U.S. patent number 3,552,508 [Application Number 04/803,911] was granted by the patent office on 1971-01-05 for apparatus for rotary drilling of wells using casing as the drill pipe.
Invention is credited to Cicero C. Brown.
United States Patent |
3,552,508 |
Brown |
January 5, 1971 |
APPARATUS FOR ROTARY DRILLING OF WELLS USING CASING AS THE DRILL
PIPE
Abstract
A drilling system employing casing as drill pipe and a bit
section which is bodily insertable and removable through the casing
and releasably attachable thereto for rotation with the casing.
Inventors: |
Brown; Cicero C. (Houston,
TX) |
Family
ID: |
25187747 |
Appl.
No.: |
04/803,911 |
Filed: |
March 3, 1969 |
Current U.S.
Class: |
175/258;
175/261 |
Current CPC
Class: |
E21B
10/66 (20130101) |
Current International
Class: |
E21B
10/00 (20060101); E21B 10/66 (20060101); E21b
009/26 () |
Field of
Search: |
;175/251,258,259,263,267,271 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Brown; David H.
Claims
I claim:
1. Apparatus for rotary drilling of wells using casing as the drill
pipe, comprising in combination with a string of casing and means
for rotating the same:
a. a bit section bodily insertable and removable through the bore
of the casing;
b. cooperating means on the bit section and the lower end portion
of the casing for landing the bit section in said lower end portion
in nonrotative relation to the casing;
c. said bit section comprising:
I. a generally tubular body;
Ii. radially movable anchor means mounted on the body for
releasably anchoring the body to the casing;
Iii. a pilot bit carried by the lower end of the body;
Iv, a plurality of angularly spaced underreamers mounted on the
body for radial movement between extended positions for enlarging
the diameter of the bore hole made by the pilot bit and positions
fully within the perimeter of said body;
v. piston means operably connected to said underreamers and
reciprocable in the bore of the body between upper and lower
positions respectively retracting and extending said
underreamers;
Vi. sleeve means in said body reciprocable with said piston means
between upper and lower positions respectively releasing and
actuating said anchor means; and
Vii. means initially securing said sleeve means and said piston
means to said body in said upper positions and releasable for
movement to said lower position in response to fluid pressure
applied to the piston means through the casing string whereby to
actuate said anchor means and to extend said underreamers.
2. The apparatus according to claim 1 wherein said initial securing
means comprise shear pins.
3. The apparatus according to claim 1 wherein said sleeve means
includes means adapted for engagement by a fishing tool to apply
upward pull to the sleeve means.
4. The apparatus according to claim 1 including means operably
connecting the piston means to each of the underreamers
comprising:
a. a crank arm angularly secured to the underreamer; and
b. crosshead pin-and-slot connections between the free end of the
crank arm and the piston means.
5. The apparatus according to claim 1 wherein said cooperating
means includes:
a. a tubular landing shoe secured to the lower end of the casing
string;
b. inwardly projecting splines in the bore of the shoe; and
c. spline grooves in the bit body open at their lower ends for
receiving the splines in response to relative downward movement of
the bit body.
6. The apparatus according to claim 5 wherein said anchor means
includes:
a. a plurality of angularly spaced latching dogs disposed in
openings in the wall of said body; and
b. an annular latching groove in the wall of said landing shoe
arranged for latching engagement with said dogs.
7. The apparatus according to claim 5 wherein said sleeve means
includes an annular relief groove about its exterior which is
registrable with said latching dogs when said sleeve means is in
said upper position to permit retraction of said latching dogs from
said latching groove.
Description
In the drilling of wells for oil and gas, for example, by the
rotary method, the drilling is conventionally done by the
employment of relatively small diameter string of drill pipe to
which a bit is secured, the entire string being rotated to drill
the bore hole. After a suitable interval has been drilled,
sometimes only a short distance but at other times for the full
depth of the well, casing larger in diameter than the drill pipe
will be run into the bore hole and subsequently cemented to seal
off the formations through which the bore hole extends. This
necessarily involves the series of operations in which the drill
string must be extended as the hole deepens, as by the addition of
sections to the drill pipe, and also the entire drill string must
be withdrawn wherever it becomes necessary to replace the bit and
then reinsert it to resume drilling. Thus making of such so-called
"round trips" are not only time consuming but also create hazards
of blowouts and other undesirable conditions in the well. After the
appropriate drilling of the hole has been completed, the drill
string must be withdrawn and casing run to the desired depth. This,
too, may present hazards because with the drill string out of the
well, control of the well becomes more difficult.
