U.S. patent number 3,878,903 [Application Number 05/421,548] was granted by the patent office on 1975-04-22 for apparatus and process for drilling underground arcuate paths.
Invention is credited to Martin Dee Cherrington.
United States Patent |
3,878,903 |
Cherrington |
April 22, 1975 |
APPARATUS AND PROCESS FOR DRILLING UNDERGROUND ARCUATE PATHS
Abstract
An improved apparatus and process for drilling an inverted
underground arcuate path is disclosed. A drill rig having an acute
angle of attack from the horizontal is placed interiorally of a pit
where it enters the ground typically normal to the sidewall of the
pit. A drill string powering a motorized drill is urged downwardly
into the ground by the drill rig. The drill at the drilling end of
the drill string has a slight angle imparted thereto. As the drill
string is urged into the ground and the drill is angularly aligned
with respect to the string, an inverted arcuate path is bored by
the drill so as to enter the ground downwardly and angularly at an
entrance point and to exit the ground upwardly and angularly at an
exit point with an inverted arcuate path therebetween. Parameters
for controlling the arcuate path without withdrawing of the drill
string to change drills or drill alignment are disclosed.
Specifically, by slowing drill speed, increasing thrust on the
drill string, and/or aligning the angularlity of the drill to
vector upwardly the radius of curvature of the drill path can be
decreased. Conversely, by increasing rotational drill speed,
decreasing thrust on the drill string, or aligning the bend of the
drill string to vector horizontally or downwardly, the radius of
curvature of the inverted arcuate path can be increased.
Inventors: |
Cherrington; Martin Dee
(Sacramento, CA) |
Family
ID: |
23670998 |
Appl.
No.: |
05/421,548 |
Filed: |
December 4, 1973 |
Current U.S.
Class: |
175/45; 175/61;
175/107; 175/73 |
Current CPC
Class: |
E21B
4/02 (20130101); E21B 7/068 (20130101) |
Current International
Class: |
E21B
7/04 (20060101); E21B 7/06 (20060101); E21B
4/00 (20060101); E21B 4/02 (20060101); E21b
047/02 () |
Field of
Search: |
;175/61,73,75,101,103,74,76,45,107 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Abbott; Frank L.
Assistant Examiner: Favreau; Richard E.
Attorney, Agent or Firm: Townsend and Townsend
Claims
What I claim as new is:
1. A method for drilling underground an inverted arcuate path
beneath an obstacle comprising the steps of: providing a drill
string; providing a drill head having at least one cutting drill
bit at the end of said drill string operative to cut independent of
rotation of said drill string, said drill head having an angular
axial alignment with respect to the axis of said drill string;
thrusting the drill string angularly downward into the ground at an
angle other than vertical; powering said drill bit through said
drill string simultaneously with said thrusting step; surveying the
azimuth and declination of said drill string proximate said drill
head at a plurality of intervals during said drilling and measuring
the length of said drill string in the ground at a correspondent
plurality of intervals from entrance into the earth at one side of
said obstacle to exit from the earth at the other side of said
obstacle whereby the path of said drill under said obstacle can be
determined; and, varying said thrust of said drill string to change
the radius of curvature of said inverted arcuate path.
2. A method as recited in claim 1 wherein said varying said thrust
includes increasing the force on said drill string to decrease the
radius of curvature of the inverted arcuate path.
3. The method of claim 1 wherein said thrusting step includes
decreasing the force on said drill string to increase the radius of
curvature of the inverted arcuate path.
4. The method of claim 1 and varying the speed of said drill head
to change the radius of curvature of said inverted arcuate
path.
5. The method of claim 1 and wherein said powering step includes
powering said drill head through said drill string by fluid
supplied to a motor operatively connected to said drill bit, and
including the step of varying the pressure of said fluid to said
motor to change said radius of curvature.
6. The invention of claim 1 and including the step of rocking said
drill head from side to side by turning said drill string to change
the radius of curvature of said inverted arcuate path.
