The Udacha Prospect is located within an area encompassing portions of PEL 91 and 106, known as the Udacha Unitization Area, which is operated on behalf of the JV by Beach Petroleum. Udacha-1, was spudded on 11 January 2006. The Udacha-1 exploration well tested a faulted anticline located on the eastern plunging edge of a prominent structure, the Kuenpinnie Nose. The primary objective was the Patchawarra Formation but secondary reservoir potential was anticipated within the Toolachee and Epsilon formations as well as in the Tirrawarra Sandstone.
The well was funded 25% by Enterprise in order that it would retain a 12.5% participating interest in the event of a commercial discovery. The well was designed to drill to a total depth of 2775 m. There were some engineering problems during the drilling of the well which resulted in difficult hole conditions.
Following the recording of hydrocarbon indications DST #1 was conducted over a portion of the Patchawarra Formation between 2482.5-2488 m. This test was unsuccessful due to tool malfunction. A successful DST was subsequently carried out in the Patchawarra Formation over the interval 2482.5-2488 m on 7 February 2006. The test resulted in a gas flow to surface in 20 minutes. The final flow rate was 0.44 million cubic feet/day (12.5 thousand cubic metres/day). The flowing pressure was building throughout the flow period and reached a maximum of 300psi against ¼ inch surface choke.
DST-1A is interpreted to have tested a zone of approximately 3 m of net gas pay with an additional 3 to 10 metres of pay likely within deeper sands. The data indicated severe formation damage had occurred due to drilling mud invasion following delays in drilling.
Because of this the recorded flow rates were anticipated to have been damaged because of prolonged exposure to drilling mud. The well was case and suspend the well for future testing and evaluation.
During September 2006 CHPT of the Udacha-1 well commenced. Testing entailed a series of controlled gas flows and shut-ins for pressure build up and volumetric calculations. The main period of testing of Udacha-1 was conducted between 6 and 17 September 2006 over the Patchawarra Formation interval 2482 - 2486.5m. Gas flow rates of nearly 1 million cubic feet per day were considerably higher than the 0.4 million cubic feet rates measured during the initial open hole DST. Following analysis of the CHPT data the operator predicted that gas flow rates in excess of 2.0 million cubic feet per day should be achievable with fracture stimulation. Volumetric estimations of raw gas reserves range between 2.0 (P90) and 7.0 BCF (P10), with a mean of 3.9 BCF(P50). Enterprise Energy NL retains a 12.5% interest in the Udacha Block.