Heretofore numerous efforts have been made to provide a system
employing the casing itself as the drill pipe in order to overcome
some of the hazards enumerated, as well as time loss. However,
these prior efforts have not proven satisfactory for various
reasons well known to those skilled in the art.
The present invention, therefore, is directed to an improved
arrangement by which the casing may be employed as the drilling
string and when used in combination with a retractable or removable
bit section will perform all of the functions of drilling and
casing of a well in a sequence or series of operations which
thereby greatly facilitates drilling operations.
In accordance with the present invention a bit section is provided
which includes both the primary bit and a plurality of radially
extendible and retractable underreamers, the entire bit section
being arranged and constructed to be insertable bodily through the
bore of the casing and moved to the lower end of the casing either
on a wire line or by simply dropping it into the casing, where,
either by gravity alone or supplemented by pumped fluid pressure,
the bit section will be forced to the bottom of the lower end of
the casing string, which is provided with a landing shoe to receive
the bit section. The bit section is provided with latch means
engageable with appropriate grooves or other latch-receiving
structure in the landing shoe. The latter includes a number of keys
or splines which are adapted to engage appropriate spline slots or
grooves in the bit section to lock the bit section to the casing
against relative rotation whereby rotation of the casing string
will be effective to rotate the bit for purposes of drilling the
well.
The bit section also includes piston means connected by crank means
to the underreamers which will be actuatable from the upper end of
the casing string by drilling fluid circulating through the system
for purposes of extending or actuating the underreamers so as to
enlarge the bore hole drilled by the pilot bit sufficiently to
allow free downward movement of the casing behind the bit as the
hole is being drilled.
To withdraw the bit section a conventional fishing tool or spear is
run into the casing on a wire line and connected to the bit
section, whereby an upward pull applied to the fishing tool will be
effective to retract the underreamers and release the bit section
from the landing shoe to which it has been anchored. The spacing
arrangement between the underreamers and latching dogs is so
designed as to assure that the underreamers are fully retracted
before the bit section is released, thereby avoiding damage to the
underreamers which might otherwise occur if they were not
completely retracted when they pass the lower end of the landing
shoe.
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 the
present invention.
In the drawings:
FIG. 1 is a longitudinal, partly sectional view showing the bit
section inserted into the casing shoe preparatory to anchoring the
bit section to the casing shoe;
FIG. 2 is a view similar to FIG. 1 showing the bit section anchored
to the casing shoe and with the underreamers in their extended
position;
FIG. 3 is a view similar to FIG. 1 showing a fishing tool engaged
with the bit section, the parts being shown after release of the
bit section and with the underreamers in their retracted position;
and
FIG. 4 is a longitudinal view of the drilling system in a well bore
showing the casing string with the bit section in place and the
drive connections at the surface.
Referring to the drawing and considering first FIG. 4, there is
shown a string of casing C carrying the bit section, designated
generally by the letter B, showing the bit section in place in a
landing shoe 10 connected to the lower end of casing C. At its
upper end casing C is connected to a power sub P which functions to
rotate the casing string during drilling, as will be described.
Power sub P is of the general form and construction disclosed in my
copending application, Ser. No. 736,179, filed Jun. 11, 1968. A
suitable drive connection between the power sub and the casing is
disclosed in my copending application, Ser. No. 778,509, filed Nov.
25, 1968 now Pat. No. 3,467,202. Power sub P is suspended form a
swivel S carried on elevators E conventionally employed as part of
the draw works of a drilling rig. The swivel has a hose connection
H by which drilling mud is pumped into the drill string of casing
C, thence through the bit section into the annulus defined by the
bore hole surrounding the drilling string, the bore hole being
designated by the letter W.
Returning now to FIGS. 1 and 2, the landing shoe and bit section B
comprise the basic drilling structure which is secured to the
casing. Shoe 10 is provided with an internally threaded socket 12
by which it is threadedly secured to the lower end of casing C.
Adjacent its lower end shoe 10 is provided with two or more
angularly spaced pins 14 which project a short distance inwardly of
the bore of the shoe and form splines for purposes which will be
explained shortly.
