ADVANCED DRILL WEIGHT REDUCING METHOD FOR GEOTHERMAL
ENERGY EXTRACTION USING TAPERED SOLID CONICAL DRILL
C. Balaji Krishna Kumar*
Department of Mechanical Engineering, Bharath University.
ABSTRACT
Energy efficient drilling technology for water wells, oil and gas wells and
geothermal wells is a present need. Generally, either percussion or rotary type of
drilling is used for drilling. This system combines both rotary and percussion type of
drilling. Experimental test shows tapered solid drill bits drills the concrete and rock
more efficiently than the grinding action of the present drilling technology.
Geothermal well drilling is designed using hydride carbide and diamond
tapered drill bit with a suspension system to reduce the weight. This drill can drill the
Earth’s crust to 5-25 kms to extract energy from hot rocks at 700°C. In order to avoid
subsidence a container is fitted after completion of drilling and water is injected into
the vessel for producing steam.
Geothermal energy extraction requires reservoir for generating steam.
Geothermal energy production requires mainly a reservoir, though there is thermal
gradient, it is not tapped. So, an innovative way to solve this problem is provided.
This system is energy efficient than any other drilling technology such as plasma or
thermal spalling and will only be the answer to all our energy needs in the future.
Key words: Drilling, Advanced drilling system, percussion and rotary drilling,
energy efficient drilling, drill weight reducing system.
higher depths. So, a weight reducing
1. Introduction
mechanism
Geothermal, Oil and gas well
is
provided.
This
mechanism is safe and will not kinder
drilling technology use Tricone bits
the
tectonic
plate
and diamond coring bits. Water bore
seismicity.
well drills use flat rock drills. All these
vibrations produced due to the drill
drill bits use grinding process for
will be less than Secondary velocity of
drilling. In this paper, these drills are
3 m/s. Thus it will drill even at 25 kms.
replaced by tapered solid drill bit
Diamond embedded Tapered drills is
which provides faster and energy
very
efficient drilling.
temperature rocks.
At
effective
movements
25
in
kms
drilling
or
depth,
hot
With the present geothermal
In order to drill effectively,
drilling technology, drilling after 20
mechanisms have been designed in this
kms can create seismicity if the load of
paper.
the drill acting at the depth is of the
circumferential
order of 25000 T, though the weight is
mechanisms and circumferential drill
supported by the mud and debris in the
mechanisms at an angle are employed
present slim hole drilling technology.
at places where there exists huge
Drilling
reservoir or void in order to hold the
with
robot
type
remote
operation can be used only up to
Diamond
drill
embedded
suspension
container.
certain depth since there may be blow
The drill geometry is
out of the robotic drilling system due
automatically modelled and meshed
to less weight and high pressure acting
with the aid of NASTRAN NX-
against the equipment weight due to
FEMAP program.
high temperature and pressure at
for hammering action. The weight
2. Methodology
holding rod consists of two parts; one
At a depth of 15 kms or more, this
part is fixed to one end of the spring or
weight reducing system will reduce
steam jacket and other end moves into
10000 tons acting on the drill bit. If
the circumferentially drilled ring by
10000 tons act on at that depth it will
means of a cylinder.
cause seismicity. Only the required 10
The suspension system
or 15 tons will act on the hot rocks to
uses steam cylinders attached to the
drill.
container and Drill weight reducing
Figure
9
Driving
rods. Using gear drive mechanism,
mechanism which is a replacement of a
shown in Fig. 13, the drilling is carried
rig type controls for drilling. This
out along the circumference. This
consists
suspension
mechanism is supported and powered
mechanism as shown in the figure to
by the drill pipe and this provides a
handle hammering action. Hammering
sturdy operation. After drilling, the
is mainly needed to break especially
circumferential drill bit has to be
granite rocks by impact loads.
retained
of
shows
springing
the
between
the
rocks
after
In geo thermal drilling the
penetration to maximum depth. After
weight of the drill with the series of
drilling the first part, the second part of
drill pipes is of the order of thousands
the circumferential drill is brought by
of tons. Hence, slow drilling process
the movement of the ladder along the
with very high torque values is used
tracks from the surface and it is
for drilling. Figure 2 shows the Drill
connected to the first part by the
weight reducing system in front view.
circumferential drilling mechanism.
This consists of spring or steam jacket
Usually a drill bit is three or four parts
connected together depending on the
circumferentially
depth required to hold the weight of
reducing system.
drilled
weight
the drill pipe. After drilling to a certain
For each depth a set of container is
depth (assume 25m) the first set of
moved forward using the mechanism
circumferential drills is placed and
shown in Fig 9. In this mechanism,
weight reducing rods are inserted into
drill pipe is fixed with bearings and
the ring of the circumferential drill
suspended over the springs. A set
bits. Again the diameter 1 m drill bit
consisting of mud fall blocking pipe,
drills to 25 m and the ladder moves the
drill weight reducing rods, and the drill
first set of drill weight holding rods to
pipe
the
drilling
calculated depth each time. Where,
pneumatic
holding plug is detachable. So, for
jackets compress and elongate based
every increase in calculated drill depth,
on air flow adjustment of compressed
holes are created at an angle along the
air in pneumatic cylinders through
circumference of the mud fall blocking
pipes. The flow of pressurised air is
container for a calculated distance into
controlled by flow adjustment valves.
the drilled hole through rock drill bits.
