Neftegaz.RU #3-17 ENG

EQUIPMENT
FIG. 6. The stabilizing anti-vibration boring bit, top plan view
element of a separate screw line,
these inserts are attached to the
body by means of soldering at the
negative angle from minus 5° and
minus 15° to the cutting surface,
which is distinct by the fact that
polycrystalline diamond inserts at
the bit edge are differently-directed
at the negative angle of 15° towards
cutting direction.
As for some other rock-destruction
tools used for mine rocks drilling,
other conditions such as kinematic
ones can be determining for
the purposes of the front angle
choosing. In that way for boring bits
type PSh-140 (РШ-140) or RBK-
42 (РБК-42) reinforced with PCD
the front angle may exceed -20°
due to the possibility of touchdown
on the rear PCD edge near the
break at high feed rates. As for
cutting drilling tools reinforced with
tungsten-cobalt inserts for mine
rocks drilling technical conditions
may be determining ones.
The suggested bit is operated in the
following way. Drilling fluid used for
the purposes of the bit cooling and
destruction products transportation
from the flushing pump to the well
surface, moves through the drilling
string rotating to the right, and the
bit body gets to the well downhole.
Then drilling fluid goes from under
the bit edge 1 it takes drilling mud
and transports it along the main 3
and the auxiliary 6 water ports to the
surface at the highest turbulence
level, because the main and the
auxiliary water ports are located
counter-current angle-wise to the
right along the screw line. At the
same time calibration PCD inserts 7
are fixed in the auxiliary water port
6; they are used for the purposes of
the well walls calibration which helps
to reduce well deviation.
The main polycrystalline diamond
inserts work in cutting mode with
differently-directed cutting force. All
of it as a whole provides possibility
for improving a mud transportation
out of the well downhole, vibration
reduction, reduction of a number of
shears and breakages; this helps to
ensure smooth trajectory of drilling
resulting in drilling mechanical
velocity increase and a bit operating
life or meter-per-bit value increase.
Therefore all the forces applied on
a bit are differently-directed, i.e.
they are directed towards the well
downhole and core, so they prevent
the bit vibration.
To summarize, we have proposed
anti-vibration boring bit consisting
of body with с connecting thread,
divided by the main water ports into
segments, which on the side surface
are provided with polycrystalline
diamond inserts, which have
negative front angles in plan to the
side internal and external cutting
surfaces and negative front angles
to the end surface of the well
downhole; the main water ports
are designed in counter-current
direction angle-wise, moreover the
bit body segments have countercurrent
angle-wise auxiliary water
ports provided along the whole bit
body height in screw line to the right
in the bit rotation direction; the bit
body height depends on the screw
line pitch of the main and auxiliary
water ports; inside the auxiliary
water ports there are two or more
polycrystalline diamond calibration
inserts, each of them represents the
Conclusions:
1. For the first time the rationale
for operating front and rear angles
choosing was given based on the
experimental data for drilling of
producing and exploratory wells
using cutting type drilling tools
reinforced with PCD.
2. The determining factors for
choosing of operating front and rear
angles of RDT reinforced with PCD
are reduction of cutting force and
reduction of bluntness area, as well
as prevention of cutting elements
touchdown on the rear edge.
References
1. M.G. Krapivin, I. Ya. Rakov, N.I. Sysoev. Mining
tools. – 3rd edition, reviewed and amended. –
Мoscow: Publishing House ‘Nedra’, 1990 – 256
pages.
2. А.А. Tretyak, Yu.F. Litkevich, К.А. Borisov.
Determining of drilling velocity and operation
time of the new generation bits reinforced with
polycrystalline diamond inserts. Neftegaz, 2016,
No. 10, pages 29 – 33.
3. Yu.F. Litkevich, А.Е. Aseeva, А.А. Tretyak.
Development of the methods for calculation
of operation time of rock-destruction tool
with polycrystalline diamond reinforcement.
Construction of oil and gas wells by land and by
sea. – 2010. – No. 12. – pages 2 – 5.
4. А.А. Tretyak. Development of the process
regulation for running of the bits reinforced
with polycrystalline diamond inserts. Mining
information-analytical bulletin. – 2011. – No. 12. –
pages 228 – 232.
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