U.S. patent number 3,746,108 [Application Number 05/118,853] was granted by the patent office on 1973-07-17 for focus nozzle directional bit.
Invention is credited to Gary E. Hall.
United States Patent |
3,746,108 |
Hall |
July 17, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
FOCUS NOZZLE DIRECTIONAL BIT
Abstract
A focus nozzle directional bit according to the present
invention includes a body having a central fluid conducting passage
adapted to be disposed in communication with the bore of a drill
string used for the drilling of a well. A plurality of branch fluid
passages are formed in the body each being disposed in
communication with the central fluid passage. A plurality of jet
apertures are defined in the body in communication with the branch
passages and are orientated to converge jets of pressurized
drilling fluid outwardly and downwardly from the bit adjacent a
lateral wall of the well bore for the purpose of directionally
eroding the same to allow the drill bit to deviate downwardly and
outwardly from the original well bore.
Inventors: |
Hall; Gary E. (Gretna, LA) |
Family
ID: |
22381132 |
Appl.
No.: |
05/118,853 |
Filed: |
February 25, 1971 |
Current U.S.
Class: |
175/61; 175/339;
175/424; 175/67; 175/393 |
Current CPC
Class: |
E21B
7/065 (20130101); E21B 7/18 (20130101); E21B
10/18 (20130101) |
Current International
Class: |
E21B
7/18 (20060101); E21B 10/18 (20060101); E21B
10/08 (20060101); E21B 7/04 (20060101); E21B
7/06 (20060101); E21b 007/04 (); E21b 007/18 () |
Field of
Search: |
;175/400,422,67,231,61,339,340,393 ;299/81 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Champion; Marvin A.
Assistant Examiner: Favreau; Richard E.
Claims
What is claimed is:
1. A drill bit for use in borehole deviation by jet deflection
comprising:
a body adapted for connection to a drill string;
means defining a central fluid passage in said body adapted to
receive drilling fluid from the interior of the drill string;
a plurality of outlet orifices being disposed adjacent the lateral
wall of a borehole into which said drill bit is to proceed;
at least two of said plurality of outlet orifices being
substantially larger than the remaining ones of said outlet
orifices, thereby allowing a substantially larger volume of
drilling fluid to flow from said two outlet orifices than the
remaining ones of said outlet orifice, said two orifices being
oriented to direct fluid flowing therefrom to converge at a point
below said bit and laterally of the vertical axis of said bore;
and
a plurality of branch conduits placing said orifices in
communication with said central fluid passage.
2. A drill bit as recited in claim 1;
said branch conduits communicating said two of said plurality of
outlet orifices with said central fluid passage being of
substantially larger dimension than the dimension of the remaining
ones of said branch passages.
3. A method of forming a directionally deviated well bore in an
earth formation comprising the steps of:
conducting a rotary drilling operation to define a well bore
extending substantially straight to a depth in the formation where
deviation of the well bore is desired;
bringing a plurality of jets of pressurized drilling fluid to bear
upon said formation causing fluid erosion of the formation, at
least two of said jets being substantially larger than the
remainder of said jets and being oriented to converge at a point
downwardly and outwardly with respect to said drilled bore to form
an eroded bore inclined downwardly and outwardly from the path of
the drilled bore;
lowering a rotary drilling bit into said eroded downwardly and
outwardly inclining well bore; and
rotating the rotary drilling bit and drilling a substantially
straight deviated bore following the path defined by the eroded
bore.
4. The method of claim 3:
wherein all of said plurality of jets of pressurized drilling fluid
are oriented to converge at a point downwardly and outwardly with
respect to said drilled bore.
5. Apparatus for producing a deviated well bore by jet erosion
comprising:
means for conducting pressurized drilling fluid into a well bore
that has been drilled to a depth where deviation thereof is
desired;
means defining a plurality of jets of pressurized drilling fluid at
least two of which are substantially larger than the remaining ones
of said jets;
means converging said two of said plurality of jets of pressurized
drilling fluid downwardly and outwardly with respect to the
original well bore to cause jet erosion of the formation
substantially along the resultant direction defined by said two
converging jets of drilling fluid.
