School of EngineeringCOURSEWORK SUBMISSION SHEET

All sections except the LATE DATE section must be completed and the declaration signed, for the submission to be accepted.

Any request for a coursework extension must be submitted on the appropriate form (please refer to http://www.rgu.ac.uk/academicaffairs/quality_assurance/page.cfm?pge=44250), prior to the due date.

Due DateDate SubmittedFor official use only

13TH APRIL 2014

13th APRIL 2014LATE DATE

MATRIC No.: 1312484

SURNAME: ABBEY HART

FIRST NAME(S): TUMINI TAMONUA REGINALD

COURSE & STAGE

MSc OIL AND GAS INFORMATION TECHNOLOGY

MODULE NUMBER & TITLEENM 501: OIL AND GAS ENGINEERING COURSE

ASSIGNMENT TITLEGENERAL FIELD DEVELOPMENT COURSE WORK

LECTURER ISSUING COURSEWORKMR MIKE ROBINSON

I confirm:(a)That the work undertaken for this assignment is entirely my own and that I have not made use of any unauthorised assistance.

(b)That the sources of all reference material have been properly acknowledged.

[NB: For information on Academic Misconduct, refer to http://www.rgu.ac.uk/academicaffairs/assessment/page.cfm?pge=7088]

ABBEY-HART 10TH APRIL 2014Signed..................................... Date ......................................................

Markers Comments

Marker

Grade

A REPORT ON THE FIELD DEVELOPMENT PLAN TAKEN FOR THE DEVELOPMENT OF THE CASABLANCA FIELD

NAME.SIGNATUREDATE

PREPARED BYABBEY-HART TUMINI (1312484)ABBEY-HART13th APRIL 2014

REVIEWED BYMR MIKE ROBINSON

EXECUTIVE SUMMARY Casablanca oilfield is a virgin field, about to start undergoing development, in order to commence production of oil and gas for high return on investment values on money spent during development. During exploration stage of this field, data and facts about the oilfield were taken by geoscientist, and passed on to engineers in order to help support and influence decisions taken, and choose certified equipments fit for use during the field development phase. The data details are shown below:

Field Location60 kilometres away from nearest land fall;

Field Water Depth300 feet deep;

Number of wells planned5 wells;

Rate Predicted for Production30,000 bbls oil quantity per day;

Field life Duration expected10 years;

Depth of reservoir12,000 feet;

Initial Pressure6,000 psia

Pressure of oil bubble point3,500 psia

Quality of CrudeSour 40 Degrees API

From the data taken by geologist, seismic survey information were acquired with the most important and a little bit disturbing one being the presence of sour crude as the quality of crude to be produced during development. Sour crude simply means that the crude contains high amount of hydrogen sulphide and other sulphuric compounds, which gives it a sour smell. Presence of this have tendencies of causing problems and therefore treatment would have to be undertaken on all produce (Oil, Gas, Water) to prevent future problems with the government.

Also occurring flow assurance issues like Asphaltene Precipitation, Wax formation etc. are expected during development so prevention methods would be placed to prevent this from occurring and causing obstruction of fluids flow from well heads to their final point of export or sales point.

Lastly, a preferred option is recommended for the progress of this project and all of this would be discussed as development planning is carried out. TABLE OF CONTENTS3EXECUTIVE SUMMARY

5INTRODUCTION

51.1 Aims of this report

61.2 Objectives of this report

61.3 Assumptions taking during Development

7SECTION A:

72.0 Analysis for Field Development

82.1 Well Head:

82.2 Manifold

82.3 Separator:

92.4 Gas Scrubber:

92.5 Compressor:

92.6 Gas Conditioning Unit:

102.7 Meters:

102.8 Pumps:

112.9 Hydrocyclones:

112.10 Water De-gassing Drum:

122.11 Heater Treater:

122.12 Storage Tank:

122.13 SBM:

122.14 Shuttle Tankers:

13SECTION A Part 2:

