The document provides an overview of the Kandhkot Gas Field located in Pakistan. It describes the key infrastructure at the field including two gas gathering mains, an injection well used to dispose of produced water, corrosion control via chemical injection, and the Kandhkot Field Gas Compression Station. The compression station helps boost pressures as the field depletes and includes components like a modified slug catcher, inlet gas filtration, suction scrubber, and compression trains.

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Submitted by:
M. Hammas Khan
Petroleum Department
Third Year PE-005
NED University of Engineering & Technology,
Karachi
Internship Report
8th
June to 3rd
July, 2015
Kandhkot Gas Field

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TABLE OF CONTENTS
PREFACE 2
HEALTH, SAFETY AND ENVIRONMENT 3
OVERVIEW 3
Gas Gathering Main (GGM) 3
INJECTION WELL AT KDT GAS FIELD 4
CORROSION CONTROL by CHEMICAL INJECTION 4
KANDHKOT FIELD GAS COMPRESSION STATION (KFGCS) 4
INTRODUCTION ...................................................................................................................................................4
COMPONENTS OF COMPRESSION PLANT..............................................................................................................5
DEHYDRATION PLANT (DHP) 6
NEED OF DEHYDRATION.......................................................................................................................................6
PROCESS OF DEHYDRATION..................................................................................................................................6
DOWNHOLE EQUIPMENTS 8
PACKERS:.............................................................................................................................................................8
MILL OUT EXTENSION:.........................................................................................................................................8
SURFACE CONTROLLED SUB-SURFACE SAFETY VALVE (SCSSV):................................................................................9
PUP JOINTS:.......................................................................................................................................................10
CROSS OVER:.....................................................................................................................................................10
CHECK VALVE:....................................................................................................................................................10
TRAVELLING JOINT:............................................................................................................................................10
SLOTTED LINER:.................................................................................................................................................10
PERFORATED SPACER TUBE:...............................................................................................................................10
TAIL PIPE ASSEMBLY:..........................................................................................................................................10
FLOW COUPLING:..............................................................................................................................................10
BLAST JOINTS:....................................................................................................................................................10
RE-ENTRY GUIDE................................................................................................................................................10
SPACER.............................................................................................................................................................10
BOTTOMNO-GO NIPPLE.....................................................................................................................................11
TOP NO-GO NIPPLE............................................................................................................................................11
SAFETY VALVE LANDING NIPPLE..........................................................................................................................11
TUBING HANGER ...............................................................................................................................................11
WELL HEAD & X-MAS TREE 11
SAFETY SYSTEM OF WELL 12

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PREFACE
Working here in PPL Kandhkot field as an internee has been a pleasure as well as a nice learning
experience where I gathered as ample of practical as well as theoretical knowledge and skills.
I would like to thank Allah Almighty for this opportunity. I would also like to thank all my bosses who
had been so co-operative despite of their responsibilities and work load and took time out for
mentoring me.
It has been my great fortune to have the advice and guidance of many talented people whose
knowledge and skills have made possible to write this report. I am thankful to all the team of Kandhkot
Gas Field specially,
Mr. Mehboob Ali
PRODUCTION ENGINEER INCHARGE (PEIC-KDT)
I am extremely thankful to:
Mr. M. Arab Bhayo (Deputy Chief Engineer Production)
Mr. Pir Ali Shah (Senior Production Engineer)
Mr. Adbul Sattar Bugti (Engineer Production)
Mr. Rameez Arshad (Engineer Production)
Mr. Abid Hassan (Trainee Engineer)
Mr. Raheel Khalid (Technician Production)
Mr. Qazi Fahim (Management Trainee)
Mr. Mushtaq Ahmed (HSE Officer)
Mr. Ashfaq Sheikh (Admin Officer)
Mr. Ahsan Iqbal (Senior Technician DHP)
Mr. M. Tayyab (Technician KFGCS)
Mr. Raja Wahid (Male Nurse)