6. The apparatus recited in claim 5;
wherein said last mentioned means converges all of said plurality
of jets of pressurized drilling fluid downwardly and outwardly with
respect to said second mentioned means.
Description
BACKGROUND OF THE INVENTION
The present invention relates generally to an improved apparatus
for the directional drilling of wells and more specifically to
improved apparatus for achieving deflection of a well bore by
controlled jet erosion thereof.
In modern oil and gas well drilling, it is increasingly important
to be able to drill to increased depths in order to gain access to
the decreasing petroleum supply. In conducting drilling operations,
especially at extreme depths, it is as well important to be able to
control the direction taken by the drilling apparatus. It is
frequently necessary to deviate the borehole from a straight
vertical path to a path laterally therefrom to obtain production of
petroleum products from a particular deposit. It may also be
important to utilize deflection techniques to correct the path of a
borehole that might have become inadvertently deviated during the
drilling process. The technique of directional drilling is
particularly important in off-shore drilling where it is frequently
desirable to drill a large number of wells from a single drilling
platform and yet retain the capability of providing efficient
drilling coverage in a designated drilling area.
The art of directional drilling consists of controlling the
horizontal angle (direction) and the vertical angle (deviation) to
control the three dimensional path of the drill well bore. While
deviation is readily controlled through proper stabilizer placement
and correct application of bit weight and rotary speed, the control
of bore direction or horizontal angle is a frequent problem of
concern in directional drilling because the hole direction will not
respond nearly so well to variation of stabilizer placement bit
weight and rotary speed. When it is necessary to accomplish
deviation of a borehole, the new or deviated hole must be drilled
with its axis shifted laterally from the original axis of the
borehole. There exists several methods for achieving correction or
deflection of well bores.
THE PRIOR ART
One method of achieving bore hole deviation concerns utilization of
a directional drilling device, referred to as a "whipstock" that is
capable of guiding a conventional rotary bit against the side wall
of a borehole to cause the bore to be deflected away from the
original path thereof. Using this directional drilling technique,
it is required that the borehole be opened from the surface down 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. A major disadvantage of this
technique is the requirement of numerous trips with the drill
string in order to complete the technique. Additionally, whipstock
operations are time consuming and expensive. Utilization of
whipstocks to achieve deflection of boreholes is considered
generally to be the most expensive method of borehole deflection
and for the most part such use is limited to extreme depths where
other methods of deflection would be generally unacceptable.
Down hole motors are also used for achieving deviation of well
bores but such devices are infrequently so used because of the
expensive nature and difficulty of use thereof.
The most prevalent method of achieving borehole deflection is
through utilization of a bit or other device capable of deflecting
a jet of pressurized drilling fluid laterally against the wall
structure of the well bore in such a manner that the well bore is
eroded laterally and downwardly thereby allowing the drill bit to
deviate from its original course to the path defined by erosion of
the well bore. Jet deflection is presently accomplished by drilling
bits having a single deflection jet nozzle or orifice that is
substantially larger than the cleaning and lubricating orifices of
the bit which jet orifice is capable of causing greater flow of
drilling fluid in that portion of the well bore that is intended to
be eroded for deflection purposes. Erosion will be localized at
that portion of the well bore adjacent the larger jet deflection
nozzle since this nozzle will allow a majority of the pumped fluid
to pass therethrough for selective erosion of a portion of the well
bore. As pumping and the resultant well fluid erosion continues,
the bottom portion of the hole will be shifted laterally as
penetration of erosion progresses. After the eroded deviated bore
has penetrated to such degree that the drill bit itself will shift
laterally and downwardly, the bit can be rotated in this newly
orientated direction and conventional rotary drilling can continue
in the direction established by jet deflection. If the jet
deflected hole is not eroded to sufficient depth, the drill bit,
when rotated, can revert back to the previous axis of the hole
instead of deflecting as desired. Experience gained in the field
has generally established that a deflected hole in the order of 3
to 5 feet of penetration depending upon the degree of consolidation
of the formation is sufficient to prevent reversion of the drill
back to the previous axis of the borehole.
