State Gas Ltd., Brisbane, has confirmed that coal seam gas is being produced from depths below 1,150 m at its Reid’s Dome field in the Bowen basin of southeast Queensland.
The flow is in addition to the known production from coal seams at 400-1,000 m.
The company had been production testing the Nyandra-4, Nyandra-7, and Nyandra-8 wells at its 100%-owned project when gas flow data from tests indicated gas was also being produced from lower seams.
The flow was confirmed with a production log test at Nyandra-4. The well intersected 40 m of net coal at 394-1,177 m with the lowest coals positioned just above the bottom of the well at 1,200 m depth. Temperature and noise logs were run to determine which zones were producing gas.
Results showed good flows from the top coals at 400-600 m and, importantly, also from the bottom section of the well below 1,150 m, which is much deeper than is typical for the region.
The outcome is commercially important for Reid’s Dome, but also for the wider area within the PL 231 permit as the coal seams dip down away from the crest of the dome.
The results prove that State Gas can produce economically at depths exceeding 1,000 m naturally, unaided by any form of stimulation, said Executive Chairman Richard Cottee. Coals at these depths need to be included in assessments of the field’s production potential right down to the full depth of the wells, he added.
On completion of the test program, Nyanda-4 was returned to production and is currently producing 138,000 cu ft/day (cfd). Nyandra-7 and -8 are producing at 7,000 cfd and 38,000 cfd, respectively..