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HEALTH, SAFETY AND ENVIRONMENT
Workers who work in PPL are responsible for their as well as their fellow workers safety.
• There are 4 assembly points located in Kandhkot Gas Field so in case of any emergency workers
are recommended to move to these assembly points.
• 5 smoking areas are there so that no fire can take place inside residential or working place
• Minimum of 20 km/hr speed is recommended inside the camp.
• Seat belt should be there while driving.
• Safety shoes, helmet are required while working in plant.
So continuous monitoring is there for the safety of workers so that risk could be minimized.
OVERVIEW
Kandhkot Gas Field is situated on the right bank of Indus River in Upper Sindh, while the field’s
reserves are located in the Habib Rahi Limestone, Sui Upper Limestone and Sui Main Limestone
reservoirs. The field was discovered in 1959 and has 28 producing wells to date. Among them well
number 1 has abandoned well 2 is observatory well to know about the water level. The average
production of the field is approximately 194MMSCF. The leading sale gas consumers include WAPDA,
SNGPL and SSGCL, whereas condensate is sold to PRL (Pakistan Refinery Limited).
Geologically Kandhkot Gas field consists of three domes:
S. No. Dome Formation Depth (m) Discovery in
1 North-East Dome
Sui Main Limestone
(SML)
5000-6000
1958
Sui Upper Limestone
(SUL)
3500-4500
2 West Dome
Sui Main Limestone
(SML)
5000-6000 1971
3 South East Dome
Sui Main Limestone
(SML)
5000-6000
1986
Sui Upper Limestone
(SUL)
3500-4500
Habib Rahi Limestone
(HRL)
2500-3000
Gas Gathering Main (GGM)
There are two gas gathering mains collecting gas form the feeder lines of different wells and delivering
it to the dehydration plant. These gas gathering mains are recognized by the sections they are divided
into i.e
1 GGM consists of section 1, 2

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2 GGM consists of section 3, 4, 5, 6, 7
INJECTION WELL AT KDT GAS FIELD
Injection wells are basically used to maintain the reservoir pressure in secondary recovery and to
dispose the unwanted liquid coming with gas specially water.
The rate of water at KDT field is high, and drainage of this water is harmful for environment because
of high content of impurities present and high salinity, so according to HSE policy an injection well
KDT-30(N) was drilled to dispose the water coming from wells to the field at 350 psi injection pressure
inside Upper Nari Formation. The well has a total depth of 821m.
CORROSION CONTROL by CHEMICAL INJECTION
In Kandhkot wells the tubular both in downhole and gathering system are internally protected by
injection of corrosion inhibitor. This inhibitor is mixed with condensate in the ratio of 1:40. Required
quantity can be injected by increasing or decreasing pump stroke.
Two methods of injection applied are:
i) Continuous Injection
For this purpose corrosion inhibitor is injected in to the casing-tubing annulus. There are Chemical
Injection Valves in the down hole. CIV ports function at a specific pressure. When annulus pressure
increases the CIV opening pressure corrosion inhibitor is injected in to the well.
ii) Batch Injection
Batch injection is used where CIV is not present in downhole. Inhibitor is directly injected in to the
tubing through swab valve. For this purpose safety valve and master valve remain open while wing
valve is shut.
KANDHKOTFIELD GAS COMPRESSIONSTATION (KFGCS)
INTRODUCTION
Due to continuing production since 1987, the field was entering the depletion phase and the well
head pressure was decreasing. Hence, PPL envisaged providing Gas Compression facility at Kandhkot
Gas Plant to cater for the continuing decline in field pressure.
The purpose of the compression facilities is to fully recover the remaining reserves from all existing
and newly connected wellheads and boost up the pressure of the gas by installing a Front End
Compressor Station after Slug Catcher to a pressure of approximately 700 psia to meet GSA
requirements.

