Some lessons learnt from drilling a shale gas well in Western Australia

Abstract

The Arrowsmith–2 well is the first dedicated shale gas well in WA. The well is situated in the central eastern area of Permit EP413, with the surface location being about 30 km north of the township of Eneabba. Norwest, as the operator and on behalf of its joint venture partners, drilled the Arrowsmith–2 exploration well in mid-2011. In 2012 the well was subsequently perforated and fracture stimulated in five discrete stages across four formations: the High Cliff Sand Stone (HCSS); Irwin River Coal Measures (IRCM); Carynginia Formation; and, Kockatea Shale. The fraccing results have shown excellent rates of gas flow for the size of the intervals fracced, and have produced oil and/or condensate to surface from the two intervals flowed back.

This paper discusses some drilling operation and design aspects of Arrowsmith–2. A review of the regional geology, basic well design, and well objectives will be given. The importance of geomechanical studies for minimising wellbore-related problems during drilling and after that for hydraulic fracturing operation will be discussed, and the results of the studies undertaken presented. The wireline logging suite run in this well was used to interpret the formations’ mechanical properties. Also, laboratory tests were performed to estimate hydro-mechanical properties of the formations. The lessons from drilling this well will be used for drilling future wells in the area with the objective of saving time and costs.