U.S. patent number 3,599,733 [Application Number 04/884,804] was granted by the patent office on 1971-08-17 for method for directional drilling with a jetting bit.
This patent grant is currently assigned to R. F. Varley Co., Inc.. Invention is credited to Robert F. Varley.
United States Patent |
3,599,733 |
Varley |
August 17, 1971 |
METHOD FOR DIRECTIONAL DRILLING WITH A JETTING BIT
Abstract
Method and apparatus are described for changing the direction
taken by a bore hole. A drill bit having at least one outlet
orifice or nozzle for drilling fluid e,g, mud, is oriented so that
the orifice is adjacent the portion of the interior lateral surface
of the bore hole into which it is desired for the drill bit to
proceed. The drilling fluid is pumped into the interior of a hollow
drill string in the bore hole and out through the orifice in the
drill bit. A portion of the drill string adjacent the bit is
adapted to be closed in a fluidtight manner by means of a back
pressure ball valve, and the portion of the drill string between
the valve and the outlet orifice includes a slip joint adapted to
be decreased in volume by an inward telescoping motion with
vertical reciprocation of the drill string. Decreasing the volume
of the drill beneath the above-mentioned valve will serve to
compress the fluid therein forcing it out of the outlet orifice at
an increased velocity. When the drill string is moved vertically
upwardly, the valve opens allowing more drilling fluid to flow
therethrough. Repetitive vertical reciprocation of the drill string
to open and close the slip joint will result in highly accelerated
jetting velocities through the outlet orifices in the drill
bit.
Inventors: |
Varley; Robert F. (Metairie,
LA) |
Assignee: |
R. F. Varley Co., Inc.
(N/A)
|
Family
ID: |
25385432 |
Appl.
No.: |
04/884,804 |
Filed: |
December 15, 1969 |
Current U.S.
Class: |
175/61; 175/318;
175/324; 175/67; 175/321 |
Current CPC
Class: |
E21B
21/10 (20130101); E21B 7/065 (20130101); E21B
7/18 (20130101) |
Current International
Class: |
E21B
21/00 (20060101); E21B 7/04 (20060101); E21B
7/18 (20060101); E21B 21/10 (20060101); E21B
7/06 (20060101); E21b 007/08 (); E21b 007/18 ();
E21b 017/046 () |
Field of
Search: |
;175/61,65,67,317,318,321,322,324,376,400 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Calvert; Ian A.
Claims
What I claim is:
1. A method for deviating the direction taken by a bore hole
towards a particular direction, said method comprising the steps
of:
orienting a jetting drill bit having at least one fluid outlet
orifice through which a relatively greater amount of drilling mud
can be caused to flow than through other bit orifices so that said
at least one orifice is generally directed towards said particular
direction and is adjacent the portion of the interior surface of
the bore hole into which said drill bit is to proceed to deviate
the direction taken by the bore hole,
pumping a drilling fluid into the interior of a hollow drill pipe
placed in said bore hole, said drill bit being attached to the
lower end of said drill pipe,
closing in a fluidtight manner a portion of said drill pipe
adjacent said drill bit, the lower end of said closed portion being
in fluid communication with said at least one outlet orifice,
and
exerting a pressure on the volume of drilling fluid enclosed within
said closed portion of said drill pipe thereby forcing said
drilling fluid from said at least one outlet orifice of said drill
pipe at an increased velocity.
2. The method defined in claim 1 comprising the additional step of
vertically reciprocating an upper part of the drill pipe after said
orienting step,
said pumping step occurring during the upward stroke of said upper
part
said closing step occurring substantially at the commencement of
the downward stroke of said upper part and said exerting step
occurring simultaneously with said downward stroke.
3. The method defined in claim 1 wherein said orienting step
comprises placing at least one of a plurality of outlet orifices
placed around the periphery of said drill bit adjacent the portion
of the interior surface of the bore hole into which said drill bit
is to be deviated.
4. The method defined in claim 1 wherein said exerting step
comprises decreasing the volume of said closed portion of said
drill pipe thereby increasing the pressure on the volume of
drilling fluid enclosed therein.
5. The method defined in claim 4 wherein said volume of said closed
portion of said drill pipe is decreased by decreasing the length of
said closed portion of said drill pipe.
