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MECHANICAL (FINAL YEAR)

NED UNIVERSITY OF ENGINEERING AND TECHNOLOGYINTERNSHIP REPORT

PAKISTAN PETROLEUM LIMITED

(SUI GAS FIELD)

INTERNSHIP REPORT

Table of Contents

S.no. Title Page no.01 Acknowledgement 0202 Sui Field Gas Compression Station SFGCS 0303 Introduction 0304 QHSE 0305 Administration 0306 Planning 0307 Operations and Machinery 0308 Workshop 0509 HVAC system 0510 Electrical 0611 PURIFICATION PLANT 0612 Introduction 0613 Instrumentation 0614 Power house 0615 Water treatment 0716 Operations 0717 Gas sweetening and gas dehydration process 0718 Maintenance 0819 PRODUCTION FACILITIES 0920 Introduction 0921 Cathodic protection 0922 Drilling at Well 95 1023 SUL dehydration plant 1024 Well operations 10

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ACKNOWLEDGEMENT

The whole praise is to Almighty ALLAH, creator of this universe. Who made us the super creature with great knowledge and enable us to accomplish this task. The internship opportunity I had with Pakistan Petroleum Limited was a great chance for learning and professional development. Therefore, I consider myself as a very lucky individual as I was provided with an opportunity to be a part of it. I am also grateful for having a chance to meet so many wonderful people and professionals who led me though this internship period.I would also like to express my deepest gratitude to all the Technical and Management staff of Pakistan Petroleum Limited for their excellent guidance, caring, patience, and providing me with an excellent atmosphere for internship. The supervision and support that they gave truly help the progression and smoothness of the internship program. The co-operation is much indeed appreciated.This internship as an integral part of B.E provides the opportunity of peeping into real professional life of the engineers. It enables me to evaluate and understand the practical applications of all the terms and techniques that we have studied during our coursework and has helped me in my professional growth by getting used to the working environment of a field.I was assigned to complete my internship comprising of 4 weeks practical work at PAKISTAN PETROLEUM LIMITED (PPL) SUI GAS FIELD. In this report I have tried my level best to explain what I have learned during this internship program.

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SUI FIELD GAS COMPRESSION STATION (SFGCS)Dated: (19th may – 28th may)

INTRODUCTION:

Due to the continuous decline of well head pressure and the rise in the Gas demand of the country the need of compression plant becomes inevitable. The Sui Field Gas Compressor Station was established in 1983 in two phase. 2 stage compression is required due to the constant decreasing pressure from the wells. Their target is to provide the purification plant the pressure of 60-65 bars while taking the pressure of 15-16 bars nowadays.

It is one of the biggest Gas Compression Station of Pakistan.

QHSE: (Quality Health Safety and Environment)

In the QHSE section of Purification Plant at Sui Gas Field, we were welcomed by Engr. Umer. He told us all about the safety and the policies that PPL is currently following. He also arranges the PPEs (Personal Protective Equipment) for us and gave us a set of useful instructions that must be followed during the field to ensure safety. He also gave us our schedule of the induction program for this plant.

These three policies are strictly followed during the field premises:

QHSE Policy Seat Belt Policy Smoking Policy

ADMINISTRATION:

After QHSE we visited the Administration section where Sir Saboor Illahi Bugti briefed us about the job responsibilities of Administration section, among which the major duties are Industrial Relations, arrangements of Boarding and lodging, arrangement of Flights, to look after the house keeping accidents, security passes and contracts dealing. In summarized way the duty of administration department is the role of communication between the locals and the upper management within the plant. In other words we can simply say that it acts like a CPU and directs the flow to the concerned departments.

PLANNING:

Planning is basically the allocation of time for the project and the resources required to successfully accomplish the project in contrast with scheduling that further includes the allocation of team that is needed for that specific project.

In PPL Plans are of basically two types;

5 year Plan (That specifies the targets in the upcoming years and expected budget allocation) Annual plan (It’s a bit detailed plan for the upcoming year and it specifies the plans with respect to each month)

Forecasting is done by going through the previous history to see what changes has to be made.

OPERATIONS and MACHINERY

GAS TURBINE GENERATORS

The total load required to drive the compressors and utilities is 6.8MW. Hence to respond to this power requirement the power generation system of SFGCS includes 4 Gas Turbine driven generators C201 (A,B,C,D) of 3.2MW each. 3 turbines are in working and one is standby always. For starting GT around 60% speed is required hence a VSD (variable speed drive) is

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used for initial rpm of turbine. VSD drives the turbine then a reduction gear box is installed which lowers the rpm as per requirement of the generators. The gear box lubrication is done with 3 pumps of which one is standby always and the lubeoil is circulated from the lube oil tanks. Also cooling is done of lube oil since we need temp of 60C or else its viscosity is affected. In control room synchronizing is done to match with power with other generators during startup.

