Oil & Gas Development
Company Ltd.
INTERNSHIP REPORT
QadirPur Gas field
Submitted by
Ahmad Nauman
Submitted to
ICE(Mr.TAHIR)
Letter no.
OGTI/115A-050/SIP#269
Duration of Internship
4Weeks
(27-08-2021 to 23-09-2021)
Table of Contents
ACKNOWLEDGEMENT ........................................................................................................
PREFACE .............................................................................................................................
HSE ....................................................................................................................................
Introduction .......................................................................................................................
Processing of gas from Header to membrane train ..............................................................
MAN TURBINE COMPRESSOR .............................................................................................
INSTRUMENT AIR PROCESSING ...........................................................................................
Fuel system ........................................................................................................................
Electrical workshop ...........................................................................................................
LABORTARY .......................................................................................................................
..................................................................................................................................................................
ACKNOWLEDGEMENT
In all humility we are thankful to Almighty Allah for giving me courage and
strength to fulfill the objectives which I had set for myself. I am very grateful to
In charge Process, Mr. Tahir & Mr. Ina mullah for their guidance. I am also thankful
to Engineers Mr. Tahir Paracha for their kind supervision. Furthermore, I would
also like to thank all the skilled workers of OGDCL for their help and guidance
PREFACE
The oil and gas processing plant does not involve a single process. It is a
combination of several processes, from the arrival of raw gas from well head to
processed gas and partially processed oil, which is sent to Refinery. In fact, during
this short duration of four weeks I went through an extensive learning process.
For me this training was very informative and full of knowledge. This report is
based on the study of areas that I have visited, and I have tried to briefly describe
the operation and working of the concerning areas, according to my knowledge
HSE
HSE stands for health safety and Quality and its main logo is ‘SAFETY FIRST’.
Safety:
Safety means a safe working and operating environment, free of danger to
personnel and equipment.
H.S.E stands for Health safety and environment. The main objective department
is to overcome the accidents due to lack of safety. This department gives safety
instruction and precaution to the visitor and employers. This department is also
check out the toxic and polluted gases with are very harm full to the people.
H.S.E department provide PPE’s (personal protective equipment’s) to the
employers and to the visitor.
PPEs consist of the following equipments
 Helmet
 Ear plug
 Mask
 Safety shoes
 Gum shoes
 Uniform
 Gloves
Ear plug, Ear plug are used to overcome the hearing problem because on the plant
side there is too much noise of gases and compressor etc. Using ear plug this
sound can be reduced. Mask, On the plant side there is too much smell of gases.
Safety shoes, these shoes have very good grip on the earth. Helmets protect from
injuries.
Precautions:
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Gases are highly flammable.
Electricity wires are totally underground to avoid the accidents. So do
not touch such kind of wires.
In any case for escaping follow the plant employers which are
completely trained for facing such conditions.
Prohibited:
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Photography
Smoking
Lighter
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
Cell phone
Weapons
Mustered point:
This is the point where all people must gather in case of any emergency.
INTRODUCTION
OGDCL is the national oil & gas company of Pakistan and the flagship of the
country’s E&P sector
QADIRPUR GAS FIELD:
Qadirpur is one of the largest gas processing fields of Pakistan. The field is located
at 8 km from Ghotki in Sindh Province. Qadirpur gas field was discovered in March
1990. After installation of gas gathering facilities and plant, gas production was
started in Sep. 1995.
Daily production of the gas and condensate is about 190MMscfd and 720BBL
respectively. The plant expansion is being carried out meet ever increasing
demand of natural gas.
