearings normally carries the
weight being imposed on the drill bit up to a predetermined amount,
an additional bearing being brought into operation to transmit
drilling weight to be imposed on the bit in excess of the
predetermined amount.
This invention possesses many other advantages, and has other
objects which may be made more clearly apparent from a
consideration of a form in which it may be embodied. This form is
shown in th drawings accompanying and forming part of the present
specification. It will now be described in detail, for the purpose
of illustrating the general principles of the invention; but it is
to be understood that such detailed description is not to be taken
in a limiting sense.
Referring to the drawings:
FIG. 1 is a side elevational view of the apparatus secured to a
string of drill pipe thereabove and to a drill bit therebelow
disposed in a bore hole, such as a well bore.
FIGS. 2a, 2b, 2d, 2e, and 2f collectively constitute a
quarter-sectional view, parts being shown in side elevation,
through the apparatus illustrated in FIG. 1, and on an enlarged
scale, FIGS. 2b, 2c, 2d, 2e, and 2f being lower extensions of FIGS.
2a, 2b, 2c, 2d and 2e, respectively.
FIG. 3 is a cross-section taken along the line 3--3 on FIG. 2a;
FIG. 4 is a cross-section taken along the line 4--4 on FIG. 2a;
FIG. 5 is a cross-section taken along the line 5--5 on FIG. 2b;
and
FIG. 6 is a vertical section through the dump valve portion of the
apparatus disclosed in FIG. 2a, the valve being in its closed
position during operation of the drilling motor.
A hydraulic downhole apparatus M is illustrated in the drawings,
the upper portion of which is connected to a tubular string P, such
as a string of drill pipe extending to the top of a bore hole H,
such as an oil or gas well being drilled, and the lower end of
which is secured to a suitable rotary drill bit A having cutters B
for operating upon the bottom C of the bore hole. The drilling
apparatus includes an upper hydraulic motor portion 10 and a lower
drive shaft portion 11 connected to the rotary drill bit, a
universal joint assembly 12 being disposed between the upper and
lower portions. As disclosed, an outer housing structure 13 is
provided, including an upper sub 14 having a threaded box 15
threadedly secured to the lower pin 16 of an adjacent drill pipe
section P, this sub having a lower pin 17 threadedly secured to an
outer stator housing 18. The stator housing has mounted therein an
elongate elastomer rubber or rubber-like stator 19 having steeply
pitched helical lobes or threads 20 coacting with an elongate
metallic hollow rotor 21 having steeply pitched helical lobes or
threads 22 companion to the stator lobes. Details of the stator and
rotor lobes and their coaction are unnecessary to an understanding
of the present invention, since they are described in U.S. Pat. No.
1,892,217. The number of stator lobes 20 is one more than the
number of rotor lobes 22. As specifically illustrated, the rubber
or elastomer stator has four helical lobes, whereas the metallic
rotor has three lobes.
The lower threaded box 23 of the stator housing 18 is threadedly
secured to the upper end of an intermediate housing portion 24, the
lower pin end 25 of which is threadedly secured to a lower housing
portion or section 26 enclosing a bearing assembly 27 extending
between the motor shaft 11 and the housing 26, and which has the
purpose of resisting radial movement of the drive shaft within the
housing structure, and for transmitting drilling weight from the
string of drill pipe P through the housing structure 13 to the
drill bit A, to force the cutters B against the bottom C of the
bore hole.
The hollow rotor 21 has a lower threaded box 28 threadedly secured
to the upper end of a rotor extension 29 having side ports 30
establishing communication between a central passage 31 through the
rotor extension and a central passage 32 of the rotor which extends
to its upper portion, the latter carrying a valve assembly 33.
As shown, a valve seat 34 is threadedly secured within the upper
end of the rotor, this seat having lateral slots or openings 35 in
its upper portion. A valve or piston member 36 is movable
longitudinally within the seat, this piston including an upper
valve head 37 slidable along the inner cylindrical seat portion 38
of the seat, the valve head carrying a suitable elastomer or other
seal 39 therein adapted to seal against the cylindrical seat 38.
