1. The document discusses various drilling methods used for extracting samples from underground rock formations. It describes percussion drilling, rotary drilling, and several variations of each method. 2. Percussion drilling involves lifting and dropping heavy tools to break rock and uses steel casing to prevent cave-ins. Variations described are down-the-hole (DTH), top hammer, and circulation drilling. 3. Rotary drilling uses a powered rotating cutting head to drill holes while lubricating with air, water, or mud. Variations are auger drilling, calyx drilling, and diamond drilling. Diamond drilling creates precise holes using diamond-tipped drill bits and is useful for applications like concrete sampling.

1. Submitted by –
NAME – ZAID HASAN KHAN
ROLL NO. – 2020GLM017
ENROLLMENT NO. - GH3487
Submitted to –
Prof. Dr. Mohammad Irfan Ahmad
DEPARTMENT of Geology
ALIGARH MUSLIM UNIVERSITY
HYDROGEOLOGY
ASSIGNMENT

2. ORE GEOLOGY & MINING
TOPIC:
Types of drilling methods.

3. Drilling :
Drilling is the process of penetrating through the ground and extracting rocks from various
depths beneath the surface for confirming the geology beneath and/or providing samples for
chemical analysis.
Purpose Of drilling:
Drilling is a key technology in several applications of strategic or societal importance,
including Exploration for and extraction of oil, gas, geothermal, and mineral resources;
Environmental monitoring and remediation; Underground excavation and infrastructure
development; and Scientific studies of the Earth’s subsurface.
Drilling is the primary tool for extracting petroleum from rocks in the subsurface.
Improvements in drilling technology that lower drilling costs and increase the rate of success
in finding and extracting petroleum will have a direct benefit to the United States in terms of
higher energy reserves, stable energy costs, and improved economic competitiveness in the
drilling and service industries, which are increasingly global in character. Drilling is also the
primary tool for extracting geothermal energy (hot water and steam) from the subsurface for
heat and electricity production. At present, geothermal energy is more expensive than fossil
fuel energy, owing in part to the high cost of drilling. The reduction in drilling costs through
the introduction of improved technologies will allow more of this clean, domestic energy
source to be utilized.
Types of Drilling Methods:
On basis of principle involved in the operation, drilling may be classified as-
Percussion drilling:
Percussion drilling is a drilling method which involves lifting and dropping heavy tools to
break rock, and uses steel casing tubes to stop the borehole from collapsing.
Percussion drilling is carried out by breaking up the formation by repeated blows of a heavy
bit or a chisel inside a casing pipe.
Percussion drilling is accomplished by crushing the rock with heavy blows delivered by a
heavy chisel-shaped bit suspended on a cable.
Percussion drilling is a drilling method which involves lifting and dropping heavy tools to
break rock, and uses steel casing tubes to stop the borehole from collapsing.

4. 1.a) Down the hole (DTH) drilling
Down-the-hole drilling is to drive the hammer which behind the drill bit by compressed air via
the drill pipe. The piston strikes the bit directly, while the hammer external cylinder gives
straight and stable guidance of the drill bit. This makes the impact of energy is not lost in joints
and allowing for much deeper percussion drilling.
Furthermore, the impact force acts on the rock at the bottom of the hole, which is more efficient,
and straighter than other methods of the drilling operation.
And DTH is more suitable for the big hole of hard rock drilling, special for rock hardness over
200Mpa. However, for the rock below 200 MPa, it will not only energy waste, but also in low
drilling efficiency, and serious wear to the drill bit. It’s because while the piston of the hammer
strike, the soft rock cannot absorb the impact completely, which seriously lower the efficiency
of drilling and slagging.

5. 1.b) Top Hammer Drilling:
The percussive force of the top hammer drilling produced by the piston of the pump in the
hydraulic drilling rig, it is transmitted to the drill bit via shank adaptor and drill pipe, This is
the difference between DTH drilling. Meanwhile, the percussion system drives the drilling
system rotation. When the stress wave reaches the drill bit, the energy is transmitted to the rock
in the form of bit penetration. The combination of these functions enables drilling holes into
the hard rock, and the air compressor only performs dust removal and slagging in top hammer
drilling.
The combination of these functions enables drilling holes into the hard rock, and the air
compressor only performs dust removal and slagging in top hammer drilling.
Impact energy multiplied by impact frequency together creates the percussive output of the
drifter. However, usually, top hammer drilling used for hole diameter maximum 127mm, and
hole depth less than 20M, which in high efficiency.
The main distinction between the top hammer method and the down the hole (DTH) method
is the placement of the percussive force within the appliance. In top hammer drilling, the
activity is concentrated at the top of the drill string, above the hole, as a hammer transmits
cyclical shock waves to the drill bit by applying a percussive force on the drill rods or tubes
(With DTH drills, the hammer is placed down-the-hole at the bit). The percussive system
strikes the drill rod with 2,000 – 5,000 strikes per minute and the rotation speed can be 60 –
200 rounds per minute. The cuttings are flushed up from the bottom of the hole with
pressurised air or water.
1.c) CIRCULATION DRILLING:
Everse Circulation drilling, or RC drilling, is a method of drilling which uses dual wall drill
rods that consist of an outer drill rod with an inner tube. These hollow inner tubes allow the
drill cuttings to be transported back to the surface in a continuous, steady flow.
Unlike diamond drilling, it compiles sample rock cuttings instead of rock core. The drilling
mechanism is most often a pneumatic reciprocating piston called a hammer, which in turn is
driving a tungsten-steel drill bit, specifically made to be able to crush hard rock.