133.0 Tie Back Development

133.1 Subsea Production Template:

133.2 Subsea Tree:

133.3 Underwater Manifold

133.4 Multi-Phase Meters:

143.5 Risers:

143.6 Flow Lines:

143.7 Umbilical Cables:

14SECTION B

144.0 Flow assurance issues faced by Casablanca and Morella facility.

144.1 Hydrates Formation:

154.2 Corrosion:

154.3 Paraffin Waxes:

154.4 Asphaltene Precipitation:

164.5 Technical Advantages of Casablanca and Morella Platform.

164.6 Technical Disadvantages of Casablanca and Morella Platform.

174.7 Commercial Advantages of Casablanca and Morella Platform.

174.8 Commercial Disadvantages of Casablanca and Morella Platform.

18Section C:

185.1 Recommendation of Preferred option

INTRODUCTION As a field consultant, I am commencing the development of a new oil field that I have been assigned to, create a flow diagram for superiors to propose on structures to be followed and carried out ensuring that equipments installed are fit of use and operation working conditions. Also perform a tieback operation to a pre-existing facility located nearby called Morella with distance of approximately 10km choosing most appropriate means with less production risk. 1.1 Aims of this report1) To prepare a plan, for the successful development of the Casablanca oil field.

2) To show Mr Mike Robinson, I do understand all concepts up to an adequate level of all the information he has been passing in class sections.3) To further students knowledge from that of the course notes by means of web and publication searches.1.2 Objectives of this report1) To learn how to prepare a flow diagram so as to help give some structure of development for Casablanca oil field.2) To know the functions of how various Equipments utilised in development stage work e.g. the roles played by a separator.3) To know how water treatment is carried out before being discharged into the environment.

4) To give recommendation, and discuss a preferred option with reasons why it was selected from both development concepts.1.3 Assumptions taking during Development1) Minimal amount of sand present, due to lack of high water cuts so sand cyclones are not installed in development.

2) High viscosity crudes present so heater treater would be needed in development.

3) Fluid coming in from the wellhead comes in at very high pressure and therefore a three stage (multi) separator is needed to step down fluid pressure.4) Morella platform is producing above, 45,000 stock tank barrel oil per day and this is going to take some years to decline to 45,000 stock tank barrel oil.

5) Presence of acidic gases (Hydrogen sulphide and Carbon dioxide) in crude, so gas sweetening is carried out.

6) No presence of Nitrogen in acidic gases so gas sweeting would not be carried out on it using Cryogenic removal process.

7) Minimal and acceptable amount salt present when oil is been separated so electrostatic de-salters are not installed.

8) Health and Safety requirement of oil in water before disposal is 40ppm maximum, for the region where oilfield is located.SECTION A:

2.0 Analysis for Field Development As the field development consultant working for RG E&P, in charge of developing the Casablanca oil field a flow diagram has been prepared shown in Figure 1.0 below to help give structure on the processes and steps that would be taken for successful development of this new oil field.