The intermediate portion 40 of the piston is reduced in diameter to
form an annular passage 41 with the valve seat, the lower portion
of the piston having an outwardly directed flange 42 provided with
a plurality of axial ports 43 extending therethrough establishing
communication between the annular passage 41 and the central
passage 32 through the rotor 21. A helical compression spring 44
has its lower portion bearing against a rotor shoulder 45 and its
upper portion against the flange 42 to urge the piston 36 upwardly
until the flange 42 engages the lower end 46 of the seat 34, at
which time the valve head 37 uncovers a portion of the seat
openings 35, permitting fluid to flow between the rotor passage 32
and the upper sub 14 and drill pipe P thereabove (FIG. 2a). When
fluid under pressure is being pumped down through the string of
drill pipe P, the valve piston 36 is shifted downwardly to an
extent limited by the flange 42 engaging an upper rotor shoulder 47
(FIG. 6), at which time the valve head 37 is disposed within the
cylindrical valve seat 34 and below the seat openings 35, thereby
closing the central rotor passage 32 to the flow of fluid
therethrough, the elastomer seal 39 preventing leakage between the
cylindrical seat 38 and the valve head 37.
The lower end of the rotor extension 29 is threadedly secured to
the upper end of an upper connector 48, the lower end of which is
operatively connected to an elongate universal joint assembly 12 of
any suitable type. This assembly includes two universal joints and
is somewhat inclined to the axis of the rotor, the lower end of the
assembly being secured to a lower connector 49 threadedly attached
to the upper end of a drive shaft extension 50, which, in turn, is
secured to the drive shaft 11 by a spline 50a. The universal joint
preferably has an elastic cover 51 suitably secured thereto to
prevent the drilling mud or other fluids flowing through the
apparatus from entering the universal joint structure and adversely
affecting the universal joints and the lubricant normally contained
within the cover. A suitable universal joint assembly, including
the two universal joints, is manufactured by the Apex Machine and
Tool Company, being illustrated in its catalog. Since the rotor 21
partakes of an eccentric or orbital movement around the axis of the
stator 19 during its rotation, the universal joint assembly 12
transmits such eccentric motion of the rotor to the motor drive
shaft 11, which is retained in a concentric relation with respect
to the housing structure 13.
The lower portion of the drive shaft 11 is constituted as a bit sub
52 having a lower threaded box 53 threadedly receiving the usual
upper pin 54 of the drill bit A, the pin and box being firmly
secured to and shouldered against one another, in a known manner.
The upper portion of the bit sub 52 has an upwardly facing shoulder
55 through which drilling weight is transmitted from the drill pipe
P and housing structure 13 to the bit sub 52 and to the drilling
bit A.
Radial and axial thrusts are transmitted through the bearing
assembly 27 between the drive shaft 11 and the outer housing
structure 13. An upper thrust ring 60 surrounds the lower portion
of the drive shaft extension 50, its inner portion overlapping an
external flange 61 at the lower end of the extension, the upper
surface of the thrust ring engaging a lower thrust shoulder 62
provided by the lower end 63 of the housing member 24. The lower
surface of this thrust ring 60 bears against an upper bearing
housing member 64, the upper end of which carries an external
elastomer side seal 65 sealingly engaging the inner wall of the
lower housing member 26, the lower end of the upper bearing housing
member being threadedly secured to a lower bearing housing member
66, the lower end of which is threadedly secured to a terminal
bearing housing member 67.
The bearing structure includes an inner upper sleeve 68 around the
drive shaft 11, the upper end of which is engaged by a nut 69
threaded on the drive shaft. The lower end of the sleeve 68 bears
against the inner race 70 of an upper radial bearing 71, of
suitable construction, this bearing preferably including roller
bearings (not shown), such roller bearings riding against the inner
wall of the upper bearing housing 64, an internal flange 72 on the
latter extending over the upper radial bearing 71 to prevent its
upward movement with respect to the housing member 64. This flange
has a filler port 73 extending therethrough that can be closed by a
plug 74 threaded into the outer portion of the port.
The lower portion of the upper radial bearing 71 rests upon a
thrust ring 75 which is engaged by a downwardly facing shoulder 76
provided by the terminus of the upper bearing housing member 64,
this thrust ring bearing against an axial upper thrust bearing 77.
