OIL AND NATURAL GAS CORPORATION Ltd.
,
Internship Report on
Introduction to Drilling
By : N. Sai Srinivas
Acknowledgement
My sincere acknowledgement to Oil and Natural
Gas Corporation Limited, Rajahmundry for giving
me a valuable opportunity to work with them. This
project report is dedicated to all the people, whom I
met, took guidance, tacked and gained knowledge
from them.
I extended my sincere thanks to BSS.KUMAR,
DGM(MECH.)-DS, for his valuable guidance to
successfully complete my internship in time,
educative and informative. I am very much grateful
to him for enhancing my knowledge pertaining to
Mechanical Engineering and for providing valuable
guidelines for my personality development.
I also extend my gratitude to ASH.CHOWDARY,I/C
Workshop for his valuable guidance in instructing
about the heavy equipped workshop in
Dowlaiswaram, Rajahmundry. And to Mr. Trinadh
(electrical in-charge) of Rig E-1400-16 for his
valuable guidance in instructing about the working
of each equipment in the rig.
Beside this I would also like to extend my sincere
thanks to entire staff people who helped me in
completing my training period and project report.
Introduction :
Until 1955, mainly private oil companies used to
carry out the exploration of hydrocarbon
resources of India.
In Assam, the Assam Oil Company was
producing oil in Digboi(discovered in 1889) and
Oil India LTD. (50% of joint venture between
government of India and Burma Oil Company)
was busy in developing two newly discovered
large fields Naharkatiya and Moran in Assam.
In West Bengal, the Indo-Stanvac Petroleum
project (a joint venue between Government of
India and Standard vacuum oil Company of
USA) was engaged in exploration work.
In 1955, government decided to develop the oil
and natural gas resources in various regions as
part of public sector development.
An Oil and Natural gas Directorate setup
was held in the end of 1995
In April 1956, the Government of India adopted
the industrial policy Resolution, Which placed
mineral oil industry amongst the Schedule ‘A’
industries, the future development of which was
to be the sole and exclusive responsibility of
state.
ONGC was formed on 14 August 1956.
ONGC is an Indian owned oil and natural gas
company headquartered in Dehradun, India.
The main Functions of ONGC is to Plan,
Promote, Organise and Implement programs for
development of petroleum resources and
production.
After 1961, ONGC discovered resources in
Gujarat (Cambay Basin).
It produces around 77% of India’s total crude oil
and around 81% of national gas production.
It is exploring and exploiting in 26 sedimentary
basins and owned and operates over 11,000 km
of pipelines in country.
ONGC went offshore in the early 70’s and
discovered Giant oil field in Bombay high.
First well : Jwalamukhi-1 in 1957 Gas stuck out
but not commercial, In 1958 Well Lunej-1 at
Cambay Gujarat.
First offshore well : Aliabet-1 in 1970 offshore
Gujarat. In 1973 first well by sagar Samrat in
Mumbai High.
ONGC became a publicly held company as of
Feb 1994.
67.5% of ONGC assets were owned by
government and other with the private
companies.
ONGC Videsh Limited (OVL) is an international
arm of ONGC.
It was formed on March 5, 1965 as
Hydrocarbons India Pvt.Ltd.
It was rechristened as ONGC Videsh Ltd on 15th
June 1989.
Primary work explore, develop and production
of oil and gas outside the India.
The company has 15 producing, 4 discovered, 18
Exploration and 4 Pipeline assets. It has 41 oil
and gas projects in 20 countries.
First well worldwide: Colonel Edwin Drake
well in 1859 in Titusville, Pennsylvania, USA.
Struck oil on August 27, 1859 at a depth of 69
feet.
First Well in India: Sep 1889 - Nov 1890 at
Digboi (well no.1 or the discovery well).Produced
from 662 feet at 20 gallon/day. Systematic
drilling started from 1891. In 1901, Asia’s first oil
refinery was set.
Works in ONGC in Drilling:
By Geologist: They do survey from earth’s
surface to find the oil and gas canals in the
ground level.
phase1-they begin with the unexplored basin
with some previous knowledge of surface
geology and reports of surface indications were
sent for verification.
phase2-is the stage of seismic survey (initial
step in offshore exploration).they blast
dynamites and record their reflections from
the ground. this will help to obtain some more
data for drilling.
Phase3-is the Exploratory or Wildcat drilling.
they used to drill the place with the survey
results. This may or may not result for
production process.
