U.S. patent number 3,661,218 [Application Number 05/039,226] was granted by the patent office on 1972-05-09 for drilling unit for rotary drilling of wells.
Invention is credited to Cicero C. Brown.
United States Patent |
3,661,218 |
Brown |
May 9, 1972 |
DRILLING UNIT FOR ROTARY DRILLING OF WELLS
Abstract
A drilling unit for rotary drilling of wells using casing as the
drill string. The drilling unit is a self-contained assembly
designed to be bodily inserted and withdrawn through the bore of a
well casing string and comprises releasable latch means for
non-rotatively locking the structure to the casing; a rotary power
unit supported by the latch means and rotatively connected to a bit
assembly. The latter comprises a main or pilot bit and a plurality
of radially extendible and retractable underreamers actuated by
fluid pressure which may first be employed for driving the power
unit.
Inventors: |
Brown; Cicero C. (Houston,
TX) |
Family
ID: |
21904344 |
Appl.
No.: |
05/039,226 |
Filed: |
May 21, 1970 |
Current U.S.
Class: |
175/107; 175/104;
166/217; 175/258 |
Current CPC
Class: |
E21B
10/345 (20130101); E21B 4/02 (20130101); E21B
7/208 (20130101); E21B 10/64 (20130101) |
Current International
Class: |
E21B
10/34 (20060101); E21B 4/02 (20060101); E21B
7/20 (20060101); E21B 4/00 (20060101); E21B
10/00 (20060101); E21B 10/26 (20060101); E21B
10/64 (20060101); E21b 003/12 () |
Field of
Search: |
;175/257,258,276,286,261,263,107,104,97 ;166/217 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wolfe; Robert L.
Claims
What I claim and desire to secure by Letters Patent is:
1. In the rotary drilling of wells, the combination of:
a. a string of well casing;
b. a drilling assembly constructed and arranged to be bodily
inserted and removed through the bore of said well casing; said
assembly comprising:
i. anchor means for releasably securing said drilling assembly to
the lower end portion of said casing and against rotation relative
thereto, including;
i.sub.1. a landing shoe carried by the lower end of the casing and
having an annular recess circumferentially about the inner wall
thereof;
i.sub.2. a tubular cage slidably receivable in said shoe;
i.sub.3. anchor dogs mounted in the wall of said cage for radial
movement into and out of said recess;
i.sub.4. a setting sleeve slidably mounted in the bore of said cage
for movement between position actuating and releasing said anchor
dogs; and
i.sub.5. means initially securing said setting sleeve in the
dog-releasing position and releasable for movement to the
dog-actuating position by application of downward jarring force to
said sleeve;
ii. a rotary drive member secured to said anchor means; and
iii. a pilot bit and underreamer assembly secured to said drive
member for rotation thereby.
2. The combination of claim 1 wherein said anchor means
includes:
a. landing pins projecting inwardly from the inner wall of said
shoe below said recess; and
b. landing slots in the exterior of said cage positioned to receive
said landing pins to limit relative downward movement of said cage
and to hold said cage against rotation relative to said shoe.
3. The combination of claim 1 wherein said rotary drive member is
fluid pressure-operated.
4. The combination of claim 1 wherein said pilot bit and
underreamer assembly comprises:
a. a tubular body connectible to the lower end of said drive
member;
b. a pilot bit carried by the lower end of said body;
c. a plurality of angularly spaced underreamers pivotally mounted
to the body above the pilot bit for radial extension and
retraction;
d. actuating means mounted in said body normally biasing said
underreamers to extended position; and
e. releasable means initially securing said underreamers in
retracted positions.
5. The combination of claim 4 wherein:
a. said rotary drive member is operated by fluid pressure applied
through said casing; and
b. release of said releasable means is effected by said fluid
pressure.
6. The combination of claim 4 wherein said actuating means
includes:
a. plunger means slidably mounted in said body;
b. crank means operably connecting said plunger means to said
underreamers; and
c. coil spring means mounted in downwardly biasing relation to said
plunger means.
