Publication Name: PESA's Eastern Australasian Basin Symposium II
Authors: D. Gillam, T. Flottmann and R. Hillis
Date Published: December 2004
Number of Pages: 27
Reference Type: Book Section
Abstract:
Reliable characterisation of natural fracture networks can improve management of tight gas reservoirs typical ofonshore Australia. However, characterisation of natural fracture networks in tight gas reservoirs is often hindered due to poor sample availability (i.e. limited core and image logs) and the absence of quality outcrop. The Goonyella Riverside coal mine in the northern Bowen Basin provides an analogue study for the development of natural fracture systems in a mildly thrusted Permian coal measure succession. A total of3,862 m of image log data from 18 closely spaced wells was integrated with 3D seismic data and outcrop observations to characterise structural style and natural fracture development at Goonyella Riverside. Three distinct stages of fracturing are observed and linked to the structural evolution of the area: (i) coal cleats and compaction related normal faults formed during Late Permian burial and diagenesis, (ii) thrust faults and subsidiary low-angle shear fractures formed during the Early to Mid Triassic Hunter Bowen Orogeny and (iii) tensile joints formed during Cretaceous uplift and unloading. Different mechanical units including massive amalgamated distributary channel sandstone bodies, laminated overbank deposits and coal seams display distinct fracture development, defining the mechanical stratigraphy. Observations made in this study may be used to improve development drilling
design and reservoir management in naturally fractured tight gas reservoirs of onshore Australia.