AWE upsizes onshore Perth Basin

Highlights

AWE Limited, the Operator of Permits L1/L2 in the Perth Basin, Western Australia, has announced initial 2P Reserves and upgraded 2C Contingent Resource estimates for the Waitsia gas field following evaluation of the Waitsia-1 and Waitsia-2 appraisal well results.

Managing Director, Bruce Clement, said the data gathered from Waitsia-2 allowed AWE to significantly increase the company’s previous estimate of gross recoverable gas and book initial 2P Reserves.

“Waitsia-2 has proved to be another major success for AWE. With three wells now drilled on the Waitsia field, we have sufficient data to increase our estimates of total gross recoverable gas, on a P50 basis, from 290 Bcf of gas to 484 Bcf of gas – an uplift of 67%,” he said.

“In total, we have now booked over 700 Bcf of gas gross as 2P Reserves and 2C Contingent Resources in fields discovered and / or appraised in 2014-15. “As previously announced, AWE is moving forward with development plans for low-cost, early-stage gas production from the Waitsia field by mid-2016. Gas marketing is making good progress and the joint venture has applied for a licence to construct a pipeline from the Senecio-3 and Waitsia-1 wells to the Xyris production facility, located near the Waitsia-2 well,” Clement said.

“In addition to the Waitsia field, we have also estimated gross 2C Contingent Resources of 237 Bcf of gas in the Senecio, Irwin and Synaphea tight gas fields in the Dongara/Wagina formation.

“The Waitsia field, together with AWE’s other onshore north Perth Basin gas discoveries, represents an exciting new project for the company. The volume of gas is substantial and should provide AWE with a highly valuable long-term domestic gas business in Western Australia,” he said.

The Waitsia-2 appraisal well was drilled to a total depth of 3530m Measured Depth below Rotary Table (MDRT). The primary and secondary targets were successfully intersected with high gas shows observed in the Kingia and High Cliff Sandstones as well as the Irwin River Coal Measures and the Carynginia Shale. Wireline logs, pressure data and samples confirm the presence of a substantial gas column and extension of the Waitsia field to the southern culmination of the mapped structural closure.

Waitsia-2 data

The Waitsia-2 data have been integrated with the information from the Senecio-3 and Waitsia-1 gas wells to estimate reserves and revised contingent resources for the Kingia/High Cliff Sandstone reservoirs over the entire Waitsia field. Sufficient technical data have been collected to justify the booking of reserves for the good quality conventional reservoirs in the areas around Senecio-3, Waitsia- 1 and Waitsia-2. Conventional good quality gas pay is defined as reservoir having greater than 11% porosity as interpreted from a combination of wireline log and core data. Average field wide porosity for this reservoir is estimated at 14.5%. Deliverability is demonstrated by flow testing of Senecio-3.

It is predicted that the conventional gas bearing reservoirs extend throughout the greater Waitsia field structure including the undrilled sectors in the south and east. Contingent resource estimates have been made for these areas using the same reservoir assumptions but further appraisal drilling is required to determine reservoir deliverability and book these as reserves.

Development planning and economic modelling indicate that the development of these reserves and contingent resources is economic under AWE’s market and gas price assumptions. The preliminary full-field development plan involves the drilling and completion of 20 vertical or deviated production wells, including the three wells drilled to date, with connection to a centralised gas processing facility. It is envisaged that export to domestic markets at a plateau rate of about 85 mmscf/d would utilise existing nearby gas pipelines. The composition of the gas (c.93% methane) indicates that only minimal processing will be required. Early production start-up will be sought subject to achieving the required regulatory approvals.

In addition, further contingent resources have been estimated for lesser quality gas bearing reservoir intervals in the Kingia and High Cliff Sandstone formations which have porosity in the range 7 to 11%.

More data and work are required to determine whether some, or all, of these Waitsia field contingent resources intervals will be booked as reserves in the future.

The Senecio-3, Waitsia-1 and Waitsia-2 wells have been completed as production wells and will form part of a future field development.

Read the article online at: https://www.oilfieldtechnology.com/drilling-and-production/21082015/awe-upsizes-onshore-perth-basin/