Complexity in tight gas sand development—an example from Perth Basin, Western Australia

Abstract

A tight gas sand (TGS) is a low permeability (>0.1 mD) gas reservoir that needs specific treatments such as advanced drilling technology, a correct way of completion and stimulation to produce gas in commercial rate. For a conventional reservoir, porosity is high and pores are fully connected, whereas for near tight and tight rocks, pores are occluded and there are little connections between the pores. Syn-depositional processes (depositional facies), post-depositional events (diagenetic processes such as cementation and compaction) and a combination of these two are the main controlling parameters that can change a conventional reservoir rock to a TGS. There are several reported TGS fields in the Perth Basin including Whicher Range in the south, Gingin, Warro, Ocean Hill, Arrow Smith, Erregulla, Corybas, Snottygobble and Senecio in the North Perth Basin. Reservoir rocks are different for each field and they vary in many aspects such as age, thickness, depth of burial and sand geometry. Tight gas sand formations in the Perth Basin include Willespie, Irwin River Coal Measure (IRCM), Wagina and Dongara sandstones, Cattamarra Coal Measure and Yarragadee Formation. This study reviews Perth Basin’s tight gas sand characteristics and the challenges that we should confront to unlock this unconventional resource.