Bit section B comprises a body 16 having a bore 17, and is
dimensioned to be insertable through the bore of casing C and into
the bore of shoe 10. Body 16 is provided about an intermediate
portion thereof with a plurality of longitudinal keyways or spline
grooves 18 adapted to receive the projecting ends of the pins 14,
whereby body 16 will be locked to shoe 10 against relative rotation
so that rotation of casing C will function to rotate body 16 and
its appurtenances. Spline grooves 18 terminate in upper end walls
19 which form stops for engagement with pins 14 to limit downward
movement of the bit body through shoe 10. An annular seal ring 20
is disposed about the exterior of body 16 above end wall 19 to seal
with the bore wall of shoe 10. At a point above seal 20, body 16 is
provided with a plurality of radial windows or openings 22 in which
are mounted latch dogs 24 which are adapted when projected
outwardly to be received in an annular latching groove 26 formed in
the bore wall of shoe 10. The latching dogs are positioned in body
16 so that they will be in registration with groove 26 when body 16
is fully inserted in the shoe and end walls 19 abutting pins 14.
The upper end of body 16 is internally threaded to define the box
or socket 28 adapted to threadedly receive a collar 30 having a
downwardly facing internal shoulder 32 spaced a short distance
below its upper end. The lower end of body 16 carries a downwardly
facing internally threaded socket 34 adapted to receive the
externally threaded shank 36 of a bit 38 which constitutes the
pilot bit and may be of any conventional design for drilling a bore
hole to any desired nominal diameter determined by the dimensions
of the pilot bit. At a point between the lower ends of splines 18
and socket 34, body 16 is provided with a plurality of
longitudinally extending radially opening slots 40 in which are
mounted underreamers 42 of any suitable and known design. These are
pivotally mounted on pivot pins 44 which extend transversely of the
respective slots for enabling the underreamers to be angularly
moved so as to be radially projected and retracted with respect to
the slots 40. The portion of bore 17 of the body which extends
between windows 22 and the upper ends of slots 40, defines a
cylinder 21 in which is slidably positioned an annular piston 46
having a seal ring 48 mounted in its outer periphery for slidable
sealing engagement with the wall of the cylinder. Piston 46 is
secured to the upper end of a square piston rod 50 having an axial
bore 51 which extends downwardly between the several underreamers
and projects through an axial opening 52 in the upper end of socket
34 and is slidable therein in response to the axial movements of
piston 46. An annular seal ring 54 is disposed in the wall of
opening 52 in sealing engagement about the lower end of piston 50.
Each of the underreamers 42 is fixedly connected to an angularly
extending crank arm 56 having its free end secured to a crosshead
pin 58 mounted in a crosshead slot 59 formed in the related side of
exterior of piston rod 50. With this arrangement it will be seen
that the movement of piston 46 downwardly will act through crank
arms 56 to rotate the underreamers outwardly and upwardly while
reverse movement of the piston will act to retract the
underreamers.
The upper end of piston 46 is secured to a setting sleeve 60 which
is inserted through collar 30 and is secured to the upper end of
piston 46 about its periphery by a threaded connection 62. The
upper portion of sleeve 60 is reduced in diameter externally to
provide the upwardly facing shoulder 64 adapted to abut shoulder 32
on collar 30. Setting sleeve 60 is initially retained in its
uppermost position at which shoulder 64 abuts shoulder 32 by means
of shear pins 66 which connect collar 30 to setting sleeve 60. Just
above connection 62 setting sleeve 60 is provided with an external
annular relief groove 68 which is adapted to receive dogs 24 when
they are retracted from latching groove 26. Relief groove 68 will
be disposed in registration with windows 22 and dogs 24 when the
setting sleeve is in its uppermost position, as shown in FIG. 1, so
that the dogs are free to move inwardly of body 16 out of grooves
26. In this position it will be also noted that piston 46 is
positioned in its uppermost position at which underreamers 42 are
fully retracted, also as shown in FIG. 1. The bore wall of setting
sleeve 60 is provided with the annular groove 70 for engagement by
a fishing tool, as will be described subsequently.
In operation, the bit section will be inserted into the upper end
of casing C and will be allowed to fall by gravity through the bore
of the casing until the bit is brought to a stop by the engagement
of pins 14 with end walls 19 of spline grooves 18. The lower ends
of spline grooves 18 ordinarily will be flared or widened
circumferentially in the well known manner to guide the spline
grooves 18 over pins 14 as the bit section seats in shoe 10. The
parts of the bit section will be positioned as illustrated in FIG.