WELL STATUS
Total Gas Wells drilled= 83
Productive wells =70
Dead wells =13
DAILY PRODUCTION
GAS STATUS:
Total raw gas available = 190 mmscf
Raw gas production for plant sale = 110 mmscfd
Raw gas sale to SNGPL for LPL = 20 mmscfd
Permeate gas to SNGPL for EEL = 30 mmscfd
Plant gas consumptions, flare & ven= 13 mmscfd
Daily fuel gas consumption at plant = 17mmscfd
CONDENSATE STATUS:
Production of condensate per day = 720 bbls
PRODUCED WATER PRODUCTION:
Produced water production per day = 4075 bbls
Reinjection = 4065 bbls
GAS COMPOSITION
C1
Raw gas
Sngpl gas
EEL gas
80.31
84.04
65075
C2
1.00
1.11
0.75
C3
0.27
0.29
0.12
C4
0.13
0.15
0.07
C5
0.06
0.07
0.04
C6+
0.09
0.06
0.06
N2
12.01
12.61
8.9
CO2
6.13
1.61
24.40
H2S ppm
69.00
14.00
200
C.V btu/scf
848
887
685.78
S.G
0.676
0.636
0.836
H2O
……
<.4
<.4
Dew point F
……
<-40
<-40
Processing for gas:
In Qadirpur gas field the well is on northern and eastern side. From northern side
well the gas is collected into the northern common header and from eastern side
well the gas is collected into the eastern common header. Northern pipe is of 30
inch and eastern pipe is of 26-inch diameter. These gases are then bringing to the
plant via these lines then these are goes to slug catchers for the separation of
water and condensate. Due to the low pressure these gases go to the compressor
where these gases compress up to 760psig. Then gases and divided from
Pretreatment 1 and pretreatment 2 from there it goes to the inlet separator for
the separation of entrained liquid and gases. Then these gases pass through the
pre-cooler, chiller economizer and chiller for cooling. After cooling the gas is sent
to the filter coalescer for filtration after that it goes to the memguard for the
removal of heavy hydrocarbons and H2S then it goes to the particle filter for the
removal of dust particle. After that the gas is sent to the membrane train for CO2
separation. The permeate is sent to the turbine for compression after compression
the compress gas is sale to the EEL while the residual from the membrane train
the sale to the SNGPL and the excess gas is goes to flare.
Some of the equipment and the process are given as follow:
Slug catcher:
The gas coming from the well are collected to the northern and eastern header.
Then it come to the plant via 30” pipeline from northern header and 26” pipeline
from eastern header. The gas then goes to slug catchers. There are two type of
slug catchers.
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
Four finger slug catchers.
New slug catcher
These slug catchers are three phase separators.
Water
Condensate
Gas
In new slug catcher the separation occurs due to gravity. The water and
condensate settle down due to the gravity while the gas due to its lighter weight
goes up. water and condensate then go to condensate water separator.
In four finger slug catcher the gas is obtained from the upper portion while the
condensate and water go to the downstream then it goes to condensate water
separator.
Front end compressors:
The gas from the slug catcher goes to the compressors because the pressure of
the gas coming from the well side is not too much high. Gas compress into the
compressor from 220 psig to 756 psig. There are fourteen compressors. The gas
coming from the slug catcher is divided to each compressor after compressing it
goes to the pretreatment one and pretreatment two.The compressors are run by
the Waukesha engine. In this engine gas is use as a fuel. Gas and air are igniting
by the spark which moves the piston and piston run the crapt shaft which runs
this cam shaft. Which further run the compressor.
Inlet separator:
The gas directed to the inlet separator from compressors. In these separator
sand pipe scales lubricating oil liquid hydrocarbon and water condensate are
removed. These are thing are removed under the action of the gravity.
Pre coolers:
Gas from the inlet separator is then cool into the pre coolers. These coolers are
shell and tube type coolers. The gas is pass through the tube and sale gas is the
cooling medium which pass through the shell side. The heat transfer is occurring
from the wall of the tubes.
Chiller Economizers:
These are also shell and tube type heat exchangers Gas from the pre-cooler is
further cool into the economizers to increase the efficiency of the chiller. The gas
is pass through the tube and the gas from the filter coalescer is the cooling
medium which pass through the shell side. The heat transfer is occurring from the
wall of the tubes.
Propane Chiller
The feed gas from the economizer then goes to chiller. Feed gas chiller is a
horizontal kettle type heat exchanger that cool the incoming gas by cross heat
exchange with propane coming from the compression-based refrigeration
system. Feed gas is cooled down to a fixed temperature 60F.Feed gas enter the
chiller from tube side and propane enter from the shell side. Propane vaporizes
by cooling the feed gas to 60F temperature. Liquid propane enters from the
bottom and leave from the top.