Figure 1.0: A process flow schematic diagram describing the process steps required for the development of Casablanca field.2.1 Well Head: During production, fluids from reservoir flow to the top of the earth surface, and are being produced at the wellhead. The wellhead helps provide a pressure containment interface for production activities carried out. The quality and quantity of reservoir fluids produced are dependent on three main factors, which are composition of hydrocarbon present, characteristics of the reservoir produced from and lastly the field development scheme set in place. The earlier first two, aforementioned factors are controlled by Mother Nature itself and the last mentioned are manipulated within the constraints of technological and market value. (Frank Jahn, et.al; pg 236, 2013).Chemical Injection is provided at the wellhead to prevent issues occurring due to flow assurance.2.2 Manifold: Productions gotten from wellheads are connected through flow lines to a tubular steel structure called manifold. This manifold acts as a focal point and gathering centre for all flow lines attached to various wellheads, in which the stream of fluids from each wellhead are commingled together and fluid production now starts here for all wellheads. This process saves time and unnecessary expenses of producing from each wellhead independently. Injection of demulsifiers occurs here to prevent an emulsion from occurring between the oil and water interphase. This makes the oil soluble in water so there would just be a single flow phase and not multiple flows because oil floats on water due to its density difference. Fluids then flow from the manifold into a separator, passing through a choke valve installed on the flow line, which causes the first pressure drop of fluid during production.2.3 Separator: Normally referred to as the heart of processing facilities during production. It separates the fluids into phases gas, oil, and water, and help to support accurate metering of it during production. When fluid flows from the manifold through the choke valve into the separator system, it comes in at a high-pressure rate and then a pressure drop occurs as it goes through each of the various phases of separation installed. As fluids enter the separator, it hits an inlet diverter, which causes a change in flow direction and velocity of the fluid. Initial gross separation in the separator, occurs at this point first with water going to bottom, oil in the middle and gas at the top. In the separator, gravity forces cause the heavier liquid droplets to fall out of the gas stream to the bottom where the liquid is collected. The liquid phase holds the liquid until an appropriate residence time required to allow the entrained gas break out of the oil and rise to the gas phase, and they do so under buoyancy forces. In addition, how easy the gases breaks out of the liquid is determined by the viscosity of the liquid present, as liquid with high viscosities imply longer residence times.2.4 Gas Scrubber: As the gas, flows out of the separator it passes a mist extractor, which acts as a barrier and causes small drops of liquid that were difficult to be separated by gravity to fall back into the liquid phase. The gas then flows into a gas scrubber, whose function is to restrict and trap condensed liquids (i.e. water and hydrocarbons) from the gases as it leaves the separators. This function of the gas scrubber helps prevent liquids from getting into the suction of the compressor thereby disrupting functionality and causing erode on compressor rotating blades.2.5 Compressor: As gas moves through the processing stages, a drop in pressure accompanies it and energy would need to be imparted into it to cause an increase in pressure, before it can be transported to the next processing stage. In this scenario, three separators are used in stepping down the pressure, so the gas pressure escaping the first separator is not same with the gas pressure escaping the second and the third separator, so in such a compressor is used to increase the gas pressure of the second and third separator to be in range with the first separator.2.6 Gas Conditioning Unit: Before the gas is made use of as fuel or flared, it goes through the condition unit, which ensures water vapour is absent in gases, as this can lead to hydrate formation and cause corrosion in the presence of carbon dioxide and hydrogen sulphide. It also ensures that contaminants like carbon dioxide and hydrogen sulphide are removed, as hydrogen sulphide is toxic.To prevent such hindrances, two processes are undertaken which are:

i. Gas Dehydration: This simply means removal of water vapour present in gases.ii. Gas Sweetening: This means the removal of hydrogen sulphide and carbon dioxide (acid gases) that are present.

These two processes are performed together using absorption technique in a contact tower or absorber. Chemical solvents such as Monoethanolamine and Tri-ethylene glycol are combined together in the contact tower, then the gases are bubbled as heat is being applied slightly above atmospheric pressure. In the contact tower, the glycol reduces the water contents sufficient to prevent water dropout from the gases, and allows for efficient removal of the hydrogen sulphide and carbon dioxide by the Monoethanolamine in the gases. This help remove possibilities of hydrate formation, which causes corrosion and blockages. 2.7 Meters: When produce such as oil and gas, are ready for export from the production installation, it goes through meters, which are used to manage and monitor the volume and quantity of produce (oil and gas) transported out of the production installation from one party to another. Specialised meters are used to perform this process, to measure the gas Ultrasonic meters are used and for the oil turbine meters are used.From the diagram in Figure 1.0, the water at the bottom leaves the separator through water dump valves installed below, which are controlled accordingly by the water level controller at the side of the separator as water changes are sensed. Water flows out of the separators and heater treater as shown in figure 1.0, to the hydrocyclones and due to pressure drops already occurred, pumps are used for the second and third separator independently to boost its flow to the hydrocyclones.

2.8 Pumps: This are devices which work similar to gas compressors, with the major difference being that they are used to impart pressure on the fluids and not gases, in order to increase flow rate, and prevent occurrence of slippage during production.2.9 Hydrocyclones: When water enters the hydrocyclones, it removes the oil contents from the water before sent out to sea. This process is known as De-oiling.