1 in which the setting sleeve is held in its retracted position by
shear pins 66. Latching dogs 24 will thus be free to retract and
are effectively retracted into relief groove 68, whereby to allow
the free movement of the bit section through the casing and into
landing shoe 10.
It will be understood, of course, that instead of simply dropping
the bit head into the casing and allowing it to fall by gravity to
the bottom, it may be lowered on a wire line or other tool string
which will be releasably secured to setting sleeve 60 in a manner
and by means well understood by those skilled in the art. If the
force of gravity is not sufficient to cause the bit section to fall
freely into the landing shoe, it will be understood that by pumping
fluid, such as water or drilling mud, into the casing this will act
against the restriction formed by the bore of piston rod 50 to
provide hydraulic pressure sufficient to drive the bit section
downwardly through the casing through any obstructing mud or the
like, until it is effectively seated in shoe 10.
When the bit section is in place, pumping of fluid such as drilling
mud into the casing may be begun, or continued if previously begun
to seat the bit section, and as the pressure builds up against the
restriction formed by the bore of piston rod 50, a force will be
attained sufficient to break shear pins 66, whereupon setting
sleeve 60, piston 46, and piston rod 50 will be forced downwardly
by the fluid pressure. The downward movement, acting through
crosshead pins 58 and crank arms 56 will rotate underreamers 42
outwardly to the positions shown in FIG. 2. As the underreamers
move outwardly and setting sleeve 60 moves downwardly the exterior
portion of the setting sleeve above relief groove 68 will pass
behind dogs 24, and by reason of the enlarged diameter of the
sleeve, will force the dogs outwardly into latching groove 26,
thereby effectively anchoring the bit section to the landing shoe.
The positions of the parts with the reamers extended and the bit
section latched to the landing shoe is shown in FIG. 2.
It will be understood, of course, that the casing string will be
rotated initially to cause pilot bit 38 to initiate drilling of the
bore hole and as drilling proceeds, fluid pressure will be exerted
against piston 46 to extend the underreamers which will radially
enlarge the bore hole cut by the pilot bit to a diameter which will
allow free passage of casing string C so that it will follow
directly behind the pilot bit and will continuously line the bore
hole as drilling proceeds.
The drilling fluid circulation will be through hose connection H,
swivel S and through a conduit in power sub P into the bore of
casing C. Thence, through the bit section, the fluid flowing
through the bore of piston 46 and piston rod 50 to the discharge
passages in the pilot bit and the underreamers. The mud flush will
return to the surface through the annulus between well bore W and
casing C. The flow restrictions provided by the bore of the piston
rod and the bit passages will assure the maintenance of sufficient
hydraulic pressure against the piston to keep the underreamers
extended as long as pump pressure is being applied.
When necessary to withdraw the bit section from the casing in order
to replace or repair the pilot bit, underreamers or any other part
of the bit section, 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 if desired, and will be
latched into groove 70 of the setting sleeve. On application of
upward pull to the fishing string, the setting sleeve will be drawn
upwardly pulling piston 46 and piston rod 50 upwardly, thereby
causing underreamers 42 to be swung inwardly of slots 40. The
spacing provided between relief groove 68 and shoulder 64 is
selected so that underreamers 42 will swing inwardly and to the
fully retracted position in slots 40 before relief groove 68 moves
opposite dogs 24 and shoulders 32 and 64 are engaged. Stated
otherwise, the distance through which setting sleeve 60 is moved
upwardly in order to allow retraction of dogs 24 will be greater
than the length of upward movement of piston rod 50 which will be
required to cause the underreamers 42 to be fully retracted. In
this way, the underreamers will be fully retracted and will not
strike the lower end of the landing shoe before the bit head is
released by retraction of dogs 24 and thereby damage to the
underreamers will be avoided.
With the underreamers in their fully retracted position, as shown
in FIG. 3, and dogs 24 also released for retraction into relief
groove 68, the entire bit section can then be pulled out of the
casing for repair, replacement or for whatever purpose may be
required. If drilling for a desired interval has been completed,
withdrawal of the bit section will place the casing in condition
for cementing. The landing shoe may be employed to receive the
usual cementing valve, if desired.
When drilling is to be resumed, the bit section, with the parts in
the original retracted positions, will be returned through the bore
of the casing to its lodgment in shoe 10, fluid pressure reapplied
to anchor the bit section and extend the underreamers, and drilling
will be resumed as previously described.
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 bore hole will be used as the drilling string and will be
continuously fed into the 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.
It will be understood that various changes and modifications 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.
* * * * *