SUL COMPRESSION

SUL (sui upper limestone) compression system includes 3 motor driven compressors of 2MW each. 2 compressors are working whereas one is standby always. Since SUL does not consist of any H2S hence it does not require any purification process. SUL from well comes to compression plants where it first enters in slug catchers and scrubbers where solid particles and moisture is removed then it is compressed and is send to DHP (dehydration plant) , further after DHP a part of it is returned to SFGCS since it is used as a fuel to drive SML turbines and the remaining is distributed.

SML COMPRESSION

SML (Sui Main Limestone) consists of 7 Gas Turbine operated 2 stage compressors. Gas turbine uses SUL as fuel and is connected to an induced gear box where rpm are increased and further compressors are driven. Centrifugal Compressors are used and the turbines used are of Frame 3 (frame shows the capacity of turbines, the greater the frame number the greater is its capacity), 6 combustion chambers are installed (3 on each side) before compressors so that its efficiency is improved and losses are reduced. The turbines are started with the help of primary turbine to give required rpm. Compressors driving the turbines are axial compressors always. Material used for rotors are alloys to give them strength.

HRL COMPRESSION

HRL (Habib Rahi Line) Compression system consist of 2 gas engine driven compressors of which one is standby. The engine is of 8 cylinder and has a whole system of cooling with fintype tubes and induced draft fan. Also scrubbers and knockout drums are installed before gas enters the compressors.

UTILITY

Its main purpose is to supply plant air and nitrogen (inert gas non-flammable and used to pressurize). Nitrogen is compressed by 3 stage compressors

MACHINERY

The machinery section in the SFGCS Station is responsible for the proper maintenance of all the machineries installed throughout the plant. Sir Fawad helped us a lot in learning different dimensions of this department. Some examples of the machineries are the generators, compressor turbines, hydraulic and lube oil pumps, fin fan coolers, compressors, motors etc. Machinery is one of the major area of Mechanical Engineers. The maintenance schedule of the different machineries and their auxiliaries is classified into three main types:

Breakdown Maintenance Preventive or Scheduled Maintenance Predictive or Conditioned Maintenance

After 10000hrs lining of combustion chamber is checked After 20000hrs whole burning path is checked After 40000hrs major overhauling is done

Work in progress during visit;

Overhauling and inspection of SML Alpha combustion chamber.Setting of axial float of Alpha Turbine.Fixing of agitator as it was producing sound due to worn out bearing.Gear box fixing which drives induced draft cooling fans.Other Learning during time period in Machinery

Bearings and its applications

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Model of compressors and their types Wet and dry sealing systems of compressors Combustions chamber designs Vibrations concepts and parameters Engines used in HRL and different pumps

Compression Operation Explained: (Generalized)

Slug Catcher: The gas from the Wells first comes to the Slug catcher where condensate and other particles from the gas are being separated.

Inlet Scrubber: There are 03 scrubbers for each header. They are horizontal cylinders with number of filters and baffle plates. The Filters are designated to remove the solid impurities while the baffle plates removes any further condensates.

Suction Knockout Drum: The function of all knockout drums is to remove any condensate and particles from the gas.

LP Compressor: This compressor is responsible for increasing the gas pressure from 15/16 bars to 24/25 bars.

LP Cooler: The gas after compressor is at high pressure as well as high temperature so in order to reduce the temperature the gas is then forced to move into the LP cooler that reduces its temperature.

Intermediate Knockout Drum: The gas then moves into the Intermediate Knockout drum to remove impurities.

HP Compressor: The gas then passes through the HP Compressor to increase the pressure to 60/65 bars.

HP Cooler: The gas then moves to the HP Cooler to reduce the temperature.

Discharge Knockout Drum: The gas before it is provided to the Purification Plant and DHP passed through the last knockout drum to remove any particles or condensate.

Discharge Header: The pressurized gas at a pressure of 65 bars then goes for further processes into the Purification Plant and DHP through Discharge Header.

WORKSHOP:

The workshop in the Compression Station is designed to perform all the specific jobs that pops out during the maintenance of any machinery. The workshop is fully furnished and equipped with all the required machines to carry out production jobs.