i. De-Oiling: This simply means the removal of oil concentration from water. There are many de-oiling techniques e.g. skimming tank, corrugated interceptor, gas floatation unit etc... But hydrocyclones are used, due to its the most common technique used offshore, and is capable of producing oil in water disposal standards of less than 40ppm or 40ppm which falls in line with regulatory health and safety requirements of region, before it is allowed to be discharged to sea.The way hydrocyclones works is it relies on centrifugal forces to separate the light oil particles left in the water phase as it passed through processing stages, leaving the water to rest at the bottom and oil on top of the water in the equipment. Water then gets collected in the water de-gassing drum.2.10 Water De-gassing Drum: As the water is collected here, it performs another effective process, by removing the gases still present even as fluid has gone through various processing stages, before the water is discharged to sea. This process is known as De-gassing.i. De-Gassing: This simply means the removal of gas concentration from water. A de-gassing drum is used in this development for that purpose.The way the de-gassing drum works is, as water enters the de-gassing drum dispersed gases slowly rise out of it and by floatation, the gases pull along with it remaining droplets of oil to the surface that were not separated by the hydrocyclones. The surface oil film is drained out and channelled back to the heater treater for dehydration, and produced now treated water is now discharged to sea through a skim pipe. Hydrogen sulphide and Carbon dioxide are also treated here as explained earlier by making use of the Monoethanolamine solvent to remove its presence.In Figure 1.0, you would have a view of the process through which the oil flows in the separator. The oil seats in the middle between the gas phase and water phase then it leaves the separator through oil dump valves installed below, which are controlled accordingly by the oil level controller at the side of the separator as oil changes are sensed from the weir located in the separator. The oil then flows out into a heater treater.2.11 Heater Treater: With the assumption of high viscosity crudes, heater treater is installed in order to promote separation and fast break out of the gas from the liquid phase. As high viscosity, fluids have tendencies of taking longer retention time to break out the liquid phase. This gives stabilization and dehydration of the oil before it goes to the storage tank and then later transport. As it is necessary for fluids to be stabilized during transport, and gas to be dehydrated to its dew point to prevent liquid drop out during transportation. 2.12 Storage Tank: When the oil comes into the storage tank, it does so with the support of a pump to impart pressure into the liquid to prevent occurrence of slippage due to the pressure dropped already occurred in process. This device simply stores oil produced from the fluid after it has gone through all processing stages available and is now awaiting exportation. RVP is carried out on the oil using Reid bomb apparatus before transportation to ensure true vapour pressure is within range of 10-12 psia required for transport by shuttle tankers. This process ensures vapour is not too high, as it is flammable and gives rise to explosion hazards if escaped to atmosphere.2.13 SBM: When the oil stored in the storage is now ready to be transported, this provides the tankers with support during extraction as the tanker is tied up to the SBM and through it, the tankers have the ability to rotate around and accommodate the weather conditions present at time of export.2.14 Shuttle Tankers: They simply are the boats, which come and take the oil away to the storage facility when it is ready for export.

SECTION A Part 2:3.0 Tie Back DevelopmentFor tieback in this development, it can be performed by either introducing a new jacket, and making use of a linking bridge to link both facilities, Or by making use of subsea equipments for the development of the tie back. This I believe to be a better option as the distance of 10km between both facilities is quite much for use of a linking bridge though it cost less, the risk involved if problems were to occur are very high. Subsea tiebacks equipments utilised are:3.1 Subsea Production Template: This support production activities to be carried out, acting as the base foundation for other subsea structures to be installed upon. Construction is carried out nearby, and taken to seabed location when constructed, in which it is gently lowered unto the seabed using a crane barge, and pile drivers installed on it are loosened, and piled into the bottom of the seabed to hold template in place and promote stability of the equipment.3.2 Subsea Tree: This equipment is placed at the bottom of the sea to seat on the template that seats on the seabed. It is required as the final step taken for completion of a well to make it viable for production start-up. It helps control and support the fluid flow from the Casablanca field providing safe conduit through it and the flow lines into the manifold.

3.3 Underwater Manifold: As described earlier this has the same function, acts as a gathering centre and focal point for production of fluids. It connects all series of wells together through flow lines, while also seating on the subsea template.3.4 Multi-Phase Meters: Also described earlier, as meters are used for many reasons e.g. government, personal files, court cases etc. it is used to know the quantity and volume of produce been sent out from one party to another party.

