Note: Descriptions are shown in the official language in which they were submitted.
HIGHLY-EFFICIENT COMPOSITE DRILL BIT FOR FORMATION
DIFFICULT TO DRILL IN DEEP WELL
TECHNICAL FIELD
The present invention relates to the technical field of PDC speed-up drill bit
structures, in particular to a highly-efficient composite drill bit for a
formation
difficult to drill in a deep well.
BACKGROUND
DC drill bits and diamond drill bits are used more and more widely in
petroleum
and geological drilling, can achieve good use effects and good economic
benefits in
hard formations, and thus are extensively valued by the petroleum and
geological
communities. The designs of conventional PDC drill bits and diamond drill bits
are
based on the principle of balanced design. The crown shapes such as a deep
cone and
a double cone, which serve as the passive anti-slant technology, are applied
to the
design and play certain centering and stabilizing effects. At present, the PDC
drill bit
is mainly composed of a drill bit body (carcass), PDC cutting teeth, a nozzle,
a gauge
protection material, a connector and the like. The formation is cut by means
of PDC
cutting teeth to achieve drilling. The nozzle is a hydraulic passage between
an inner
cavity of the drill bit and the outside. The main functions of the nozzle are
to clean the
bottom of the well, to carry rock debris away from the bottom of the well, to
prevent
drilling bit balling, to reduce repeated cutting, to improve the rock breaking
efficiency,
and further to play a hydraulic rock breaking effect under certain drilling
parameters.
During operation, a drill bit body that rotates at a high speed drives the PDC
cutting
teeth to rotate at a high speed to cut the hard formation, and meanwhile, the
fluid
ejected from the nozzle discharges the debris from the shaftway.
However, during the process of cutting the hard formation, due to the
excessive
hardness and large size of a rock, the PDC cutting teeth are damaged. The long-
term
use will also cause fatigue damage of the PDC cutting teeth and shorten the
service
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life of the drill bit. However, after the PDC cutting teeth are damaged, it is
necessary
to replace the new drill bit, which seriously reduces the rock breaking
efficiency. In
addition, during the drilling of the hard formation by the drill bit, the
generated debris
is just stuck in the nozzle, so that fluid that is introduced into the drill
bit body cannot
be smoothly ejected from the nozzle, and the PDC cutting teeth cannot be
cooled.
Meanwhile, the debris cannot be removed from the shaftway, which further
reduces
the rock breaking efficiency.
SUMMARY
TECHNICAL PROBLEM
An objective of the present invention is to overcome the defects of the prior
art,
and to provide a highly-efficient composite drill bit for a formation
difficult to drill in
a deep well, which has the advantages that the structure is compact, the rock
breaking
efficiency is improved, the service life of PDC cutting teeth is prolonged,
nozzles can
be prevented from being blocked by rocks or debris, and the manufacturing cost
is
low.
SOLUTION TO PROBLEMS
TECHNCIAL SOLUTION
The objective of the present invention is achieved by the following technical
solution: a highly-efficient composite drill bit for a formation difficult to
drill in a
deep well comprises a drill bit body, bit cones and nozzle anti-blocking
mechanisms,
wherein a fluid cavity is formed inside the drill bit body; a crown portion is
arranged
at the bottom of the drill bit body; a conical drill bit is fixedly arranged
on the bottom
surface of the crown portion and located in the center of the crown portion; a
plurality
of nozzles which are distributed around the conical drill bit are arranged on
the
bottom surface of the crown portion, each nozzle being communicated with the
fluid
cavity; a plurality of main blade wings are fixedly arranged on the bottom
surface of
the crown portion along the circumferential direction of the drill bit body;
an auxiliary
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blade wing is fixedly arranged between every two adjacent main blade wings; a
plurality of PDC cutting teeth are fixedly arranged on each main blade wing
along the
length direction of the main blade wing; the bit cone is further fixedly
arranged on
each main blade wing; each bit cone comprises a conical body fixedly arranged
on the
top surface of the respective main blade wing, wherein a ring of inserted
teeth,
disk-shaped teeth and milling teeth are fixedly arranged in sequence on the
outer
surface of the conical body and between a small end surface and a large end
surface;
the exposing height of each of the inserted teeth, the disk-shaped teeth and
the milling
teeth is greater than the exposing height of the PDC cutting teeth; the nozzle
anti-blocking mechanism which is located in the respective fluid cavity is
arranged
above each nozzle; each nozzle anti-blocking mechanism comprises a hollow
steel
pipe, an unloading plate, a pushing plate, a spring and a plug, wherein the
plug is
fixedly arranged in each nozzle and is internally provided with a guiding
hole; the
hollow steel pipe which is movable vertically is slidably mounted in the
guiding hole;
the upper end of each hollow steel pipe extends into the fluid cavity, and the
pushing
plate is welded to this extension end; the pushing plate is located in the
fluid cavity;
the lower end of each hollow steel pipe extends into the nozzle, and the
unloading
plate is welded to the outside of this extension end; the unloading plate is
located
inside the nozzle; each hollow steel pipe is further sleeved with the spring;
one end of
each spring is fixedly arranged on the bottom surface of the fluid cavity, and
the other
end of the spring is fixedly arranged on the bottom surface of the pushing
plate.
