Note: Descriptions are shown in the official language in which they were submitted.
Background of the In _ntlon
This disclosure relates to the perforation of a well
casing. It was designed specifically for use on water wells, but
can be used in conjunction wi-th steeL casings on any type of well
structure.
The need ~or perforating a well casing is well known in
the drilling industries. By perforating a casing at various depths
corresponding to the strata in which liquid is located, one can
combine the flow from several di~ferent layers to achieve the pro-
duction requirements of a particular well.
Various types of devices have been previously proposedfor perforating well casings. Laterally movable punches are exem-
pli~ied by the devices shown in the patents to Jobe United States
2,~82~913, Frogge United States 3,212,5~0 and Grable United States
3,720,262. These involve the application of substantial pressures
necessary to push a punch radially through a well casing and to
subsequently retrieve the punch for tool removal.
A fluid jet perforator is illustrated in United States
patent 3,266,571. Explosive perforators are used widely in oil
drilling operations. However, the cost of these devices is such
as to make them prohibitive in the drilling of a conventional
water weIl.
A number of United States patents granted in the period
from 1915 to 1924 utilized the rolling engagement of a toothed
wheel to perforate the casing of a well. These patents are as
follows: Graham 1,162,601; ~obIe 1,247,140; Baash 1,259,310;
Baash 1,272,597; Làyne 1,497,919; Layne 1,500,829; and Layne
1,532,5g2.
Most of these patents illustrating a toothed wheel per-
forating tool utilize inclined slots or guides to cam the wheelradially outward as the perforating tool is moved downwardly in a
well casing b~ mechanical foxce. They do not provide positive
control of the wheeI placement for accurate elevational position
ing of the resulting perforations. The last two patents to Layne
disclose a per~oxating wheel mounted on a pivoted arm. The arm is
wedged radially outward by a mechanical pin controlled by a cable
which can be pullecl at the working surface. The wheel pressure is
directed onto the pin, which will therefore be wedged within -the
tool under substantial forces. Mechanical arrangements must be
provided to accommodate possible breakage of the control cable.
~ hile these patents showing perforation by a rotatable
wheel illustrate projected developments more than fifty years old,
such perforating tools are not generally available on the market
today. The present device has been developed to provide a mechan-
ically simple and effective means for assuring the application of
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the substantial radial pressures required to perforate steel well
casings of the type conventionally used for water wells. ~he
present tool is designed specifically for use in conjunction with
conventional pneurnatic drilling equipment. No extraneous trigger-
ing devices, cables or mechanical interlocks are required. It
utilizes the pneumatic pressure conventionally available within
the drill rod to preset the wheel for rolling engagement with the
wall of the well casing. Actual peri~oration is accomplished by
rolling movement of the extended toot.hed wheel due to downward
movement of the tool under the influence of the connected drill
rod. Retraction of the wheel by reverse rolling movement is
assured upon the reversal of the movement oE the drill rod as the
tool is pulled upwardly.
~ ccording to one aspect of the invention, an apparatus
is provided for perforating a well casing located within a bore
hole, such apparatus including an upright elongated body arranged
along a central longitudinal axis and adapted to be inserted into
a well casing, means for mounting the upright body on the end of
a drill rod for imparting movement to the body relative to the well
casing in a direction generally parallel to the central longitud-
inal axis, roller means mounted along one side of the uprigh-t
elongated body for rolling engagement within the weIl casing,
wheel means having a plurality of outwardly extending teeth, car-
rier means pivotally mounted on -the upright body about a first
fixed axis perpendicular to the central longitudinal axis, means
rotatiny the wheel means on the carrier means about a second axis
spaced to one side of the first axis and parallel thereto, movable
piston means slidably mounted on the elongated body for recipro-
cating movement relative to the body and parallel to the central
30 axis, and means pivotally connecting the piston means and the car- -
rier means about axes relatively parallel to the first axis for
imparting angular movement to the carrier means about the first
axis between a first angular position in which the sebond axis is
elevationally below the first axis and the wheeI means is inwardly
clear of the well casing and a second angular position in which
the teeth of the wheel means extend beyond the side of the bbdy
and frictionally engage the well casing in opposition to the
roller means.