3.5 Risers: This is a large steel pipe diameters installed, and the function it plays is, it serves as a drill string conduit raising and collecting fluids gathered at the seabed manifold installed below and then sends it upwards for processing through the subsea flow lines installed.3.6 Flow Lines: This plays the part of conveying and transportation of oil, gas, and all other constituents around installations, and also from the Casablanca facility to the pre-existing Morella facility.3.7 Umbilical Cables: These are offshore underwater cables installed and deployed into the seabed to ensure safe transfer of electrical or hydraulic energy to equipments used subsea.

SECTION B

4.0 Flow assurance issues faced by Casablanca and Morella facility.Both platforms face few common flow assurance issues likely to occur, though they may occur at different areas, they do still occur. Moreover, some have low tendencies of occurring due to presence of Mediterranean climate. Foreseen issues on both platforms are:4.1 Hydrates Formation: Occurs due to physical bonding of lighter constituents and water present in gases, and is visible to human eyes in the form of iceberg structures. They are formed in conditions of high pressure and low temperature, and the risk of it occurring here are low due to Mediterranean climate but they can still occur. If it were to occur, on the Casablanca field it would occur on wellheads and flow lines. Then on Morella, it would also occur on flow lines and available equipments. These plug equipments and pipelines there by obstructing flow and causing blockage to flow of fluids. Control Measures: If it occurred, its controlled with use of Tri-Ethylene glycol solvent in which performs water dehydration present in gases.

4.2 Corrosion: Occurs from the hydrates formed, but in the presence of acid gases (Hydrogen sulphide and Carbon dioxide). Corrosion leads to many problems such as contamination of fluids, structural failure, rusting, and operation shutdown. On both fields they can occur on flow lines and equipments used in the presence of hydrates.

Control Measures: Can be controlled by making use of corrosion resistant pipes, and through chemicals solvents such as corrosion inhibitors like Monoethanolamine and Imodazolines4.3 Paraffin Waxes: These are crystalline in nature, and are formed at temperatures below cloud point. Also it has low tendency of occurring due to Mediterranean climate. If waxes were to occur, they would cause production choking. On both platforms, if it occurred it would occur in flow lines. Control Measures: If it occurred, its controlled by injection of paraffin inhibitors such as, Ethylene vinyl acetate or Alkyl phenols or Vinyl Polymers or through insulation of flow lines.4.4 Asphaltene Precipitation: Formed through oxidation, in the presence of impurities along with resins and aromatics in the crude oil, giving rise to metallic looking molecular substances (Asphaltene). In both platforms they can occur in flow lines, and cause the flow lines to have depositional tendencies. Also causes reduction in diffusion rate. Control Measures: Can also be controlled through injection of Asphaltene inhibitors such as Aromatic solvents or Dodecyl benzene Sulphuric Acid.4.5 Technical Advantages of Casablanca and Morella Platform.Casablanca Platform (FPSO)Morella Platform (Tieback)

1Decommissioning of the well once depletion has occurred in reserves is easily done, as FPSO are floating structures that can be easily moved from Casablanca field to a new location.Installation of the tieback from Casablanca would stop Morella reservoir reserves from depleting in coming years and give maximization and extension of the reservoir life span.

2They have capacities to handle more variable and large production streams due to the availability of storage and offloading equipments installed on-board vessels.

4.6 Technical Disadvantages of Casablanca and Morella Platform.Casablanca Platform (FPSO)Morella Platform (Tieback)

1During exportation of produced fluids to the facility, it is done by use of shuttle tankers, in which are constrained to weather conditions at time of export. At a combined production rate it would produce above 75,000 barrels per day and its more than the required capacity. This means a delay in start date of production

2During offloading of produce, there is risk of spillage occurring on surface when offloading from FPSO into shuttle tankers. As subsea equipment are utilized, it is at a major financial disadvantage, as equipments needed for subsea operations are very expensive to purchase.

3Presence of flow assurance issues are likely to occur such as Asphaltene PrecipitationAfter the purchase of equipments, it is very difficult to carry out interventions or equipment maintenance processes if problems are to occur.

4.7 Commercial Advantages of Casablanca and Morella Platform.

Casablanca Platform (FPSO)Morella Platform (Tieback)

1Less extra added cost involved during processing as all requirements needed for processing, storage and transportation are installed upon vessels.It cost a lot less to acquire as FPSO are very expensive to rent, and also do take longer duration to construct one together.