7. A method for drilling underground an inverted arcuate path
beneath an obstacle comprising the steps of: providing a drill
string; providing a drill head having at least one cutting drill
bit at the end of said drill string operative to cut independent of
rotation of said drill string; said drill head having an angular
axial alignment with respect to the axis of said drill string;
thrusting the drill string angularly downward into the ground at an
angle other than vertical; powering said drill bit through said
drill string simultaneously with said thrusting step; surveying the
azimuth and declination of said drill string proximate said drill
head at a plurality of intervals during said drilling and measuring
the length of said drill string in the ground at a correspondent
plurality of intervals from entrance into the earth at one side of
said obstacle to exit from the earth at the other side of said
obstacle whereby the path of said drill under said obstacle can be
determined; and, varying the speed of said drill bit to change the
radius of curvature of said inverted arcuate path.
8. A method as described in claim 7 wherein said varying of the
speed of said drill bit includes the step of increasing the
rotational speed of said drill bit to increase the radius of
curvature of said inverted arcuate path.
9. The method as described in claim 7 wherein said varying the
speed of said drill bit includes the step of decreasing the
rotational speed of said drill bit to decrease the radius of
curvature of said inverted arcuate path.
10. The invention of claim 7 and including the step of varying the
thrust of said drill string to change the radius of curvature of
said inverted arcuate path.
11. The method of claim 7 and including the steps of powering said
drill head by fluid communicated through said drill string to a
motor operatively connected to said drill bit and controlling the
radius of curvature of said inverted arcuate path by varying the
pressure of said fluid.
12. The invention of claim 7 and including the step of rocking said
drill head from side to side by turning said drill string to change
the radius of curvature of said inverted arcuate path.
13. A method for drilling underground an inverted arcuate path
beneath an obstacle comprising the steps of: providing a drill
string; providing a drill head having at least one cutting drill
bit at the end of said drill string operative to cut independent of
rotation of said drill string, said drill head having an angular
axial alignment with respect to the axis of said drill string;
thrusting the drill string angularly downward into the ground at an
angle other than vertical; powering said drill head through fluid
supplied under pressure through said drill string to a motor
operatively connected to power said cutting drill bit; surveying
the azimuth and declination of said drill string proximate said
drill head at a plurality of intervals during said drilling;
measuring the length of said drill string in the ground at the
correspondent plurality of intervals from entrance into the earth
at one side of said obstacle to exit from the earth at the other
side of said obstacle whereby the path of said drill under said
obstacle can be determined; and, varying the pressure of said
drilling fluid through said drill string to control the radius of
curvature of the inverted arcuate path.
14. The invention of claim 13 and including the step of varying
said thrust of said drill string to change the radius of curvature
of said inverted arcuate path.
15. The invention of claim 13 and including the step of changing
the speed of said drill head to change the radius of curvature of
said inverted arcuate path.
16. The invention of claim 13 and including the step of rocking
said drill head from side to side by turning said drill string to
change the radius of curvature of said inverted arcuate path.
17. The method as recited in claim 13 wherein said powering step
comprises increasing the pressure of drilling fluid through said
drill string to increase the radius of curvature of said inverted
arcuate path.
18. The invention of claim 13 and including the step of decreasing
the pressure of drilling fluid through the drill string to decrease
the radius of curvature of said inverted arcuate path.
19. A method for drilling underground an inverted arcuate path
beneath an obstacle comprising the steps of: providing a drill
string; providing a drill head having at least one cutting drill
bit at the end of said drill string operative to cut independent of
the rotation of said drill string, said drill head having an
angular axial alignment with respect to the axis of said drill
string; thrusting the drill string angularly downward into the
ground at an angle other than vertical; powering said drill head
through said drill string simultaneously with said powering and
said thrusting step; surveying the azimuth and declination of said
drill string proximate said drill head at a plurality of intervals
during said drilling and measuring the length of said drill string
in the ground at a correspondent plurality of intervals from
entrance into the earth at one side of said obstacle to exit from
the earth at the other side of said obstacle whereby the path of
said drill under said obstacle can be determined; and, varying the
azimuth of the drill string about the axis of said drill string by
rocking said drill head from side to side by turning said drill
string to change the radius of curvature of the inverted arcuate
path.