According to another aspect of the invention, an appa-
ratus is provided for perforating a well casing located within abore hole and comprising an elongated body having a central longi-
tudinal axis and being of a size to be received within the well
casing, guide means mounted on the body for engagement with the
well casing, carrier means pivotally mounted on the bodv about a
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first fixed axis perpendicular to the central axis, wheel means
having a plurality of peripheral outwardly extending teeth, means
rotatably mounting the wheel means on the carrier means about a
second axis parallel to the first axis and spaced to one side
thereof, movable piston means slidably mounted on the body for
motion parallel to the central axis, :means pivotally interconnect-
ing the movable piston means and the carrier means ahout axes
respectively parallel to the first axis for imparting pivotal move-
ment to the carrier means about the first axis in response to move-
ment of the piston means relative to the body in one direction so
that the carrier is moved between a first position having the teeth
spaced inwardly from the well casing to a second position having
the teeth in frictional engagement with the well casing, and means
on the body for moving it relative to the well casing in the one
direction for causing the teeth to perforate the well casing as
the continuing frictional engagement and rolling of the teeth rela-
tive to the well casing move the carrier means ~rom the second
position to a third position in which the teeth project through
the well casing.
Description of the Drawings
Fig. 1 is a transverse elevation view taken through the
perforator within a section of a well casing;
Fig. 2 is a similar fragmentary view showing the wheel
preset for rolling engagement against the well casing;
Fig. 3 is a second fragmentary view shbwing the perfora-
tion of the well casing; and
Fig. 4 is a side view of the perforator as seen gener-
ally along line 4-4 of Fig. 3, the well casing being broken away
for clarity.
Description of the Preferred Embodiment
The drawings illustrate an exemplary form of the per-
forator as used within a steeI casing at 10. This particular model
of the perforator is scaled for use on water weIl casings. The
standard casing having a six inch interior diameter is designed
to carry five or six gallons of water per minute. Such a casing
typically has a wall thickness of .250 inch. In water well drill-
ing, the standard procedure for perforating such a casiny is to
pull the casing upward to the yround surface, perforate it at the
desired elevation by a separate tool and procedure and return it
down the bore for use. This process is time consuming and risks
damage to both the bore and the casing.
The present tool is designed for use in conjunction with
a conventional pneumatic rotary drilling system. It can be used
with any type of drilling equipment if auxiliary air pressure is
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provided to the interior of -the drill rocls. The lower end of a
typical string of drill rods is show~ in E'ig. 1 at 18. The drill
rods are hollow and form a vertical air channel to the tool mech
anism at their lower end. The size of equipment used in con~unc-
tion with six inch standard water well casings typically employs
drill rods having a diameter of four and one half inches.
The drill rods 18 conventionally support a drilling bit
(not shown) which is turned by pressurized air supplied at the
surface equipment. Air under pressure is blown down through the
center of the drill rod 18. It turns the bit and exhausts through
the bit to ~low the drilled cuttings to the surface. Such drill-
ing systems are widely used today.
No modification of the drill rods or surface equipmen-t
is required to use the present perforator. However, before attach-
ing the tool, the conventional bit backflow valve (not shown) must
be removed from the lower end of the drill rod 18 to allow mounting
of the perforator tool~
The perforator frame is in the Eorm of an upright elon-
gated body essentially presented by two parallel metal plates 11.
The elongated body is arranged along a central longitudinal axis,
illustrated as vertical a~is A-A, coaxial with the axes of drill
rods 18 and weLl casing 10. Plates 11 are dimensioned to fit
freely within the well casing 10 to accommodate vertical movement
or turning movement about the casing vertical axis. They are
fixed to a horizontal cap 12 at their upper ends and are rigidly
spaced apart by a series of roller shafts that mount a front roller
13 and a pair of vertically spaced rear rollers 14 at the front
and back sides of the elonyated body respectiveIy. The rollers
13, 14 cooperate with four side rollers 15 received within the
respective plates 11, to engage the interior walls of the weIl
casing 10. Rollers 13, 14 and 15 serve as guide means to maintain
the elongated body in a coaxial position along the center axis of
well casing 10 and prevent collapsing of casing 10 as it is being
perforated.