6. The hammer is used to remove rock samples which are pushed through the machine with
compressed air. When air is blown down the annulus (ring-shaped structure) of the rod, the
pressure shift creates a reverse circulation, bringing the cuttings up the inner tube. When the
cuttings reach a deflector box at the top of the rig, the matter is moved through a hose attached
to the top of the cyclone.
The drill cuttings will travel around the cyclone until they fall through the bottom opening into
a sample bag. These bags are marked with the location and depth of the place where the sample
was collected and can be transported directly to the assay lab for analysis.
Grade control is used to define the ore grades and blocks in the pit. For an exploration program,
the quality of the samples is imperative for mine planning and blasting—the samples must be
reliably accurate.
RC drilling is the superior method used for grade control in open pit mining operations
because:
• samples obtained via RC drilling are free of contaminants
• the samples are collected at the drill and sent directly to the lab to be assessed
• RC sampling requires less handling than other methods
• less handling results in cost reduction and faster turnaround times
The reliability of the cuttings produced during RC drilling is an industry asset. RC grade
control is the most cost effective and efficient method to differentiate between waste rock and
minerals.
2) Rotary drilling:
Rotary drilling is used to form a deep observation borehole or for obtaining representative
samples of rock. The drilling method involves a powered rotary cutting head on the end of a
shaft, driven into the ground as it rotates. The system requires lubrication (air, water or drilling
mud) to keep the cutting head cool.
There are two types of rotary boring, open-hole and core drilling. Material recovered from
open-hole drilling is mixed with the drilling lubricant. It is unsuitable for effective sampling,
and it is often difficult to observe and record the strata. Open-hole boring is only suitable for
rapid drilling to enable core recovery at a greater depth or for the installation of monitoring
wells. Core drilling is carried out using wire-line, double or triple-tube core barrels with
diamond or tungsten-tipped core bits.

7. Rotary Drilling
Rotary Drilling Classification

8. 2a) AUGER DRILLING:
Auger drilling uses a drill bit that looks a lot like a screw—it’s made of steel casing, with
curved flights that are rotated while the rig drill head applies pressure to move the bit further
into the ground. The rotation of the flights is important, because it mechanically moves
material to the surface. Augers can be mounted on a variety of machines or trucks, and come
in different lengths and diameters—anywhere from 2 to 18 inches.
Auger technology is extremely versatile and can be used on environmental, geotechnical,
dewatering and construction projects. The most common reasons to use it are for soil borings,
setting wells, collecting groundwater (just like Archimedes dreamed!) and gathering
geological data.Auger is great for geologies containing sand, gravel, clay or urban fill. It’s also
a good choice when a deep hole is needed—many other methods can’t achieve the same depths
that auger can.
There are a lot of upsides to using auger drilling:
• It’s capable of deep drilling.
• Drilling fluids aren’t required with auger technology (which provides a cleaner sample
for environmental projects).
• There’s a wide range of boring diameters that can be achieved.
• It can be mounted and used on nearly any rig or truck.
• It’s a cost effective technology.
But, as with any drilling method, there are drawbacks:
• It has limited ability in heavy urban fill (such as concrete, brick and wood) and dense
till.
Auger Drilling Bits

9. • This technology can generate more waste than other drilling methods, which will require
disposal.
2.b) CALYX DRILLING:
Calyx drilling Method of core drilling performed by the rotation of a steel cylinder and cutting
with chilled shot, about 2.4 mm diameter, which cuts a formation core. Circulating water
carries the cuttings up to a basket-like space at the top of the core barrel. The core is wedged
into the barrel and pulled up one barrel-length at a time. Shafts up to 2 m diameter can be
drilled, and holes to a depth of more than 300 m.
2.c) DIAMOND DRILLING:
Diamond Drilling is a form of core drilling which uses a rotary drill with a diamond drill bit
attached in order to create precisely measured holes. As diamond is the hardest naturally
occurring material in the world, it is ideal for creating openings in a range of materials
including concrete, metal and glass.
A diamond drill is a precision instrument, creating clean, accurate holes with diameters of
between 8mm to more than 1500mm. As it is a non-percussive technique, structural integrity
is maintained around when drilling. Every diamond drill runs water through the driving shaft
to ensure that the workspace remains free of dust. They can be operated in either a vertical or
horizontal direction depending on the requirements.
Although diamond drills are primarily used on concrete, it is a versatile tool that can be
deployed on virtually any material including glass, metal, stone, asphalt and tile. Diamond
Drilling is utilised in any situation where precise holes are required including creating large
openings for ducts, smaller holes for pipes or wiring, creating holes for the placement or
anchoring bolts, or even for concrete sample analysis. Holes can be created to an almost
unlimited depth.
Diamond Drilling Bits
Diamond Drilling illustration

10. Diamond Drilling offers a number of significant advantages over conventional drilling.
Cutting is more accurate than percussive techniques which means that there is less chance of
damage which could affect structural integrity. The equipment is lightweight and highly
portable and can be used in situations where space is at a premium. As the procedure is
relatively quiet, it can be done in virtually any location without fear of creating excess noise.
Very little dust is produced with Diamond Drilling so it creates little mess or disruption.
At times, it will be necessary to carry out drilling underwater. Diamond Drilling is the most
efficient way to carry out drilling underwater. As these drills are portable, they are easy to
maneuver in water. Often when carrying out this kind of work, multiple drills are used
simultaneously in order to improve efficiency.
Diamond Bit