20. The invention of claim 19 and including the step of varying
said thrust of said drill string to change the radius of curvature
of said inverted arcuate path.
21. The invention of claim 19 and wherein said powering of said
drill bit is provided by pumping fluid under pressure to a motor in
said drill head operatively connected to said drill bit through
said drill string; and, varying said pressure of said fluid through
said drill string to control the radius of curvature of said
inverted arcuate path.
22. The invention of claim 19 and including the step of varying the
speed of said drill bit to change the radius of curvature of said
inverted arcuate path.
Description
BACKGROUND OF THE INVENTION
The present invention relates to drilling inverted underground
arcuate paths from one surface point to another.
The traditional method for laying pipelines, telephone cables and
other underground conduits is to dig an open trench, lay the
conduit in the trench and then close the trench. This method is
quite efficient in general, but problems arise when an obstacle
such as a water course or a heavily traveled road is encountered,
and the conduit must traverse the obstacle.
When a road is encountered, the road must either be closed, the
traffic diverted, or parts of the road closed and the conduit laid
in sections, all of which are inconvenient and interfere
substantially with the use of the road. When a conduit must span a
water course, other problems arise. First, the trench must be dug
to a depth considerably below the level at which the conduit is to
be laid since the current will partially fill the trench before the
conduit can be inserted. This is a significant problem because such
trenches have a generally triangular cross section, and the volume
of dirt which must be removed increases with the square of the
depth of the trench. Such trenching also stirs the alluvium at the
bottom of the water course interfering with the natural flora.
Even after a trench has been dug in a water course, difficulties
arise in placing the conduit therein. One method of placing the
conduit is to float it across the span of the water course and then
remove its buoyancy to sink the pipe into the trench. The
difficulty with this method is that the water course must be closed
to traffic, floating objects are trapped by the floating conduit,
the current of the river bends the conduit, and when the conduit is
sunk, it quite often misses the trench. A second method is to
attach a sled or skid to the leading end of the conduit, and drag
this leading end through the trench to lay the conduit. With this
method, the conduit must be coated with a substance to give it
negative buoyancy, and this coating is quite expensive since the
entire length of the conduit must be so coated.
Traditional methods of digging wells cannot be adapted to digging
arcuate paths such as that required for implacing a pipeline or
other conduit under an obstacle. Such methods utilize a drill
string which enters the ground substantially normal to its surface,
and the path must undergo a 180.degree. turn to span the obstacle.
Such a path would result in the drill string extending vertically
upwardly at the other side of the obstacle with the weight of the
drill string acting against the forward motion of the drill. Since
the weight of the string is used to drive the drill, such a method
cannot be used.
Traditional well drilling methods rely on the weight of the pendant
drill string to achieve a substantially vertical hole. When an
angular bend in the hole was desired, it was formerly the practice
to lower a whip stock shim into the bottom of the hole which forced
the drill off at an angle. Later methods utilize a self-powered
drill which has a drill stem slightly angularly inclined with
respect to the drill string. The problem with both of these methods
is that the entire drill string must be removed from the hole,
either to lower the whip stock or to mount the inclined drill.
After the angle has been made, the entire drill string must be
withdrawn again to remove either the whip stock or the inclined
drill. This is extremely time consuming and inefficient since drill
strings may be many thousands of feet in length. Furthermore, these
methods provide no means for controlling the bend along its length
other than removing and replacing the drill string whenever a
change in angle is desired. Hence, these methods are unacceptable
for drilling controlled arcuate paths and can only be used for
intermittent bends and/or constant radius turns.
Techniques have been developed for drilling holes along a
substantially linear horizontal path for placing telephone lines
under streets and the like. However, these methods employ drills
which proceed in a straight line, and to achieve an arcuate path, a
pothole must be dug and the drill manually redirected. Such a
method is often acceptable in traversing obstructions such as a
road, but cannot be used for traversing a water course because the
required potholes cannot be dug.
