ADS Rig#6 had drilled the well using conventional (overbalanced) water-based drilling techniques to a depth of 2359m into the top of the Bandanna Formation. Casing was then run and the well suspended on 28 August 2006 in preparation for stage-two operations, to test the main Permian objectives (Bandanna and Tinowon Formation sandstones) using underbalanced drilling techniques. A specialist coiled tubing unit, owned and operated by BJ Services, was mobilized to drill the remainder of the well. Stage 2 saw the well deepened to a total depth of approximately 2500m.
The Bellbird West-1 well targeted a structure west of Bellbird-1 (drilled in 1984) which encountered oil and flowed at a modest rate of 30 barrels per day on test. Bellbird West-1 is fully funded by farminees, and following completion of drilling Great Artesian will retain a 50% interest in the permit. As part of the farmin agreement, the main target zones were drilled using nitrogen under-balanced techniques. Under-balanced drilling has been shown to inhibit formation damage and preserve the reservoir properties in some instances where water based drilling muds might otherwise cause swelling of the constituent clays with consequential clogging of potentially porous and permeable zones. The expectation was that if oil bearing reservoirs, similar to those encountered by Bellbird-1,were penetrated using under-balanced drilling techniques, a significantly higher flow rate might be achieved on production or test.
Pre-drill potential recoverable reserves from the Permian objective for the Bellbird West Prospect ranged from 0.3 MMBO (P50) to 1.6 MMBO (P10).
Under the farmout terms Rawson Resources Ltd (“Rawson”) will earn 50% interest in the Bellbird Block of ATP552P by funding 100% of the farmin well on the Bellbird West Prospect using underbalanced drilling techniques through the Permian reservoir section. Under a separate agreement Rawson is farming-down a 25% portion of its farmin interest to Ausam Resources Pty Ltd (“Ausam”) for Ausam funding 50% of the cost of the well.
After the completion of the second drilling phase, Bellbird West-1 was plugged and abandoned with oil shows.