Filter coalescer
The feed gas is goes to the filter coalescer to remove the any entrained liquid.
When liquid enter the vessel liquid formation occur due to the expansion. Liquid
drop to the bottom and gas pass through the filters. There are 180 filter elements
are placed inside vessel. When gas pass through these filters the liquid particles
are trap into the filter.
There are three chamber of the filter coalescer.
1. Expansion chamber, where the liquid formation occurs.
2. Filter element chamber, in this chamber the gas is pass through filter for
removal of entrained liquid.
3. Mess pad also removes the liquid.
Memguard
Memguard technology incorporates three cycle adsorption refrigeration and
cooling. There are two memguard on this plant. One has four vessels and the
other have five vessels. These vessels are operating on the cyclic process. For
five vessel memguard, three vessels are on adsorption, one on cooling and the
last one on heating. The residence time for adsorption vessel is 135 minutes
and for cooling and heating is 45 45 each. For four vessel memguard, two
vessels are on adsorption, one on cooling and the last one on heating. The
residence time for adsorption vessel is 90 minute and for cooling and heating
is 45 45 each. In these vessels there are beds which adsorb the hydrocarbon
and the H2S. These chemicals are of different types such as:
MG-3
MG-5
MG-6
Cosmax
These chemicals are supported on the ceramic balls. Mg3 Mg5 and Mg6
adsorb the hydrocarbon while cosmax adsorb the H2S.
Adsorption cycle:
During the adsorption cycle the feed gas enters the top of the
adsorber, while purified natural gas leave from the bottom. At the end of the
adsorption phase the adsorber is loaded with impurities concentrated at the
top.
Regeneration cycle:
In the regeneration step the adsorber is regenerated with hot
regeneration gas ‘from bottom to top, and the impurities water and heavy
hydrocarbons are desorbed and removed via the top of the vessel.
Cooling cycle:
Following the regeneration step the adsorber is cooled with
cold stream from the memguard product. The cooling gas enters at the top and
exists at the bottom thus the adsorber is cooled to adsorption temperature
before it is put back into adsorption step.
Gas Heater:
The cool gas is heated to regenerate the adsorption beds. Gas is heated in the
gas heaters. These are consisting of four coils; each coil is equipped with a
tube wall temperature element in each of the two heater sections. The heater
is natural gas fired 550F.
Gas Cooler:
These are simple air cooler equipped with the 3 fans. These
are designed such that the system continuously operates if any one of them turn
off.
Particle filter:
The particle filter is a vertical vessel which hold 45 cartage filters. Any dust
particle is removed into these cartage filters which are coming from the
memguard.
UOP membrane system for separation of gases:
Membrane system work under the permeation action. The gases such as CO2 and
H2S permeate while the CH4 goes straight and not permeated. The permeate is
then collected to the common header while residual collected into the other
header. The permeation is occurring due to the pressure gradient. After
permeation the permeate pressure is up to 6-7 psig. while the residual is at high
temperature.
In this plant there are three membrane trains. Train one and two are of same
capacity. Each train can handle 250 mmscfd feed. There are 6 banks in these
train and each bank have 6 tubes with 8 membrane elements in each tube. While
train 3 can handle 300 mmscfd feed. There are 7 banks in these train and each
bank have 7 tubes with 10 membrane elements in each tube.
Membrane element:
The separex membrane elements consist of cellulose acelate membranes that are
bended on to a woven cloth support. The membrane itself has two layers a
relatively thick micro porous layer. A membrane element is a spiral wound
assembly with a hollow perforated tube. Each leaf contains to membrane cloths
composite layers that are separated by a rigid porous fluid conducted permeate
cannel spacer.
Four stage turbine:
Four stage turbine is basically use to enhance the pressure of permeate up to 450
psig. The gas from the membrane train is enter to the 1st stage scruber then it
enter to the turbine compressor where it compress and its temperature raise and
it go to the three fin fan cooler then it goes to 2nd stage scruber then it again
compress in turbine compressor then it cool after cooling it enter into the 3rd stage
scruber after removal of liquid it again enter to the turbine compressor after
compressing it again cool then it pass through the 4th stage compressor then after
passing through filter coalescer and heater it sale to the EEL.