Conventional roller cone cutter type drilling bits generally
referred to as roller bits or rock bits are frequently utilized for
drilling in consolidated formations. Roller bits are generally
provided with three jet orifices or apertures communicating with
the drill string which direct jets of drilling fluid against the
bottom of the well bore immediately adjacent the cutters to wash
away eroded formation particles and to provide the drilling bit
with proper cooling and lubrication. The three apertures direct
drilling fluid in evenly distributed manner within the borehole and
therefore will not cause deflection of the well bore if allowed to
erode the same without rotation of the bit.
Jet deflection bits may be of generally the same construction as
conventional bits but are usually provided with a jet deflection
orifice or aperture that is substantially larger than the remaining
apertures of the drill bit. For example, the conventional
lubrication, cleaning and cooling orifices may be in the order of
1/4 inch in diameter while the directional jet orifice may be in
the order of 3/4 inch diameter. This design allows a substantially
larger volume of drilling fluid to emerge from the directional jet
orifice and results in uneven or selective erosion of the well bore
along that portion thereof intended to be deflected. Inefficiency
of jet deflection is frequently extremely pronounced at extreme
depths and it is believed that such inefficiency results due to the
extremely high hydrostatic pressure created by the heavy drilling
fluid and due to attenuation of jet nozzle velocity in the region
of drilling fluid high pressure intensity, in the distance the jet
stream must travel from the nozzle face to the bottom of the well
bore. Well bore erosion from single jet deflection drills is
frequently substantially attenuated or damped because the jet
deflection nozzle is located a substantial distance (usually in the
order of 6 inches) above the bottom of the well bore and
effectiveness of the jet stream to erode the bottom of the hole is
substantially reduced.
A method of overcoming the problem of jet attenuation or damping
has resulted in the provision of a modified jet deflection bit
having the usual cleaning, cooling and lubrication passages and
incorporating, in place of the conventional third roller, an
extended deflection jet that extends downwardly near the hole
bottom adjacent one side thereof. This jet is substantially larger
than the remaining three cleaning, cooling and lubrication jets
thereby resulting in the creation of a substantially larger jet
flow in the direction of intended hole deflection. The extended jet
orifice structure places the deflection orifice much closer to the
bottom of the well bore than conventional jet deflection devices
and overcomes to a degree the problem of jet attenuation. While jet
attenuation is substantially reduced by the extended jet nozzle
type deflection bit, it is obvious that the rotary drilling
capability of the bit is also substantially reduced by replacement
of the usual third roller cutter with the offset extended jet
nozzle.
With increasing borehole depth, however, the amount of time
necessary to perform a conventional jet deflection operation and
accordingly the cost thereof is substantially affected by
consolidation of the formation. For example, it has been found at
depths greater than 1500 feet the time required for sufficient jet
deflection to achieve a deflected borehole will increase directly
with the depth involved. For depths of approximately 12,000 feet
and greater, it has been found to be virtually impossible to
economically utilize jet deflection with the conventional equipment
and techniques presently available. It is now believed that the
primary cause of the increased drilling expense associated with the
increased borehole depth in directional drilling, using mud as the
drilling fluid, is the effect of hydrostatic pressure of the
drilling fluid acting against the formation being drilled.
