Oil Field Development Schemes

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Development of Oil & Gas Fields

Tom Mangum, VetcoGray Senior Services Training Manager

Development Schemes (<300m) Section 4

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Offshore Field Development

• Offshore fields are developped using :

– Fixed platforms (steel or concrete) : > 90% – Floating platforms : < 10%

– Surface and/or subsea wells

• Comprehensive studies are necessary to select the most appropriate and cost effective field architecture (ref. to Field development process)

• Main field architecture options : – Wells

– Drilling mode – Platforms

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Field Architecture Options (1)

• Wells

– Surface wells

• Single wells (mainly in shallow water) • Multi-wells cluster

– Subsea wells

• Satellite wells

• Multi-wells cluster

– Combination surface + subsea wells – Well profile • Vertical, deviated • Horizontal • Extended reach • Multi-drains Selection depends on :

– Platform type : fixed or floating

– Reservoir geometry (extended, compact, multi-layers, ….)

– Artificial lift and well intervention requirements

– Costs

Extended reach well

Deviated well Subsea satellite well

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Field Architecture Options (2)

Drilling mode (fixed platforms)

Max water depth Drilling deck ~ 110 m Tender Drilling Rig Compact Drilling Rig Jack-up Drilling Rig

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Field Architecture Options (3)

Platforms

– Fixed

• Steel

– Structure piled in the seabed – Or, self elevated platform

(rare) • Concrete – Floating

• Semi-submersible (associated with subsea wells only)

• Tension Leg Platform – TLP

(associated with surface or subsea wells)

Selection depends mainly on :

– Water depth

– Type of wells (surface, subsea)

– Environmental conditions (waves, wind, current)

– Topsides equipment (weight, size) – Construction strategy & constraints

(yard availability, …) – Costs Floating platforms Fixed Steel Platform Fixed Concrete Platform

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Field Architecture Options (4)

–

Onshore storage and loading

• Tanker loading at jetty (case 1) • Tanker loading from floating

buoy (case 2)

–

Offshore storage and loading

• Floating storage + Tanker loading at

buoy (case 3)

• Floating storage + tandem loading

(case 4)

• Oil storage and loading

tanker Production Plant Case 3 Floating storage tanker Loadin g buoy Case 4 Case 2 Case 1 Floating buoy tanker storage Production Plant storage tanker

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Oil Storage And Loading (Examples)

Tankers loading at jetty (case 1)

Tanker

Oil Storage

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Conventional Development Scheme With Fixed Platforms

DP2

TCP2

TP1

QP

Frigg field (UK/Norway)

DP2 TP1 TCP2 DP1 QP CDP1 Norway UK Wells Wells Gas treatment Gas treatment & compression Living quarters

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Oil processing Flare

Drilling

Living quarters

Oil storage

Mobile drilling rig (jack up)

Conventional Development Scheme With Fixed Platforms

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Conventional Development Scheme With Fixed Platforms

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Subsea Development Scheme With Floating Platform

Buchan field (UK)

Shuttle tanker 4 wells template Loading buoy Exploration well Production semi-submersible DRILL MASTER 2 Satellite wells Risers Development scheme

• 7 subsea wells (2 Satellites + 4 template + 1 explo

recovered)

• Floating production platform • Loading buoy

• Operator : BP

• Location : North Sea UK • Water depth : 119 m

• First Prod : 1981

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Mixed Development Scheme With Fixed Platforms

Gullfaks field satellites (Norway)

(Gullfaks South, Rimfaks, Gullveig)

Gullfaks A

• Operator : Statoil

• Location : North Sea Norway • Water depth : 315 – 345 m • Discovery : 1979

• Sanction : 1996

Development scheme :

• Subsea wells tiedback to existing subsea platform Gullfaks A

• 8 subsea templates, 31 slots • Prod capacity : 125 000 b/d

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Subsea Development Scheme With Floating Platforms

Troll C

Troll B

• Operator : Norsk Hydro

• Location : North Sea Norway • Discovery : 1979

• Water depth : 315 – 345 m

TROLL B

Oil & gas provinces

• First oil : 9/1995

• 21 subsea oil producers • 24 subsea gas producers • Oil production : 270 000

b/d

• Semi-sub production unit

TROLL C Gas province • First gas : 1999 • Prod capacity : •Oil : 190 000 b/d •Gas : 9 Mm3/d

• Semi-sub production unit

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Platform Functions

• Offshore platforms are used for different

functions :

– Development drilling – Fluids processing – Water, gaz injection – Utilities

• Functions can be :

– Split (one platform = one function )

– Integrated (one platform = several functions ) – Living quarters – Flare – Storage Field examples Processing Flare Drilling Living quarters Oil storage

Mobile drilling rig (jack up)

Split

Integrated

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Fixed Platform Concepts

• Two main concepts of fixed platform

– Gravity based platforms

• Platform stability is provided by one compartment, filled with sand, located at the base

• Concept used for concrete platforms • Very limited number of applications :

less than 30 out of 20 000 platforms worlwide

– Tubular steel frame platforms

• Structure (Jacket) piled in the seabed • Deck(s) supported by the piles

• Specific concepts

– Self installed platform

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Fixed Steel Platform : Vocabulary

Lifted deck Boat landing Cut piled after setting Jacket Anodes Seabed Pile anchored In seabed Sea level Horizontal brace Barge bumper Conductor area Deck Jacket Bracing stub Vertical diagonal Jacket leg can

Jacket walkway Horizontal diagonal Boat landing Jacket leg PILE SKIRT PILE LAUNCH TRUSS Launch runner

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Types Of Riser

Side View

Top View

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Platform Loads

Wind Waves Current (surface) Tid e Total weight Topsides load Water depth Environ. conditions Weights Lower deck Drilling Rig Area Storm gap Example Upper deck

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Installation And Transport Loads

Transport

!

