Tracer testing at the Habanero EGS site, central Australia  

Authors / CoAuthors

Ayling, B.F. | Hogarth, R.A. | Rose, P.E.

Abstract

The Habanero Enhanced Geothermal System (EGS) in central Australia has been under development since 2002, with several deep (more than 4000 m) wells drilled to date into the high-heat-producing granites of the Big Lake Suite. Multiple hydraulic stimulations have been performed to improve the existing fracture permeability in the granite. Stimulation of the newly-drilled Habanero-4 well (H-4) was completed in late 2012, and micro-seismic data indicated an increase in total stimulated reservoir area to approximately 4 km². Two well doublets have been tested, initially between Habanero-1 (H-1) and Habanero-3 (H-3), and more recently, between H-1 and H-4. Both doublets effectively operated as closed systems, and excluding short-term flow tests, all production fluids were re-injected into the reservoir at depth. Two inter-well tracer tests have been conducted: the first in 2008, and the most recent one in June 2013, which involved injecting 100 kg of 2,6 naphthalene-disulfonate (NDS) into H-1 to evaluate the hydraulic characteristics of the newly-created H-1/H-4 doublet. After correcting for flow hiatuses and non-steady-state flow conditions, tracer breakthrough in H-4 was observed after 6 days (compared to ~4 days for the previous H-1/H-3 doublet), with peak breakthrough occurring after 17 days. Extrapolation of the breakthrough curve to late time indicates that approximately 60% of the tracer mass would eventually be recovered (vs. approximately 80% for the 2008 H-1/H-3 tracer test). This suggests that a large proportion of the tracer may lie trapped in the opposite end of the reservoir from H-4 and/or may have been lost to the far field. The calculated inter-well swept pore volume is approximately 31,000 m³, which is larger than that calculated for the H-1/H-3 doublet (~20,000 m³). A simple 2D TOUGH2 tracer model, with model geometry constructed based on the current conceptual understanding of the Habanero EGS system, demonstrates good agreement with the measured tracer returns in terms of timing of breakthrough in H-4, and observed tracer dispersion in the tail of the breakthrough curve.

Product Type

nonGeographicDataset

eCat Id

82626

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Keywords

• External PublicationScientific Journal Paper

( Theme )

• geothermal

( Theme )

• geochemistry

( Theme )

• hydrogeology

( Theme )

• energy

( Theme )

• fluid flow pathways

• SA

Australian and New Zealand Standard Research Classification (ANZSRC)

• Hydrogeology

• Published_Internal

Publication Date

2015-01-01T00:00:00

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Australian Government Security ClassificationSystem    

Classification - unclassified

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Special, MOU, etc.

Access - restricted

Use - license

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notPlanned

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geoscientificInformation

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Publication of geothermal research conducted at Geoscience Australia in collaboration with Geodynamics Limited and the Energy and Geoscience Institute at the University of Utah.

Parent Information

Extents

[-28.0, -27.0, 140.0, 141.0]

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Source Information

Interwell tracer test data from Geodynamics' Habanero project aquired and interpreted in this study. Raw geochemical tracer data aquired during an inter-well tracer test on site in June 2013, and interpreted during this study. Data owned and provided by Geodynamics Limited; IP associated with processing and interpretation of this data held by Geoscience Australia.