INDUSTRIAL TRAINING REPORT

ON
“Comprehensive Report on Production Gathering, and
Environmental Facilities”

ONGC MEHSANA ASSET

Bachelor of Technology
in
Petroleum Engineering

By

Makdiya Darshan Harsukhbhai( Roll no. 21BPE090 )

Under guidance of

Mr. Parth Chauhan

Department of petroleum energy

School of Energy Technology
Pandit Deendayal Energy University
Gandhinagar-382007.
Gujarat-INDIA

1,June,24 - 30,June,24

1
 APPROVAL SHEET

This thesis / dissertation / report entitled (title) by (Author name) is recommended for the
degree of Bachelor of Technology-Petroleum Engineering
Examiners

______________________

______________________

______________________

Supervisors

______________________

Date:

Place:

2
 Student Declaration

I Makdiya Darshan Harsukhbhai hereby declare that this written submission represents my ideas in my
own words and where others’ idea or words included. I have adequately cited and referenced the
original sources. I also declare that I have adhered to all the principles of academic honestly and
integrity and have not misrepresented or fabricated or falsified any idea / data / fact / source in my
submission. I understand that any violation of the above will be cause for disciplinary action by the
PANDIT DEENDAYAL ENERGY UNIVERSITY.

_____________________________
(Signature of student)

Makdiya Darshan Harsukhbhai

(Name of student)

21BPE090

(Roll no.)

Date: _______________

3
 PREFACE

The main objective of any Petroleum Engineering Student is to get as much of practical knowledge as
possible. Being an able to have a practical knowledge by doing internship at ONGC Mehsana and
working on project. As practical knowledge is as important as theoretical knowledge, I am thankful of
having a project.

Throughout internship I had great experience and got on field experience by looking and involving in
each work done on the field.

4
 ACKNOWLEDGEMENT

The training here at Oil & Natural Gas Corporation (ONGC), Mehsana Asset in Surface Team has
been a great experience, both educative and enjoyable at the same time. would like to thank the entire
Human Resource Department of the Mehsana Asset for their support and co-operation throughout the
training period 01.06.2024 to 30.06.2024.

I wish to express my indebted gratitude and special thanks to Mr. Parth Chauhan ( Sub Surface Team)
of Mehsana Asset Oil & Natural Gas Corporation Limited (ONGC) for his esteemed guidance and
giving me an opportunity to gain an insight into the working of an industry.

Makdiya Darshan Harsukhbhai

Student of B.Tech (PETROLEUM)
Pandit Deendayal Energy University
Trainee
Camp: Oil & Natural Gas Corporation Limited, Mehsana Asset

5
 ABSTRACT

Oil industry or the oil patch, includes the global processes of exploration, extraction, refining,
transportation (often by oil tankers and pipelines), and marketing of petroleum products. To fulfil the
demand of energy, In 1958, ONGC drilled first exploratory well on lunej structure near Cambay.
Cambay basin which deposited during Middle Eocene to recent Deposits.Oil which we produce is with
impurities, water cut and many other contaminants. To remove this impurities oil is sent to Surface
Production Facilities. In North Kadi area of Mehsana Asset, NK-CTF cum GGS is established to treat
produce oil and gas. Oil, gas, effluent and other contaminants are removed from Produced oil. Oil is
sent to storage tank and pumped to refinery, gas is treated and water is sent to NK-ETP plant for
further processing. The ultimate goal of Surface Production Facility is to remove maximum water, gas
and other contaminants to get pure oil.

6
 Table of Content

Serial Content Page

No. No.
1. Introduction 8
2. Production Tool Yard and Storage 13
3. Group Gathering Station( NK GGS-3) 17
4. Polymer flooding plant 21
5. Effluent Treatment plant 25
6. Rig WR-50-40(MWD 51) 28
7. Lectures 30
8. Conclusion 37
9. Reference 38

7
Chapter -1: INTRODUCTION

1.1 A BRIEF ABOUT ONGC INDIA

 ONGC is the largest crude oil and natural gas Company in India, contributing around
71% to Indian domestic production. Crude oil is the raw material used by downstream
companies like IOC, BPCL, HPCL and MRPL (Last two are subsidiaries of ONGC) to
produce petroleum products like Petrol, Diesel, Kerosene, Naphtha, and Cooking Gas
LPG.

 ONGC has a unique distinction of being a company with in -house service capabilities in
all areas of Exploration and Production of oil & gas and related oil-field services. The
market cap of ONGC is one of the best among PSUs in India. ONGC is the biggest
wealth creator in the country.