This produces hammering action and
This is done in order to prevent entire
drilling is completed to further depths.
weight of the drill pipe, of length 15
next
25
circumferentially.
m
after
The
After drilling to 10 kilometres
is
inserted
together
for
a
kms or more, to act on the drill bit.
the temperature and pressure of the
Three set of containers are fixed to
system increases along with the depth.
the ladder system shown in fig. 9
This pressure is blocked by the weight
which are suspended by springs to the
of the Solid tapered drill bit and blow
gears based on the weight against free
out
fall and the ladder can move on tracks
is
prevented
by
the
through the entire depth as shown in
depth and is made to seat on the
Fig.
already drilled circumferential drill
5.
The
ratchet
and
pawl
mechanism, pawl with springs prevent
pins.
Similarly
the
the ladder from freefall and holds it on
containers is moved in to the depths.
to the tracks. The pawl releases the
For 10 Km, 10000 containers are
gear only if the spring force is
required. After drilling to certain depth
exceeded by the engine. While the
each container is moved and placed on
ladder is moving upwards it moves
the
freely. This mechanism is shown in
holder pins.
circumferential
next
drilled
set
of
weight
fig. 8. During circumferential drilling
The lead part of the drill is
the ladder is fixed to the stops on the
made sharp with a diamond tip and the
container.
body has steps of various diameters.
After drilling to certain depth using the
Carbide buttons with diamonds are
1 m drill, holes are drilled to the
brazed along with High-speed steel
circumference
and
are
drill body. The drill can be two fluted
moved
placed
the
or three fluted. Three fluted drill are
mechanism shown in fig. 9. Then the
more advantageous than two fluted.
first set of container is moved by using
Coolant for the drilling operation is
the ladder system so it releases the first
provided through a separate hose.
set of springs. This makes the other set
Suction of debris after drilling is done
of
container
through the drill pipe. After a certain
compress. The container is first fixed
depth the debris comes out and is
to the ladder and locks are detached for
sucked through the drill pipe.
and
springs
above
containers
using
the
the first container to move freely. So,
the first container advances into the
Cementing
and
grouting
is
not
essential but can be used if necessary
after drilling certain depth.
Geothermal
for carrying thrust loads exclusively
a
and at speeds below 2000 rpm. At high
temperature starting between 500°C to
speeds, centrifugal forces cause the
1000°C. Generally, even 20-25 kms
balls to be forced out of races.
depth can produce high geothermal
Therefore
zones
reservoirs.
recommended that angular contact ball
Cryogenic technology will be required
bearings should be used in place of
to cool the drill and its mechanisms are
thrust ball bearings.
at
even
very
high
zones
The thrust ball bearings are used
without
have
temperatures
at
high
speeds
it
is
and
pressures, beyond 25 kms.
3. Placing of container in voids
or gaps
5. Springs
A concentric spring is used to
obtain greater spring force within a
given space and to insure the operation
The drills are drilled at a certain
of a mechanism in the event of failure
angle for penetration into the top and
of one of the springs. A concentric
bottom portion of the void or reservoir
spring for drilling is to exert a
using the mechanism in Fig 14 and Fig
maximum force of 5000 N under an
15. Then the container is attached to
axial deflection of 40 mm. Both the
the holder pins using connectors as
springs have same free length and are
shown in Fig 16.
subjected to equal maximum shear
stress of 850 Mpa. If the spring index
4. Thrust and torque
for both the spring is 6 then design for
the
load
shared
and
for
main
Bulk weight = W/V
dimensions of the spring including
Dry unit weight Xd = X/ (1+W) =
number of active coils in each spring.
Wd/V
Also, Xd = G. Xw / (1+e)
Vw = Ww / Xw
Vs = Ws / Xs = Ws/g. Xw
6. Calculations
Vv= (V- Vs)
where,
Weight of the container
Volume V, Dry weight Wd, Wet
Weight per metre length of a 10 mm
weight W and Specific gravity G.
thick container = 248 Kgs.
Weight of 10 mm thick hollow drill
For Earth’s density of 2000 Kg/m2,
pipe of 150 mm diameter for a 1 metre
The depth required to be drilled
length = 200 Kgs.
circumferentially is 3 m using 10 cm
For every metre depth 500 Kgs load of
diameter drill. This depth can take a
container and drill pipe is balanced by
weight of 500 Kgs for 4 m length.
the weight holding system.