Machines in the Workshop:

Shaping Machine Drilling machine Band saw Machine Wire brushing and buffing Machines Grinders Universal Milling Machine Lathe Machine Guillotine Machine Sheet Bending Machine Pipe Bending Machine Sheet Rolling Machine Liquid honing Machine Dry Blasting Machine Annealing Machine Computerized Balancing Machine

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HVAC SYSTEMS:

Heating, Ventilation and Air Conditioning is very important in the design of medium to large industrial offices.

Ventilation in the HVAC is the process of changing or replacing air of any space to provide high indoor air quality which involves temperature control, removal of moistures and unpleasant odor. It also prevents the stagnation of interior air. The HVAC system in the SFGCS consists of 03 Chillers and 04 AHU (Air Handling Units). The chillers uses R-22 Refrigerant with a cooling capacity of 160 Ton.

CHILLERS:

Circulating refrigerant enters the compressor in the saturated vapor state and is compressed to a high pressure which ultimately rises the temperature as well.

That refrigerant is now in the superheated vapor state and passed through condenser wher it is condensed by the surrounding air (rejects heat from the system).

Now the refrigerant is in the saturated liquid state then passed through the expansion valve where sudden reduction in pressure causes the adiabatic flash resulting in the liquid and vapor refregerant mixture.

The mixture of refrigerant is at lower temperature and goes through the shell and tube type heat exchanger where the hot water from the AHU is present in the tubes and gives off heat to the refrigerant and then circulates back to the AHU. The Saturated vapor state of refrigerant then goeas back to the compressor.

AHU: (Air Handling Units)An air handler, or air handling unit (often abbreviated to AHU), is a device used to regulate and circulate air as part of a heating, ventilating, and air-conditioning (HVAC) system.

Procedure:

The Hot air from the buiding is sucked and passed through a series of filters and the reaches a heat exchanger. In the Heat Exchanger cool water is flowing in the tubes that comes directly from the chillers. The water exchanges heat and reduces the temperature of air. The cooled and fresh air is then forced back into the building.

ELECTRICAL:

The SFGCS has its own power generation department and Electrical workshop that is responsible for repairing the electrical appliances.

Distribution: There were 09 substations that manages the distribution throughout the plant. 01-05 Substation contains 02 transformers each and remaining 06-09 contains 01 transformer each. All these 14 transformers are stepdown which gives the output voltages of 2.4 KV and 400 V from the input of 6.6 KV for the High Tension (HT) and Low Tension (LT) lines respectively.

PURIFICATION PLANTDated: (29th may – 6th June)

INTRODUCTION:

The Purification Plant of PPL Sui Gas Field is responsible for all the operations necessary to be carried out to supply the Purified Gas to the SSGCL and SNGPL. The major infrastructure in Purification Plant consists of 08 Purification banks, 06 Dehydration Units, Water treatment plant, 10 Boilers, Old Power House and New Power House. It is currently purifying 350 MMscfd of SML against the threshold of 900 MMscfd.

The Purification Plant of Sui Gas Field was established in 1952 and it is also considered as one of the largest Gas Purification Plant of Asia.

INSTRUMENTS:

In the instruments section Mr. Shahzad briefed us about the major instruments that are controlled by this section includes Control valves, Gages, Level meters etc. The control bench includes DCS (Honeywell USA) and for boilers they are using Programmable logic controller (PLC) by (LN Bradley USA).

The controllers may be of two types which includes the Power supply cards, Input/ Output cards and key controllers. The programming language that is used in these controllers is Ladder Logic that is based on the function block mnemonics.

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Apart from control valves the also uses Solenoidal valves and bypass valves. In the sales monitoring station they controls the Moisture analyzer and Gas Chromatograph.

In the workshop of the Instruments section Sir Shahjee is the man Incharge there and he gives brief explanation about the Level Troll (Make: SPRIANO).

The certain amount of time for which a specific condition is to be observed to actuate a valve is known as Retention Time.

LEVEL TROLL:

The level transmitters are microprocessor based instruments that combines the analog signal advantages (4-20mA) together with the flexibility of digital communication (Standard FSK) using HART or FIELDBUS protocol. They can be remotely configured by a universal handheld terminal (HHT) or by PC with a dedicated Interface.

POWER HOUSE:

The electrical department look after the power generation and distribution around the plant and the residential area of the Sui Gas Field. The main machineries in Electrical Department includes;

Induction Motors (around 130) The biggest motor is used for compressing air whose capacity is 95 KW.