As specifically illustrated, this bearing includes an upper race
78, a lower race 79, and intervening bearing balls 80, the lower
race resting upon an upwardly directed shoulder 81 of the lower
bearing housing member 66, the bearing itself surrounding a thrust
sleeve 82 extending from the upper radial bearing 71 to a load
transmitting ring 83 at its lower end. The lower race 79 of the
upper thrust bearing rests upon a thrust ring 84 that engages a
yield ring 85 which functions as a stiff spring. The yield ring
including upper and lower portions 86, 87 and an intermediate
outwardly bowed portion 88. The lower end of the yield ring bears
against an external flange 89 on the thrust sleeve 82. By way of
example, the yield ring 85 will deflect when subjected to axial
loading, but will not take a permanent set until after a load in
excess of a predetermined value, such as 20,000 pounds, has been
imposed thereon. When such load is exceeded, the outer housing
structure 13 and lower bearing housing member 66 can move
downwardly to a slight extent, so that a downwardly directed
shoulder 90 on the lower bearing housing member 66, which engages a
lower thrust ring 91, can force the latter against an intermediate
axial thrust bearing 92, including an upper race 93, a lower race
94 and intervening ball bearing elements 95, to engage the lower
race 94 with the load transmitting ring 83. This ring engages a
thrust sleeve 96 disposed within a lower axial load transmitting
bearing 97, the sleeve engaging the inner race 98 of a lower radial
bearing 99, the race 98 engaging a lowermost thrust sleeve 100
abutting a ring 101 that engages the bit sub shoulder 55. The lower
race 102 of the lowermost axial thrust bearing 97 rests upon a ring
103 which, in turn, rests upon the upper end 104 of a bearing
housing member extension 67 that is threadedly secured to the lower
bearing housing member 66.
The lower radial bearing 99 transmitting its load from the inner
bearing race 98 through roller or corresponding bearings (not
shown) to the extension 67, the outer portion of the lower bearing
99 resting upon an upwardly directed shoulder 105 on the extension.
The extension has a downwardly facing shoulder 106 resting upon a
companion upwardly facing shoulder 107 on the lower housing member
26, the extension having a filler port 108 extending therethrough
closed by a threaded plug 109. The entire bearing assembly can be
filled with lubricating oil by removing the upper and lower plugs
74, 109 and injecting the lubricant through the ports 73, 108 and
through the entire bearing assembly 27, this lubricating oil also
filling the annular space 110 between the upper sleeve 68 and upper
bearing housing member 64, as described hereinbelow. The plugs 74,
109 are then replaced to close the ports 73, 108.
The drilling mud, or other liquid externally of the bearing
assembly 27, is prevented from entering the bearing structure. The
upper sleeve 68 has a side seal 111 sealingly engaging the
periphery of the drive shaft 11, the lowermost sleeve 100 also
having an internal elastomer seal 112 engaging the periphery of the
drive shaft. This lowermost sleeve rotates with the drive shaft 11,
there being a rotating seal mounted in the lower bearing extension
67, including an inner seal member 113 engaging the periphery of
the lower sleeve backed by an elastomer seal ring 114. The external
pressure is transmitted to the oil in the bearing structure by an
annular booster piston 115 disposed in the annular space 110
between the upper sleeve and the upper bearing housing member. This
annular piston has a lower seal ring 116 engaging the inner wall of
the upper bearing housing member 64 and an upper seal ring 117
engaging the inner wall 118 of the upper bearing housing member 64,
this latter wall having a slightly greater internal diameter than
the internal diameter of the upper bearing housing member engaged
by the lower seal 116, an internal seal 119 bearing against the
periphery of the upper sleeve 68 to permit the upper sleeve to
rotate with respect thereto.
Fluid pressure acts downwardly over the annular booster piston 115
over the area S between the internal and external seals 119, 117 to
force the piston downwardly against the body of oil in the annular
bearing space 110. The lower portion of the annular piston has an
area R smaller than the area S between the internal seal 119 and
the lower seal 116 exerting its force against the oil, or other
lubricant, in the bearing assembly. Thus, the annular piston 115
functions as a booster, the total pressure exerted on its upper
portion acts over a smaller area R of the lower portion to impart a
greater unit pressure to the oil in the bearing assembly. It is to
be noted that a bleeder port 120 is provided through the upper
bearing housing member 64 between the upper and lower seals 117,
116 and a bleeder port 121 is also provided through the lower
housing 26 communicating with the other port 120 to prevent
entrapment of any fluid between the upper and lower seals.
