INEXV2DOC05_nergaard

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Part V

Offshore drillingtechnology

Carita, Banten, Indonesia14 December 2005

Prof. dr. Arnfinn Nergaard

University of StavangerSmedvig Offshore

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V - Offshore drilling technology

Part 1 The drilling process

Part 2 Drilling platform types

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First drilling rig type

Colonel Drake

Titusville, USA, 1859

The ‘inventor’ of rotarydrilling for petroleum exploitation.

Source: Kenneth Larsen, Statoil

Offshore drilling technology - Part 1

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Drilling operation

How do we do it?

We use energy to break up the rock and create a hole

The energy consists of rotation and hydraulic forces

The energy is optimised by ‘tuning’ drilling parameters

After drilling a section of the well, it is sealed off with steel pipe to ensure integrity for the followingwell section



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Drilling operation How do we do it?Drill large hole

Cement casing in place

Run casing in open hole

Drill hole Run casing in open hole

Cement casing in place

Drill hole

Turn drill bit to the right and pump!



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30" cond.20" casing133 lb/ft

13 3/8" casing72 lb/ft.

11 3/4" linercontingency

9 5/8" casing.53.5 lb/ft

7" liner32 lb/ft

+/- 80 m, driven

+/- 400 m

+/- 3700 mMD+/- 3000 mTVD

+/- 5000 mMD+/- 4000 mTVD

+/- 7500 mMD+/- 6000 mTVD

Possible HC's

Build 40 - 45 deg angle starting from about 1000 m.Maintain angle to TD.

16" casingor liner

+/- 1000 m

How do we do it?



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Drilling bits



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Hoisting system

Block line

Travellingblock

Drill string standsstored in derrick

Derrick

Rig floor

Draw-works

Crown block



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Rotation system

Shows Varco'sTop Drive Systems

Additional, thetraditional rotary table is widely used.



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Circulating system

High pressure pumps

Piping

Shale shakers

Fluid tanks

Solids control equip

Well

Fluid returns



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Pressure control system

Control unit

Cement unit

From mud pumps

Choke manifoldwith valves

Well

Control lines

DrillpipeBag type BOP

Ram BOP

Ram BOP

Ram BOPChoke lines

Junction box



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Subsea BOP stack



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Well design30" cond.20" casing133 lb/ft

13 3/8" casing72 lb/ft.

11 3/4" linercontingency

9 5/8" casing.53.5 lb/ft

7" liner32 lb/ft

+/- 80 m, driven

+/- 400 m

+/- 3700 mMD+/- 3000 mTVD

+/- 5000 mMD+/- 4000 mTVD

+/- 7500 mMD+/- 6000 mTVD

Possible HC's

Build 40 - 45 deg angle starting from about 1000 m.Maintain angle to TD.

16" casingor liner

+/- 1000 m



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Directional drilling designConventional motor

Rotational steerable system



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Extended reach well in Statoil



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Statoil extended reach wells



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World extended reach wells



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V - Offshore drilling technology

Part 1 The drilling process

Part 2 Drilling platform types

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Overview - Drilling platform types


Exploration Production

Floaters Buttomsupport

Surfaceplatforms Subsea

Sem

is

Ship

s

Jack

-ups

Perm

anen

t

Tend

ers

Sem

is

Ship

s

Jack

-ups

Land

Offshore

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Land rigs

Deutags‘T-47’ land rig.

Drilling at BP's Wytch Farm field inSouthern England.

Extended reach wells to12,000 m horizontaldisplacement



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Offshore semi submersible drilling rigs

Floating

Moved by towing vessels, or by its own power

Station keeping through anchors or propellars(Dynamic Position)

Blowout Preventer is on sea bed

Any weather condition, any waters, but problems with ice

80 - 3000 m water depth

Approximate costs: 50,000 - 250,000 USD/day



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Semi submersible drilling rigs

Principles:BOP on sea bottomRig connected to wellhead via a riserRig moves with the sea motionAnchored or dynamic position system



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Semisubmersible drilling rigs

Smedvig’sWest Ventureis a deepwater semisubmersible

Dynamic positioning

One of the world's largest semis


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Semisubmersible drilling rigs

Smedvig’sWest Alpha semisubmersible rig


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Drill ships

Floating

Moved by its own power

Station keeping by anchors or propellars (dynamic position)

Blowout Preventer is on sea bed

Any weather condition, any waters, but problems with ice

80 - 3000 m water depth

High payload capacity, will ‘travel and drill’ with minor support

Good for remote areas, high speed




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Drill ships

Transoceans‘Deepwater Millenium’drill ship.



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Drill ships

Smedvig’s West Navigator drill ship has the double Ram Rig concept.


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Offshore jack-up rig characteristics

Present throughout the world

Water depth 20 - 125 m

Can drill wells through platform

Can ‘skid over’ onto platform

Moving a jack-up is a critical operation




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Jack-up rigsShallow water cantilever jack-up.

Jacked down and preloading prior to commencement ofoperations.



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Platform rigsStatoil’s‘Troll A’ drilling rig

Offered for sale!



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Tender support vessel characteristics

Supports a drilling operation on a platform

No drilling facilities required on platform

Extensively used in the Far East

Quick rig-up and rig-down

Effective in shallow water depths

Effective in good weather conditions

Approx. costs: 20,000 - 50,000 USD/day



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Tender support vessels

Smedvig’s‘T-8’, working in the Far East.


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West Seno - The mini TLP


West Alliance

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HC pay zone

TSVFPSO

mini TLP

+/-1500m

+/-1000m

Field development exampleDrill more wells from TLP and connect TLP to subsea wells



INEXV2DOC05_nergaard

Documents

kenneth larsen

drilling processpart

drilling bitssource

drilling operationhow

tuning drilling parametersy

drilling platform types2so

placerun casing

open holecement casing