Refrigeration cycle of Propane:
The vapor of propane is then directed to the compressor which are run by the
Waukesha engines. These vapors are compress then these are sent to the
condenser where these vapors are condensing and liquefy. The condenser consist
of 8 fin fan coolers and air is the cooling medium the propane moves in the tubes.
After condensing this liquid is then directed to the propane receiver where Joule
Thomson effect occur, and the temperature of the propane is reduced. Then it is
directed to the chiller for cooling the feed gas.
Water handling:
The water and condensate from the slug catcher enter to the condensate water
separator. In this separator the water and condensate are separated due the
difference of their density. Condensate has low density than water, so it comes on
the top while water has higher density, so it remains at the bottom. If any gas
remains there it exits to the flare from the top. The condensate enters the flash
tank for extra settling then it is directed to the storage tank and the water from
the condensate water separator enter to the corrugated plate interceptor. In C.P.I
there are plates from which condensate can overflow because it is on the upper
surface while water remain at the bottom. The condensate is directed to the pit
from where it is sent to the storage tank via pumps and water from the C.P.I is
directed to the sand separator and filtration occurs then it is send to the water
storage tank from where it is injected to the earth via heavy duty pumps.
FLARE SYSTEM:
The system is provided to dispose of the excess Gases in normal operation and
emergency condition as well in safe and efficient manner. All the Vessels,
Membrane Trains, Air Coolers and Gas supply System to Utilities are provided
with the PSVs, calibrated at specific Pressure and they use to Pop-Up in case of
operating Pressure exceeding the calibrated ones. The Gas from all these PSVs
along with the permeate generated are combined in a single Header Down stream
of which is provided with a Flare Knock Out Drum, which removes any entrained
liquids and directs the Dry Gas towards the Flare. The Flare is ignited with Flame
Front Ignition System in which LPG is used during startup. After that the sustained
combustion prolongs in the Flare throughout.
Valve:
In this plant there are many kinds of valve which are control the flow rate in the
pipeline and they also use to isolated and depressurized the pipeline for the
mechanical work of the pipes and equipment’s. The types of the valve are given
as follow.
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Ball valve
Globe valve
Gate valve
Butterfly valve
Neddle vale
Temprature and pressure profile:
Equipment
Tempraure (F)
Pressure
(psig)
Sr
no
Inlet
Outlet
Inlet
Outlet
1
Compressors
127
116.5
724
742
2
Inlet
separator
116.5
116.5
742
742
3
Pre coolers
116.5
88
742
742
4
Economizer
88
69
743
738
5
Chiller
69
60
738
738
6
Filter
coalescer
60
60
738
738
7
Memguard
79
8
Particle filter
78
79
91
738
738
738
738
UTILITIES:
All Plants depend on uniform supply of utilities for proper functioning. Utilities can
think to be as a “FOOD” for a Plant. The utilities at Qadirpur Plant are discussed
below.
FUEL SYSTEM
As the Natural Gas is plentiful here so it is used as Fuel at Plant and residential
area. At the Plant the Fuel Gas is used to run


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Gas Turbines
Power Generators
Compressor Engines
Regeneration Gas Heater.
In Condensate Storage Tanks
At the residential area Fuel Gas is mainly used for cooking and heating. The
Average daily consumption of the Fuel Gas for the above-mentioned purposes
is around 8 MMSCFD. This Fuel Gas is taken from Sales Gas Line during normal
operation but in the case of emergency or startup of the Plant, the Raw Gas
coming straight from the wells is used. The Fuel Gas taken from Sales Gas Line
is treated to knock out any entrained Liquids and its pressure is also made to
let down from 800 Psig approximately to 400 Psig and 80 Psig. For this
purpose, there are two systems i.e., old and new. Both include HP knock out
Vessels V-5300 and V-6300 for old and new systems respectively. And in the
old system the LP knock out vessel V-5302 upstream of which is an Electric
Heater E-5301 to remove water. Before the Gas is finally delivered to the
usage points, it also passes through the strainers.
