1.1 Different Types of Drilling Units

Question 1

Jackup Drilling Unit

Depth, Shallow, Designed, Jacked, Preload

Answer 1

• 152m/500ft
• Very shallow
• Designed to move around
• Platform is jacked up after rig legs are lowered onto the sea floor
• Preload tanks are filled with water to simulate added deck weight and prevent punch-through in the future

Question 2

Drillship

Depth, Exploratory, Dynamic

Answer 2

• 3600m/12000ft
• Exploratory wells
• Dynamic positioning system

Question 3

Semi-Submersible (General)

Depth, Support, Statbility, Transit, Cal&a, C&wral&a

Answer 3

• 1600ft-3000ft
• Pontoons support the deck and house machinery and ballast tanks
• Pontoons are either flooded or evacuated with water for stability
• Pontoons are usually above or at water level during transit
• Mooring arrangements for 1600ft: use chain anchor legs and anchors
• Mooring arrangements for 3000ft: use chain and wire rope anchor legs and anchors

Question 4

Semi-Submersible - With Anchors

Filled, 8ma&c, Installation

Answer 4

• Pontoons are filled up with water and lowered to a predetermined depth
• This unit is fitted with eight mooring anchors and chains
• Very stable installation

Question 5

Semi-Submersible - With Thrusters

Dynamic, Anchoring

Answer 5

• Dynamic positioning system used to keep unit on station
• For use in waters too deep for anchoring

Question 6

Fixed Platform

Depth, Long-term, Contains, Built

Answer 6

• 1700ft
• Very long-term use
• Contains drilling equipment, production facilities and crew quarters
• Platform is built on concrete or steel legs directly anchored on the sea floor