1.2 BRIEF DESCRIPTION ABOUT THE ONGC MEHSANA ASSET

 Oil & Natural Gas Corporation Ltd. is one of the leading public sector enterprises in the
country with substantial contribution to the energy demand in particular and industrial
and economic growth in general. Born as a modest corporation house in 1956 as
commission, ONGC has growth today into a full-fledged integrated upstream petroleum
company with in-house service capabilities and infrastructure in the entire range of oil
and gas exploration and production activities. It is one of the ten Public Sector enterprises
(Navaratna) of India and has achieved excellence over the years and is on the path of
future growth.

 For practical implementation of the programs, ONGC has created a number of work
units called projects (now asset) and executed in various operational programs spread
throughout the length and breadth 2 of the country. The MEHSANA project is one such
asset of the onshore area. The Mehsana project covers an area of about 6000 sq kms.
From the north part of the Cambay basin between latitude 23.23’ and 23.45’ and
longitude 71.45’ and 72.45’ east. It is situated at a distance of 72 kms of Ahmedabad city
in the North West direction. of the country. The MEHSANA project is one such asset of
the onshore area. The Mehsana project covers an area of about 6000 sq kms. From the
north part of the Cambay basin between latitude 23.23’ and 23.45’ and longitude 71.45’
and 72.45’ east. It is situated at a distance of 72 kms of Ahmedabad city in the North
West direction.

Fig.1.1 ONGC MEHSANA ASSET

8
 Mehsana project was started as an independent project on 7th November, 1967 when it
was bifurcated from Ahmedabad project for administrative and operational convenience
the project’s establishment was shifted to Mehsana and Ahmedabad project for closer
administrative and operational control when the exploratory drilling in this part was
vigorously taken up. At present Mehsana project comprises Mehsana district and parts of
Banaskantha, Patan and Ahmedabad districts.

 EXPLORATION efforts around Mehsana date back to the year 1964. Though the very
first well drilled on Mehsana horst did not give encouraging results, subsequent well
Mehsana-2 in allora structure gave a lead for further exploration.

 The Mehsana project is well known for its heavy oil belt, characterized by high viscosity
crude. Due to the viscous nature of crude resulting in the adverse mobility ratio and low
API gravity, the primary oil recovery factor is in the range of 6.5 to 15.8%. The
techniques of IN-SITU COMBUSTION “AN ENHANCED OIL RECOVERY
PROCESS” for this heavy oil field was successfully implemented at Mehsana project on
pilot basis in 1990. The success of process at the pilot project further led to the
commercialization scheme that are currently under various stage of implementation at the
Mehsana project. Under commercialization scheme a major project name BALOL MAIN
IN-SITU COMBUSTION PLANT has been implemented to exploit the heavy crude oil
of Balol oil field.

 THE BALOL MAIN ICP has been commissioned on 15-011999.

Fig.1.2: The major oil field under the MEHSANA ASSET and North Kadi, Sobhasan, Balol,
Santhal, Jotana, Nandasan, Lanwa, Becharaji, Linch and other small fields.

1.3 Sedimatery Basin India:

There are 26 sedimentary basins in India, covering a total area of 3.4 million square
kilometer. The area is spread across onland, shallow water up to 400 meter water depth and
deepwater farther up to Exclusive Economic Zone (EEZ). Of the total sedimentary area, 49%
of total area is located onland, 12% in shallow water and 39% in the deepwater area. There
are 16 onland basins, 7 located both onland and offshore and 3 completely offshore.
Tectonically, these basins are classified into 3 groups, based on origin from rifting (intra-
cratonic and peri-cratonic), plate collision and crustal sag.

9
These basins are divided into three categories based on maturity of hydrocarbon resources as
under:

• Category-I: Basins, which have reserves and already producing.

• Category-II: Basins, which have contingent resources pending commercial production
• Category-III Basins, which have prospective resources awaiting discovery

Fig 1.3: 26 sedimentary basins in India

10
1.4 Petroleum System
A petroleum system is a geologic framework that describes the origin, migration, and
accumulation of hydrocarbons (oil and gas). It's a complex system with five essential elements
that must work together for a deposit of oil or natural gas to form. These elements include:

 Source rock: This is a rock that contains organic matter, such as plant and animal debris,
that can be converted into oil and gas under high pressure and temperature. Source rocks
are typically fine-grained sedimentary rocks like shale or limestone.