SUMMARY OF THE INVENTION
The present invention provides an apparatus and process for
drilling an inverted underground arcuate path. A drill rig having
an acute angle of attack from the horizontal is placed interiorally
of a pit where it enters the ground typically normal to the
sidewall of the pit. A drill string powering a motorized drill is
urged angularly downwardly into the ground by the drill rig. The
drill at the drilling end of the drill string has imparted thereto
an angle usually in the range of 1.degree.-10.degree. but possibly
larger. As the drill string is urged into the ground and the drill
is angularly aligned with respect to the string, an inverted
arcuate path is bored by the drill so as to enter the ground
downwardly and angularly at an entrance point and to exit the
ground upwardly and angularly at an exit point with an inverted
arcuate path therebetween. Parameters for controlling the arcuate
path without withdrawing of the drill string to change drills or
drill alignment are disclosed. Specifically, by slowing drill
speed, increasing thrust on the drill string, and/or aligning the
angularity of the drill to vector upwardly the radius of curvature
of the drill path can be decreased. Conversely, by increasing
rotational drill speed, decreasing thrust on the drill string, or
aligning the bend of the drill string to vector horizontally or
downwardly, the radius of curvature of the inverted arcuate path
can be increased.
The present invention allows for drilling a hole beneath a surface
obstacle to avoid the necessity of utilizing the standard trenching
method for laying a conduit across the obstacle. When the obstacle
is a road or water course, traffic along that obstacle is in no way
impeded. Ecological disturbances such as interfering with the
natural flora on a river bottom are minimized. The conduit can be
placed far below the depth of the water course so that shifts in
the water course will not expose it. Also, the entrance and exit
points of the conduit can be far removed from the edge of the
obstacle so that levies and natural shores need not be breached.
Furthermore, all of the aforementioned difficulties associated with
laying a pipe in a trench are eliminated.
The present invention provides means for controlling the course of
the inverted underground arcuate hole as it is being drilled. The
following parameters are utilized: thrust on the drill string,
speed of the drill rotors, volume of drilling mud passed to the
drill, and azimuth of the inclined drill bit. By manipulating these
parameters, the pitch of the drill bit as it travels is
controllable to allow the path of the drill bit to be selectively
varied as the hole is being drilled. This allows for continuous
drilling of the hole from the entrance to the exit, and eliminates
the necessity for removing and replacing the drill bit or other
apparatus, greatly reducing the time and expense required to drill
the hole.
The novel features which are believed to be characteristic of the
invention, both as to organization and method of operation,
together with further objects and advantages thereof will be better
understood from the following description considered in connection
with the accompanying drawings in which a preferred embodiment of
the invention is illustrated by way of example. It is to be
expressly understood, however, that the drawings are for the
purpose of illustration and description only and are not intended
as a definition of the limits of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective schematic cross-section of the operation of
the present invention in drilling an inverted arcuate hole under a
water course;
FIG. 2 is a side elevation view of the inclined drill rig of the
present invention;
FIG. 3 is a fragmentary side elevation section of the drill head
utilized in the present invention;
FIG. 4 is a side elevation section illustrating the control over
the drill head achieved by the present invention;
FIG. 5 is a plan section illustrating a different manner of control
over the drill head of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The schematic view of FIG. 1 illustrates a water course 10 having
banks 12 and 14. A house 16 is located on bank 14. An underground
inverted arcuate hole along path 18 passes from adjacent the
surface on bank 12 to adjacent the surface on bank 14. A plurality
of discrete survey points 20 are located along path 18. It should
be noted that path 18 passes between the bottom of water course 10
and a layer of shale 22. The arcuate hole 18 of FIG. 1 is formed by
an inclined drill rig apparatus 24 located on bank 12 of water
course 10. The hole is dug from its entrance point on bank 12 to an
exit point on bank 14 past house 16 utilizing the method and
apparatus of the present invention.
