MOORING IN THE OTWAY BASIN

Published April, 2021

 Author: Mark Mithran   

The Otway Basin located Off the coast of Victoria, is a challenging location for offshore drilling operations.

LOCATION

JACK-UP'S ARE NOT ABLE TO PUNCH THEIR LEGS THROUGH THE SOIL...

Therefore Semisubmersible Drilling Rigs with moorings are preferred. 

DRILLING RIGS

Based on past history, with smaller anchors and large Rigs, anchoring has always been a point of concern due to the hard seabed bottom.

SEABED

The Otway Basin is known to have extreme weather especially in the winter months, with seas upto 19m height.

ENVIRONMENT

Apart of that, the location is very shallow (70m-100m) and current profiles for this shallow water depth are strong.

ENVIRONMENT

WHY IS  MOORING  IN THE OTWAY BASIN NOT LIKE  IN THE NORTH WEST SHELF?

The very shallow water depth makes the mooring line tensions very sensitive to the environment.

MOORING ENGINEERING

…and hard to maintain rig offsets.

MOORING ENGINEERING

KNOWING PAST HISTORY OF OPERATING IN THE OTWAY BASIN, HOW DID WE MOOR HERE?

We designed a less stiff mooring system and optimized operating tensions.

MOORING SYSTEM

We thought about the ‘skipping rope effect’ of the chain in shallow water currents.

MOORING SYSTEM

We thought about ball swivel contact.

MOORING SYSTEM

ANCHORING

The hard bottom meant the need for a HHP anchor that is suitable for these conditions. 

STEVSHARK REX

We custom designed a STEVSHARK REX for these soil condition which lived upto the challenge.

DISCOVER HERE  MORE ABOUT...(to be decided)