Phase4-is the discovery phase, follows the
successful completion of some wildcat wells. At
this stage reservoirs are established and
hydrocarbons are discovered.
Phase5-the production phase begins to provide
exploration with reserve estimates and a
history of hydrocarbon potential of basin.
Seismic Survey:
Pertaining to waves of electric energy, such as
that transmitted by P-waves and S-waves, in
the frequency range of approximately 1 to 100
Hz.
A Source such as a Vibrator unit, dynamite
shot, or air gun, generates acoustic or elastic
vibrations that travel into earth with different
seismic responses and filtering effects, and
return to surface to be recorded as seismic data.
Hydrophones are used in the sea and geophones
in the wellbores to record the seismic signals.
Seismic energy is studied by scientists to
interpret the composition, fluid content, extent
and geometry of rocks in the subsurface.
In marine seismic survey the air guns are
periodically activated, such as every 25m, and
resulted sound waves travels into the earth, is
reflected back by underlying rock layers to
hydrophones on the streamer and recorded as
seismic data.
Do you know how geologists tell the
reservoir has oil or gas?
They do this by passing geophones, which record
the physical properties in the rock such as
resistivity, porosity, density, radioactivity, and
pore pressure.
Porosity : It is the relative amount of void space
in a rock. Rock is having the 1/3rd of its total volume
has 33% porosity. It also determines capacity for
having reservoir fluids.
Porosity Values
Negligible 0 – 5%
Poor 5 – 10%
Fair 10 – 15%
Good 15 – 20%
Very Good 20 – 25%
Excellent > 25%
The Porosity Value depends on the package of
molecules. They are
Cubic Packing of spheres – 0.48
Rhombic Packing of spheres – 0.27
Packing of Two Sizes of spheres – 0.14
Permeability: It determines the ease with which
reservoir fluids can move out or flow within rock.
It depends on porosity. If porosity is 0%,
Permeability will also be 0%. If porosity is 20%,
Permeability may be 0 to any percent
depending on porosity, particle size, shape.
Open fractures have very good permeability.
Permeability means interconnectedness of pore
of rocks. These pores allow hydrocarbon to move
from one place to another place.
Permeability in petroleum – producing rocks is
usually expressed in units called millidarcys
(one millidarcys is 1/1000 of a Darcy).
Types of Drilling:
Exploratory drilling
To establish commercially viable oil and gas
reservoirs
Development drilling
To exploit confirmed reserves.
Oil Rig/ Gas rig : It is a structure with heavy
equipment for drilling an oil/gas well.
Rig selection :
Surface Location (land, inland water, offshore).
Estimated maximum hole depth.
Requirements to drill the hole.
Cost to be invested.
Chances of Availability of natural resources.
Rigs in Rajahmundry: There are total seven
rigs under the Rajahmundry Asset, ONGC. They are
E2000-I
E2000-III
BI-2000-II
E1400 – 16
E1400 - 17
E760M
EV -2000-1
Types of rigs:
There are many different
types of drilling rigs
which rig selection
depends on the specific
requirements of each
drill site. Rigs are
generally categorized as
onshore(land) or
offshore(marine).
On-shore RIGS:
Onshore rigs are all similar, and many modern
rigs are of the cantilevered mast, or “Jack knife”
derrick type. This type of rig allows the derrick
to be assembled on the ground, and then raised
to the vertical position using power from the
draw works, or hoisting system.
These structures are made up of prefabricated
sections that are moved onto the location by
truck, barge, helicopter, etc.
Off-shore rigs:
Offshore drilling is divided into two types:
Fixed structure types and Floating structure
types.
Barge rig:
They are floating offshore drilling vessels
but it is not self-propelled.
The drilling equipment is on the barge.
They are generally capable of drilling in water
depths of less than 12ft, or, in the case of a posted
barge, perhaps to 20ft.
Jack-up rig:
This is a self-elevating rig, and is used for
smaller, shallower offshore deposits.
The rig’s floating platform is towed into
position by barges, then lowers its support
legs down to the sea floor, raising the rig
above the water’s surface.
Semi - submergible rig:
They are the most common type of offshore
drilling rigs, combining the advantages of
submersible rigs with the ability to drill in deep
water.
The semisubmersible rig does not rest on the
seafloor.
This rig is a floating deck supported by
submerged pontoons and kept stationary by a
series of anchors and mooring lines, and, in
some cases, position-keeping propellers.
