The Jansz Gas Field, Carnarvon Basin, Australia

Abstract

The Jansz gas field is located in permit WA-268-P, 70 km northwest of the Gorgon gas field in the Carnarvon Basin. The Jansz–1 discovery well was drilled in April 2000 and intersected 29 m of net gas pay in an Oxfordian age shallow marine sandstone reservoir. The well drilled a stratigraphic trap on the western limb of the Kangaroo Syncline.The Io–1 well was drilled in January 2001 in the adjacent permit WA-267-P (18 km from Jansz–1) and intersected the same Oxfordian sandstone reservoir penetrated by Jansz–1, with a total of 44 m of net gas pay. The Tithonian and the Upper Triassic Brigadier Sandstone gas reservoirs at Geryon–1 (1999) and Callirhoe–1 (2001) in WA-267-P are in pressure communication with the Oxfordian gas reservoir at Jansz–1 and Io–1. Consequently, the three different age reservoirs comprise a single gas pool, with a common gas/water contact.The Jansz gas field has been delineated by four wells and 2D seismic. The gas sandstones have a prominent amplitude versus offset response, which defines the field limits. The Jansz gas field is confirmed by drilling to be an areally extensive (2,000 km2) gas accumulation with a gross column height of 400 m and an estimated 20 TCF (566 G.m3) recoverable sales gas, which represents 40% of the discovered gas resources in the deepwater Carnarvon Basin. The size of the Jansz gas field and its remoteness from existing pipeline gas markets suggests that an export LNG project will be the basis for its development.

Geochemical and geomechanical evaluation of the Mungaroo Formation, offshore northwestern Australia

“…Continuous subsidence during Oxfordian (~163-157 Ma) caused a maximum flooding surface that correlates with the widespread deposition of the deep marine Dingo Claystone unit (~167-147 Ma), except to the NW most zone within the Exmouth Plateau (Figure 2) (Chongzhi et al, 2013). At this time, the Kangaroo synclinal formed after an extensional reactivation of Triassic faulted blocks in the Rankin Platform (Jenkins et al, 2003); this synclinal was an important depocenter, here the turbiditic and deltaic sandstones of the Dupuy Formation and Angel Sandstone deposited (Figure 2), containing a significant contribution of Mungaroo Formation sediments (Jenkins et al, 2003;Moss et al, 2003).…”