Description
Rotary drilling of wells is commonly performed using a string of
relatively small diameter drill pipe by which a larger diameter bit
is rotated to drill a bore hole of the desired diameter. Casing to
fit the large diameter bore hole is then inserted in the bore hole
to line and support the wall thereof. Drilling in the uncased bore
hole and the multiple operations involved in running separate
drilling and casing strings necessarily increase the cost of the
well and is subject to hazards of various types well known in the
drilling industry.
Various systems have been proposed for drilling using the casing
string as the drill pipe and such systems are disclosed in certain
of my earlier copending applications, to wit: Ser. No. 778,509,
filed Nov. 25, 1968 now U.S. Pat No. 3,552,507; Ser No. 803,911,
filed Mar. 3, 1969 now U.S. Pat. No. 3,552,508; and Ser. No.
857,046, filed Sept. 11, 1969 now U.S. Pat. No. 3,552,509. These
systems employ separate bit assemblies, which are designed to be
bodily inserted and removed through the casing and locked to the
lower end thereof for rotation by the casing. Such bit assemblies
include combinations of main or pilot bit with a plurality of
radially extensible and retractable underreamers.
As noted, the earlier systems contemplate arrangements in which the
casing string itself is rotated to drive the bit section. This
requires a rotary power apparatus at the surface to rotate or drive
the casing string, and while such systems are found to be practical
and reasonably successful, some problems occur which it is
desirable to avoid to make the system even more successful from a
practical standpoint. The principal problems include those arising
form the need to provide an effective power apparatus for rotating
the relatively large diameter casing particularly when the string
has reached an extended length as the bore hole attains
continuously increased depth.
The present invention contemplates an improved system which employs
the separate form of drilling unit which is bodily inserted and
withdrawn through the casing string, as in the earlier
applications, but which includes as a part thereof a rotary power
unit for driving the bit section while the casing string remains
stationary and is merely fed into the bore hole behind the bit as
the hole deepens. The power unit may be any of several known types
of hydraulic motor or turbine units or may be an electrically
powered motor of known design.
More specifically, the illustrative embodiment of the present
invention contemplates a drilling unit which comprises an anchor or
latch element for releasably securing the unit to the lower end of
the casing; a bit section comprising a main or pilot bit and a set
of radially extendible and retractable underreamers; and a rotary
power drive member connecting the anchor element to the bit. The
rotary drive member is in the form of a hydraulic motor which is
driven by pressure fluid, such as drilling mud pumped down through
the casing. The underreamers are pivotally mounted to the body of
the bit section and connected to an actuating plunger which is
spring biased to urge the underreamers to their extended positions.
The underreamers are initially secured in reacted position by shear
pins or the like which are breakable by fluid pressure applied to
the plunger, the pressure fluid being the same as that employed to
drive the power unit.
By the described system a well bore can be drilled to a desired
depth while the hole is being continuously lined with casing
without requiring rotation of the latter. The drilling unit can be
inserted into and removed through the bore of the casing as
required at any time during the drilling procedure.
Other and more specific objects and advantages of this invention
will become more readily apparent from the following detailed
description when read in conjunction with the accompanying drawing
which illustrates a useful embodiment in accordance with this
invention.
In the drawing:
FIGS. 1A and 1B, together, comprise a longitudinal sectional view
of the drilling tool inserted in the casing string on a running
string immediately prior to being locked to the casing; the
underreamers of the bit section being shown in their retracted
positions;
FIGS. 2A and 2B, together, comprise a view similar to FIGS. 1A and
1B showing the anchor element locked to the casing and the
underreamers in their extended relation;
FIG. 3 is a view similar to FIGS. 1A and 2A, showing the running
tool in process of being released from the anchor element;
FIG. 4 is a partial view of the tool portion illustrated in FIG. 3
showing a fishing tool in engagement with the anchor element
preparatory to effecting release thereof to permit withdrawal of
the drilling unit from the casing;
FIGS. 5 and 6 are cross-sectional views taken respectively on lines
5--5 and 6--6 of FIG. 1A;
FIG. 7 is a cross-sectional view taken in line 7--7 of FIG. 2B;
and,
FIGS. 8A and 8B, together, comprise a longitudinal sectional view
of the hydraulic power unit employed for rotating the bit
section.
Referring to the drawing, there is shown the lower end of a string
of pipe P, conventionally referred to as casing, to which is
threadedly connected a landing shoe 10 having a bore 11 matching
the bore of the casing, and flared at its lower end 12. A plurality
of angularly spaced splines or landing pins 13 project into bore 11
and an annular latching or anchor recess 14 is provided in the wall
of bore 11 a short distance above landing pins 13.
The drilling unit, designated generally by the letter U comprises
an anchor sub-assembly A, a power drive assembly B connected to the
anchor sub-assembly, and a bit section C connected to drive
assembly B for rotation thereby. The overall dimensions of the
drilling unit as a whole are made such that the unit may be bodily
inserted and withdrawn through the bore of casing P.
anchor sub-assembly A includes a tubular body 16 having an axial
bore 18 and terminating at its lower end in an externally threaded
pin 20 by which it is connected to the housing 22 of the power
drive assembly B. The upper end portion of body 16 is enlarged in
internal diameter to define the enlarged bore 24 enclosed by a
tubular cage 26. The latter has a plurality of angularly spaced,
rectangularly shaped, radial openings 28 in which correspondingly
shaped anchor dogs 30 are mounted for radial movement into and out
of anchoring engagement with recess 14. The extension of body 16 is
provided with a plurality of angularly spaced, longitudinally
extending spline slots 32 open at their lower ends to receive
landing pins 13 and closed at their upper ends to form landing
shoulders 34 to be engaged by pins 13 for landing the drilling unit
in the landing shoe 10 and forming a non-rotative connection
between the anchor sub-assembly and the landing shoe. The spacing
between shoulders 34 and openings 28 is made such that when the
anchor assembly is landed on pins 13, dogs 30 will be in
registration with recess 14. An annular seal element 36 is
circumferentially mounted in the exterior of body 16 between
shoulders 34 and openings 28 to seal off bore 11 below anchor
recess 14. The upper end of cage 26 is connected to a running
collar 38 which has an annular seal 40 circumferentially mounted in
the exterior thereof to seal off bore 11 above recess 14.
The anchor sub-assembly includes a tubular setting sleeve 42
mounted for axial sliding movement in bore 24 of the anchor cage.
Sleeve 42 carries an annular external enlargement 44 intermediate
its ends adapted to project anchor dogs 30 radially outwardly into
anchoring engagement in recess 14 when the sleeve is moved
downwardly sufficiently to move enlargement 44 behind the dogs
(FIG.2A) and to release the dogs for retraction from recess 14 when
the sleeve is subsequently moved upwardly to raise enlargement 44
above the dogs (FIG. 1A).
The external diameter of the portion of setting sleeve 42 above
enlargement 44 is made sufficiently less than the internal diameter
of collar 38 to provide an annular space 46 of sufficient width to
receive therebetween a shear sleeve 48. Setting sleeve 42 is
initially secured in its upper inactive position with respect to
dogs 30 by one or more shear screws 50 which extend transversely
through collar 38, shear sleeve 48 and into setting sleeve 42. When
thus shear-pinned together, the lower end of shear sleeve 48 rests
on the upper end of cage 26. The upper end of shear sleeve 48 is
provided with an inwardly extending lip 52 adapted to overhang an
external shoulder 54 on the running collar 56 carried by the lower
end of a conventional running tool string S, the details of which
do not form a part of this invention.