 Reservoir rock: This is a porous and permeable rock that can store oil and gas. Reservoir
rocks are typically sandstone or carbonate rocks, such as limestone or dolomite. The pores
in the rock must be large enough to hold the oil and gas, and they must be interconnected
so that the fluids can flow.

 Seal rock: This is an impermeable rock layer that traps the oil and gas in the reservoir rock
and prevents it from migrating upwards. Seal rocks are typically fine-grained sedimentary
rocks like shale or claystone.

 Trap: A trap is a geologic structure that allows oil and gas to accumulate in the reservoir
rock. Traps can be formed in a variety of ways, such as folds, faults, or stratigraphic pinch-
outs.

 Maturation: This is the process by which organic matter in the source rock is converted
into oil and gas. Maturation occurs over millions of years as the source rock is buried deeper
and deeper in the Earth's crust and subjected to increasing temperatures.

Fig 1.4: Petroleum system

If all of these elements are in place and have functioned correctly, a petroleum system can form
and lead to the accumulation of a commercially viable deposit of oil or gas. Petroleum systems
are essential for the exploration and production of oil and gas. By understanding how petroleum
systems work, geologists can identify areas that are more likely to contain oil and gas deposits.

11
1.5 North Kadi Field
North Kadi field, lying in the Ahmedabad-Mehsana Tectonic Block of Cambay Basin in India
was discovered in 1968.Hydrocarbon accumulations in the area have been established mainly
from Kalol pays of Middle Eocene age, with Linch, Mandhali & Mehsana pays, lying within
Kadi and Cambay Shale of lower Eocene age, also contributing to hydrocarbon production.
Accumulations in shallow, post-Kalol sands have also been established sporadically from
Balol pay within Tarapur formation (Upper Eocene to Oligocene age) and from pays within
Babaguru and Kand formations (Miocene age).

Fig 1.5 :North Kadi Field

12
Chapter-2: PRODUCTION TOOL YARD AND
STORAGE (PTYS)

2.1 Description of Production tool yards

Production tool yards in the petroleum industry are vital for storing equipment and materials
used in oil and gas exploration, drilling, and production operations. These yards are designed
to provide safe, secure, and efficient storage for a wide variety of items, including:

1. Drill pipe
2. Fishing tool
3. Artificial lift
4. Tubing
5. Casing
6. Valves
7. Pumps
8. Generators
9. Accumulator
10. Support vehicles

The specific layout and organization of a production tool yard will vary depending on the size
and needs of the operation.

Fig 2.1 :PTYS is located Sobhasan in Mehsana .

2.2 Tools in PTYS

2.2.1 Perforation washing tool

A perforation washing tool is a specialized piece of equipment used in the oil and gas industry
for cleaning perforations in well casings and sand screens. Perforations are small holes
created in the casing to allow oil and gas to flow into the wellbore. However, these
perforations can become clogged with debris or formation material, reducing well
productivity.

13
 Fig 2.2.1: Perforation washing tool
2.3.2 Mechanical packer:

A mechanical packer is a downhole tool used in oil and gas wells to create a seal between the
tubing (pipe that carries produced fluids) and the casing (larger diameter pipe that lines the
wellbore). This isolates the production zone from the rest of the wellbore and allows for
controlled production, injection, or treatment fluids.

Fig 2.3.2 :Mechanical packer

2.4.3 Permanent packer:

Permanent packers are designed to stay downhole for the entire life of the well. They play a
crucial role in isolating the production zone and managing well pressure
throughout production.

Fig:2.4.3 Permanent packer

2.5.4 Mechanical bridge plug:

A mechanical bridge plug is a downhole tool used in oil and gas wells to isolate specific
sections of the wellbore. Unlike a packer that creates a seal between the tubing and casing, a
bridge plug completely blocks the wellbore at a designated depth. This isolation is crucial for
various well intervention operations.

14
 Fig 2.5.4 :Mechanical bridge plug
2.2.5 Scrapper:

In the oil and gas industry, a scrapper, also sometimes referred to as a pig, is a device used for
cleaning pipelines. These handy tools travel through the pipeline propelled by the flow of the
product itself (oil, gas, etc.) or by an external pressure source. Their purpose is to scrape away
and remove unwanted buildup from the internal diameter of the pipeline.

Fig 2.2.5 :Scrapper

2.2.6 Accumulater:

An accumulator is a pressure vessel charged with gas (nitrogen) over liquid and used to store
hydraulic fluid under pressure for operation of blowout preventers.

