Hess Exploration Australia Pty Ltd (Hess), a subsidiary of US-based independent energy company Hess Corporation, has been operating offshore Western Australia since 2007.  Exploration drilling in WA-390-P, as part of the largest exploration commitment to date in Australia, commenced in 2008.  Hess has drilled 20 exploration and appraisal wells in the block since 2008 and up to 18 wells will be required in the development and production phases.

Hess Exploration Australia Pty Ltd employs more than 100 people in the Perth head office.

Hess’ Environmental, Health, Safety and Social Responsibility Approach

Hess’ Environmental, Health, Safety and Social Responsibility policies and the management systems that support them ensure our business is conducted with due regard to the health and safety of employees, contractors and customers in an environmentally-sound manner and in the spirit of partnership with the countries and communities in which we operate.

Above all, Hess is a company that cares – about our people about our impact, about our reputation, and about always doing the right thing.

Project Summary

Hess has discovered natural gas in exploration Permit WA-390-P in the Northern Carnarvon Basin and has entered the refine phase of the project.  Equus has been granted Major Projects Facilitation Status by the Federal Minister for Infrastructure and Transport, The Hon, Anthony Albanese MP.

The natural gas fields Hess would develop range from 1.6km to 4km below the seabed, in between 1000m and 1200m of water about 300km West of Dampier and 240km North of Learmonth.

The Equus Gas Fields Development Project commenced Front End Engineering and Design in November 2011.  Hess has 100% equity in Equus, and expects to consider a final investment decision in 2013.

The Equus Project will involve the installation of a subsea gathering system tied back to an offshore platform for preliminary processing and compression, with a subsea pipeline connecting to existing third party infrastructure feeding an onshore gas processing facility.

The proposed new infrastructure is as follows:

• Subsea production wells and associated flowlines and risers;
• An offshore floating production system to undertake preliminary processing and compression.  The platform will have about the same deck area as the drilling rig Hess used in the Permit from 2008 to mid-2012;
• A gas export pipeline solely within Commonwealth waters.

Floating Production System

The Floating Production System (FPS) for the Equus development consists of a semi-submersible vessel moored in approximately 1070 m water depth.

The production system will include inlet reception, gas dehydration and compression, MEG/condensate separation, MEG regeneration and reclamation, water clean-up and disposal and condensate export.  In addition, the platform will have utility systems, including but not limited to heating and cooling medium systems, compressed air, nitrogen, firewater, living quarters, helideck, and liferafts.

The FPS will be permanently moored using a catenary mooring system.  The topsides will have a dry weight in the order of 15,000 tonnes, and the hull will have a dry weight of approximately 25,000 tonnes.

Some of the key dimensions of the facility are:

• Hull draft in operating condition – 32m
• Air gap to underside of topsides – 26m
• Hull keel to top of legs – 58 m
• Hull width and breadth (outside of legs) – 84m x 84m
• Mooring arrangement – 4 x 4 chain and wireTopsides lower deck to main deck (TOS) – 16m
• Topsides length (excluding flare boom and heli deck overhang) – 105m
• Topsides width – 60m
• Flare boom length – 85m

The Export Pipeline system will be installed in Phase 1 and will consist of a 508 mm (20”) diameter carbon steel pipeline between 120km and 285km in length depending on the final selected tie-in location. The export pipeline will be connected to the FPS by a 406mm (16”) diameter, 3000m long carbon steel LWSCR.

It is anticipated that the Export Pipeline will be tied into the third party facility using a pipeline end manifold (PLEM) which may include a pressure protection system (PPS)

A control umbilical will be required between the third party host facilities and the PLEM/PPS structure.

All connections between the Export Pipeline and the third party tie-in connection will be diver assisted, bolted, flanged connections.

Depending on the tie-in location, the Export Pipeline may be routed in water depths up to 1400m and traverse the continental shelf escarpment where the water depth changes from 1050m to 250m over an 8km length of the route.  At localised areas along this crossing, gradients approaching 40° are encountered.