SUMMER INDUSTRIAL TRAINING AT ONGC AGARTALA,TRIPURA

Topic- ROLE OF CIVIL ENGINEERS IN EXPLORATION & PRODUCTION OF HYDROCARBONS

Presented by:-

Anamika Debbarma

DC2011BTE0127

7th Semester

Dept. of Civil Engineering

OIL AND NATURAL GAS CORPORATION LIMITED(ONGC)

Oil and Natural Gas Corporation Limited (ONGC) is an Indian state-

owned oil and gas company headquartered in Dehradun, India

It is one of the largest Asia-based oil and gas exploration and production

companies, and produces around 77% of India's crude oil (equivalent to around

30% of the country's total demand) and around 81% of its natural gas.

ONGC is one of the largest publicly traded companies by market

capitalization in India.

ONGC was founded on 14 August 1956 by the Indian state, which currently

holds a 74.14% equity stake.

It is involved in exploring for and exploiting hydrocarbons in 26 sedimentary

basins of India, and owns and operates over 11,000 kilometers of pipelines in

the country.

ABOUT TRIPURA ASSET

ONGC started systematic geological mapping in Tripura in 1962 along with

shallow drilling at selected locations.

Almost the entire state has been investigated with the help of aerial

photographs, Landsat Imageries and detail to semi-detail geological mapping.

Structurally, Tripura Fold Belt which is a part of Assam Arakan Fold Belt is

characterized by series of parallel, elongated, and doubly plunging asymmetric

anticlines

GENERAL GEOLOGY

OIL EXPLORATION AND PRODUCTION:AN OVERVIEW

Out of 26 identified basins, only seven petroliferous basins have been put

on commercial production. These are Mumbai offshore, Cambay, Assam-

Arakan including the Tripura-Cachar area, Cauvery, Krishna-Godavari,

Mahanadi and Rajasthan basins.

ROLE OF CIVIL ENGINEER IN HYDROCARBON GENERATION

Offshore: Activities related to exploration and developments are carried out

both offshore (sea) and onshore.

1. Exploration Phase: During exploration stage, Jack up rigs which stand on

the legs and carry out the drilling activities from the drill floor are deployed. As

the legs of these rigs stand on the sea floor these are to be penetrated into the sea

floor so that stable base is provided for drilling of borehole.

Seabed Survey: This is carried out by deploying Survey Vessels which

contain Side Scan Sonar, Echo sounder etc.

Using these equipments grid survey in N-S and E-W directions are

carried out at a spacing up of about 500m and in all directions up to a Km

surrounding the identified place.

To reach the identified place Global Positioning System is used. The Side

Scan Sonar gives the seabed picture which indicates undulations in the

seabed as well as any obstructions.

With the echo sounder bathymetry (Water depth) of the area is known.

Echo sounder works on the principle of sound wave reflection.

Geotechnical Investigation: There are specially designed offshore vessels for carrying out Geotechnical Investigation.

Soil investigation up to about 40m is carried out in ONGC to determine soil characteristics i.e type of soil and bearing Capacity.

If soil is not having sufficient bearing capacity, there is likely of legs punching through and with the result the rig becomes unstable and may sink also. Hence soil investigation in offshore is a must prior to start of drilling activities.

2.Development Phase:

Once reservoir is established, development wells are drilled and the produced hydrocarbons are required to be transported to end users i.e. the industries which use.

The produced hydrocarbons contain oil mixed with gas. These are to be separated and for this purpose processing units are to be installed.

In offshore this is carried out at process platforms. It is a huge structure for installation of these structures; various activities like design, fabrication, transportation and installation are involved in the process.

Onshore: The role of Civil Engineers is challenging in Onshore Hydrocarbon

Exploration and Production.

1.Exploration Stage:

Once location is identified for Hydrocarbon Exploration based on survey the

first step is to physically mark the location. This process is called stacking.

The work of Civil Engineers starts with stacking of location. Next activity

after stacking is Land Acquisition.

Civil Works at Drill site consist of following activities:

-Foundation for main rig.

-Ancillary Foundations for small units.

-Accommodation for drilling crew and security personnel.

-Hardening of site.

Excavation of pits for waste material and also suitable measures to arrest

seepage of harmful chemicals to surrounding fields which may cause

damage to environment.

-Providing water supply by suitable means i.e., by drilling tube wells at

site/laying pipelines from nearby wells/supply by tankers.

-Construction of approach road.

-Earth filling in case of low lying areas.

-Earth cutting jobs in case of high ground.

-Pile foundations in case bearing capacity of soil is very less.