2.2.6 Accumulater:

2.2.7 Blow out preventer (BOP):

In the oil and gas industry, BOP can stand for "Blowout Preventer". This is a critical piece of
equipment that sits on top of a wellbore to prevent uncontrolled release of oil and gas. It's like
a giant safety valve.

15
 Fig 2.2.7 : Blow out preventer (BOP)

2.2.8 Fishing tools :

Fishing tools are specialized equipment used to retrieve lost or stuck objects from inside a
wellbore. These tools are essential for the oil and gas industry, as they can prevent costly delays
and well abandonment.

Fig 2.2.8: Fishing tools

There are many different types of fishing tools, each designed for a specific purpose. Some of
the most common types of fishing tools include:

1. Overshots: Overshots are used to grip and retrieve drill pipe or casing that has become
stuck in the wellbore. They work by latching onto the outside of the pipe

2. Spears: Spears are used to retrieve broken or lost equipment from the wellbore. They work
by stabbing into the inside of the equipment.

3. Junk baskets: Junk baskets are used to capture debris and other materials that may be
blocking the wellbore. They are essentially large baskets that are lowered into the wellbore.

4. Mills: Mills are used to grind up or crush stuck pipes or other obstructions in the wellbore.
The crushed material can then be circulated out of the wellbore.

16
Chapter -3: Group Gathering Station( NK GGS-3)

3.1 Brief about Group Gathering Station

Group Gathering Stations typically serve as a central collection point where the oil and gas
produced from different wells are gathered and processed before being transported via pipelines
to larger processing facilities such as refineries or gas processing plants.

At these stations, the oil and gas are separated from each other and from any impurities that
may be present, and initial treatment processes such as dehydration, desalting, and stabilization
may be carried out to prepare the hydrocarbons for transportation and further processing.

The design and specific functions of a group gathering station can vary depending on the
characteristics of the reservoir, the composition of the produced fluids, and the production
volumes involved. These facilities play a crucial role in the early stages of oil and gas
production to ensure that the hydrocarbons are efficiently and safely processed for
transportation to downstream facilities.

Fig 3.1 :General Layout GGS

17
3.2 Basic detail of GGS NK-3

Serial Name of the Surface Unit in GGS NK-3 Total no.

No.
1. Wells connected to GGS 80
2. Group header 2
3. Test header 1
4. Bath heater 2
5. Horizontal test separator 1
6. Horizontal group separator 2
7. Scrubber 1
8. Heater treater 1
9. Wash tank (each 100m3) 2
10. Oil storage tank (each 400m3 ) 4

3.2.1 Group header

In a Group Gathering Station (G.G.S.), a Group Header is a key component of the facility that
serves as a distribution point for the fluid components, such as oil, gas, and water, coming from
various wells or gathering lines.
Group header connects to Bath heater.

3.2.2 Test header

To test particular well or single well testing and connects test separator .

3.2.3 Indirect Bath Heater (IDBH):

Indirect water bath heaters are used for the heating of a process fluid. They are used to increase
the fluid temperature according to the process requirement.

➢ In IDBH two coils are fitted. In one coil hot water is passed and in another coil processing
oil is being passed.
➢ These both coils are in one fluid.
➢ As we pass hot water from coil, Heat transfer takes place between Hot water and fluid in
chamber.

3.2.4 SEPARATORS:

 An oil/gas separator is a pressure vessel used for separating a well stream into gaseous and
liquid components.
 Or we can say that separator is used to flash the well fluid to separate into liquids and gas
at a controlled pressure.

18
 Fig 3.2.4 : Horizontal Group Separator

1. Horizontal Group Separator:

It is also a two-phase horizontal cylindrical vessel just the same as the previous one but here
fluid from all the well comes .
➢ Fluid from indirect bath heater comes in two-phase horizontal separator through Inlet.
➢ Here gas and oil are separated.
➢ Gas gathers in upper part of separator.
➢ Gas is collected through outlet which is placed at upper part of horizontal separator and sent
to gas scrubber.
➢ Oil is collected from below part of horizontal separator.

2. Gas Scrubber :

The purpose of a gas scrubber is to eliminate harmful

particulates and liquid hydrocarbons from natural gas.
➢ Gas scrubber extract oil particles from gas.
➢ Gas from Separator is sent to gas scrubber.

3. Test Separator:

A test separator is a vessel which is used to separate and

measure small amounts of oil and gas.

