Successful fluid discrimination in tight, overpressured reservoirs using AVO inversion

Abstract

In 1995, the Longtom-1/ST1 wildcat well - drilled in the northern part of the offshore Gippsland Basin - encountered dry gas in tight, overpressured sandstones. The reservoir is situated in the Admiral Formation of the Emperor Subgroup. The Longtom-2/ST1 exploration well confirmed significant vertical and lateral extension of these prospective gas sands in 2004, and also provided very encouraging production test and core data. The recent Longtom-3 and -4 wells have demonstrated the viability of this new play by confirming significant lateral continuity of the thicker gas sands and demonstrating high gas flow rates. A multi-disciplinary and interactive approach, guided by seismic inversion techniques and real-time petrophysical data, resulted in the successful planning and execution of the Longtom-3 (for more information see Lanigan et al., 2007) and subsequently the Longtom-4 drilling and evaluation program.