Each auxiliary blade wing is fixedly arranged on the bottom surface of the
crown
portion and welded with the respective blade wing into a whole.
The main blade wings are uniformly distributed on the crown portion.
The crown portion is at least provided with three main blade wings.
Each unloading plate is parallel to the corresponding pushing plate.
Each hollow steel pipe is parallel to the axis of the drill bit body.
An internal thread is arranged inside each nozzle, an external thread is
arranged
outside each plug, and the external thread of the plug is connected to the
internal
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thread and is fixed to the corresponding nozzle.
The bit cone has a triangular, semi-circular, trapezoidal or wedge-shaped
section.
BENEFICAL EFFECTS OF THE INVENTION
BENEFICAL EFFECTS
The present invention has the advantages that the structure is compact, the
rock
breaking efficiency is improved, the service life of PDC cutting teeth is
prolonged,
nozzles can be prevented from being blocked by rocks or debris, and the
manufacturing cost is low.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a semisectional view of the present invention;
FIG. 2 is a bottom view of FIG. 1;
FIG. 3 is a sectional view of a bit cone;
FIG. 4 is a locally enlarged view of part tin FIG. 1;
in drawings, reference symbols represent the following components: 1-drill bit
body; 2-bit cone; 3-fluid cavity; 4-crown portion; 5-conical drill bit; 6-
nozzle; 7-main
blade wing; 8-auxiliary blade wing; 9-PDC cutting teeth; 10-conical body; 11-
inserted
teeth; 12-disk-shaped teeth; 13-milling teeth; 14-hollow steel pipe; 15-
unloading plate;
16-pushing plate; 17-spring; 18-plug; 19-guiding hole.
EMBODIMENTS OF THE INVENTION
DETAILED DESCRIPTION
The present invention will be further described below in conjunction with the
accompanying drawings, and the protection scope of the present invention is
not
limited as follows:
As shown in FIGS. 1-4, a highly-efficient composite drill bit for a formation
difficult to drill in a deep well comprises a drill bit body 1, bit cones 2
and nozzle
anti-blocking mechanisms, wherein a fluid cavity 3 is formed inside the drill
bit body
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1; a crown portion 4 is arranged at the bottom of the drill bit body 1; a
conical drill bit
is fixedly arranged on the bottom surface of the crown portion 4 and located
in the
center of the crown portion 4; a plurality of nozzles 6 which are distributed
around the
conical drill bit 5 are arranged on the bottom surface of the crown portion 4,
each
nozzle 6 being communicated with the fluid cavity 3; a plurality of main blade
wings
7 are fixedly arranged on the bottom surface of the crown portion 4 along the
circumferential direction of the drill bit body 1. In this embodiment, the
main blade
wings 7 are uniformly distributed on the crown portion 4; the crown portion 4
is at
least provided with three main blade wings 7; an auxiliary blade wing 8 is
fixedly
arranged between every two adjacent main blade wings 7; a plurality of PDC
cutting
teeth 9 are fixedly arranged on each main blade wing 7 along the length
direction of
the main blade wing 7.