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 damped or attenuated in the short interval of
distance (6 to 8 inches) from the nozzle to the face of the
formation being eroded as indicated above. At substantial well
depths, the jetting fluid is emitted into a fluid environment of
extremely high pressure simply because hydrostatic pressure is a
direct function of the depth of the fluid environment. At shallow
borehole depths, hydrostatic pressure will have an insignificant
effect from the standpoint of attenuation. The high pressure fluid
environment of greater borehole depth reduces or substantially
attenuates the velocity of the jetted drilling fluid and therefore
substantially reduces the effectiveness of the jetting stream
before it strikes the formation being eroded.
It is therefore a primary object of the present invention to
provide novel jet deflection apparatus capable of achieving
sufficient controlled jet flow that attenuation will not interfer
to a substantial degree with controlled deflective erosion of the
well bore.
It is a further object of the present invention to provide novel
jet deflection apparatus capable of converging jets of flowing
pressurized drill fluid to cause elective impingement of such jets
upon a lateral portion of the well bore to result in efficient
erosion of the same.
It is an even further object of the present invention to provide
novel jet deflection apparatus that is capable of achieving
efficient jet deflection at substantial well depths without
decreasing the rotary drilling effectiveness of a roller bit
structure in which such apparatus may be incorporated.
Among the several objects of the present invention is noted the
contemplation of novel jet deflection apparatus providing an
efficient jet nozzle erosional pattern for exceptional efficient
jet erosion in dense formations.
It is also an object of the present invention to provide novel jet
deflection apparatus providing the capability of focusing all of
the nozzles thereof at a single point and retaining a capability of
efficient rotary drilling subsequent to completion of a jet
deflection operation.
It is another important feature of the present invention to provide
a novel jet deflecting bit structure that is simple in nature,
reliable in use and low in cost.
Other improvements of the function and of facility of design will
be apparent from the following description taken in conjunction
with the drawings in which:
FIG. 1 is a diagrammatic illustration of a preferred embodiment of
a drilling apparatus utilizing a jet deflection bit constructed in
accordance with the principles of the present invention.
FIG. 2 is a sectional view of a jet deflection bit constructed in
accordance with the present invention and illustrating branch fluid
passages being connected with a central fluid passage defined in
the structure thereof.
FIG. 3 is a bottom view of a jet deflection drilling bit
constructed according to the principles of the present
invention.
FIG. 4 is an elevational view of a jet deflection bit constructed
to carry out the present invention and illustrating focusing of the
deflection jets during operation thereof.
FIG. 5 is an elevational view of a jet deflection bit structure
defining a modified embodiment of the present invention and
illustrating focusing of all of the nozzles during the deflection
operation.
FIG. 6 is a diagrammatic plan view illustrating shifting of a
deflected bore from the path defined by the original well bore.
BRIEF DESCRIPTION OF THE INVENTION
The present invention accomplishes efficient jet deflection by
directing a plurality of deflection nozzles in such manner as to
produce converging jets of high velocity drilling fluid that
impinge in deviated manner upon the wall structure of the stratum
defined by the well bore. A rotary roller bit structure
incorporating the present invention may be provided with enlarged
jet deflection nozzles, as compared to the cleaning and lubricating
nozzle or nozzles thereof, which are connected through
appropriately sized passages to a central flow passage that is in
turn communicated with a drill string through which pressurized
drilling fluid passes during the drilling operation. The jet
deflection nozzles are oriented to converge jets of flowing
drilling fluid laterally and downwardly of the bit structure in
order to impinge upon the adjacent formation during the jet
deflection operation. The impinging action created by the
converging jets of drilling fluid function effectively to prevent
substantial attenuation of the jetting fluid and thereby result in
efficient fluid erosion.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring now to the drawings for a more detailed understanding of
the present invention, in FIG. 1 there is illustrated generally at
10 a conventional drilling rig structure including a drilling
platform 12 that supports the entire drilling apparatus. A borehole
14 is formed in the earth by rotation of a bit 16 connected to the
lower extremity of a drill string 18 having a plurality of pipe
joints 20 threadedly secured one to the other in conventional
manner. The connection between the rotary bit 16 and the drill
string 18 may be accomplished by direct threaded connection of the
bit with the lower-most section of drill stem as shown or, if
desired, may be accomplished by any one of a number of commercially
available connection devices, such as drill collars, bumper subs
and the like, without departing from the spirit or scope of the
present invention. The drill string 18 extends through a casing 22
that is cemented into the upper portion of the formation to provide
optimum sealing at the upper portion of the well bore and to
provide for supporting hangers and the like from which production
tubing is supported after completion of the well.
