Development options are under consideration for the Middleton gasfield, which was discovered when a test on this well recorded one of the largest flow rates of any exploration well in the Cooper Basin.
The Middleton-1 exploration well was drilled to test the hydrocarbon potential of small faulted anticlinal closure on a prominent basin-ward trending “nose” on the western flank of the Patchawarra Trough, about 5km west northwest of the Raven Gasfield, 9km northwest of the Moonanga Gasfield, and 24km southeast of the Sellicks oilfield.
The primary objective of the well was the Early Permian Patchawarra Formation (gas and/or oil) and had secondary potential in the Permian Toolachee and Epsilon formations and the Early Permian-Late Carboniferous Tirrawarra sandstone. Each of these reservoir intervals is commercially productive in the Cooper Basin.
Middleton-1 spudded on the 15th February 2006. Total depth of 2841.0m, reached on 2nd March 2006. Dull to moderately bright, bluish-white fluorescence (5 to 25%) was noted in drill cuttings in the Tirrawarra Formation between 2781.0 – 2793.0m. Several sands within the Patchawarra Formation had good gas shows.
A conventional bottom hole test, DST-1, was conducted over the Patchawarra Formation while the well was being drilled but resulted in a misrun. After drilling to TD, logs were acquired and DST 2, an inflate straddle drill stem test, was then conducted over approximately the same zone attempted by DST 1 in the Patchawarra It flowed gas to surface after 3 minutes during the second flow period. The final stabilised flow after a 135 min flow period was recorded as 11.8 MMscfd. This is one of the most significant gas flow rates reported in the Cooper basin from an exploration well.
Middleton-1 was cased and suspended as a new field gas discovery and the rig released on 10th March 2006.