Lifting

!

Launch stresses may control design of some structural

members

Launching

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Piling

F wind F wave + current Piles Forces on piles at seabed level Soil reactions Soil Soil Soil Water Water Water Classical pile

Insert pile Skirt pile

Different types of pile Forces

• The insert pile allows to increase the driving depth

• The skirt pile allows to reduce the diameter of the jacket legs

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Pile Installation

Drill pipe Drilled hole Drill bit Jacket leg Drilling rig Drilling platform Cemented pile Soil Installation barge Main battered pile Main battered pile Drilling Subsea hammer Skirt pile Installation barge Hammering Barge Subsea Hammer Skirt pile

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Pile Driving

Piles

Pile Driving Operation

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Pile Driving

Pile Drive Hammer

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Installation Of Jacket By Launching _{Installation Of Self-floating Jacket}

Jacket Installation

Installation of jacket by lifting

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Jacket Installation

Launching Transport on barge

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Heavy Lift Vessels

Balder Thialf

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Module Support Frame (MSF)

Jacket piles

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Topsides Drilling & Production Platform

DRILLING DECK & MAIN RIG

1. Export pipeline 2. Mud mat 3. Skirt pile sleeve 4. Skirt pile 5. Anodes 6. Conductors 7. Export riser 8. Jacket leg 9. Barge bumper 10.Boat landing 11.Riser guard

12.Motor control center & switchgear control building 13.Escape capsule

14.Living quarters 15.Helicopter pad 16.Bulk storage 17.Mud pump package 18.Derrick

19.Flare boom 20.Lift gas compression

PRODUCTION DECK 21. Water injection pump 22. Generator

23. Deaerator

24. Waste heat recovery unit 25. Firewall

26. Diesel storage 27. Wellheads

28. Chemical injection skid 29. Production manifold

30. Production separator 31. Crude oil heater 32. Test & cleanup separator 33. Injection gas compressor

CELLAR DECK

34. Potable water storage 35. Emergency generator 36. Water injection charge pump 37. Media filter

38. Cooling water cooler Cooling water surge drum Cooling water pumps 39. Air compressor 40. Sea water pumps

41. Gas lift & water injection manifold 42. Fire water pump

43. Crude oil cooler 44. Crude oil pipeline pump 45. Electrostatic treater

46. Inlet dehydration filter separator Glycol contactor

Outlet dehydration filter separator 47. Production water treating 48. Glycol regenerator 49. Slug catcher 50. Plated deck 51. Flare scrubber

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Concrete Platforms

BERYL «A»

118 m 1975 Drill & Prod

40 150 000 0.9 28 000 BRENT «B» 140 75 Drill & Prod

38 160 000 1.0 24 000 FRIGG TCP2 104 77 Gas treatment -21 000 BRENT «D» 140 76 Drill & Prod

48 160 000 1.2 24 000 STATFJORD «A» 145 77 Drill & Prod

42 300 000 1.3 50 000 STATFJORD «B» 145 81 Drill & Prod

42 180 000 1.9 50 000 STATFJORD «C» 145 84 Drill & Prod

42 200 000 2.0 50 000 Water depth (m) Year installed Function Nb well slots

Peak production (bopd) Storage capacity (Mb) Max deck weight (tons)

• Concrete platforms are gravity based

• Their use has been limited essentially to the North Sea & North Atlantic (Canada)

• They are used for very large fields in severe environment necessitating heavy topsides equipment

• They also provide large oil storage capacity at the base

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Concrete Platform Concepts

Multipod Monopod

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The Different Types Of Sealines

• Flowlines

– Transport the fluids from the wells, located on a surface wellhead

platform or on the seabed, to the production platform

– Generally small diameter (4 to 12’’) and short length ( up to ~10 km )

• Pipelines (or trunk lines)

– Transport the fluid from the production platform to the export terminal

(onshore of offshore) for loading oil tankers or to the gas utilization center (LNG plant, power plant,…)

– Generally large diameter ( up to 36’’) and long length (several hundreds

of km)

• Loading lines

– Transport the fluid from the storage facility to a nearby loading facility

(buoy or other)

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Sealine : General Description

A sealine generally consits in :

– A steel pipe

– An anti-corrosion protection (coating)

– An external concrete layer to provide mechanical protection and

weight

Pipe characteristics :

• Steel grade : X + … (ex. : X65) • External diameter – OD (ex. : 32’’) • Wall Thickness – WT ( 0.75’’) • Chemical composition • Resilience • Dimensional tolerances Steel pipe Concrete layer (1’’ to 5’’ thick) Anti-corrosion coating WT OD

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Sealine Installation Method (Logigram)

Pipe Welding

Offshore

Onshore

Pipe preparationin standard lenght :

• 12 m « joints »

• 24 m « double joints »

Transportto site :

• Supply vessel • Barge

Welding and laying :

• Barge 1st generation • Barge 2nd generation • Barge 3rd generation Conventional “ S” lay Shallow water < 200 m “J” lay water depth > 200 m

Pipe preparationin long sections (up to

several km)

Transportto site :

• Surface tow (with buoyancy modules) • Bottom tow

• Spooled (small diameter, short lenght)

A few connections to perform offshore

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S-lay And J-lay Methods

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Pipe Lay Barges

Brown & Root Semac 1

Allseas Lorelay Stena Apache