6. The method defined in claim 5 wherein said drill pipe comprises
at least two sections in axial alignment jointed at adjacent ends
thereof by a slip joint having a telescoping portion therein,
said closing step taking place at a point along the length of said
drill pipe above said slip joint,
the length of said closed portion of said drill pipe being
decreased by closure of said slip joint.
7. The method defined in claim 6 comprising the additional step of
vertically reciprocating the structure comprised of said drill pipe
and the upper part of said slip joint after said orienting step,
said structure being lifted on the upward stroke thereof a distance
equivalent the length of travel of said telescoping portion of said
slip joint,
said pumping step occurring during the upward stroke of said
structure,
said closing step occurring substantially at the commencement of
the downward stroke of said structure and
said closure of said slip joint occurring simultaneously with said
downward stroke.
8. A process for jet directional drilling using a slip joint and
back pressure valve assembly in jet deflection drilling wherein the
direction of a bore hole is deviated towards a predetermined
direction by jetting substantial quantities of high pressure fluid
in the preferred direction of bore hole deviation, said process
substantially increasing the jet deflection drilling speed and the
possible operating depth of jet deflection drilling and comprising
the steps of:
disposing said slip joint and back pressure valve assembly in the
lower end of a hollow drill string above a jet deflection bit
having at least one outlet orifice through which a relatively
greater amount of drilling mud can be caused to flow than through
other bit orifices,
orienting said at least one outlet orifice towards an interior
portion of said bore hole which is generally oriented in said
particular direction,
pumping a drilling fluid into the interior of said hollow drill
string,
extending said slip joint by exerting a lifting force on said drill
string,
admitting a substantial quantity of said drilling fluid past said
back pressure valve into the central interior portion of said slip
joint during said extending step, and
rapidly closing said slip joint by releasing at least some of the
lifting force on said drill string, and
trapping said substantial quantity of drilling fluid behind said
back pressure valve to force said substantial quantity of drilling
fluid through said at least one outlet orifice during said closing
step to thereby substantially increase the pressure and velocity of
the jet-deflecting fluid thus increasing the jet deflection
drilling speed and the possible depth of effective jet deflection
drilling.
Description
This invention relates to an improved method for directional
drilling, and in particular, a method of directional drilling in
which increased fluid velocities are achieved and an apparatus
placed in a drill string for increasing the fluid pressure and
thereby the velocity.
In modern oil and gas well drilling it is increasingly important to
be able to drill to increased depths to have access to the
decreasing petroleum supply. In working at these greater depths it
is, as well, important to be able to control the direction taken by
the drilling apparatus. That is, it is often necessary to deviate
the bore hole from a straight vertical path laterally therefrom to
get to a particular deposit. This technique is particularly
important in off-shore drilling where it is desirable to place as
few rigs as possible but to have the ability to drill throughout as
wide an area as possible.
One of the more commonly used prior art devices for directional
drilling was the whipstock. The whipstock would be used to guide a
conventional rotary bit against the sidewall of a bore hole and to
cause the bore to be deflected away from the original bore hole
path. Using this directional drilling technique it is required that
the bore hole be opened from the surface downward to an earth
formation that is sufficiently consolidated to accept the whipstock
which then must be set, using orienting and directional survey
equipment, to assure the driller that the whipstock is properly
aligned in the hole. Another major disadvantage of this technique
is the fact that the bore hole itself must be drilled to a
sufficiently large diameter to be able to accept the whipstock
body.
The disadvantages of the foregoing directional drilling device were
overcome with the advent of a technique for directional drilling
known as "jet deflection." The jet deflection method combines
hydraulic washing and mechanical cutting to direct the path of the
bore hole in the desired direction away from the true vertical. In
this method, a drill bit carries a hydraulic nozzle which is
oriented in the direction of or adjacent the lateral surface of the
bore hole through which the desired deviation is to take place. The
drilling fluid, e.g., mud, which is normally circulated through the
drill string and bit is circulated to a greater degree against the
aforementioned lateral wall to erode that surface so that the drill
bit is deviated in the direction that it is desired for the bore
hole to take. In many cases, after sufficient penetration in the
desired direction has taken place, vertical movement of the drill
string is permitted, and the drill bit is reciprocated up and down
to achieve a cutting effect, for example by increasing and
decreasing the weight applied thereto by the drill string and the
collars. The bore hole will then be deviated in the desired
direction, i.e. the direction in which the jet is oriented. During
this operation no rotation of the drill bit and drill string takes
place until the desired deviation is achieved, but a cylindrical
hole will still be obtained by the vertical reciprocation of the
drill string.