Power drive unit B may be of any suitable and known form capable of
rotating the bit section, the details of which do not form a part
of this invention. However, for purposes of this description, there
is illustrated in FIGS. 7A and 7B, more or less diagrammatically, a
form of power unit, commercially known as a "Dyna-Drill,"
manufactured by Dyna-Drill Company of Long Beach, California, which
is essentially a hydraulic motor of the Mayno screw type,
comprising a single thread rotor 60 running in a rubber lined
spiral passageway 61 and adapted to be rotated by hydraulic fluid
pumped down through casing P. Rotor 60 is suitably connected to a
drive shaft 62 the lower end of which carries a threaded pin 63 by
which the drive shaft is operatively connected to the bit section C
by means of a tubular coupling 64 having a threaded box 65 at its
upper end for receiving pin 63 and an externally threaded pin 66 at
its lower end.
Bit section C includes a tubular body 70 having a bore 71 and an
internally threaded box 69 at its upper end for receiving coupling
pin 66. The lower end of body 70 carries a tubular collar 72 having
an axial bore 73 and terminating in an internally threaded box 74
adapted to receive the hollow shank 75 of a conventional bit 76
which may be a roller-type bit as shown or may be a drag-type or
other known form of bit adapted to serve as the main or pilot bit
in boring the drill hole.
The wall of body 70 above collar 72 is provided with a plurality of
angularly spaced, longitudinal slots 68 in each of which is
pivotally mounted an underreamer, designated generally by the
letter R.
An annular piston 77 is slidably reciprocable in bore 71 above
slots 68 and forms the head of a downwardly extending tubular
plunger 78 having a bore 79 which opens through the center of
piston 77. The lower end of plunger 78 extends slidably through the
central opening 80 of a conical cap 81 closing the upper end of
bore 73 of collar 72. Plunger 78 is resiliently biased downwardly
by a strong coil spring 82 mounted in compression between piston 77
and the inner end of coupling 64.
Each of the underreamers R comprises a cutter arm 83 and a crank
arm 84 extending at an angle to the cutter arm. A pivot pin 85
extends transversely through the crank arm adjacent its juncture
with the cutter arm and is journaled in the walls of slot 68 (FIG.
7). The free end of the cutter arm carries an inwardly extending
cutter shaft 86 on which is rotatably mounted a frustoconical
cutter 87 of a generally conventional design. Crank arm 84 is
formed with an extension 88, the free end of which carries an
inwardly projecting crosshead pin 89 positioned in a crosshead slot
90 provided in a related side portion of plunger 78 (FIG. 7). With
this arrangement, it will be seen that movement of plunger 78
downwardly will act on crosshead pins 89 and thence through
extensions 88 and crank arms 84 to rotate the underreamers
outwardly while reverse movement of the plunger will act to retract
the underreamers. Since coil spring 82 normally tends to urge
plunger 78 downwardly and thereby bias the underreamers to their
extended positions, the underreamers are initially secured in the
retracted position (FIG. 1B) by means of shear pins 91 which extend
transversely through the cutter arm into the walls of the related
slots 68. Breaking of shear pins 91, as will be described
hereinafter, will release the underreamers for movement to their
extended positions.
A plurality of jets 92 are mounted in the walls of cap 81 and
directed so as to discharge fluid upwardly and outwardly at an
angle selected to cause the fluid to strike the teeth of the
extended cutters 87 to wash cuttings therefrom, as well as to
impinge on the wall of the well bore at points immediately in
advance of the cutters to apply a softening or erosive action
thereon which will improve the cutting efficiency of the
underreamers.