So for 20 Kms weight of 5000 T, the
So for 10 Km, 10000 containers are
number
required.
required is 100, 000 at approximately 4
of
circumferential
drills
metre gap.
Weight based on volume at depths
Results and discussion
Weight
based
on
depth
can
be
calculated using the system shown in
This system of drilling is faster
Fig 1.
than
the
conventional
drilling
Water content = (W-Wd)/Wd
technology, at the same time a 1 metre
hole is created instead of one 6 inch
affected. After the zone is cooled then
hole. Hence this drilling methodology
again drilling can be made to higher
is cost effective and produces more
depths. This mechanism works as
steam
conventional
sturdy as the circumferential drilling
geothermal drilling. One hole of 1
mechanism even at any temperature
metre is equal to 10 holes of 6 inches
and pressure more than 1000 ˚C and
diameter in present drilling technology.
1000 bar pressure. This design is more
This type of drilling is possible
efficient and durable than the present
than
the
even without a geothermal reservoir.
The diameter of the geothermal drilling
technology.
Thermal
insulation
for
the
hole can stepwise starting from 10
initial few kilometres depth will make
metres and then to 7 metres and then
the design more efficient. Insulation
reduced up to 1 metre. At certain
for various regions of container for the
places 10 metre diameter can be
initial 5 km would prevent heat loss.
constantly used for drilling without
stepwise reduction up to certain depth.
This type of drilling with 3
Thus this system reduces cost,
time and labour in completion of well
construction.
metre diameter and 10 foot long drill
can replace 30 times by size, the
drilling
using
technology.
slim
This
hole
References
drilling
mechanism
is
[1] Dr. William C. Maurer, Novel
effective than the present rigs. To
drilling techniques, 15-105 pp.
extract energy it is required to drill to
[2] Bent Sorenson (2004), Renewable
certain depth till the life of the parts of
energy, third edition, academic press,
the drilling mechanism does not get
Elsevier Inc. pp 282-289.
[3]
Drilling
data
handbook
and
Air
pressured
Pipes
With
valves
practices manual, Oil and Natural Gas
Suction
through
Drill pipe
Piston and
cylinder for
moving in and
out of the rings
of the
circumferential
drill
corporation of India pp.
[4] Gene culver, Geo heat center,
Klamath Falls, Oregon, “Drilling and
Ladder
with
equipment
s
Pneumatic
Cylinders that
provide the action
of springs
well construction”, pp 129-164.
[5] John Rowley, Seiji Seito, Roy
Long, Advanced drilling system for
drilling geothermal wells – an estimate
Fig 2. Drill weight reducing system in
of cost savings- World Geothermal
front view
Congress 2000, pp 2399-2404.
Figures:
Cylinder
Rod holder
ring
Fig 3 Detailed view of weight holding
Air
Vv
Vw
Water
Ww
W
V
Vs
Solids
rod with cylinder.
Ws
Springs or
steam
jackets with
holding pins
Weight
holding
rods
Fig 1 Weight based on volume at
depths.
Bearing
Ladder on
tracks
Lock
s
Fig. 4. Schematic layout of the drill
weight reducing system in top view.
Holders
Controlled
by Robot
Thermally
insulated
electrical
wires
Robot
To
motor
To
motor
Camera
Helical
worm type
gear
Note:
Driving
mechanism
from the
surface to
be
supported
without
hindering
the gripper
and working
mechanism.
Pins along the
1m dia weight
holder and mud
fall blocking
barrel
Coolant hose
Motor / Engine /
steam turbine to
Drive the ladder
along the tracks
Gears as
grippers on
the tracks
with 3
ton/cm2
capacity of
the ladder
with all
equipments
Fig 5. Ladder and track system
Fig. 9. Driving mechanism
Fig. 6: Model meshed.
Gripper
Cementing
initially for
1 km for
the Gripper
Fig. 7: Model with constraints.
Rings
Fig. 8: Model with 100N loads on the
Ladder
Stops
driven by
mechanism
driven by
gear on the
tracks with
cryogenic
protection.
nodal each point.
Fig 10. Circumferential drilling and
ladder stop mechanism.
Fig 12. spring and steam cylinder
working process.
Engine
Robot
Piston/cylinder
Journal
Bearingblock -100
Kgs
Ladder
Gears with
pawl and
springs to hold
the pawl
against free
fall of the
ladder.
Figure
11.
M
es
h
e
d
Gears on the
ladder fixed to
the engine.
H
el
ic
al
B
E
A
R
I
N
G
Rack and Pinion
G
ea
r
Ratchet
and
Pawl
Piston/cylinder
Engine
Piston/cylinder
mechanism for ladder movement along
tracks.
Fig 13. Circumferential drilling using
gear drive mechanism
Length of
spring L1.