The drill string is connected at the upper extremity thereof to a
kelly bar 24 of noncircular cross section, that extends in
vertically movable but nonrotatable rotation through a rotary table
26 driven in any desirable manner to impart rotation to the drill
string and to the drill bit 16 connected thereto. The upper
extremity of the kelly bar 24 is rotatably fixed or secured in
sealed manner to a swivel 28 that is in turn supported by the hook
30 of a traveling block by a connecting link 32. The Traveling
block is connected by a cable that extends in conventional manner
through a crown block secured to upper portion of the rig 10. For
purposes of simplicity, neither the traveling block nor crown block
is illustrated herewith, it being obvious to employ such structures
in the drilling of well bores.
For the purpose of supplying pressurized drilling fluid, to the bit
16 during the drilling operation, a supply of drilling fluid,
generally referred to as drilling mud, is maintained within a
reservoir or slush pit 34 and is transported from the slush pit to
a conduit 36 by one or more mud pumps 38. a flexible hose 40 is
secured between the conduit 36 and the inlet pipe 42 of the swivel
28 thereby maintaining fluid communication between conduit 36 and
the swivel as the kelly is raised and lowered. The drilling fluid
follows a path designated by flow arrows through the swivel 28,
kelly 24 and through the drill pipe 20 to the bit 16 where it exits
from the bit through a plurality of orifices 44. The purpose of the
drilling fluid is to wash drill cuttings from the vicinity of the
rotary drill and to provide for cooling and lubricating the drill
as it is rotated to form the well bore. Drilling fluid flows from
the bit upwardly through the annulus 46, defined between the drill
string and the well bore, and carries drill cuttings upwardly to a
conduit 48 that conducts the drill fluid to a shale shaker 50 where
the drill cuttings are removed by passing the drill fluid through
one or more screening devices. Drill fluid exiting the shale shaker
50 flows through a conduit 52 back to slush pit 34 where fine
particles of drill cuttings are allowed to settle out by gravity
and where the drill fluid is further treated to prepare the same
for recirculation through the drill string and bit. During the
drilling operation, the rotary table 26 is driven and through its
nonrotatable relation with kelly bar 24 induces rotation to the
drill string 18 which in turn rotates the bit 16 with continuous
circulation of drilling fluid from the mud pump 38 through the
swivel, kelly and drill string to the drill bit with return of the
drilling fluid to the slush pit through the shale shaker.
To carry out borehole deviation in a manner according to the
present invention, a conventional rotary drilling bit is replaced
with a bit constructed in accordance with the present invention and
which conveniently may take the form of the bit illustrated
generally at 16 in FIGS. 3 and 4 having a plurality of nozzles or
orifices orientated to converge flowing jets of drilling fluid
downwardly and outwardly to produce an eroded deflection well bore
54 which may be followed by the bit and drill string as the same
are lowered for further rotary drilling operations.
In accordance with the present invention, a jet deflection
operation may be carried out by placing, adjacent the formation to
be drilled in deflected manner, a plurality of jets of pressurized
drilling fluid that are directed to converge downwardly of the
drill bit and outwardly with respect to the axis of the original
borehole. A drill bit capable of achieving jet deflection in this
manner may conveniently take the form illustrated in FIGS. 3 and 4
which illustrate a bit generally at 16 having a body member 60
provided with a threaded extremity 62 adapted for threaded
engagement with the internal threads of a drill collar, drill stem
or the like 64. As indicated above, the drill bit may also be
supported by a bumper sub or by any one of a number of other
commercially available devices for use in conjunction with a rotary
drilling bit. A plurality of rollers or rotary cutters 66, 68 and
70 are rotatably secured to the lower extremity of the body 60
which rotary cutters engage the formation as the bit is rotated to
cause cutting or chipping away of the formation.