In the use of the apparatus, the drill bit A is secured to the
lower end of the drive shaft 11 and the upper sub 14 is threadedly
secured to the lower end of the string of drill pipe P through
which the apparatus is lowered through the drilling mud in the bore
hole H to the bottom C thereof. During the lowering movement, the
dump valve 33 is in its open position, as illustrated in FIG. 2a,
which permits fluid to flow upwardly through the usual jets or
nozzles (not shown) in the drill bit into its central passage 122,
through the drive shaft passage 123, and into its extension 50,
from where the fluid flows outwardly through the side ports 124
into the annular space 125 above the bearing assembly and between
the housing structure 13 and the drive shaft extension 50, lower
connector 49, universal joint assembly 51 and the rotor extension
29, the annular space communicating with the lower end of the
elastomer or rubber stator 19. This fluid can continue flow
inwardly through the side ports 30 into the central passage 31 of
the rotor extension 29, from where it flows upwardly through the
passage 32 of the hollow rotor 21 and through the ports 43 in the
valve flange 42 into the annular space 41 between the valve piston
36 and the cylindrical seat 34, the fluid then flowing outwardly
through the openings 35 in the upper portion of the seat, and into
the upper sub 14 for continued flow in an upward direction through
the drill pipe P.
Because of the presence of the drilling motor 10 at the lower end
of the drill pipe P, it is not necessary to rotate the string of
drill pipe and the outer housing structure 13, which are actually
held stationary at the top of the well bore. Drilling mud or other
fluid is pumped down through the drill pipe P and into the upper
sub 14, the pressure of the fluid forcing the valve piston 36
downwardly to close the upper openings 35, as illustrated in FIG.
6. This closes the rotor passage 32, requiring the drilling mud to
flow through the spaces formed between the rotor 21 and rubber
stator 19, such fluid passing axially along the stator and rotor
and causing the rotor to rotate, fluid continuing to flow
downwardly until it discharges from the lower end of the elastomer
stator into the annular space 125. From the annular space,the
drilling mud, or other fluid, passes through the side ports 124 of
the shaft extension 50 into the shaft passageway 123, flowing from
such passageway into the drill bit passageway 122 and discharging
from its nozzles (not shown) against the cutters B and toward the
bottom C of the bore hole, for the purpose of cleaning the cutters
and flushing the cuttings in a lateral outward direction and
upwardly through the annular space in the well bore surrounding the
drill bit and the apparatus M, effecting drilling of the hole and
the removal of the cuttings therefrom to the top of the bore hole
H.
During the drilling action, an appropriate drilling weight is
imposed on the drill bit A by allowing a portion of the weight of
the drill pipe P to rest upon the housing structure 13. This
drilling weight is transmitted from the housing structure through
the upper thrust ring 60 to the upper bearing housing member 64,
and from its lower shoulder 76 through the thrust ring 75 to the
upper axial thrust bearing 77, from where it is transferred through
the thrust ring 84 to the yield ring 85 and to the flange 89 of the
thrust sleeve 82, which bears against the load transmitting ring
83. This ring bears against the thrust sleeve 96, the downward
thrust or load being transferred therefrom through the inner race
98 of the lower bearing and through the lower thrust sleeve 100 and
ring 101 to the bit sub shoulder 55. The drilling weight or force
is then transmitted through the bit sub 52 to the drilling bit A to
force its cutters B against and into the bottom C of the bore hole
H.
It will be noted that so long as the drilling weight imposed on the
bit does not exceed the load transmitting capacity of the yield
ring 85 before it begins taking a permanent set, the drilling load
is being transferred through the upper thrust bearing 77 only, the
initial distance between the intermediate thrust ring 91 and the
load transmitting ring 83 being greater than the axial extent of
the intermediate bearing 92. When the predetermined load
transmitting capacity of the yield ring 85 reaches a value at which
it commences taking a permanent set, the intermediate axial thrust
bearing 92 is engaged by both the lower thrust ring 91 and the load
transmitting ring 83, whereupon a certain portion of the drilling
weight is transferred from the shoulder 90 of the lower bearing
housing member 66 to the lower ring 91 and through the intermediate
bearing structure 92 to the load transmitting ring 83, this bearing
92 then transmitting its portion of the axial thrust or drilling
weight in parallel with the load that is being transmitted through
the upper axial thrust bearing 77. The intermediate thrust bearing
92 will transfer the additional load that exceeds the load at which
the yield ring 85 commences taking a permanent set. Accordingly,
both axial bearings 77, 92 are dividing the load, which prevents
the bearings from being overloaded and contributes to their greatly
extended life, and the effective drilling life of the drilling
motor itself. While the drive shaft 11 is being rotated by the
rotor 21 at the required speed, the radial bearings 71, 99 are
preventing the drive shaft from shifting laterally within the
housing structure 13, retaining it coaxial therewith.
