Ainsworth, Bruce, Bas Spaargaren, Robert Seggie, Peter Stephenson, David Johnson, Jean-Paul Koninx, and Joe Mcnutt , Woodside Energy Ltd, Perth, Australia
The giant Sunrise-Troubadour gas-condensate field is located in the Timor Sea some 450 km northeast of Darwin, Northern Australia. Since its discovery in 1974, six wells have been drilled to appraise the structure: the three most recent date to 1997-98. Middle Jurassic (Plover Formation) marginal marine sandstones form the main reservoir. The trap is a broad, approximately 3500 square km, tilted fault block. Information from the recent appraisal campaign has been integrated with a grid (1 x 3 km) of modern 2-D seismic data and together they have been used to formulate field development plans. Description of the subsurface relies on a range of discrete 3-D reservoir modeling scenarios which cover the full spectrum of subsurface uncertainties.
Deterministic and probabilistic modeling of sand and shale bodies has been combined with statistical seismic inversion techniques to determine rock properties (thickness, net-to-gross, porosity) in the large, greater than 10 km, interwell areas. An iterative approach was followed whereby depositional geometries from initial 3-D geological models formed the a priori inputs for the inversion runs. The resulting inversion property models were then used to update the 3-D static geological descriptions before transfer to a dynamic simulator.
This sophisticated approach draws from all available geological and geophysical information, maximizes integration of these disparate data types into a coherent static description of the subsurface, gives confidence to contractible proven gas volumes, and limits the requirement for further expensive appraisal drilling.
AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia