| Abstract |
Geodynamics Limited has been developing an Enhanced Geothermal System (EGS) at Habanero in the Cooper Basin, Australia, since 2002. Prior to the hydraulic stimulation of Habanero 4 in 2012, the system produced over 44,000 seismic events, of which over 31,000 events could be located. In November 2012, a large hydraulic stimulation was carried out in the Habanero field. The intent of the stimulation was to expand the existing EGS geothermal reservoir and to gain a better understanding of the geothermal system, through the seismic response caused by the stimulation. The stimulation was conducted through Habanero 4, situated approximately 680 m North East of Habanero 1, which had been used for the original stimulations in 2003 and 2005. Over 34 ML of water was injected into the existing “Main Fracture” at a depth of 4,077 m total vertical depth (TVD) over a 3 week period. During stimulation, seven seismic stations were used to transfer data in real time to the central processing office with an additional 17 stations recording in an offline mode and incorporated into the workflow in post-processing. In this three week stimulation period, over 27,000 events were recorded, of which over 20,700 events were located. Event magnitudes calibrated by recordings of the permanent network of Geosciences Australia were in the range of ML -1.6 and 3. Hypocenter locations indicate that seismicity occurred on the same sub-horizontal layer structure identified in previous stimulations. The seismic cloud growth is consistent with the previous 2003 stimulation performed through the Habanero 1 well. However, it exhibits different characteristics compared to the 2005 re-stimulation through Habanero 1 where a pronounced Kaiser effect was observed near the injection well (Baisch et al.,2009). This paper aims to provide an overview of the seismicity produced through the 2012 stimulation of Habanero 4 and how its growth relates to previous stimulations of the Habanero field. |