Rick Wilkinson
OGJ Correspondent
AWE Ltd., Sydney, reported it has confirmed a southern extension to its onshore north Perth basin Waitsia gas field when appraisal well Waitsia-3 encountered strong gas shows across a 1,250-m gross interval, including the Kingia and High Cliff Sandstone reservoir targets.
The well reached a TD of 3,612 m having been drilled through all primary and secondary targets.
The Kingia reservoir was reached at 3,211 m and the underlying High Cliff reservoir at 3,362 m, which was 80 m deeper than forecast.
Three cores were cut in the Kingia before the well was cased and suspended for future testing and production.
Initial interpretation of the Kingia suggests excellent conventional reservoir qualities, which AWE says are the best yet observed in Waitsia field. The gross Kingia reservoir of 52 m contains 20 m of net gas pay and reservoir quality is better than in the previous Waitsia-1 and 2 wells.
Gas samples taken indicate the total inert gases content is below 7%.
Waitsia-3 confirms the laterally extensive nature of this reservoir and is particularly pleasing since it is a long step-out 10.8 km south of the Waitsia-1 discovery.
AWE says the High Cliff Sandstone was gas-bearing, but thinner than predicted and preliminary analysis indicates it is a tight reservoir.
Gas was observed, nonetheless, at the base of this reservoir at 3,360 m, which is 10 m below the gas-water contact seen in the rest of Waitsia field. AWE says this may indicate substantial further upside.
Overall the Waitsia-3 well has exceeded predrill expectations and has provided new appraisal and exploration opportunities within the L1/L2 permits.
The well is the first of two appraisals in the company's appraisal drilling program for 2017 designed to evaluate gas potential in the southern extension of the field.
AWE now will move straight on to Waitsia-4 appraisal.
The company anticipates a further upgrade to field reserves once drilling and analysis is completed before yearend.
The last reserve announcement in 2016 put the 2P reserves at 344 bcf of gas. The 2P reserves plus the 2C contingent resources for the field were estimated at 630 bcf.
In addition, the total gross 2P reserves plus 2C contingent resources when combining Waitsia with nearby finds at Senecio, Irwin, and Synaphea are an estimated 867 bcf of gas.
Waitsia, discovered in September 2014, is the largest onshore conventional gas field found in Australia for the last 30 years and is capable of supplying the domestic market with 100 terajoules/day for 10 years from conventional reservoirs.
Last month the company announced the beginning of the design competition phase of front-end engineering and design of the Waitsia gas project Stage 2 (OGJ Online, June 8, 2017).
The design for the facilities includes a gas plant with carbon dioxide extraction, collection hubs, and flowlines.
Four contractors have been selected to submit designs: Quanta-Suez, ATCO Australia, SNC-LAVALIN, and Clough.
The design competition will begin immediately and will be followed by a commercial phase.
AWE is targeting completion of all phases of FEED by yearend.
The project's Stage 1A came on stream in August 2016 at a capacity of 10 terajoules/day. Stage 1A involved connection of the Waitsia-1 and Senecio-3 gas wells to the upgraded nearby Xyris production facility. The gas is flowing into the existing Parmelia pipeline and Alinta Energy is taking up to a maximum quantity of 9.6 terajoules/day under a signed 2½-year take-or-pay gas sales agreement.
Waitsia is about 370 km north of Perth and 16½ km east-southeast of Dongara.
AWE and joint venture partner Origin Energy Ltd., also of Sydney, are equal partners.