3.2.5 HEATER TREATER:

A heater treater in oil and gas is a 3-phase
separator vessel that utilizes heat and mechanical separation devices to
facilitate the separation of oil-water emulsions before transporting the dry
oil through pipelines.

➢ A heater treater consists of four sections that perform the following

functions:
i. Degassing
ii. Heating
iii. Differential oil control
iv. Coalescing

19
 Fig 3.2.5 HEATER TREATER:

3.2.6 Storage Tank

Have to types of two storage tank

1 . Vertical Oil storage Tank:

The GGS separates the oil from the water and gas that are also produced from the wells. The
oil is then stored in tanks at the GGS before being transported to a refinery. These storage
tanks are typically large, cylindrical tanks with conical roofs. They can be made of
steel or concrete.

Number of vertical tank- 4

Capacity of vertical tank- 400m3

2. Wash Tank

Wash Tank is a tank that is useful for temporary storage of liquid fluid (liquid) that comes
from the boot gas. The liquid fluid entering the wash tank consists of a mixture of crude oil
and water. At the Wash tank the process of separation between crude oil and water.

Number of vertical tank- 1

Capacity of vertical tank- 200m3

Oil Production

 Approx 1500-1600 m3 of oil dispatched through CTF.

Gas production

 Production - 200-300 m3 of gas .

20
Chapter-4: Polymer flooding plant

4.1 About Polymer flooding plant

Fig 4.1: North Kadi Polymer flooding plant

Polymer receiving and storage: Dry polymer is received in bulk and stored in silos.Polymer
mixing: The polymer is mixed with water to create a solution with the desired viscosity. This
may involve several stages of mixing and hydration to ensure the polymer is fully dissolved.

The polymer solution is filtered to remove any impurities that could damage the reservoir
formation.Injection: The polymer solution is injected into the oil reservoir through injection
wells.The specific design of a polymer flooding plant will vary depending on the size and
needs of the oilfield, but all plants will include these essential elements.

Fig 4.1.2 : Layout of Polymer flooding plant

21
4.2 About Polymer Flooding

Polymer flooding can be an effective way to increase oil recovery, but it is important to carefully
consider the economics of the process before implementing it. The cost of the polymer, the cost
of building and operating the plant, and the potential environmental impacts must all be
taken into account.

Fig 4.2 : Polymer flooding

4.3 Polymer Injection Pump

Polymer injected into the well by using polymer injection pump.
Number of pump = 14

Fig 4.3 Polymer Injection Pump

22
4.4 Polymer
Hydrogenated polyacrylamide (HPAM) is a type of water-soluble polymer commonly used in
polymer flooding, a technique for enhanced oil recovery (EOR). In polymer flooding, HPAM
is added to injected water to increase its viscosity. This thickened water improves sweep
efficiency by:

 Reducing channeling of water through the reservoir

 Increasing the contact area between the injected water and the oil
 Displacing more oil towards production wells
 HPAM is a versatile polymer that can be tailored to specific reservoir conditions.Different
molecular weights and degrees of hydrolysis can be used to optimize HPAM performance
for a particular reservoir.

Fig 4.4- Polymer preparation plant

4.5 Water Treatment Plant

Treats water to remove impurities such as suspended solids, organic matter, and bacteria. The
specific treatment processes used will depend on the quality of the effluent water and the desired
quality of the treated water.

Fig 4.5 : Desired water parameter at the outlet of water treatment plant

23
 Fig4.5.1 : Typical parameter range of feed of NK Polymer Plant

4.6 Storage tanks

4.6.1 Raw water tank:

A raw water tank is a large container used to store untreated water from sources like rivers,
lakes, or wells. This water will then be treated in a water treatment plant to make it safe for
drinking or industrial use.

Number of Raw water tank -1

Capacity - 200/254m(net/nominal)

4.6.2 ETP tank:

An ETP tank, or effluent treatment plant tank, is a large container designed to hold and treat
water generated by Effluent treatment plant.

Number of ETP water tank -2

Capacity - 200/254m(net/nominal)

4.6.3 Polymer storage tank:

A polymer storage tank is a container used to store polymers, which are water-soluble
polymer commonly used in polymer flooding.