Length of
spring L 2.
Length of
spring L 3.
L 3 Expands
to L 1 length
and attaches to
the next pin.
Similarly,
L2
Compresses
to L3 and
then expands
to L1.
Similar
method of
length
transformation
as in springs
from L3-L2L1 to L1-L3L2, air
pressured
screw type
piston cylinder
for hammering
action.
Ladders
carrying
equipments
driven by
sequence of
gears from
the top and
using steam
turbines
/cylinders
along tracks.
Roller
Bearing
Note:
Pressurised air
pipes provide air
to the pneumatic
pressured screw
type cylinders.
Suction of the
debris after
drilling is done
using attachable
pipes for the
required depth.
The weight of
the whole
system is
calculated and
reduced by
providing more
number of
circumferential
pins.
Drill pipe collar
Robot
Piston/cylinder
Fig 15. Circumferential drilling at a
Piston/cylinder
Journal
Bearingblock -100
Kgs
downward angle using gear drive
Bearing1 and
rack 1
assembly
mechanism
Engine
BEARINGS
Meshed
Helical
Gear
Helical-tapered
tooth rack and
Piston/cylinderpinion
Piston/cylinder
helical
heRack and
Pinion
Fig 16. Container weight holding
Fig 14. circumferential drilling at an
device at voids or gaps.
upward
angle
using
gear
drive
Ø1m
mechanism
Diamonds
Embedded
Length = 1 m
Robot
Piston/cylinder
Figure
17.
Analysis
based
on
Piston/cylinder
Journal
Bearingblock -100
Kgs
Bearing1 and
rack 1
assembly
BEARINGS
Meshed
Helical
Gear
Helical-tapered
tooth rack and
Piston/cylinder pinion
helical
Debris
heRack and
suction
Pinion
pipe
Experimental
model.
Engine
Piston/cylinder
dimensional
analysis
Gear
Press
fitted
Steam
pipe
Cryogenic
material lock
HSS
lock
Cryogenic
Bearing
assembly
Drill pipe
Cryogenic
Lock system
Figure
Cryogenic drill pipe
18.
Cryogenic
protection
system for locks and drill pipe after
depth of 25 kms.
Threaded
Nut for
holding
the
steam
without
leakage
and then
more
pipes are
attached
for
extensio
n
after
removal
of the
nut for
each step
under
depth.
Treads – Internal
and external
Spring
Figure 20.
Steam flow adjusting
mechanism.
Ladder
Roller bearing
assembly.
Cryogenic
protection
material
over the
sides.
Steam
cylinder
assembly
Latch type
Cryogenic
seal open
close
system for
movement
of steam
cylinder
pin.
Front view
of the latch
Figure
19.
Set of Gears driven from the top and by
stationary steam turbines on the container.
HSS Gear in the middle
Upper
Latch
Circular
Tight Seals
without
friction.
Stationary steam
turbine inserted
with seal
Cryogenic
material
Latches
opens for
the ladder
movement
and closes
by springs
after ladder
is moved.
Side view
of the latch
Cryogenic
latch
Front view
Roller with
Bearing
Support on
the ladder.
Top view
protection
system for bearings after depth of 25
Figure 21. Cryogenic protection on the
kms.
tracks and ladder assembly after depth
of 25 kms
Fig. 24. Analysis of the container using
Guide
blades
Steam
turbine
rotor
blades
Nastran NX
Grouting and Cementing
Ø 1m
Container-weight reducing plugs
Power from
insulated steam
turbines to
actuate other
mechanisms such
as stops and
mechanical robots
using gears.
Ladder on
the track.
Ø0.7m
Ø 0.03m
Ø 0.75m
Figure 22. A steam turbine on the
ladder.
Ø 0.85 m
Aluminium Or Mild steel
Container with holders
Fig. 25. Schematic layout of the
container weight reducing system.
Ø2m
Ø 1.75 m
Thread
movement
Cam
operated
oil lamp
Ø 1.5m
Ø1m
Oxygen
supply
for
(Better
mas)
Lamp.
Ladder
Along
tracks
Note:
Plastics or
Polymers
Can be
used as
coolant
till 25 kms
depth or
magma is
reached in
the weight
reducing
system of
geothermal
drilling.
15 kms
20 kms
Gripper
robot
Drill bit
portion 1
Figure 23. Futuristic Stepwise drilling
for Geothermal Energy extraction
Robot
Journal
Bearingblock -100
Kgs
Drill bit
portion 2
Step wise
drill pipe.
25 kms
Collapsible
Shaft Piston
controlled
Engine
Bel
t
Dri
ve
Piston/Cylinder
Piston/
Cylinder
Note: Belt
drive for
circumferenti
al drilling can
be used for
initial depths
for
temperatures
not exceeding
100° C.
Fig 26. Belt drive