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COMPONENTS OF COMPRESSION PLANT
Modified Slug Catcher Area
Production fluid from the feed gas pig receiver pipelines is fed into a modified slug catcher having 12
fingers to separate the natural gas from the liquids. The stabilized condensate/water mixture is
transferred to existing Condensate Separation tank.
Inlet Gas Filtration
Slug Catcher gas contains liquid droplets and fine solid debris particles. Gas is transferred to the Inlet
filters where mist and droplets are removed and solid particles are separated from the gas for the
protection of the compressors and the plant. The gas is then sent to the Compression System.
Suction Scrubber
The suction scrubber is designed to remove entrained condensation particles and other fluids from
downstream of inlet gas filtration prior to feed to compressor units.
Compression Trains
The compressor station consists of a total of three gas turbine driven centrifugal compressors, each
associated with suction scrubber, interstage scrubber, interstage cooler, outlet cooler and anti-surge
controls.
The gas is fed to suction scrubber and compressed in stage-1 of compressors, then cooled in an inter-
stage cooler. Then again transferred to suction scrubber and compressed in stage-2 of compressors
and moved to discharge cooler and then moved to discharge scrubber.
Condensate Recovery System
Condensate from all the compressor scrubbers is collected in Condensate Recovery Header and is
flashed in the Condensate Flash Vessel for stabilization. The stabilized condensate joins the
condensate from Slug Catcher prior to transmit to the Condensate Separation Tank.
Service Water System
In order to meet raw water & fire water requirements two Bore Hole Pumps along with Bore Water
Filters are used. Raw water is stored in Fire Water Tank. Two Service Water Pumps are installed
downstream of the fire water tank. These pumps supply water to different utility stations e.g.
Compressor, Fuel Gas Skid, Inlet Filters, and Condensate Recovery etc.
Firefighting System
This System consists of Fire Water Tank, Fire Water Pumps & Fire Water Jockey Pumps. Two Bore Hole
Pumps supplies raw water to Fire Water Storage Tank. Fire Water Pumps and Fire Water Jockey pumps
take suction from Fire Water Storage Tank. All relevant fire protection devices including hoses,
hydrants, safety showers and monitors are tested to ensure correct operability.

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DEHYDRATION PLANT (DHP)
Dehydration plant at Kandhkot was installed in 1987 as two units (unit 1 and unit 2) each with a
capacity of 30 MMSCFD. Later on with increase in demand the plant was extended to unit 3 and unit
4 and later to unit 5 with 100,130 and 140 MMSCFD capacities respectively. Currently only unit 3 and
unit 4 are in service producing 188 MMSCFD of gas at an average heating value of 824 BTU per cubic
feet with 4-5 lb/MMSCF moisture contents. 1.5, 98 and 88 MMSCFD of this gas is supplied to SSGCL
(Sui Southern Gas Company Limited), WAPDA and SNGPL (Sui Northern Gas Pipe Line) respectively.
A part of it is consumed in the power house at field for producing electricity. The higher hydrocarbons
in the range of gasoline are recovered from the gas as condensate and dispatched to PRL (Pakistan
Refinery Limited) for sale.
NEED OF DEHYDRATION
Water in the form of vapors and droplets is the most undesirable impurity in natural gas and this it
needs to be removed. The process of removing this water from natural gas is called dehydration.
Most of the vapors, droplets and particles are removed by condensation and gravity settling, however,
the remaining vapors of hydrocarbons and water are removed by filtration and absorption. The
principle reasons for the removal of water vapor from natural gas are:
 At a suitable temperature water in natural gas can form solid ice-like hydrates that can plug
pipelines & equipments.
 Water in natural gas causes corrosion in pipelines, particularly if it also contains H2S & CO2,
due to its acidic nature.
 Water in natural gas may condense in pipelines causing slugging flow conditions.
 The heating value of natural gas decreases due to presence of water vapors.
 Water droplets can cause errors in metering system of gas.
PROCESS OF DEHYDRATION
All dehydration units installed in parallel have same principles and range of equipments though differ
in capacities. Each unit consists of:
1. Gas Scrubber
It is a vertical tower with plates installed inside. Sudden expansion of gas entering the scrubber causes
cooling so condensing a part of vapors on the baffle plates. Level controller controls the level of the
liquid inside scrubber through a level control valve by opening and closing it.
2. Pre Gas Filters
Gas enters the filter and passes through the filter cloth into the inner perforated cylinder, liquid
droplets and particles are removed and gas enters the second part leading to outlet.