With increasing bore hole depth, however, the amount of time
necessary to perform the jet deflection operation and accordingly
the cost thereof will be substantially increased. For example, it
has been found that at depths greater than 1,500 feet the time
required will increase directly with the depth involved. For depths
of approximately 12,000 feet and greater it has been found that it
is virtually impossible to economically utilize jet deflection with
the presently available equipment and using conventional
techniques. The foregoing is particularly true where the
circulating fluid in the drill string is mud. If the circulating
medium is air or a similar gas, it has been found that the rate of
penetration is substantially uneffected. Because mud is the more
widely used drilling fluid in that it is more economical, it is,
however, necessary to arrive at a means for obtaining greater
penetration with mud as the drilling fluid at the greater
depths.
It is now believed that the primary cause of the increased drilling
expense associated with increased bore hole depth in directional
drilling using mud as the drilling fluid is the effect of
hydrostatic pressure acting against the formations being drilled.
Hydrostatic pressure is the pressure exerted due to the depth and
weight of the drilling mud column. Hydrostatic pressure increases
as a direct function of either the depth of the mud or the weight
of the mud column. As drilled depth is increased, the velocity of
the drilling fluid being emitted from the jet nozzle is dampened or
reduced in the short interval of distance (6 to 8 inches) from the
nozzle to the face of the formation being eroded. At these greater
depths, the jetting fluid (e.g. mud) is being emitted into a fluid
environment of high pressure intensity. Because hydrostatic
pressure is a direct function of depth, the fluid environment at
shallow bore hole depth will be such that the pressure will be
significantly decreased. The high-pressure fluid environment at
greater bore hole depths reduces the velocity, and therefore the
effectiveness, of the jetting stream before it strikes the
formation being eroded.
It is therefore an object of this invention to provide a method
which will significantly increase the velocity of the drilling
fluid being emitted from a bit when the jet deflection technique is
being used for bore hole deviation.
It is another object of this invention to provide a method for
using the jet deflection technique of bore hole deviation which may
be used economically at increased bore hole depths, particularly
where mud is being used as the drilling fluid.
The aforementioned and other objects may be obtained by using the
invention described herein which may be best understood by
reference to the description given hereinbelow of a preferred
embodiment constructed and operating according to the principles of
this invention in conjunction with the drawings in which:
Fig. 1 is a diagrammatic illustration of a preferred embodiment of
a drilling apparatus modified according to the principles of this
invention to carry out the method of this invention;
FIG. 2 is a side cross-sectional view of a preferred embodiment of
a slip joint having a back pressure valve included therein
constructed according to the principles of this invention and
adapted to be placed in a drill string to carry out the method of
this invention; and
FIG. 3 is a cross-sectional view of the embodiment of FIG. 2 taken
along the line 314 3.
Referring to the drawings and in particular FIG. 1, it will be seen
that a bore hole 34 has been started into the earth, and the
deviation of the bore hole has been partially carried out by means
of the jet deflection technique described herein. The direction to
be taken by the bore hole 34 is shown by the arrow in the lower
portion thereof.
A conventional drilling rig, generally indicated by the numeral 10,
along with a drilling platform 12 supports the entire drilling
apparatus. The bore hole 34 has been drilled vertically by means of
rotary operation of a drill string 22. The drill string 22
comprises an axially adjacent series of drill pipes 24 and drill
collars 27 as needed. As shown in FIG. 1, a drill collar 27 is
placed at the lower end of the pipe string 24 with a rotary drill
bit being attached thereto. A drill bit 30 shown in FIG. 1 as being
attached at the lower end of collar 27 is particularly adapted for
use with the jet deflection technique of this invention to be
described hereinbelow. The drill pipes 24 and drill collars 27
allow the flow of a circulating medium downwardly therethrough, and
in this preferred embodiment this circulating medium is mud. An
annular pipe 26 is placed around the drill pipe 24 at the upper
portion thereof in bore hole 34 to guide the drilling mud which is
flowing upwardly in the bore hole, and a conduit 40 communicates
with the pipe 26 to conduct the drilling mud away from the bore
hole. The conduit 40 passes through a conventional shale shaker 42
which acts to remove solid particles from the drilling mud, and the
drilling mud is then allowed to flow by means of conduit 41 into a
reservoir 44.
