TAG Oil has confirmed the presence of oil shale with the first of the three well spudded at its Waitangi Hill programme.
The stratigraphic well, drilled to a total depth of 171m, encountered a strong oil-wet gas kick combined with significant pressure at 149m, and hit the core with free oil in a conventional sandstone reservoir at 171m.
Through the stratigraphic wells, TAG will begin collecting modern data to appraise a conventional development of the historical Waitangi Hill shallow oil discovery.
The wells will also enable the firm to further assess the viability of the underlying Waipawa Black Shale and Whangai Shale source rock formations as unconventional targets.
Waipawa Black Shale and Whangai Shale are naturally fractured, mature and accessible at shallow depths due to recent uplifting, and have generated high-quality light sweet crude.
East Coast Basin experiences over-pressures due to competent seals and rapid uplift in the area, and oil and gas seeps throughout the 2.4 million acres area, which confirms that the formations are widespread.
The gas, oil and core samples will undergo further analysis before planning the next two Waitangi Hill wells with equipment capable of handling anomalously pressured shallow oil and gas zones.