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3. Absorber or Contactor Tower
Wet gas coming from pre gas filters reaches the vertically mounted vessel called contactor tower or
absorber. Contactor tower has two sections; the upper section contains bubble cap trays varying from
8 to 12 in numbers and lower section called as inlet scrubber contains baffle plates. At the end of
bubble cap trays there is a chimney tray collecting the liquid from the last tray.
Gas enters the inlet scrubber and strikes against the baffle plate. Any droplets present in gas are
removed along with some condensation. Gas then passes through each tray and interacts with the
glycol present on it. Lean glycol is introduced on to the first tray and excess amount trickles down
through the down comer onto the next tray. Rich glycol collected in the chimney tray is regenerated
and again pumped to the absorber.
4. Gas Glycol Heat Exchanger
The gas enters the heat exchanger at 60-80 F and hot lean glycol at 180-210 F. Average difference in
the temperature of glycol across the heat exchanger is 105 F. So gas is heated and glycol cools down
therefore the absorbing capacity of glycol is improved. The gas is then sent to post gas filters.
5. Post Gas Filters
Some of the glycol vapors are entrained in the gas, part of these vapors are removed by demister pad
and remaining in the post gas filters. These filters same in design and operation to the pre gas filters.
The glycol vapors and droplets removed are again drained to pit.
6. Glycol Regeneration Plant
The rich glycol from absorber chimney tray is delivered to the glycol regeneration system. The glycol
is heated to a temperature where absorbed water vapors are converted into steam. This hot lean
glycol is cooled and reused instead of wastage.
i) KimrayPumps
Wet glycol coming from tower reaches glycol pumps also called as Kimray pumps. Each pump has
two piston and cylinder arrangements so there are two suction and two discharge points, one suction
and discharge for the hot lean glycol from surge tank to absorber and the other for high pressure
(650 Psig) cold rich glycol from absorber to low pressure flash vessel (75 Psig). The rate of circulation
of glycol is adjusted according to the flow rate of the gas.
ii) Flash Separator
The rich glycol from absorber is pumped to the flash separator. Sudden decrease in pressure inside
flash vessel causes the gas absorbed in glycol to flash off. The entrained droplet of glycol are removed
and gas is used as fuel in reboiler. The pressure is maintained at 75 Psig in order to circulate glycol
through still column, filters and into the oil skimmer mounted at the top of the reboiler.
iii) Glycol & CharcoalFilters
Glycol passing through the flash separator enters the ‘Glycol Filter’ from the top. The filters elements
are similar in design and operation to those of pre gas filter elements. Glycol enters from the outside
of the filters into central cavity and collected in bottom. A part of suspended particles are removed in
glycol filter. Glycol leaving the filter enters the charcoal filter. Charcoal filter has a column filled with