Gas Turbine Generators (04) Make: SOLAR and KAWASAKI Capacity: ≅1MW eachSpeed: 22000 rpm max.Gas: Purified Methane

Steam Turbine Generators (02)Capacity: 880 KW and 440 KW Speed: 7000 rpm

UPS (02 pairs)Capacity: 30 KVA

Diesel Generators (05)Capacity: 250 KW each

The plant load is approximately 300-500KW and the Steam Turbine Generators are dedicated to makeup this load and apart from this, 100KW from Gas Turbines is also utilized for Plant. The Diesel Generators act as backup for Plant.

Among 04 Gas Turbines the 03 remains in functioning and provides electricity to the residential area, messing and hospital while the remaining 01 acts as a backup.

WATER TREATMENT:

Water treatment is important because the water supplied to the boiler should be demineralized or non-conductive or else it would produce scales and would damage boiler. Similarly soft water is used for cooling purpose.Hence these above outputs are performed by 2 major processes

Reverse osmosis Ion exchange which demineralizes water

OPERATIONS:

The operation section of purification plant is responsible for the controlling all the parameters in the running banks and the Glycol units. The two major operations are done at Purification Plant.

Gas Sweetening Process: (Removes H 2S and CO2 by the aid of MEA) Gas Dehydration Process: (Removes moisture by the aid of TEG)

Apart from these processes the water treatment is also monitored by this department.

GAS SWEETENING PROCESS:

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Inlet Scrubber : The Sour Gas is first introduced in the scrubber and where entrained droplets or slugs of liquid are removed from the gas stream by impaction devices.

MEA Contactor: The Sour Gas then enters the bottom of the Contactor (Tray Column) and the objective is to provide intimate contact between the gas and the amine solvent so that the H 2S and CO2 molecules can transfer from the gas phase to the solvent liquid phase

MEA Scrubber: The Sweet gas then enters the MEA Scrubber and the MEA particles are removed from it which are then recycled.

Flash Tank: The rich amine solution is sent from the Contactor to a flash tank to recover hydrocarbons. The pressure is dropped as it enters the tank, allowing the lightest of the hydrocarbons to flash. The heavier hydrocarbons remain as a liquid, but separate from the aqueous amine because of lighter density.

Lean/Rich Heat Exchanger: The rich solvent is preheated before entering the stripper. Because the lean amine exiting the reboiler must be cooled before entering the absorber.

MEA Reactivator: The rich amine enters from top and counters the steam from reboiler that breaks the bonds between MEA and acid gases and therefore absorbs these gases.

Reflux Accumulator: The steam along with acid gases then goes into the condenser where steam is condensed and the acid gases are allowed to pass to the reflux accumulator where any particles of lean amine are redirected to the stripper and the acid gases are flared off.

GAS DEHYDRATION PROCESS:

Glycol Absorber: The wet gas enter the bottom of absorber and the dry glycol is sprayed from top absorbing all water contents from gas and exiting as wet glycol.

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Dry Gas/Dry Glycol Heat Exchanger: The dry gas is used to lower the temperature of the Dry glycol before entering the Abosrber.

Flash Drum: The wet glycol then enters the flash tank where pressure is reduced and hydrocarbons vapors are removed and liquid hydrocarbons are skimmed off.

Dry/Wet Glycol Heat Exchanger: The wet glycol is preheated before entering the stripper. Because the dry glycol exiting the reboiler must be cooled before entering the absorber.

Glycol Stripper: The wet glycol after passing through heat exchanger then enters from the top of the stripper where glycol is thermally regenerated by the aid of reboiler and exits as dry glycol from the bottom of stripper which is then used for the next cycle.

Reflux Accumulator: The steam along with some glycol particles after passing through condenser then enter into the reflux accumulator where water vapors are allowed to escape and glycol particles reenters the stripper.

MAINTENANCE:

In the maintenance section I meet Sir Adeel. This section deals with the maintenance of the whole plant. This section is further divided into two categories:

a) Rotary: Turbines, Fans, Gearboxes, Engines, Fire Engines, Pumps, Motors etc.b) Stationary: Vessels, Tanks, Boilers, Heat Exchangers, Pipes etc.

In Maintenance department we were welcomed by Deputy Chief Engineer Mr. Yousuf who did a detailed discussion on major machinery equipment such as Fans, Pumps, Compressors, Blowers. Also he explained us the structure of cooling towers with the placement of gears, motors and bearings in induced fan. Details of different type of pumps were discussed (centrifugal, rotary, reciprocating of plunger type). Components such as bearings and couplings were discussed. Also turbines were discussed. From stationary side he discussed boilers and heat exchangers in detail and the importance of valves and governers.

