A REVIEW OF THE U.S. TIGHT GAS INDUSTRY FROM THE PERSPECTIVE OF SELECTED AUSTRALIAN AND NEW ZEALAND BASINS

The recovery of natural gas from low permeability sandstones in the US has been made commercially possible due, to a large degree, to advanced technologies. The US currently produces 2 TCF annually from tight gas sandstone reservoirs. Large efforts have been directed towards identifying and developing the more productive basinal areas, or 'sweet spots9 of tight gas reservoirs. The identification of natural fractures prior to drilling, through the use of remote imagery in combination with established methods such as magnetic and gravity mapping, is currently being pioneered. Reduction in well-bore stimulation costs through development and application of advanced hydraulic fracture technology has improved the economics of tight gas production. The use of 3D fracture models in combination with realistic insitu stress profiles, appropriate proppants and effective quality controls have greatly increased well productivities through smaller, more efficient fracture treatments. Treatments have been successfully designed to avoid damage to natural fractures.Large tight gas sandstone resources similarly exist in the Cooper and Perth Basins of Australia and in the Taranaki Basin of New Zealand, although these resources remain largely untapped. To date, less than 50 BCF has been produced from Australian and New Zealand tight sandstones, largely from the Tirrawarra Sandstone and Patchawarra Formation of the Cooper Basin and the Ngatoro/McKee Formations of the Taranaki Basin. These formations compare well however, in terms of depositional environments with prolific US tight gas producing formations. They appear to be well placed to take advantage of the experiences and technologies gained by their US counterparts as well as through site specific adaptation of such technologies and the development of new technologies.