In order to cause the drilling mud to flow downwardly through the
drill pipe 24 a conventional mud pump 46 draws the mud out of
reservoir 44 and sends it under pressure through a conduit 48. The
conduit 48 extends through a swivel 16 and communicates with a
kelly bar 18. The kelly bar 18 couples the circulating drilling mud
to the drill pipe 24. During the normal operation of the drilling
apparatus a rotary table 20 enclosing kelly bar 18 and the drill
pipe 24 causes these elements to rotate to carry out normal
drilling action.
In order to carry out bore hole deviation in a manner according to
this invention, the conventional rotary bit is replaced by a bit 30
which includes at least one nozzle or orifice 32 through which a
greater amount of drilling mud can be caused to flow than through
any remaining orifice in the bit. Further, a slip joint 26 is
interposed in drill string 22 in a portion thereof near the bit 30.
The drill string has included therein a back pressure valve 28
which will prevent the pressurized drilling mud from flowing
upwardly through the drill pipe 24. The structural details of this
slip joint and back pressure valve will be more completely
described hereinbelow with reference to FIGS. 2 and 3.
The bore hole deviation technique described herein requires
vertical reciprocation of the drill string. A link 15 extends
upwardly from swivel 16 and is coupled to a hook 14. A vertical
drive by any well-known means (not shown) acts on hook 14 to cause
vertical reciprocation of the drill string.
In order to deviate the bore hole 34 from its vertical path using
the technique of jet deflection described herein the drill bit 30
is oriented so that the nozzle or nozzles 32 will direct flow of
drilling mud therefrom against the lateral wall of the bore hole in
the direction it is desired for the bore hole to take. With pump 46
operating to send drilling mud under pressure down through the
drill pipe 24 in the manner described above the drill string 22 is
lifted by means of hook 14 a distance equal to the length of travel
of the telescoping slip joint 26 as it telescopes outwardly. After
the drill string has traveled upwardly the aforementioned distance,
it is lowered as rapidly as possible back down into the bore hole
34. At this time, the back pressure valve 28 in the top portion of
slip joint 26 closes trapping the drilling mud contained in the
slip joint 26 and the drill pipe therebelow. The weight of the
lowering drill string 22 causes the slip joint 26 to telescope
inwardly on itself reducing the total volume of the area closed by
valve 28. The mud contained in the enclosed volume is compressed by
the closure of slip joint 26 and is thereby accelerated out of the
orifices 32 in bit 30. The above-described operation of vertically
reciprocating the drill string 22 to open and close the slip joint
26 is carried out repetitively. The increased jetting velocities
die to closure of the slip joint will erode the earth formation
adjacent the orifices 32 of nozzle 30 in the desired direction of
deviation, and the vertical reciprocation of the drill string will
cause drill bit 30 to cut into the aforementioned earth
formation.
It has been found by using the technique and equipment described
herein jetting velocities may be achieved which are two to four
times greater than the velocities of conventional jetting equipment
using pumps on the earth surface. That is, conventional equipment
relies only on the pumping action of a pump similar to pump 46
described in FIG. 1 to obtain the needed jetting velocities at the
orifices in the drill bit. As pointed out hereinabove, the
hydrostatic pressure at increased depths will resist this pumping
action to an extent that the jetting velocities are significantly
reduced thereby reducing the efficiency of the orifices as a means
for eroding the earth formation in the bore hole. By using the slip
joint 26 to obtain a pressure pulse on a downward stroke of the
drill string 22, this problem is overcome, and the jetting
velocities are increased by the orders of magnitude set forth
above.
FIGS. 2 and 3 illustrate the structural details of the slip joint
26 and the back pressure valve 28. As will be seen from the
description hereinbelow, the back pressure valve 28 is actually an
integral part of the slip joint 26 and is placed directly above the
telescoping portion of the slip joint.
Slip joint 26 includes an upper stepped cylindrical member 60 which
mates with the drill pipe 24 thereabove. The interior surface 62 of
cylinder 60 converges from a diameter substantially equivalent to
the inner diameter of the drill pipe and then abruptly diverges
outwardly to form an angular shoulder 63. From that point
downwardly the interior surface of member 60 is of a diameter
substantially equivalent to the inner diameter at the very upper
portion of interior surface 62. An inner cylindrical member 66 is
threadably engaged with the lower portion of the interior of end
member 60 and extends downwardly therefrom. The inner member 66 is
coaxial with end member 60 and is of an inner diameter
substantially equivalent to the inner diameter of the lower portion
of end member 60 thereby forming a conduit for the drilling mud to
flow through.