The bit cone 2 is further fixedly arranged on each main blade wing 7. In this
embodiment. the bit cone 2 has a triangular, semi-circular, trapezoidal or
wedge-shaped section. Each bit cone 2 comprises a conical body 10 fixedly
arranged
on the top surface of the respective main blade wing 7, wherein a ring of
inserted
teeth 11, disk-shaped teeth 12 and milling teeth 13 are fixedly arranged in
sequence
on the outer surface of the conical body 10 and between a small end surface
and a
large end surface; the exposing height of each of the inserted teeth 11, the
disk-shaped
teeth 12 and the milling teeth 13 is greater than the exposing height of the
PDC
cutting teeth 9; the nozzle anti-blocking mechanism which is located in the
respective
fluid cavity 3 is arranged above each nozzle 6.
Each nozzle anti-blocking mechanism comprises a hollow steel pipe 14, an
unloading plate IS, a pushing plate 16, a spring 17 and a plug 18, wherein the
plug 18
is fixedly arranged in each nozzle 16 and is internally provided with a
guiding hole 19;
the hollow steel pipe 14 which is movable vertically is slidably mounted in
the
guiding hole 9; each hollow steel pipe 14 is parallel to the axis of the drill
bit body 1;
the upper end of each hollow steel pipe 14 extends into the fluid cavity 3,
and the
pushing plate 16 is welded to this extension end; the pushing plate 16 is
located in the
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fluid cavity 3; the lower end of each hollow steel pipe 14 extends into the
nozzle 6,
and the unloading plate 15 is welded to the outside of this extension end; the
unloading plate 15 is parallel to the pushing plate 16 and located inside the
nozzle 6;
each hollow steel pipe 14 is further sleeved with the spring 17; one end of
each spring
17 is fixedly arranged on the bottom surface of the fluid cavity 3, and the
other end of
the spring 17 is fixedly arranged on the bottom surface of the pushing plate
16.
Each auxiliary blade wing 8 is fixedly arranged on the bottom surface of the
crown portion 4 and welded with the respective blade wing 7 into a whole. An
internal
thread is arranged inside each nozzle 6, an external thread is arranged
outside each
plug 18. and the external thread of the plug 18 is connected to the internal
thread and
is fixed to the corresponding nozzle 6.
The working process of the present invention is as follows:
before working, a conical threaded end at the upper end of the drill bit body
1 is
connected to an internal thread of the drill pipe to install the entire PD C
speed-up
drill bit; during working, the drill pipe is lowered and rotates at a high
speed; the drill
pipe drives the PDC speed-up drill bit to rotate at a high speed; the PDC
speed-up
drill bit enters the hard formation, such that the conical drill bit 5
primarily breaks the
large rock; the broken rock is further broken by the milling teeth 13, the
disk-shaped
teeth 12 and the inserted teeth 11 and finally broken by the PDC cutting teeth
9 to
obtain debris finally. Therefore, the PDC cutting teeth 9 do not directly
break the
hard large-size rock, such that the PDC cutting teeth are protected well,
thereby
ensuring that the PDC cutting teeth can work for a long time and improve the
rock
breaking efficiency.
During the drilling process, a worker operates a high pressure pump on the
ground and pumps a high pressure fluid into the fluid chamber 3 through the
high
pressure pump, wherein a part of the high pressure fluid hits the top surface
of the
pushing plate 16, and the remaining part of the high pressure fluid directly
passes
through the inner cavity of the hollow steel pipe 14 and the nozzle 6 to
finally act on
the bottom of the well. The fluid reduces the temperature of the PDC cutting
teeth to
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ensure proper operations of the PDC cutting teeth. If the debris generated
during the
drilling blocks the nozzle 6, the high pressure fluid hitting the top surface
of the
pushing plate 16 applies a downward acting force to the pushing plate 16, to
drive the
hollow steel pipe 14 to move downwards along the guiding hole 19. Meanwhile,
the
spring 17 is compressed to further drive the unloading plate 15 to move
downwards.
The debris stuck in the nozzle 6 is discharged by the unloading plate 15
downwards to
the outside of the nozzle 6, and a lower port of the nozzle 6 is plugged to
prevent the
debris from entering therein, such that the nozzle is effectively prevented
from being
blocked, thereby ensuring that the PDC cutting teeth can be continuously
cooled, and
further ensuring the smooth proceeding of rock breaking.
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