L03 - DRILLING & SUBSEA WELLHEAD

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

WELL TYPES Production Platform

Mobile Drilling Vessels

Flowline

Xmas tree

Satellite well

Development wells Appraisal well Wildcat well (dry hole)

(at reservoir boundary) Original Exploration/D iscovery well

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

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

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.

DEVELOPING THE DRILLING PLAN - Bottom Hole Targets

BRITANNIA FIELD - North Sea

XMAS TREE WHEN IN PRODUCTION MODE 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

BLOWOUT PREVENTOR WHEN IN DRILLING MODE

WELLHEAD

WELLHEAD FIXED TO TOP OF INNER CONDUCTOR SEA BED 120 m OUTER CONDUCTOR

36” HOLE 30” CASING

26” HOLE

200 m

INNER CONDUCTOR

183/4” CASING 450 m 171/2 ” HOLE 133/8” CASING

SURFACE STRING 1300 m

121/4” HOLE

INTERMEDIATE STRING

95/8” CASING

2600 m LINER

81/2” HOLE

3200 m

7” CASING

A TYPICAL NORTH SEA CASING DESIGN

RESERVOIR

JOINT OPERATORS CONOCOPHILLIPS AND CHEVRONTEXACO

OFFSHORE DRILLING RIGS

Station keeping normally using Dynamic Positioning Thrusters

Legs sit on seabed JACK UP

Shallow water SEMI-SUBMERSIBLE DRILLI NG RIG

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

DRILLSHIP

Normally Deepwater

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 seal the subsea production tree • To support and seal the well casing • To support and seal the 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

Vetco H-4 mandrel profile

• 18” 3/4 x 15 Ksi now available • Deepwater wellheads designed for much higher bending and tension loads Cameron hub profile

18 ¾” HP wellhead housing

Wellhead to casing hanger Metal Seal assembly Bypass Area Wellhead to casing hanger Metal Seal assembly Passive Pre-loaded lockdown system

7” casing hanger – For Glenelg the tubing hanger is at this elevation and replaces the 7” casing hanger 10 3/4” casing hanger 13 3/8” casing hanger Wellhead to casing hanger Metal Seal assembly High strength load shoulder

10 3/4” casing 13 3/8” casing 20” casing 30” conductor A Annulus B Annulus C Annulus

TYPICAL SUBSEA WELLHEAD

Wellhead Housing Joint • Provides a mechanical connection and sealing preparation for the BOP stack and tree. • Provides landing, locking, and sealing preparations for the subsequently run casing hangers

Permanent Guide Base

Mounted to the low pressure conductor housing. structure with guideposts for guiding equipment onto or into the wellhead, or it may be a guidelineless style with funnels.

GUIDE BASE WITH 4 STANDARD GUIDE POSTS

SUBSEA WELLHEAD