The body 60 is provided with a central fluid passage 72 to conduct
drilling fluid into the bit structure for distribution to a
plurality of lateral fluid passages 74, 76 and 80. Each of the
lateral passages may be provided with enlarged internally threaded
apertures which receive externally threaded nozzles 82, 84 and 86
respectively therein. Of course, other nozzles structures including
nozzles defined by bores in the body structure of the bit may be
provided as desired.
As indicated above, jet deflection according to the present
invention is accomplished by directing jets of pressurized drilling
fluid in such a manner that the jets converge downwardly and
outwardly with respect to the bit structure to cause deflective
erosion of the well bore immediately below the drill bit. As
illustrated in FIGS. 3 and 4, apparatus for such jet deflection may
conveniently take the form of a pair of jet nozzles 82 and 84 that
are substantially larger in dimension than the remaining cleaning
and lubricating nozzle 86. Nozzles 82 and 84 being of larger
dimension than the cleaning and lubricating nozzle will logically
conduct a substantially larger volume of pressurized drilling fluid
as compared with the cleaning and lubricating nozzle 86 thereby
resulting in pronounced fluid erosion of a lateral portion of the
well bore.
After the deflective borehole has been extended by jetting to such
an extent that rotation of the drill bit will not cause the bit to
return to the direction established by the original bore (usually 3
to 5 feet) the bit 16 will then be lowered into contact with the
bottom of the deflective bore and then will be rotated in
conventional manner to drill a substantially straight bore along
the direction established by the deflected bore. As the bit is
rotated, the converging jets of drilling fluid emerging from
nozzles 82 and 84 will function along with the cleaning and
lubricating nozzle 86 to circulate drilling fluid in evenly
distributed manner only for lubricating and cleaning purposes. The
jet deflection capability of drill bit 16 will not detract from the
efficient drilling capability of the bit because proper cleaning,
cooling and lubrication of the cone cutters will be effectively
achieved.
With reference now to FIG. b, jet erosion of a well bore to achieve
jet deflection in accordance with this invention is
diagrammatically illustrated. The original well bore is shown in
solid line at 90 while the deflected bore 92 is illustrated in
broken lines with its center disposed at the wall of the original
bore. Jet deflection nozzles 91 and 93 direct fluid in converging
manner adjacent the bore 90 to erode the bore 92 while cleaning,
cooling and lubricating nozzle 95 directs drilling fluid downwardly
in conventional manner. Obviously as penetration of the eroded bore
continues, the center of the eroded bore will have downwardly and
outwardly in angular relation with the original bore. The focus
nozzle directional bit of the present invention incorporates a more
efficient jetting pattern by incorporating a plurality of
orientated nozzles so positioned on the bit that the jet streams
emerging will focus at a point a few inches ahead and laterally
orientated with respect to the bit. The focusing point can be
selectively orientated by altering the nozzle structure in such a
manner as to achieve optimum erosion due to the impingement of a
plurality of jet streams tending to erode the deflection bore from
a plurality of points at the bottom of the well bore. The larger
flow of drilling fluid emitting from the focused nozzles and
direction of the jets of drill fluid toward a focused point
effectively overcomes the problem of attenuation that frequently
becomes prevalent when deflection is attempted at substantial
depths.