The inclined drill rig apparatus 24 of the present invention is
illustrated in more detail by way of reference to FIG. 2. Apparatus
24 includes ramp 30 mounted to the ground 32 in a pit 34. Forward
wall 36 of pit 34 is inclined with respect to horizontal 38 and is
adapted to be normal to the slope of the inclined ramp 30. The
appropriate angle of declination of ramp 30 is governed by the
length and depth of the desired arcuate hole and is hence variable.
Angles of declination from 5.degree. to 35.degree. down from
horizontal have been utilized in practice with the preferred range
lying between 10.degree. and 30.degree. to achieve the desired
control over the drill head. FIG. 2 illustrates a mid-range angle
of declination from the horizontal of 22.degree..
A power source 40 rides along ramp 30 on wheels 42. Movement of
power source 40 along the ramp is controlled by the use of line 44
which dead ends at the extremeties of the ramp, but which wraps
around a powered winch 46 on power source 40. Power source 40 is
usually an internal combustion engine having a plurality of power
take-off attachments, but a wide variety of power sources could be
employed. Power source 40 is utilized to thrust the drill string 48
angularly downwardly into ground 50 as illustrated by arrow 52 by
driving winch 46. Controls are provided for winch 46 to control the
forward thrust on drill string 48. Drill string 48 comprises a
plurality of drilling pipes as known in the oil well drilling art,
and in fact, standard oil well drilling materials are used to form
the drill string. In the present invention, drill string 48
ordinarily does not rotate to operate the drill, but is rotatable
in azimuth about its axis to control the drill head as will
hereinafter be illustrated. Hence, power source 40 is capable of
providing selective rotational control over the azimuth of drill
string 48 as well as thrusting the drill string into the ground by
means of winch 46.
Power source 40 is also adapted to force drilling mud through the
hollow interior of drill string 48 to power the drill head and
remove loosened particles from the drilled hole. A tube 54 from a
source of such drilling mud (not shown) provides the drilling mud
to power source 40. Drilling mud circulates down through the hollow
interior of drill string 48 and then back around the exterior of
the drill string and out of the drilled hole as illustrated by
arrow 56 where it is dumped in the lower portion of pit 34. A
certain amount of such mud 58 is allowed to collect in pit 34, but
most of the mud is returned to its source through tube 60. The
entrance to the drilled hole at face 36 of pit 34 is provided with
a conduit 62 extending outwardly through face 36. Drilling mud
exiting the drilled hole thus does not run down face 36 of pit 34
and erode the pit, allowing the pit to retain its preferred
configuration.
FIG. 3 illustrates the attachment of a drill head casing 70 to the
end 72 of drill string 48 opposite power source 40. Drill head 70
is of the type known in the art wherein the drilling mud forced
through drill string 48 is used to power the drill. Drill head 70
is of the type which has an angular bend 74 with respect to the
axis of drill string 48 so that the drill bit portion 76 of drill
head 70 is angularly inclined as illustrated. The angular bend 74
of drill 70 can be varied, and inclinations of from 1.degree. to
5.degree. are well known in the art. However, it has been found
advantageous in the present invention to increase the angular bend
at least to 10.degree. and possibly greater in many applications to
achieve the desired control over its movement. The angular bend 74
shown in the figures is probably too large for most applications,
however, and is probably an exaggeration. The upper bound of this
parameter has yet to be determined. The cutting portion 78 of drill
bit 76 is thus angled significantly with respect to drill string
48. Cutting tip 78 is of the type known in the art and usually has
three rotors each having a plurality of cutting teeth.
A surveying instrument 80 is adapted to slide through the hollow
interior of drill string 48 to a position adjacent drill head 70.
Surveying tools 80 known in the art are primarily of the
"single-shot" variety, i.e., the tool takes a single reading and is
then withdrawn through drill string 48 for assessment. Surveying
instrument 80 ordinarily measures the azimuth and declination of
the leading end 72 of drill string 48. This data together with the
length of the string and a history of the drill path allow the
current position of drill head 70 to be determined.