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granular charcoal that adsorbs the carbon and remaining suspended particles. There are two Glycol
and two Charcoal filters, one is taken in service and other held standby.
iv) Glycol-GlycolHeatExchanger/ Preheater
It is a double pipe heat exchanger mounted on the regeneration skid. Glycol from
charcoal filter passes through the inner smaller diameter pipe while hot lean glycol coming from
reboiler flows through the outer large diameter pipe. In this way hot glycol transfers its heat to wet
glycol and preheating it. This preheating saves the fuel gas required to provide heat for preheating
the rich cold glycol.
v) Skimmer Still Column
Wet glycol coming from heat exchanger goes to oil skimmer. It is mounted on the top
of reboiler beside still column. Glycol through oil skimmer enters the lower part of still column filled
with two inch diameter pall rings. The stripping gas stripes off the absorbed vapors and gas. Glycol
falls into the reboiler outer part.
vi) Reboiler
It consists of two concentric shells. A pilot ignited gas burner is in the inner one & glycol coming from
still column is in the outer shell. These burners heat the heat the glycol to required temperature. An
automatic temperature controlling device is installed to by closing and opening the fuel line to
burners. The combustion gases escape to atmosphere through stack.
vii) Surge Tank
It is simply a glycol storage tank. Lean glycol from reboiler after being cooled in heat exchanger is
stored in surge tank. Glycol level in surge varies with the change in ambient temperature. From here
hot/lean glycol is pumped to absorber tower through heat exchanger by glycol pumps.
DOWNHOLEEQUIPMENTS
PACKERS:
Packers are used to isolate the casing and the tubing so to protect the annulus from corrosion by
formation fluids and limit the pressure in the annulus. The use of packer makes it possible to put a
fluid in the annulus called Packer or Annular fluid. There are two types of packer:
i) Permanent packer ii) Retrievable packer
As the name suggests the permanent packer are requires to be milled out so it consists of material
which can be easily drilled out whereas retrievable packer can be easily retrieved without having to
be milled out.
MILL OUT EXTENSION:
In packer, there is a tubing expansion to protect the tail assembly. When the packer is milled then it
has a larger ID with catcher which holds the tail assembly. There is also a seal extension.

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SURFACE CONTROLLED SUB-SURFACE SAFETY VALVE (SCSSV):
In case of emergency there should be equipment below surface which can shut or open the well.
Other safety equipments also provide safety but in case if the well head suffers any kind of damage
like blast then all of the safety equipments will suffer, so to provide maximum safety SSSV are used.
There is a control line of hydraulic pressure comes up from the tubing hanger and attached to it. There
are two types of SSSV:
i) Ball type ii) Flapper type
Ball type SSSV are now obsolete because it sometime fails to complete shut the well. In flapper type
as long as the pressure is provided by the control line the flapper remains open but as the pressure is
released then the flapper moves and shut the well.
According to the setting classification there are two types of it:
i) Tubing retrievable ii) Wireline retrievable
If the tubing retrievable SSSV suffers any kind of damage and fails to close then we place Insert type
SSSV above it.
Connection between packer and tubing:
i) ANCHOR SEAL ASSEMBLY:
It has an elastic thread which fixes the tubing with packer. A seal is provided by the sealing element.
It has 5-7 seals.
ii) LOCATOR SEAL ASSEMBLY:
It has only the sealing elements which allow the tubing to slide in the packer.
Circulating devices:
These devices are used to communicate between the annulus and the Tubing, placed over the packer.
These are also a potential source of leakage. These are:
i) SLIDING SLEEVE DOOR SSD:
The tubing and annulus communication is established or cut off by means of a sliding sleeve. By
means of a shifting tool lowered on the slick line, the sleeve is shifted so as to open or close the ports
machined in the body of the valve. It is also used for the mud return flow during work over operations.
ii) SIDE POCKET MANDREL SPM:
Usually they are used to lift the viscous oil in artificial recovery by injecting gas. Also they are used to
inject the chemicals in the casing tubing annulus like corrosion inhibitors.

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PUP JOINTS:
It is also a tubing with small length. Also called as Spacer.
CROSS OVER:
Cross overs are used to join two tubings with different sizes.
CHECK VALVE:
It is used for the tubing leakage check, placed above SSD. A high pump pressure is applied, if there is
no leakage then the pressure will raise to a certain maximum value. In this way tubing leakages are
checked.
TRAVELLING JOINT:
It has a flexibility to contract and expand.
SLOTTED LINER:
It is used for protection against sand production.
PERFORATED SPACER TUBE:
It serves as an alternate flow path for fluid.
TAIL PIPE ASSEMBLY:
All the equipments below the packer are collectively called as Tail Assembly.
FLOW COUPLING:
Flow coupling are used where the velocity is much anticipated and where the chances of internal
erosion are very high like in SSSV. Its interior profile are so designed that it decreases the velocity.
BLAST JOINTS:
Blast joints are thick tubulus used in front of perforation so that the high velocity fluid coming from
perforation can’t erode the tubing i.e. it prevents external erosion.
RE-ENTRY GUIDE
It is the first part of tubing string starting from the tail. It is made of carbon steel. The lower part of
re-entry guide is cut in a shape of half mule shoe. The half mule type cut is given to increase the cross
sectional area. The purpose of this space between production formation & re-entry guide is to avoid
the erosion.
SPACER
This part consists of pup joints with wall thickness equal to re-entry guide. It is made of carbon steel.
Spacer provides a space b/w re-entry guide & bottom no-go nipple. Its purpose is to envelop &
protect the strings of gauges set in bottom no-go nipple.