They have a water-depth operating range of
20ft to 2000ft.
Drillship rigs :
Drill ships are most often utilized for extremely
deep water drilling at remote locations.
A “floater” like the semi-submersible, a drillship
must maintain its position at the drilling
position by anchors and mooring lines, or by
computer-controlled dynamic positioning
equipment.
Most drillship has greater storage capacity than
other types of rigs, allowing efficient operation
at remote locations.
Drilling Equipment :
Mast / Derrick : It is the basic structure of
the rig which is placed on the derrick floor to
support the drilling process.
Crown block : An assembly of Pulleys mounted
on beams at the top of the mast. The drilling
line is run over the pulleys down to the hoisting
drum.
Travelling Block : An arrangement of pulleys
or sheaves through which drilling cable is
threaded, which moves up or down in the
derrick or mast
Swivel : A rotary tool that is hung from the
rotary hook and travelling block to suspend and
permit free rotation of the drill pipe. It also
provides a connection for the rotary hose and a
passageway for the flow of drilling fluid into
the drill pipe.
Hook : A large, hook-shaped device from which
the swivel is suspended. It is designed to carry
maximum loads ranging from 100 to 650 tons
and turns on bearings in its supporting housing
Kelly: The heavy square or hexagonal steel
member suspended from the swivel through the
rotary table. It is connected to the topmost joint
of drill pipe to turn the drill stem as the rotary
table turns.
Rotary Table : The
principal component of a
rotary machine is used to
turn the drill pipe and
support the drilling assembly.
It has a bevel gear
arrangement to create the
rotational motion and an
opening into which bushings
are fitted to drive and
support the drilling assembly.
Draw Works: The hoisting mechanism on a
drilling rig. It is essentially a large winch that
spools off or takes in the drilling line and thus
raises or lowers the drill stem and bit.
Mast
Drawing
line
Draw
Works
Derrick
floor
Drill pipe: The heavy seamless tubing used to
rotate the bit and circulate the drilling fluid
from swivel to drill bit and again back to the
shale shaker. Joints of pipe 30 feet long are
coupled together with tool joints.
Drill bit: The cutting or boring element used in
drilling oil and gas wells. Most bits used in
rotary drilling are roller-cone bits. The bit
consists of the cutting elements and the
circulating element.
The circulating element
permits the passage of
drilling fluid and
improve drilling rates
Air Winch: It helps to lift the heavy pipe lines
to the derrick floor. It rotates with the help of
the pressurized air.
Power packs: Diesel engines with the
alternators are the power packs which it
produces electricity to run the drill.
Generator which produces electricity with the help of alternator
Alternator helps the generator to convert mechanical into
electrical energy
Mud Pumps: A large reciprocating pump used to
circulate the mud (drilling fluid) on a drilling rig.
The piston helps to suck and pump the mud into the
swivel through delivery pipe. It has the stroke length
of 10 inch with maximum rated power of 1100 at 150
rpm, weight of 17,000kg.
Blow out preventer(BOP): One or more
valves installed at the wellhead to prevent the
escape of pressure either in the annular space
between the casing and the drill pipe or in open
hole (for example, hole with no drill pipe)
during drilling.
VISIT
I had visited the ONGC workshop in Dowlaiswaram
and Rig E-1400–16, which is drilling at
Mandapeta- 44(MDAM).
Seen the
Prototype model of rig and its working
Mud pump and its parts
Travelling block and its working
Diesel engine and alternator
Rotary table
Draw works and it’s chain mechanism
And other parts used in the drilling like crown
block wheels, hook, swivel, air winch, Kelly
spinner etc...
Got complete explanation from the rig in-charge
Conclusion :
From the above report we conclude that every equipment,
whether major (or) minor is important in the Drilling
operations. Minor equipment can have standby units. So,
major equipment like Draw works, Crown block, Travelling
block, Hook cannot have standby during operation. Hence,
the equipments are very critical. It is very essential to
follow the scheduled maintenance of these equipment to
minimise shut downs and Rig down time as a whole. ONGC
Rigs produce their own power for operations.
Asset Workshop carries out the repairs of most of the
equipment pertaining to Drilling, Surface, and Well
Services etc. Health check-up of equipment is done during
rig movements by Workshop to prevent down time of
equipment while in operation. Whenever possible,
equipments are tested after repair.
***
I sincerely thank the ONGC employees for guiding me and
for the opportunity given to carry out internship.
***