STATIONARY: on going actvities

Boiler Maintenance Project: (Contractors AEPL)

The complete overhauling of Boiler 09 is in progress. There are two types of Boilers installed in the PPL which includes the Forced draught type (forced the outer air to flow inside of the boiler) and Induced draught type (Draw out the inner air). The feed water is highly treated and must be free from all corrosive acids and minerals that causes scaling normally Demineralized water is used. The feed water is also passed from the DE aerator to remove any air present in the water. The feed water and the steam pressure is maintained at 450 psi.

Overhauling of Heat Exchangers:

There were shell and tube type heat exchangers installed both single and double pass. There were two cooling towers both consists of a fan, a turbine and a gear box. The secondary cooling tower consists of a large building with fins mounted on all the walls and the hot water is forced from the top to pass through that fins, the fan sucks the surrounding air that extracts the heat from the water in its way down. In this way the secondary cooling tower drops the temperature of the hot water which is then recycled.

PRODUCTION FACILITIESDated: (7th June – 11th June)

INTRODUCTION: The Production department is responsible for all the wells operations, well safety and DHP unit, moreover the billing section also comes under this Department.The Well Summary is as follows:

Total Drilled Abandoned ProducingSML Wells 52 05 46SUL Wells 22 02 18Dual Wells 17 01 16PUB Wells 03 01 00HRL Wells 02 00 02

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Total 96 09 84

PRODUCTION CYCLE

WELL OPERATIONS:

After the security clearance our convoy was allowed to leave the Sui Gas Field and we visited around 20 wells and the job of the crew of well operation is as follows:

To ensure that all valves are in correct positions To record the readings of temperature, pressure and flow from the orifice graph. To check the oil level of hydraulic pump. To ensure the working of all gages. To ensure that the well fence is in correct condition. To report any unusual activity to the concerned personnel ASAP.

CATHODIC PROTECTION:

“It is the chemical or electrochemical reaction of a metal with its environment resulting in its progressive degradation or destruction.”

In Sui Gas Field there are a lot of pipelines and around 84 wells thousands of feet deep and all are exposed to the environment. Due to natural tendency of metal to get back to its ore condition it is necessary to employ some system that prevents them from corrosion.

The tendency of every metal to get back to its ore condition can be defined as the Electrode Potential. So in Cathodic Protection System the metal is made cathode of the electrochemical cell and an external current is supplied negative enough to prevent the electrons from escaping the surface of the metal and results in the elimination of the anodic area.

Two common practices of Cathodic Protection System are as follows:

a) Sacrificial Anode System: As the name suggests there is no current source but an anode with larger Electrode potential then cathode (Well casing) to prevent the current flow.

b) Impressed Current Cathodic Protection System: In this system there is an external DC source and Anodic Ground Bed.

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GAS WELLS SEPERATOR LIQUID

GAS

SML

SUL DHP

P.PLANT

SSGCL

SNGPL

H 2O

DISPOSAL TANK

CONDENSATE

Corrosion Inhibitors

Well Safety

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In Sui Gas Field the second one is installed on all wells with major components as follows; Power Sources: Thermoelectric Generators (TEG) by (Global Thermoelectric; Calgary, Canada) & ORMAT Energy

Converters (OEC) by (ORMAT; Texas, USA). Both utilizes the heat energy by burning natural gas of the respective well.

DRILLING AT WELL 95:

o Deep drilling operation carried out at well 95 in seek of a good pressure.o It has been estimated that if this deep drilling project gets successful and a high pressure is achieved then the

field could carry on with supply of gas for further 50 years.o The depth aimed in this deep drilling operation is 3280m.o Mud circulation system was briefed, its main significance is hydrostatic pressure, cooling of the drill bit since due

to friction it will heat up and lastly to bring up cuttings.

o

SUL DEHYDRATION PLANT

o Consists of 2 units, each has capacity of 80mmcfd with inlet pressure supply from SFGCS of around 900psio Gas first enters upstream gas filters which removes any solids or moisture, further it enters absorber where main

contact with glycol occurs. There are 9 bubble cap trays in an absorber, gas gets in contact with glycol and glycol absorbs all the moisture in it. Further the gas enters downstream filters to remove glycol carryover and then it is supplied to SNGPL and SFGCS.

o Lean Glycol on the other hand enters surge tank then enters absorber, after absorber it goes to double acting pumps and followed by flash separator which removes any gas separator. Glycol then enters a shell and tube type heat exchanger and then glycol filters and finally into fire type boiler where all the moisture is removed in the basis of boiling point temperature difference.

WELL OPERATIONS VISIT:

o Christmas tree arrangement present on every head of the well includes; Swab valve, Wing Valve , Subsurface safety valve and Master valve.

o Completion assembly.

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