L3 - DRILLING & SUBSEA WELLHEADS

• EXPLORATION METHODS

• RESERVOIR MODELLING AND DRILLING PROGRAMME

• TYPICAL SUBSEA WELLS

• OFFSHORE DRILLING VESSELS

• DRILLING A SUBSEA WELL

• WELLHEADS – Design & Function

• WELLHEADS - Connection to BOPs and Trees

Mobile Drilling VesselsProduction Platform

Wildcat well

(dry hole)

Appraisal well

(at reservoir boundary)

Development wells

Original Exploration/Discovery well

Satellitewell

Xmas tree

Flowline

Note

Development wells may be vertical wells or more complex extended reach or horizontal wells

WELL TYPES

Reservoir engineering is defined as the application of scientific principles to drainage issues arising during the development and production of oil and gas reservoirs.

The science explores the engineering operations involved in analysing the production behaviour of oil and gas wells, including well performance engineering, reservoir aspects of well erformance, restricted flow into the wellbore, rate decline analysis, and fundamentals of artificial lift.

• Build reservoir architecture utilising G&G mapping

• Populate model with reservoir properties utilising G&G integration

• Evaluate production tests

• Flow analysis Water drive, gas injection,water flood, etc.

• Volumetrics

• Reservoir simulation

• Production history match

DEVELOPING THE DRILLING PLAN - Bottom Hole Targets

BRITANNIA FIELD - North Sea

450 m

200 m

1300 m

2600 m

3200 m

120 m

WELLHEAD

OUTER CONDUCTOR

INNER CONDUCTOR

INTERMEDIATE STRING

SURFACE STRING

SEA BED

171/2 ” HOLE

133/8” CASING

121/4” HOLE

95/8” CASING

81/2” HOLE

7” CASING

36” HOLE

30” CASING

26” HOLE

183/4” CASING

BLOWOUT PREVENTOR WHEN IN DRILLING MODE

XMAS TREE WHEN IN PRODUCTION MODE

A TYPICAL NORTH SEA CASING DESIGN

WELLHEAD FIXED TO TOP OF INNER CONDUCTOR

IN PRODUCTION MODE A 5½ “ PRODUCTION TUBING IS HUNG FROM THE WELLHEAD/TREE TO THE RESERVOIR. IT IS PACKED OFF THERE. WHEN THE CASING IS PERFORATED THE OIL FLOWS UP THE PRODUCTION TUBING AND THROUGH THE TREE

LINER

RESERVOIR

JOINT OPERATORS -CONOCOPHILLIPS AND

CHEVRONTEXACO

JACK UP

SEMI-SUBMERSIBLE DRILLI NG RIG

DRILLSHIP

OFFSHORE DRILLING RIGS

Legs sit on seabed

Shallow water

Shallow and Deepwater. Station keeping by Mooring Lines or Dynamic Positioning Thrusters

Normally Deepwater

Station keeping normally using Dynamic Positioning Thrusters

SEDCO EXPRESS

DRILL SHIP

PRIDE AFRICA & ANGOLA - Working in Deepwater Angola

OFFSHORE DRILLING SYSTEM

RUNNING WELLHEAD AND CEMENTING CASING

Casing lowered into funnel up capture on guidebase

RUNNING WELLHEAD AND CEMENTING CASING

Wellhead locked into housing

Subsea Wellheads / Purposes

• To support BOP and seal with well casing during drilling

• To support and sealthe subseaproduction tree

• To support and sealthe well casing

• To support and sealthe production tubing hanger

Subsea wellheads

• Most widely size used : 18” 3/4 (Nom. Bore)

• Other sizes: 13” 5/8 , 16” 3/4 (Brasil) and 21 ” 3/4

• 18” 3/4 x 15 Ksi now available

• Deepwater wellheads designedfor much higher bending and tension loads

Vetco H-4 mandrel profile

Cameron hub profile

Wellhead to casing hangerMetal Seal assembly

Wellhead to casing hangerMetal Seal assembly

Wellhead to casing hangerMetal Seal assembly

High strength load shoulder

Bypass Area

Passive Pre-loadedlockdown system

13 3/8” casing hanger

10 3/4” casing hanger

7” casing hanger – For Glenelg thetubing hanger is at this elevationand replaces the 7” casing hanger

18 ¾” HP wellhead housing

30” conductor

20” casing

13 3/8” casing

10 3/4” casing

C Annulus

B Annulus

A Annulus

TYPICAL SUBSEA WELLHEAD

• Provides a mechanicalconnection and sealingpreparation for the BOP stack and tree.

• Provides landing, locking, and sealingpreparations for the subsequently run casing hangers

Wellhead Housing Joint

Permanent Guide Base

Mounted to the lowpressure conductorhousing. structure withguideposts for guidingequipment onto or into the wellhead, or it may be a guidelineless style withfunnels.

GUIDE BASE WITH 4 STANDARD GUIDE POSTS

SUBSEA WELLHEAD