Based on operational requirements, the Fuel Gas is divided into two types:
i) High Pressure Fuel (HP Fuel 400 Psig)
ii) Low Pressure Fuel (LP Fuel 80 Psig)
High Pressure Fuel Gas is only used in Gas turbines in normal operation, for
high jetting requirements. It is also used for Waukesha Engines startup. While
the Low-Pressure Fuel Gas is used to run Power Generator Engines, Propane
Compressor Engines, Regeneration Gas Heater and to maintain a Positive Head
in the Condensate Storage Tank to avoid condensate undue evaporation.
During the startup of Plant, the limited amount of Diesel is used to run the
Diesel Engine driven Generator, to fulfill the initial Power requirements and LPG
is used for the Flare system startup.
COOLING TOWER
Three Induced Draught Cooling Towers are used to cool the Jacketed Water. The
Jacketed Water serves as to cool the Lubricating oil in the Power Generator
Engines. To avoid the scaling in the Pipelines, the Vendor specified Chemicals
are dosed in Cooling Towers. Hot Water from the Plate Type Heat Exchanger
enters the top of Cooling Tower where it is distributed uniformly. The down falling
water meets upward moving air and thus it exchanges its heat contents with the
air and gets cooled down. The cooled Water is sent into the circulation via
Centrifugal Pumps. The Chemical dozed into the Cooling Towers is mainly
Sodium Xylene Sulphonate. The material of construction of Cooling Tower
Casing is FRP (Fiber Reinforced Plastic) and the extended surface is in the form
of studs, and it is some Solid Polymeric Material.
INSTRUMENT AIR
At the Plant, Instrument Air is used run the various controlling devices so the
constant Instrument Air supply is very necessary. To generate the Instrument Air
three Positive Displacement Compressors are installed out of these two are Piston
type Compressors and one is Screw type. The Piston Type Compressors intake the
atmospheric Air and compress them in two stages followed by inter-stage Cooling
system. The compressed Air is first stored in the Vessel V-5803 and then it is
made free from moisture contents, by passing it through the Adsorbing Dryers. It
consists of an Aluminosilicates Beds which are regenerated after specific time.
After Drying the Compressed Air, it is stored in V-5302 and distributed to the
whole Plant. The Screw Type Compressor is a backup sort of equipment used when
both Piston Type Compressors are not in the operation.
NITROGEN PACKAGE:
Nitrogen Package is provided to get the Moisture Free Low Dew Point Nitrogen
Gas for the purpose of Purging and High-Pressure Testing. This Package
incorporates the membranes and the Blowers. It takes Compressed Air from
Instrument Air section and then separates the Nitrogen using Membranes. The
Nitrogen Gas used for Purging is Low Pressure approximately at 90 Psig, while
the Gas for High Pressure Testing is at 900 Psig approximately. It is stored in
Nitrogen Storage Tank V-5815. From it is distributed to the whole Plant where
required.
Electrical Workhshop



Switch gear room
Powerhouse
UPS system
Switch Gear room is a room from where all the motor are controlled all on/off
systems are placed in this room. In powerhouse there are 6 electricity
generating engines. One is diesel engine which is use in case of any emergency
when gas engine is not working properly. While the other five engine are gas
engine.
Capacities of engines are as follow:
Diesel engine=1Mwatt
Gas engine= 824 K Watt
LABORATORY
The laboratory provides the Quality Control and assurance services to the Plant
and its products. For this purpose, the following tests are performed in the
Laboratory:

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
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

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
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

PH
TDS
TSS
BOD
COD
BS&W
Viscosity
Conductivity
Gas Analysis
Free Chlorine
Vapor Pressure
Specific Gravity
Relative Humidity
H2S Concentration
Carbon Dioxide Concentration
The equipment used to perform the above-mentioned tests are as follows:







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Multi-meter
BS & W Centrifuge
Viscometer
Gas Chromatograph
Spectrophotometer
Reid’s Vapor Pressure Apparatus
Hygrometer
Titrometric equipment
Draeger Tube
Orsat Apparatus
Distilled Water Unit
Furnace
BOD Incubator