Gorgon, Northern Carnarvon Basin, Australia

The Gorgon area gas fields are located offshore, approximately 60km from Barrow Island and approximately 200km west of Dampier, on the Australian mainland. Five fields have so far been discovered - Gorgon, Chrysaor, Dionysus, West Tryal Rocks and Spar. Collectively called Greater Gorgon, these fields have been extensively appraised, including the eight wells in Gorgon itself. The field is being developed by the Gorgon Venture, a joint venture of ChevronTexaco, Shell and ExxonMobil. ChevronTexaco, with a four-sevenths interest, is the operator of the Gorgon development on behalf of the Gorgon Venture.

RESERVES

Up to 13.8 trillion ft³ of hydrocarbon reserves have been certified as proven in the Greater Gorgon area. This includes 9.6 trillion ft³ of proven hydrocarbon reserves in the Gorgon field itself - enough for a two-train LNG Project. Proven plus probable reserves in the Greater Gorgon area therefore exceed 17.6 trillion ft³, with certified possible reserves increasing that total to 21.5 trillion ft³.The proven reserves in the Greater Gorgon area are the energy equivalent of a 2.25 billion barrel oil field. The raw gas contains 12-15% carbon dioxide.

SEISMIC

3D seismic has been completed for all fields, and the three largest have fully developed reservoir-simulation models.

DRILLING

Gorgon was found in 1980, following a discovery in West Tryal rocks in 1973.

NEARBY RESERVES

In addition, CTMS won the exploration rights in 1997 to a 5,469km² area, immediately west of Gorgon, known as WA-267-P. This expansive area has seven major prospects, which are being drilled in an aggressive programme. Seismic work for this area has already been completed.

CTMS was awarded the licence with a bid of six firm exploration wells and the acquisition of seismic data. The licence covers some 5,469km², which is roughly the equivalent to 24 North Sea exploration blocks. Water depths for WA-267-P exceed 1100m in some areas. In addition to WA-267-P, CTMS has a drilling obligation for a firm well in WA-205-P. CTMS has contracted the deep-water semi-submersible drilling rig Marine 500. In mid-July 1999, the rig Marine 500 arrived off the Pilbara coast of Western Australia. The AU$300 million programme , which is being supervised by WAPET is expected to be completed during the next three years. Expected discoveries in the new area will raise the potential for future expansion of the Gorgon Project. Exploration prospects are also being evaluated to the east of the Gorgon field in WA-25-P and to the north and east of the Chrysaor and Dionysus discoveries in WA-253-P.

The initial programme for WAPET will comprise three wells. The first well, Euryale, is located in the exploration permit WA-205-P, immediately west of the Gorgon gas field. The second and third wells will be drilled in exploration permit WA-267-P, which lies north and west of WA-205-P. At the end of the three-well programme, the Marine 500 will undertake work for another operator, before returning to WAPET in the first quarter of 2000, to complete a four- or five-well drilling programme.

DEVELOPMENT

The joint venture partners are currently investigating gas contracts, before proceeding to the next phase of the work. Current plans for the initial stage of the project call for a phased subsea development of the Gorgon field, starting at North Gorgon. Subsea wells will be tied back to a gravity-based platform, located in the shallower water depths to the east of the field. On the platform, the gas will be processed, prior to export via trunkline to the LNG plant site in the Burrup Peninsular. The current greenfield Gorgon LNG plan is based on two liquefaction trains, each capable of producing 4 million tons/year. In 1998, the partners appointed the consortium of Clough Kvaerner and Schlumberger to undertake the design of offshore infrastructure for this Gorgon project.