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BOTTOM NO-GO NIPPLE
It is a carbon steel pipe with some obstructions on the inner side along the wall. Its purpose is to set
& hold the instruments run into the hole. Normally pressure gauges are set in this nipple during well
testing and bottom hole pressure survey which measure bottomhole parameters.
TOP NO-GO NIPPLE
It isolates the producing zone, whenever required, by setting an isolation plug in it in order to shut in
the well for workover or for investigation of gas communication between annulus and tubing.
SAFETY VALVE LANDING NIPPLE
It serves the purpose of hosting Sub-Surface Safety Valve (SSSV). It has larger outer diameter & is
internally provided with a place for locking & sealing SSSV. It is threaded on each.
TUBING HANGER
It is set in the tubing head or spool & then locked down by tie down bolts. It suspends the tubing
string, isolates the annulus & provides the path for ¼” control line to operate SCSSV. Both single &
dual tubing hangers are available. A dual tubing hanger has two parts separated vertically. Each part
hosts one tubing string.
WELL HEAD & X-MAS TREE
It is a combination of some valves, tee joints & flanges, attached to the upper most part of tubing
head or spool with the help of an adapter flange. The valves are valves installed in Christmas tree are:
MASTER VALVE
It is the lowest valve on the vertical run of X-mas tree. As evident by its name, it is the most important
valve in X-mas tree. When it is closed, it shuts off the flow to the reminder of the tree.
WING / SIDE VALVE
It is on the horizontal run of X-mas tree. It is joined to X-mas tree by a tee joint. Production is taken
from this valve. When it is closed, it isolates the feeder line from X-mas tree.
SWAB VALVE
It is the top most valve on the vertical run of X-mas tree. This valve is not for production purpose. It
only provides an access to the tubing for the entry of wire line tools, acid jobs or any other well
servicing activity like snubbing, swabbing, etc. in ordinary conditions this valve is kept closed.
TEE JOINT
It makes the major structure of X-mas tree. It provides a connection to X-mas tree from the tubing
string. If the well has single tubing string then only one tee joint (with one inlet & two outlets) is used.
If there is a dual well then two tee joints are used, one for each tubing string.
SURFACE SAFETY VALVE (SSV):
It is a surface type safety valve present in the Christmas tree, used to shut the well. It consists of a
piston and a return type spring. It is pneumatically operated. As long as the control line remains

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pressurized, the opening port remains in front of the tubing and flow occurs. But as the pressure is
released, the return spring compresses ant the blind face comes in front of the tubing so the well is
shut down.
SAFETY SYSTEM OF WELL
ESD FUSIBLE PLUG
It consists of a loop called as ESD loop. There are 5-7 Plugs in the loop. It is a plug, which actuates at
a temperature of 282F. As plug fuses, line depressurizes and ESD loop shuts the well automatically.
HIGH AND LOW PRESSURE PILOTS
These pilots monitor high or low pressure in the feeder line and on a high-pressure condition, the
high pilot blocks the control pressure line signaling to the control panel which will close the surface
safety valves (SSV). On a low-pressure condition, which could represent a failure at the wellhead or a
flow line rupture, the pilot blocks the control pressure line-signaling to the control panel to close both
SCSSV and SSV.
WELL CONTROL PANEL
Well control panel is designed to close a hydraulic controlled sub-surface safety valve (SCSSV) and
pneumatic surface safety valve (SSV). The control panel monitors the status of the well high or low-
pressure sensors and provides shut in of the well due to high or low-pressure condition.