The upper end of the elongated body is mounted to the
lower end of drill rod 18 by means of a threaded male connector
16 fixed to cap 12~ The connector 16 is complementary to the con-
ventional threaded lower end 17 provided on the lowermost section
of drill rod 18. The threaded connection between the elongated
body of the perforator and the drill rod permits the body to be
mo~ed vertically and to be'rotated about its ~entral vertical axis
in response to forces imparted to it through the drill rod 18.
Vertical and rotational movement of drill rod 18 is controlled by
conventional surface drilling equipment (not shown).
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Actual perforation of the casing 10 is accomplished by
rollin~ engagement Oe a wheel 22 having a plurality of radially
projected teeth 23 formed about its circular periphery. The teeth
23 are shaped to facilitate puncturing or piercing of the casing
10 as the wheel 22 rotates counterclockwise while rolling downward
within the casing. This rolling movement produced a vertical row
of evenly spaced openings or apertures 33 (Fig. 3).
The wheel 22 is rotatably supported to one side of a
pivoted carrier comprising a pair of carrier plates 20. The plates
20 straddle wheel 22. They are pivotally mounted at the center of
plates 11 by outwardly directed stub shafts 21. Shats 21 pivot-
ally mount carrier plates 20 on the elongated body about a first
axis B-B perpendicular to its central longitudinal axis A-A. The
shafts 21 are received through the respective plates 11, and piv-
otally mount carrier plates 20 about a first axis on the elon~ated
body or ~rame of the perforator. The plates 20 in turn rotatably
mount the wheel 22 about a second axis at a wheel shaft 28 parallel
to the fi.rst axis and spaced to one side th reof. Both the first
axis at shafts 2I and the second axis at shaft 28 are horizontal.
The operating mechanism is completed by a pneumatically
operated piston assembly. It includes a vertical shaft 24 slida-
bly recei.yed through the cap 12 for reciprocating movement along
the'yerti,cal axis o~ the weIl casing 10. The upper end of shaft
24 is enlarged at 25 and includes peripheral seals i.n sliding
engagement against the interior walls of the drill rod 18. Shaft
24 is surrounded by a compression spring 26 which yieldably urges
thè piston as~embly to its upper position shown in Fig. 1. It .is
movable downwardly in response to air pressure'within drill rod 18.
The'lower end of shaft 24 is operati~ely connected to
the carri,ex plates 20 by means of an interposed connecting link
27. Link 27 is pivoted to the carrier plates 20 abowt a third
horizontal axis by a transverse shaft 29. The axis of shaft 20
is positioned at the side of the first axis at 21 opposite.to the
location of the second axis at 28. Link 27 is pivotally connected
to shaft 24 of the piston assembly about a fourth horizontal ~xis
b~ a pivot connection 40. Both the third axis at 29 and the fourth
axis at 40:are also paxallel to the'second axis B-B.
Tha'wheel 22 is movably mounted on the elongatea body
for movement radially inward or outward reIative to the surround-
ing well casing. Fig. 1 illustrates the retracted or initialnon-operative position of wheel 22. In this first position, the
axis of wheel 22 is located at an eIevation below the elevation of
the axis B-B of the carrier plates 20 at the stub shafts 21 and
wheeI 22 is clear of the interior wall of cas.ing 10. The plates
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20 are angularl~ located by enyagement of an upper abutment or
stop 36 ~ixed to one plate 11. They are helcl agains-t s-top 36 by
the action of spring 26~
Fig. 2 illustrates the devlce in readiness for perfora-
tion o~ the well casing 10. Air pressure has been applied to the
upper end of the piston assembly, thereby forcing the carrier
pla-tes 20 to be pivoted in a counterclockwise direction from the
position shown in Fig. 1 to a condition at which the teeth 23 on
wheel 22 frictionally engage the interior wall of casing 10. The
air pressure re~uired at the piston assembly need not be sufficient
to pivot the carrier plates 20 to an angular position wherein the
well casing 10 would be actually perforated by the teeth 23.