In the event the drill bit A is lifted from the bottom C of the
bore hole while fluid is being pumped through the drilling motor
10, and the rotor 21, universal joint 12, drive shaft 11 and bit A
are rotated, the load transmitting ring 83 will rest upon the
lowermost axial bearing 97 to support the downward thrust imparted
on the rotor by the drilling fluid exerting against its lobes 22,
and the weight of the bit drive shaft 11 and the universal joint 12
thereabove. This load is transferred through the lower thrust ring
103 to the upper end 104 of the bearing sub 67.
All of the bearing parts are immersed in the bath of oil extending
from the lower fill port 108 up to the annular booster piston 115.
The pressure of the drilling mud is being imposed upon the annular
booster piston 115, exerting its force against the oil in the
bearing section, the unit pressure exerted against the oil in the
bearing section always being higher than the pressure externally
thereof, because of the fact that the area S of the upper portion
of the annular piston is greater than the area R of the lower
portion of the annular booster piston acting upon the oil. This
prevents the drilling mud or foreign fluids from entering the
bearing section and contaminating the oil, resulting in damage to
any of the bearing parts.
When the apparatus is to be removed from the bore hole, the pumping
of fluid down through the drill string ceases, relieving the
pressure on the drilling motor and the force holding the valve
piston 36 in its closed position (FIG. 6), the spring 44 shifting
the piston to its open position (FIG. 2a). Fluid can drain from the
drill pipe P, flowing downwardly through the openings 35, annular
passage 41, hollow rotor passage 32, and the side ports 30 into the
annulus 125, from where the liquid drains through the lower
extension ports 124 into the hollow drive shaft passage 123 and the
drill bit passage 122, exiting through its nozzle or jets into the
well bore H. Thus, the drill pipe P automatically drains while the
apparatus is being elevated in the bore hole to be removed at its
surface, preventing the pulling of a wet string; that is,
preventing the drilling mud from overflowing at the top of the bore
hole onto the rig floor, wetting the equipment and personnel.
As was pointed out above, for a given pressure differential of the
drilling fluid being pumped through the drilling motor when
drilling is taking place, the torque generated through use of the
three lobe rotor is about one and three-fourths times as great as
prior drilling motors of the Moineau type that use a single lobe
rotor only. The fluid drilling motor illustrated can be operated at
at least twice the pressure differential of the prior drilling
motors, which means that twice as much hydraulic horsepower can be
applied to the motor. This fact, coupled with the ability to
develop a torque of about one and three-fourths times as great as
the prior drilling motor at any given pressure, results in the
present motor being capable of generating at least three and
one-half times the torque of the prior drilling motors. While
drilling, because of such much greater torque, the motor has the
capability of permitting approximately three and one-half times as
much drilling weight to be imposed on the bit, as compared to prior
drilling motors.
The present drilling motor also rotates at a much slower speed than
prior drilling motors, with the pumping of drilling fluid at the
same volumetric rate and at the same differential pressure through
the motor. By way of example, pumping at a rate of 350 gallons per
minute at a differential pressure of 225 p.s.i., results in the
prior drilling motor rotating at about 400 r.p.m.; whereas the
present drilling motor operating under the same conditions rotates
at approximately 280 r.p.m. This permits drilling bits, designed to
operate at slower speed, to be used effectively with the present
drilling motor. It also results in a decrease in the amount of
vibration developed by the rotor, and this decrease in vibration is
further enhanced by the fact that the rotor is hollow, having a
much smaller mass than if it were solid. The use of the hollow
rotor enables the dump valve 33 to be built into the rotor itself,
permitting appropriate drainage of the drill pipe P while coming
out of the hole, and automatic filling of the drill pipe as the
apparatus is being run in the hole.
It is apparent that a drilling motor has been provided having a
much longer life than prior drilling motors, capable of developing
a much higher torque, and permitting a greater drilling weight to
be imposed upon the drill bit, if required. The longer life is in
part attributable to the slower rotating speed of the motor and to
the bearing assembly, which is sealed against entry of foreign
matter thereinto that would contaminate the lubricant, producing
damage to the bearing parts. Thus, the drilling motor is capable of
staying at the bottom of the bore hole a longer time, since the
drill bit rotating at a slower speed lasts longer, the increased
life of the drilling motor itself making it unnecessary to
prematurely pull the apparatus and drilling bit out of the
hole.
* * * * *