2.Production Stage:

Once production is established, a common place called Group Gathering

Station needs to be established.

Group Gathering Station is a collection centre where hydrocarbons are

collected from different wells through pipelines.

These hydrocarbons are separated into different components i.e. Oil, Gas

etc. through processing. After processing these components are sent to

different end users.

3. Various Stages of Execution of Work:

Once a work is identified , the first activity is to carry out preliminary

survey i.e. to examine the site condition so that cost estimates & land

acquisition proposals can be made.

Soil investigation is also carried out to decide the type of foundation. If the

bearing capacity of soil is low, pile foundations may be required to be

installed.

Depending on the soil conditions, the design of foundations and other

structures is carried out

Development & Production

When exploratory drilling is successful, more wells are drilled to

determine the size and extent of field. These wells are called appraisal

wells .

Subsequent wells to extract hydrocarbons are called “development”

or “production” wells. After drilling these producing wells, the wells

are to be prepared for production before drilling rig departs.

The heavy drill pipe is replaced by lighter weight tubing in the well.

The commercial hydrocarbon wells are free flowing i.e., the

underground pressure drive the liquid and gas up the bore well to the

surface.

Once the hydrocarbon reaches the surface, it is routed to central

production facility through pipelines which gathers and separates the

produced fluids (oil, gas and water).

Civil Works in Tripura Asset,Agartala

Name of the work: ROAZ Agartala, Tripura Asset

Location: Near Sekarkote, Agartala; Tripura. It is Exploratory Location.

Method of construction: Contractual method

Specification: Central public works department (CPWD)/ Tripura Public Works Department (TPWD)/ Bureau of Indian standard

Estimated cost of the project:The estimate has been framed to Rs 1.89 Crore

Construction activities involved: Earth cutting in soil by mechanical means with dozer, earth excavator, like machineries etc. including cutting and pushing

Carriage of earth by mechanical transport including loading ,unloading and stacking.

Providing and laying in position specified grade of reinforced cement

concrete 1:2:4 for Foundations

Reinforcement for R.C.C work is done with thermo-mechanically treated

bars or with cold twisted deformed steel bars.

Approach Road with Brick on edge Soling and flat Brick Soling

Area hardening by brick aggregates in two layers with proper

consolidation of sub base and top layers with 10 tonnes road roller with

vibrator.

Sheds with Brick wall, GI sheet roofing, false ceiling, doors windows etc.

Fire water Reservoir, over head water tank for water required in cooking,

Toilets Etc.

Shed with brick wall and GI sheet roofing for storage of chemicals.

Other miscellaneous works like Bamboo palasiding work for earth retain,

Platform for diesel Tank, Security huts etc as per requirement.

Name of the work:RODI Agartala, Tripura Asset

Location: Konaban GCS, Agartala. . It is Development location.

Method of construction: Contractual method

Specification: Central public works department (CPWD)/ Tripura Public Works Department (TPWD)/ Bureau of Indian standard

Estimated cost of the project:The estimate has been framed to Rs 3.20 Crore.

Construction activities involved: Earth cutting in soil by mechanical means with dozer, earth excavator, like machineries etc. including cutting and pushing .

Carriage of earth by mechanical transport including loading, unloading and

stacking.

Providing and laying in position specified grade of reinforced cement

concrete 1:2:4 for Foundations.

Reinforcement for R.C.C work is done with thermo-mechanically treated

bars or with cold twisted deformed steel bars.

Approach Road with Brick on edge Soling and flat Brick Soling

Area hardening By Brick aggregates in two layers with proper consolidation

of sub base and top layers with 10 tonnes road roller with vibrator.

Sheds with Brick wall, GI sheet roofing, false ceiling, doors windows etc.

Drilling and installation of Tube wells, Fire water Reservoir, Over head water

tank for water required in cooking, Toilets Etc.

Shed with brick wall and GI sheet roofing for storage of chemicals.

Other miscellaneous works like Bamboo palasiding work for earth retain,

Platform for diesel Tank, Security huts etc as per requirement.

CONCLUSION

After completing the summer training at ONGC Agartala, now we can

say that we have polished our book knowledge with our practical works

at different sites.

We have understood various techniques, process of production of

hydrocarbons, both offshore & onshore projects of ONGC.

A civil engineer plays a vital role in today’s world. It may be planning,

estimation, construction etc in each & every department, a civil

engineer comes into the picture.

It has been a great experience in working with different engineers at

the site under the guidance of our mentor and we are grateful to both the

organization and the mentors.

THANK YOU