It should be noted by way of reference to FIG. 3 that the hole 82
dug by drill head 70 is curved along its length as a result of
angular bend 74 in drilling head 70. Drilling head 70 rests on the
bottom of hole 82 at position 92 below bend 74 when the drill head
is vectored upwardly as illustrated, causing the curved path of
hole. If the parameters on drill head 70 are maintained constant,
hole 82 will have a constant upward curvature as illustrated by
hole 82 in FIG. 4. However, the apparatus of the present invention,
as illustrated in FIG. 2, provides means for controlling the
angularity of the hole along its length and thus its eventual
contour.
Specifically, the forward thrust on drill string 48 exerted by
power source 40 through winch 46 can be increased, and such action
will decrease the radius of curvature as illustrated by phantom
hole 90. The apparent reason for this fact is that drill head 70
rests at two points, the bottom of the angular bend illustrated at
92, and the leading end of the hole illustrated at 94 in FIG. 4.
Increasing the forward thrust on drill string will apparently force
drill head 70 against position 94, reducing the gravitational load
at position 92, thereby increasing the pitch (angle from
horizontal) of drill head 70. Conversely, decreasing the forward
thrust on drill string 48 exerted by power source 40 will increase
the radius of curvature of the hole illustrated by the phantom hole
96.
A further control feature provided by the apparatus of the present
invention is that the forcing of drilling mud through the interior
of drill string 48 by power source 40 is controllable. Increasing
the force on the drilling mud has two effects on the drill; first,
the speed of the drill rotors on tip portion 78 is increased; and
second, the volume of drilling mud expelled through tip 78 of drill
head 70 is increased. This increase in the flow of drilling mud
will result in increasing the radius of curvature of the hole as
illustrated by phantom 96. Conversely, decreasing the flow will
decrease the radius of curvature as illustrated by phantom 90. The
exact mechanism of this phenomena is not fully understood, but it
would appear that both the increase in the speed of rotation of
tips 78 and the increase in the drilling mud flowing therethrough
reduces the friction at point 94, resulting in a corresponding
increase in the gravity effect at point 92, thereby increasing the
radius of curvature of the path and vice versa.
A further control feature of the apparatus of the present invention
is illustrated by way of reference to FIG. 5. Drilling head 70 is
ordinarily positioned so that drill bit 76 is vectored upwardly. It
is known that the azimuth of drill bit 70 can be altered by
rotating drill string 48 to make horizontal turns in the drill
path. However, the present invention provides the additional
control of rocking drill head 70 from side to side as illustrated
by arrows 98, 98' or in a full circle in rapid fashion. This will
not result in a hole which corkscrews but rather will tend to
increase the radius of curvature of the arcuate path without
introducing a significant horizontal turn.
In operation, the apparatus of the present invention is utilized as
follows. First a pit 34 is dug at one side of an obstruction which
is to be traversed with a pipeline or other underground conduit.
The forward surface 36 of the pit is inclined from the vertical at
a preselected angle. The angle is dependent on the depth of cut
desired and the width of the obstacle. A ramp 30 is next placed in
the pit, and has a lower end terminating at the forward face 36
thereof. Power source 40 is mounted on ramp 30 and the drilling of
the hole is initiated. Drilling of the hole can be begun with
traditional straight line drilling methods. However, the control
provided by the present invention allows for the preferred method
of initiating drilling with the inclined drill head 70.
The apparatus of the present invention allows the drill head 70 to
be directed in a controlled manner beneath the obstruction to
surface at the other side. Controlling the thrust on drill string
48, the force of drilling mud into the drill string, and azimuth of
the drill head all can be utilized to control the direction of the
drilling. Hence, the present invention provides a method whereby a
hole can be drilled continuously under an obstruction from one side
to the other for the laying of the conduit.
Although a preferred embodiment of the present invention has been
illustrated in detail, it is apparent that modifications and
adaptations of that embodiment will occur to those skilled in the
art. In particular, the configuration of the drill rig apparatus
can be varied, and different mechanisms employed to vary the
control parameters of the present invention. However, it is to be
expressly understood that such modifications and adaptations are
within the spirit and scope of the present invention, as set forth
in the following claims.
* * * * *