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Most of in-situ stress data in the Australian continent comes from wellbore stress analysis in deep hydrocarbon reservoirs, and earthquake focal mechanism solutions near the Australian plate boundaries, where geophysical tools facilitate understanding of the present-day stress patterns. This resulted in a paucity of stress information in many other regions such as the northern Bowen Basin, which is an active mining province, but with low seismicity rates and limited deep petroleum exploration. The mining industry runs several hundred kilometres of image logs annually to characterise geotechnical attributes. These logs provide an image from the borehole wall, which facilitates analysis of stress-related borehole deformations for in-situ stress characterisation. This paper examines the orientation of horizontal in-situ stress using different types of image logs in mine boreholes across the northern Bowen Basin. Analyses of 128 km of image logs in 680 vertical boreholes resulted in the interpretation of 9046 pairs of stress-related indicators including 735 drilling induced fractures and 8311 borehole breakouts. Our comprehensive database comprises 890 quality-ranked data records for the orientation of maximum horizontal stress (S Hmax), which makes the Bowen Basin as a basin with the highest data density in the world in terms of quality-ranked stress information according to the World Stress Map. Statistical analysis of S Hmax orientation reveals that the mean S Hmax orientation in northern Bowen Basin is N018° ± 16°. The results show that this orientation is consistent over long distances, which is in contrast with several eastern Australian basins. This uniform stress pattern agrees well with plate-scale geomechanical model predictions, which further highlights the impact of plate boundary forces in the contemporary stress pattern of this region. Detailed image log investigation did not show any systematic rotation of stress; however, some small-scale stress perturbations were observed in the vicinity of sharp stiffness contrasts and geological structures. • The most comprehensive quality-ranked basin-wide stress map in the world according to the World Stress Map database. • High-resolution stress mapping using mine borehole data. • Regional uniform stress pattern and localized (wellbore scale) stress perturbations near major geological structures. • Analysis of stress orientation versus depth. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes the methodology used to derive the economics of CO2 storage in coal with enhanced coalbed methane recovery. A significant difference between CO2 storage in coal seams and storage in saline aquifers is that the incrementally recovered natural gas constitutes an additional revenue stream. In the case of CO2 storage in coal it is necessary to distinguish between CBM (primary coalbed methane recovery), CO2-ECBM (enhanced coalbed methane recovery caused by and including the injection of CO2), and CO2 storage with incremental CBM recovery (Storage-ICBM). The methodology is demonstrated by means of a case study that evaluates the economics of carbon capture and storage with incremental CBM recovery (CCS-ICBM) at the Spring Gully CBM prospect in the Bowen Basin, QLD, Australia–Australia’s most productive CBM basin. Economic analyses of the Spring Gully development show that the specific cost of CO2-ECBM is A$37/t CO2 avoided (equivalent to US$31/t at an assumed long term exchange rate of A$1.00 = US$0.85) including capture costs. However, this incorporates the benefits of the underlying CBM project and therefore underestimates the cost of CCS-ICBM. The incremental cost of CCS-ICBM is A$92/t (US$78/t) excluding these benefits. The results demonstrate the importance of using an appropriate methodology to determine and present storage economics. If no distinction between CO2-ECBM and Storage-ICBM is made, the real costs of storage will for most cases be significantly underestimated and could potentially lead to poor investment decisions and the selection of economically unviable storage sites. [Copyright &y& Elsevier]