2It can be recycled thereby reducing cost. As at the end of its life span, it can be converted to a tanker used in transportation of produce (oil and gas) to locations.Compared to the FPSO this requires a lower initial capital investment to be used in development planning stage.

4.8 Commercial Disadvantages of Casablanca and Morella Platform.Casablanca Platform (FPSO)Morella Platform (Tieback)

1Lesser allocation of sales returned back from the Morella facility after sale of produce, since they possess sweet crude and we possess sour crude so we are is contaminating the sweet crude in their facility.Since subsea equipments are utilized, staffs would have to be trained to achieve required competent skills in order to be able to manage subsea equipments.

2Premium would still be paid to the Morella facility for processing of the sour crude in the Casablanca facility. Reduction of produce value will occur from this operation, due to the mixture of the sweet crude in this facility with the sour crude in the Casablanca facility, as the sour would contaminate the sweet crude.

Section C:

5.1 Recommendation of Preferred optionAfter careful assessment of all field development options, I do recommend the use of option 1 that is the wellhead jacket and FPSO structure over option 2 for four main reasons, which are:

i. FPSO are very flexible structures, can be used on subsequent upcoming projects immediately after decommissioning of one, and even can be used on tieback development as well. ii. In option 2, there would be a delay in cash flow, because engineers would have to wait for a couple of years before production can commence at its full capacity, or they can decide to start production and later on choke wells. Nevertheless, this has effects on the flow of cash.iii. From option 2, there would be a decrease in revenue when making use of it, because measuring meters are not 100 percent accurate iv. Use of option 2, has technological requirements as subsea expertise and costly subsea interventions are needed.ReferencesDEVOLD H., 2013. An Introduction to Oil and Gas Production, Transport, Refining and Petrochemical Industry Oil and Gas Production Handbook. Edition 3.0 Oslo 2006 2013, ABB Oil and Gas. ISBN 978-82-997886-3-2. http://www04.abb.com/global/seitp/seitp202.nsf/0/f8414ee6c6813f5548257c14001f11f2/$file/Oil+and+gas+production+handbook.pdf [Accessed on 9 4 2014].FMC TECHNOLOGY: Flow Assurance Competence Centre. https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=9&cad=rja&uact=8&ved=0CHAQFjAI&url=https%3A%2F%2Fwww.fmctechnologies.com%2F~%2Fmedia%2FSubsea%2FServices%2FFlow%2520Management%2FDatasheet_FlowAssuranceCC.ashx%3Fforce%3D1%26track%3D1&ei=oPpIU-PcCcTy7AakrICgAw&usg=AFQjCNEnwQvjwKZUgKS9oGswBu4LQelncQ&sig2=ujJmSyK1M54b_xwDz6PsBg&bvm=bv.64542518,d.d2k [Accessed 12 -04 - 2014].HERMAN, G.N., 2006. Flow Assurance and Multiphase Pumping. Petroleum Production pdf. Submitted to the Office of Graduate Studies Texas A & M University. https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CC8QFjAA&url=http%3A%2F%2Frepository.tamu.edu%2Fbitstream%2Fhandle%2F1969.1%2FETD-TAMU-1180%2FNIKHAR-THESIS.pdf%3Fsequence%3D1&ei=x5dIU4LmCcix0AXLxYDIBQ&usg=AFQjCNF6nUonEhtINyaEDjCA8Hb0VELMzA&sig2=_yHaJQW0Mr2PRr9_OPLKbA&bvm=bv.64542518,d.d2k [Accessed 29 03 - 2014].JAHN, F., COOK, M., and GRAHAM, M., 2003. Hydrocarbon Exploration and Production, ELSEVIER, 1998. ISBN: 0 444 82921 0 (Paperback).Bibliography Robert Gordon University Campus Moodle "Gas Sweeting Notes".Robert Gordon University Campus Moodle "Separator Systems Notes".Robert Gordon University Campus Moodle "Oil Treating Notes".Robert Gordon University Campus Moodle "Produced Water Treatment Notes".Abbey-Hart Reginald Page 20 1312484