In operation, drilling unit U will be suspended from running string
S by the connection between running collar 56 and shear sleeve 48,
all of the several parts being in their inactive or retracted
positions as seen in FIGS. 1A and 1B. Running string S will usually
be a conventional wire line string including conventional jars (not
shown) by which jarring impacts can be directed through the running
string to the tools suspended thereon. The thus suspended drilling
unit will be lowered through the bore of casing P until the anchor
sub-assembly is landed on pins 13 in the landing shoe. Thereupon,
downward jarring blows applied through the running string will
serve to break the inner portions of shear pins 50 which secure
setting sleeve 42 to shear sleeve 48, the latter being held
stationary by its seating on the upper end of cage 26. Thereupon,
the downward jarring will drive setting sleeve 42 downwardly
sufficiently to move enlargement 44 behind dogs 30 projecting them
outwardly into recess 14 (FIG. 2A) and thereby anchoring the unit
to the landing shoe.
With the drilling unit thus anchored to the lower end of the
casing, upward pull, accompanied by upward jarring, if necessary,
will be applied through the running string and running collar 56 to
shear sleeve 48 to thereby apply sufficient upward force to break
the portions of shear pins 50 connecting shear sleeve 48 to collar
38 (FIG. 3). This releases the running string from the drilling
unit allowing the running string to be withdrawn from the casing
and leaving the drilling unit anchored to the lower end of
casing.
Fluid, such as water or drilling mud will now be pumped down the
casing and through the several connecting bores in the drilling
unit. The fluid will pass through passageway 61 actuating rotor 60
and shaft 62 to rotate the bit section. The pressure fluid
discharging from passageway 61 will flow into bore 71 of the bit
section applying pressure to piston 77 by reason of the flow
restriction formed by the reduced diameter flow passages defined by
bore 79 of the plunger and the still smaller diameter jets and wash
ports through which the fluid finally discharges from the bit
section. The fluid pressure thus applied to the plunger will
supplement the force of spring 82 sufficiently to break shear pins
91, thereby releasing the underreamers for movement to their
extended positions and being held extended by the combination of
the forces exerted by spring 82 and the fluid pressure while the
bit section is being rotated by the power drive unit. As the
drilling progresses, sections of casing will be added to the upper
end of the casing string similarly to the procedures employed in
conventional rotary drilling using ordinary drill pipe.
When necessary to withdraw the drilling unit from the casing in
order to repair or replace the pilot bit, underreamers or any other
part of the unit, then, as seen in FIG. 4, a fishing tool,
designated generally by the letter T, of any generally conventional
form, the details of which do not form a part of this invention,
will be run into the casing bore on a wire line or tubing string,
as desired, and will be latched beneath a downwardly facing
shoulder 93 in the bore of setting sleeve 42. On application of
upward pull to the fishing string, the setting sleeve will be drawn
upwardly moving enlargement 44 above dogs 30, to the position shown
in FIG. 1A, thereby releasing the dogs for retraction from recess
14. Continued upward pull will then draw the underreamers inside
landing shoe 10, the flared lower end 12 of the latter acting on
the underreamer arms to collapse the underreamers against the
opposition of spring 82 in response to the upward pull being
applied to the drilling unit and thus allow the entire drilling
unit to be withdrawn through the casing bore to the surface.
When drilling is to be resumed, the drilling unit, with the parts
in the original retracted positions, will be returned through the
bore of the casing to its lodgment in shoe 10, re-anchored therein
and fluid pressure reapplied to rotate the bit section and thereby
resume the drilling operation.
From the foregoing it will be evident that a drilling system is
provided in which the casing itself, which is ordinarily required
to line the previously drilled bore hole, will be continuously,
non-rotatively fed into the bore hole as the drilling proceeds,
thereby obviating all of the additional operations conventionally
required in rotary drilling and for casing the well. The hazards
accompanying the conventional drilling and casing operations,
including those arising from "round trips" of the drill string,
will be obviated, drilling operations greatly facilitated, and time
of operation substantially reduced.
While the illustrative embodiment discloses the use of a fluid
pressure-type power drive, it will be evident that drive unit B may
be a fluid operated turbine, or an electric motor. Various other
modifications and variations may be made in the details of the
illustrative embodiment within the scope of the appended claims but
without departing from the spirit of this invention.
* * * * *