Number of Polymer water tank =1

Capacity - 200/254m(net/nominal)

Fig 4.6.1: Raw water tank

24
Chapter-5: Effluent Treatment plant

5.1 About Effluent Treatment Plant (ETP)

 Oil & gas industry generates waste water from the water extracted from the geological
formations and from chemicals used during exploration, well drilling and production of oil
and gas.
 Water extracted from separation process of oil is contained emulsified oil and many other
harmful contaminations.
 This water is addressed as Effluent.
 In Effluent treatment process this waste water is treated and then injected after one
thousand meters under the surface .
 Effluent is treated in Effluent Treatment Plant (ETP)

Fig 5.1 : plant Layout

5.2 FACILITIES AT NK-ETP PLANT

Here are the different parts of an effluent treatment plant (ETP) :

Fig 5.2 : Process Layout

25
5.2.1 Buffer Vessel:

A buffer vessel is a tank used to store and equalize the flow of wastewater entering the ETP. It
helps to smooth out fluctuations in flow rate and wastewater characteristics, which can improve
the efficiency of the treatment process.

5.2.2 Raw WaterTank:

The raw water tank is a tank used to store the water From GGS-NK 1,2,3 before it is treated.
There are two raw tanks A and B of each 2000 m3

5.3.3 Oil Skimming tank:

➢ The effluent from the battery limit and the streams coming from
within the Lie system shall be received in the Oil Skimming tank.
➢ Effluent is allowed to enter in Tank.
➢ Settling time is given to Effluent so free oil could come on surface.
➢ This free oil is collected through rotating oil skimmer

5.3.4 Corrugated Plate Interceptor (CPI):

A Corrugated Plate Interceptor (CPI), also sometimes called a Tilted Plate Interceptor (TPI), is
a unit used in effluent treatment plants specifically designed to remove free oil and suspended
solids from wastewater during the primary treatment stage.There are two CPI of each 65 in.

Fig 5.3.4 :Corrugated Plate Interceptor (CPI)

5.3.5 Chemical hous and Dosing Facilities:

The chemical house is provided for preparing of different chemicals required for dosing which
include chemicals like caustic, De-oiling Polyelectrolyte, Alum, Biocide, Oxygen Scavengers
and Corrosion inhibitor and to house respective dosing tanks

5.3.6 Flocculation:

26
Flocculation is a crucial stage in wastewater treatment that promotes the clumping together of
minuscule suspended particles and organic matter into larger flocs. These flocs are subsequently
easier to remove through sedimentation or filtration processes.

There are two flocculation present in this ETP.

5.3.7 Nutshell Filter:

A nutshell filter is a type of filter used in effluent treatment plants using walnuts as filter. Its
purpose is to remove residual oil and suspended solids from the effluent.

5.3.8 Fine Filter:

The choice of fine filter will depend on the specific requirements of the effluent treatment plant.
membrane filters is more effective at removing a range of 10 microns contaminants.

5.3.9 ETP tank:

An ETP tank, or effluent treatment plant tank, is a large container designed to hold and treat
water generated by Effluent treatment plant.There are two tanks of each 2000 m3. and
diameter*hiegth of 15m*12m.

Fig 5.3.9: Effluent Treatment Plant Tank

5.3.10 Chemical Lab :

The typical quality of the treated effluent coming out effluent Treatment plant is measured in
a lab ETP is as follows:
Oil & grease emulsified oil <10 ppm
pH <7.5 pH
Total suspended Solids <10 ppm
Turbidity <100

5.4 Production of Effluent Treatment Plant

27
 2400 m3 goes to 6 effluent disposal well and 400m3 goes polymer flooding plant.

Chapter-6 : Rig WR-50-40(MWD 51)

6.1 About Type of Rig

Rig WR-50-40(MWD 51) is a hydraulic automatic workover rig which is a type of equipment
used in the oil and gas industry for servicing existing oil wells. Unlike traditional workover rigs
that rely on manual operation, hydraulic automatic rigs use hydraulics and automation to
perform tasks like lifting and lowering pipes, reducing the need for human intervention.

6.1.1 Hydraulics:

Hydraulic systems use pressurized fluid to power machinery. In a hydraulic automatic workover
rig, hydraulic cylinders provide the force needed to move the pipes. This allows for precise
control over the movement of the pipes, which is important for safe and efficient well servicing.

6.1.2 Automation:

Automatic workover rigs use computer controls to automate many of the tasks involved in well
servicing. This can include things like raising and lowering the pipes, making connections, and
monitoring the wellbore pressure. Automation can improve safety and efficiency by reducing
the risk of human error.

Fig 6.1.2 :Rig Floor

6.1.3 Detail of Rig WR-50-40(MWD 51)

Capacity of the rig is 50 tons.