Starting with wheel 22 in the position shown in Fig. 2
perforation is then accomplished by maintaining the air ~ressure
on the piston assembly as the elongated body o~ the perforator is
forced downwardly in the well casing by movement imparted to it
through drill rod 18. As illustrated in Fig. 3, this results in
continuing frictional engagement and rolling movement between the
teeth 23 of wheel 22 and the well casing 10. The downward direc-
tion of movement of the perforator is indicated by arrow 34 andthe direction of rotation of wheel 22 is indicated by arrow 35.
As the wheel 22 rolls, it is forced radially outwaxd by continued
pivotal movement o~ plates 20 to the third position shown in Fig.
3. In this third position, the carrier plate 20 has moved beyond
the position shown in Fig. 2 to a condition wherein the three axes
along the carrier plates 20 are aligned in a common horizontal
plane. This is defined by a lower abutment or stop 30 fixed to
the inside surface of one plate 11 in the pivotal path o~ movement
of a carrier plate 20. Stop 30 limits the downward movement of
the pivotal connection between the carrier plates 20 and the con-
necting link 27.
An abutment plate 31 spans the separation betwean the
plates 11 and has a vertical surface facing toward the wheel 22.
The plate 31 is located alongside the pivotal path of movement of
the ~nds of carrier plates 20 opposite to wheel 22. The inner
ends of carrier plates 20 include complementary sur~aces 32 shaped
to permit sliding engagement between the carrier plates and the
abutment plate 31 as the carrier plates 20 reach the horizontal
position shown in Fig. 3. Plate 31 serves as a fixed abutment
to resist the transverse pressure exerted on the wheel 22 as it
rolls along the well casing 10. It serves as a stationary back-
stop and rein-forces the pivotal connections between the carrier
plates 20 and the supporting parallel plates 11, in order that the
substantial lateral pressure required to perforate the steel well
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casing will not be transm:i-tted totall~ to the rotation~l bearings.
The use of the perforator is believed to be evident ~rom
the above disclosure. It can be readil~ attached to a conv~ntional
drill rod assembly and can be lowered to the desired elevation by
use of conventional drill control systems and techniques. When
wheel 22 is at the elevation at which perforations are desired,
it is readied for use by the application o~ air pressure through
drill rod 18. The resulting downward movement of shaft 24 swings
the carrier plates 20 and wheel 22 to the second or intermediate
condition shown in Fig. 2, with the teeth 23 in frictional engage-
ment with the interior wall o~ the well casing. Actual perfora-
tion is then accomplished by moving the tool downwardly by appli-
cation of force through the drill rod 18, which completes move-
ment of carrier plates 20 and wheel 22 (Fig. 3). When the desired
number of perforations have been completed, as monitored by the
distance moved along the drill rod 18, the application of pneu-
matic pressure through the drill rod 18 is terminated. Wheel 22
is then retracted by lifting the elongated body upwardly in the
well casing 20, allowing the teeth 22 to roll out of the perfora-
tions or apertures 33. The carrier plates are returned to theirfirst or retracted condition (Fig. 1) by the combined action of
the upward rolling mo~ement of wheel 22, the depending wheel
weight, and the force exerted on sha~t 24 by spring 26. Should
any mechanical components fail, the wheel 22 will be free to roll
and swing downwardly and inwardl~ as the per~orator is raised
from the well casing.
~ fter a desired row of perforations has been formed, the
wheel 22 can be retracted and the eIongated body can be angularly
rotated about the axis of the well casing 10 to position the wheel
22 at a different angular position for production of another row
of apertures. By raising and lowering the elongated bbdy at
several different angular positions, one can provide any desired
number of vertical rows o~ p~rforations or apertures through the
well casing.
The perforator is mechanically very simple, yet it pro-
vides accurate location o~ apertures along a vertical row. The
perforations are accomplished without distorting the well casing
configuration~ which is maintained by its engagement by the sev-
eral rollers 13, 14 and 15. These rollers prevent the casing ~rom
collapsing, The` two rear rollers 14, which are diametrically
opposite to the wheel 22 within the casing 10, provide a reaction
force in opposition to the pressure applied through the perforating
teeth 23. ~owever, this force is applied to a much larger area
and does not deform the casing itseIf.
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