Perth basin oil field could open Australia's fourth offshore theater

The country would gain a fourth offshore producing area if the Cliff Head oil discovery on WA-286-P in the Perth basin off Western Australia were declared commercial.

April 3, 2003

2 min read

By OGJ Editors
HOUSTON, Apr. 3 -- The country would gain a fourth offshore producing area if the Cliff Head oil discovery on WA-286-P in the Perth basin off Western Australia were declared commercial.

Based on an early 2003 delineation program, Roc Oil Ltd., Sydney, as operator has estimated recoverable volumes at 20-30 million bbl of oil and said the commercial threshold is likely to be 15 million bbl at $17/bbl. Technical and commercial studies are under way, and results are expected in the third quarter of 2003.

Original oil in place is put at 66-99 million bbl. Four wells at Cliff Head had a common oil-water contact. As currently mapped, the field covers about 6 sq km with 100 m maximum vertical relief (see map, OGJ, Feb. 10, 2003, p. 36).

The field would likely be developed with 5 to 7 wells, all horizontal or highly deviated and with downhole pumps. Recovery from one well was 3,000 b/d constrained by surface facilities even though the crude oil is 30% paraffin and has 6-8 cp viscosity.

Production could start by 2005 at 10,000-20,000 b/d initially and would be Roc's first operated offshore project.

An 11-km insulated pipeline would transport the raw production stream to shore, and separated produced water would be returned to the field in a parallel line for pressure maintenance. Development options include one or two small wellhead platforms and a single buoy mooring.

The early 2003 five-well drilling program cost $13 million (US) and included two cored appraisal wells and a production test. Roc put individual cost items at $1.5 million/vertical well, $2.4 million/cored deviated appraisal well, and $2 million/production test, all exclusive of rig mobilization-demobilization costs of $500,000/well.

Preliminary development cost estimate is $3.50/bbl. All three exploration wells were dry.
Roc said it is working to limit effects on rock lobster fishing and humpback whale migration.
Meanwhile, Kerr-McGee Corp. was awarded 100% interest in WA-337-P and is participating with 50% interest in Santos Ltd.-operated WA-339-P, both offshore in the northern Perth basin.

The Timor Sea, Northwest Shelf, and Bass Strait are the country's only offshore producing theaters heretofore.