28
Depth -2300m-2500m
Casing - 2 cp ( conductor and Production)
Tubing - 2 7/8 & 3 1/2 in

Fig 6.1.3: Rig WR-50-40(MWD 51)

6.2 About the workover operating:

6.2.2 Work -Zone Transfer

A zone transfer in a wellbore is the process of isolating a section of the well (zone) that is no
longer productive or has become problematic, and redirecting production to a new, more
productive zone. This helps to:

 Extend well life: By accessing fresh oil and gas reserves, the well can continue
production for a longer period.
 Improve overall production: By isolating a depleted zone, total well output can be
increased by focusing on the new, productive zone.

29
 Fig : Workover plan

6.2.2 Workover plan:

1). Subdue the well brine of s.g. 1.015.g. Done with 1258.

2). RX, 180P. Test Bop at 150ksc.

3). Release upstroke & P/O completion string.

4). R/I SE + SCR + POP. up to 2162m( F/c). Test integrity @ 150kx. Check injectivity.

5) Set BP at 1960m Test Sp at 100ks you then

6) Perforate intervel 1877-81M 18 SPM (Tentative). Test injectivity & Report.

7) TII, TSC (For future HF requirement) & Expensive joint with HP [ CCl :1832,18421851.5,
1861, 1871m]

30
Chapter-7: Lectures

7.1 Well logging:

Well logging is a crucial technique used in the petroleum industry to gather information about
the properties of rock formations underground. This information is vital for determining the
presence and viability of hydrocarbon reservoirs.

7.1.1 Types of Well Logs

There are various types of well logs, each measuring a specific property of the formation. Some
of the most common types of logs include:

 Resistivity Logs: Measure the electrical resistance of the formation, which can indicate the
presence of fluids, such as water or hydrocarbons.

Fig 7.1.1:Resistivity Logs:

 Porosity Logs: Measure the amount of pore space within the rock, which can hold fluids.
There are two main types of porosity logs: neutron porosity logs and density porosity logs.

Fig 7.1.2: Porosity Logs

31
 Gamma Ray Logs: Measure the natural radioactivity of the formation, which can help
identify different rock types. Shale formations typically have higher radioactivity than
sandstone or limestone formations.

Fig 7.1.3: Gamma Ray Logs

 Spontaneous Potential (SP) Logs: Measure the voltage generated by the natural electrical
currents within the formation. SP logs can be used to identify permeable zones and
formation boundaries.

Fig 7.1.3: Spontaneous Potential (SP) Logs

 Caliper Logs: Measure the diameter of the borehole, which can help identify cavings
(chunks of rock that have fallen into the borehole) and other wellbore problems.

Fig 7.1.4: Caliper Logs

32
7.1.2 Applications of Well Logging

Well logs are used for a variety of purposes in the petroleum industry, including:

 Identifying hydrocarbon reservoirs: Well logs can be used to identify zones of porosity and
permeability, which are essential for hydrocarbon accumulation.
 Evaluating reservoir potential: Well logs can be used to estimate the porosity, permeability,
and fluid saturation of a reservoir, which are critical factors for determining the amount of
hydrocarbons that can be produced.
 Planning well completions: Well logs are used to help design well completions, such as
perforations and sand control measures.
 Monitoring reservoir performance: Well logs can be used to monitor the performance of a
reservoir over time, such as tracking changes in fluid saturation and pressure.

Fig 7.1.4: well logs

7.2 Water coning

Water coning is a phenomenon encountered during oil and gas production from reservoirs. It
refers to the unwanted upward movement of water, displacing oil, towards the wellbore due to
pressure changes.

Fig 7.2 : water coning in vertical well

33
 Cause: It occurs in reservoirs where oil sits above a layer of water. When oil is extracted,
the pressure in the reservoir near the wellbore decreases. This pressure difference creates a
force that draws the underlying water upwards.

 Impact: Water coning is undesirable because it reduces the amount of oil recovered from
the well and increases the complexity of processing the extracted fluids. Separating
produced water from oil adds cost and reduces overall production efficiency.

7.2.1 Factors affecting water coning is crucial for reservoir management:

 Reservoir properties: Permeability (the ease with which fluids flow through rock
formations) and the thickness of the oil layer relative to the water layer influence coning.

 Production rate: Higher production rates lead to a larger pressure drop around the wellbore,
increasing the tendency for water coning.

 Wellbore configuration: Vertical wells are more prone to water coning compared to
horizontal wells drilled within the oil layer.