An outer cylindrical member 70 is threadably engaged at 71 with the
outer surface of end member 60 at the lower end thereof. Outer
cylindrical member 70 includes a series of trapezoidal splines 72
(see FIG. 3) spaced circumferentially therearound. The splines 72
do not extend the full length of member 70 and abruptly end therein
to form shoulders 65. The length of splines 72 are made to be equal
the desired distance of travel of the telescoping slip joint. A
sliding cylindrical member 74 is placed between members 66 and 70
and is concentric therewith. The sliding member 74 has formed
integrally thereon around its upper edge a series of trapezoidal
teeth 76 which mate with the splines 72. The teeth 76 extend
axially along the outer surface of member 70 a distance only a
fraction of the entire length of the sliding member 74. The sliding
member 74, throughout the entire distance of travel of the slip
joint 26, extends below the lowermost end of inner member 66
abruptly increasing the width of the fluid conduit through the slip
joint. A cylindrical bottom end member 78 is threadably engaged at
79 with the lowermost end of the sliding member 74. The outer
diameter of end member 78 is substantially equal to the outer
diameter of outer cylindrical member 70, but the inner diameter of
member 78 is of a configuration such that a connection area 84 is
formed for effectively mating with bit 30 or with some short
section of drill string connected thereto as will be apparent to
those in the art. A pair of closely placed O-ring seals 80 are
embedded in the lower portion of the outer surface of inner
cylindrical member 70 and form a seal between said member and the
inner surface of sliding member 74.
The back pressure valve is formed in the slip joint 26 by a ball
member 68 which is of a diameter such that it will fit within the
shoulder 63 forming a fluid seal therewith when back pressure is
acting thereon. When the valve is not operated to close slip joint
26, the ball 68 rests on a frame support 69 which is attached to
and extends upwardly from the upper end surface of cylindrical
inner member 66.
During the upward stroke of the drill string 22, as described
above, drilling mud is pumped by a pump 46 downwardly through the
drill pipe 24, the slip joint 26 and the drill pipe 24 and drill
collar 27 placed below the slip joint 26. During this upward stroke
the ball 68 will rest on support 69 and will, at least partially,
be held thereon by the force of the drilling mud being pumped
downwardly in the direction of the arrows through slip joint 26.
Further, during this upward stroke the teeth 76 will slide
downwardly through splines 72 until at the apex of the upward
stroke of the drill string the teeth 76 will rest on shoulders 65
of the outer cylindrical member 70.
As the drill string 22 begins its rapid downward stroke, the weight
of the drill string will cause slip joint 26 to begin to close,
i.e. the teeth 76 will begin to travel upwardly in the splines 72.
By commencing the closure of the slip joint 26, a significant back
pressure will be created therein, and this back pressure will cause
ball 68 to rise and be wedged in the area formed by shoulder 63.
The fluid back pressure acting against ball 68 will hold it in a
sealed relationship with shoulder 63. The slip joint will continue
its closing motion until teeth 76 come to rest against the
lowermost end surface 75 of cylindrical end member 60. Because
valve 28 is now closed, the drilling fluid within slip joint 26 and
the drill 24 therebelow will be compressed and forced out of the
orifices 32 in bit 30 at an increased velocity in the manner
described hereinabove. The formation of a conduit of increased
diameter by the lower portion of sliding member 74 better enables
the slip joint 26 to withstand the higher forces found therein
during the closure portion of the operation.
While slip joints are known to those skilled in the drilling art,
they are only used to telescope the drill string rapidly in order
to transmit shock loads to lower string members in order to free
them from a stuck condition in the well bore. The slip joint 26
constructed as described hereinabove differs from the presently
available equipment in that its above-described structure is
particularly designed to compress substantial volumes of drilling
fluid under very high pressures and be structurally competent to
withstand the axial loading applied by the weight of the drill
string during its downward stroke.
It will be apparent to those skilled in the art that the preferred
embodiment and the mode of operation of same described hereinabove
are only exemplary and that modifications may be made within the
scope of the appended claims.
* * * * *