After the jet deflection operation has been completed and the drill
is rotated to achieve further rotary penetration along the newly
defined deflected bore, it is found that the jet deflection
characteristics of the present invention will not adversely affect
rotary drilling operations. In the case of single angulated nozzle
directional bits, it has been determined that the bit will be
subjected to exceptional wear because two of the three rotary
cutters will be insufficiently lubricated and cleaned because a
major portion of the drilling fluid is concentrated at the
deflection nozzle thereby allowing an insufficient flow of drilling
fluid to the remaining cleaning and lubricating nozzles. It has
been found that the converging jetting nozzles of the present
invention creates sufficient fluid distribution at the bit to
cooperate with the lubrication and cleaning nozzle 86 to
sufficiently remove drill cuttings and to achieve effective cooling
and lubrication. The bit, therefore, will not be subjected to
exceptional wear after a rotary drilling operation is commenced
subsequent to a jet deflection operation.
With reference now to FIG. 5 of the drawings, a modified embodiment
of the present invention is illustrated which comprises a bit
illustrated generally at 96 having a body structure 98 adapted to
be threadably secured to an internally threaded drill stem, collar
or drill sub 100 in conventional manner. A plurality of rotary
cutter cones, one being illustrated at 102, are rotatably carried
by the body 98 for cutting away the formation as the bit is lowered
within the well bore in siliar manner as discussed above. A central
fluid passage 106 is formed in the body 98 and is disposed in
communication with a plurality of branch passages 108, 110 and 112
conducting drilling fluid from the central fluid passage to a
plurality of jet deflection nozzles 114, 116 and 118 through which
drilling fluid emergizes adjacent the rotary cutters. Each of the
nozzles is orientated to direct drilling fluid to converge
downwardly and outwardly with respect to the bit thereby causing
jet erosion of the formation to produce a deflective well bore in
similar manner as the bit structure illustrated in FIG. 4. The
branch passages 108, 110 and 112 and the associated nozzles 114,
116 and 118, if desired, may be of the same physical dimensions
thereby concentrating a plurality equal jets of flowing drilling
fluid at a single focus point to cause even more efficient jet
deflection by eroding the formation at three or more points.
After the deflected bore has been jetted to a sufficient depth to
prevent the bit from returning to the path of the original well
bore, the bit 96 may be rotated to cause substantially straight
drilling from the bore deflection downward along the path defined
by the deflected bore. The nozzles 114, 116 and 118 will, during
the rotary drilling operation, conduct evenly distributed jets of
drilling fluid to all of the rotary cutter cones for effective
cleaning, cooling and lubrication thereof. The jet deflection
capability of bit 96 will not detract in any manner from the rotary
drilling capability thereof.
If desired, the laterial passages 108, 110 and 112 and the
associated jet deflection nozzles 114, 116 and 118 may be of
different size if desired to produce optimum jet deflection erosion
characteristics. It is only necessary, according to the present
invention, that the converging jets of drilling fluid be capable of
eroding the well bore from more than one point and also be capable
of efficiently distributing drilling fluid during a subsequent
rotary drilling operation.
In view of the foregoing, it is apparent that I have provided a
novel focus nozzle jet deflection bit that effectively offsets the
problem of jet attenuation by defining a more efficient jetting
pattern that facilitates jet erosion of the formation at a
plurality of points to achieve more efficient jet penetration. My
invention therefore will achieve efficient jet deflection at
substantial depths even when the formations are consolidated to the
point that jet deflection would ordinarily be considered in an
inefficient operation. My invention is also capable of
accomplishing efficient jet deflection without sacrificing the
rotary drilling effectiveness of the drilling bit. A jet deflection
operation may be accomplished within the spirit and scope of the
present application by utilizing at least two, and perhaps several
converging jets of pressurized drilling fluid, orientated in any
suitable manner, to achieve optimum jet deflection without
sacrificing rotary drilling capability. Other variations of the
invention will be apparent to those skilled in the art.
Accordingly, without burdening this description will all such
possible variations, the foregoing description is to be understood
as illustrative only and not as any limitation upon the scope of
the invention as defined in the following claims.
* * * * *