7.2.3 Here are some approaches to mitigate water coning:

 Optimizing production rates: Maintaining a moderate flow rate can help balance pressure
and reduce water breakthrough.

Fig: Critical production rate

 Water injection techniques: Injecting water into specific zones of the reservoir can help
maintain pressure and push oil towards the wellbore.

 Advanced well completions: Techniques like packers and slotted liners can restrict water
inflow from specific zones within the reservoir.

By understanding and addressing water coning, oil and gas companies can improve reservoir
management, optimize production efficiency, and recover more hydrocarbons.

34
7.3 Enchance Oil Recovery:

Enhanced oil recovery (EOR) is a technique used to extract more oil from an oilfield after
primary and secondary recovery methods have reached their limits. Primary recovery relies on
natural reservoir pressure to push oil towards production wells. Secondary recovery methods,
such as waterflooding, inject water into the reservoir to maintain pressure and sweep additional
oil towards the wells.

EOR techniques target the remaining oil that is trapped in the rock due to various factors, such
as high viscosity, tight rock formations, or poor sweep efficiency from prior recovery methods.
By employing different techniques, EOR can increase the ultimate recovery of oil from a
reservoir by 30% to 60% or more, compared to 20% to 40% using primary and secondary
recovery alone.

7.3.1 There are three main categories of EOR techniques:

 Thermal recovery injects heat into the reservoir to thin viscous oil and improve its
flowability. Common thermal recovery methods include steam flooding and cyclic steam
stimulation.

Fig 7.3.1 : Thermal recovery

 Gas injection injects gases like natural gas, carbon dioxide (CO2), or nitrogen into the
reservoir. These gases can interact with the oil in several ways to increase recovery, such
as reducing oil viscosity, creating miscible flooding (where the injected gas mixes with
the oil), or providing pressure support to push oil towards production wells.

Fig 7.3.2 : Gas injection

35
 Chemical EOR injects chemicals like polymers or surfactants into the reservoir to alter
the properties of the oil and rock. Polymers can increase the viscosity of water to improve
sweep efficiency, while surfactants can reduce interfacial tension between oil and water,
allowing for better oil displacement.

Fig 7.3.3: Chemical EOR injects

The selection of the most appropriate EOR technique depends on various factors, including
the properties of the reservoir rock and oil, the economic feasibility of the project, and
environmental considerations. EOR projects can be complex and expensive, and careful
evaluation is required to ensure their technical and economic success.

The mobility ratio is a concept used in reservoir engineering to describe the relative ease with
which one fluid can displace another in a porous medium, such as an oil reservoir.

It is defined as the ratio of the mobility of the injected fluid (the fluid being forced into the
reservoir) to the mobility of the displaced fluid (the fluid that is being pushed out
of the reservoir).

Fig 7.3.4: Areal Sweep Efficiency ,% is a function of Mobility Ratio ,M

36
CONCLUSION
 It was a wonderful learning experience by doing my internship with the engineers and
professionals of ONGC Mehsana Asset. The sessions were very insightful and expanded
my knowledge about the field and work culture we find in actual, After going through the
Whole course. The coordinator along with all the professionals, who were in on-or-the-
other way involved during the whole course of our training, were very supportive and
doubts were cleared with utmost intricacies. Sharing their experience and giving their
professional knowledge about the oil & gas industry would surely going to help me in my
future.
 During the whole course of internship, I had learn a great many things and gone into their
more intricate aspects, such as Crude oil processing, well maintenance, effluent handling
etc. in fields, how various operations are carried out, how things are done in real, how
there is healthy working environment created in order to avoid any danger due to
employee stress and workload and how to work in altogether as a team

37
Reference
List the websites, articles, papers studied for fulfillment of Industrial Training.

1. NK-CTF cum GGS plan book.

2. Plan of NK-ETP .

3. Surface Production Operations, Volume 1, Third Edition Design of Oil Handling Systems
and Facilities by Maurice Stewart, Ken E. Arnold (z-lib.org)
4. Photos from Sciencedirect.com/ ProceePrincipal.com/ MultiplexGroup/
ResearchGate.com

5. Untapped Hydrocarbon Potential of Post Kalol pay sands of North Kadi-South Santhal
Field, Cambay Basin, India /Pusan Misra, Sumit Pal, Suryaprakash Lahoti, Ramashray
Yadav, Radhakishan Gupta, ONGC, Western Onshore Basin, Vadodara, India

38