Abstract
In 2013, Armour Energy commenced evaluation of conventional and unconventional gas reservoirs within the Paleoproterozoic (Pre-Cambrian) Supersequences within the Isa Superbasin, North Queensland, Australia. In 2012, a vertical well with a sidetracked lateral was drilled targeting the Lawn Hill Shale Member (Lawn), offsetting the 1990's Egilabria 1 well, which exhibited gas shows in the same interval.
Egilabria 2 was the first recent vertical well in the area, which was subsequently sidetracked to create a 567m lateral wellbore, Egilabria 2 DW1. Egilabria 2 exhibited gas shows and flows whilst underbalanced air-drilling across Wide, Doom and Lawn Supersequences. An extensive set of logs and cuttings data were collected in Egilabria 2 aiding targeting and geologic correlation in the sidetracked lateral.
Egilabria 2 DW1 lateral was drilled, cased, cemented, and a multi-stage ‘plug-and-perf’ style of frac treatment was employed. Before shutting in the well post-frac for an extended buildup, during the inaccessible ‘wet season’ in this area, frac fluid was flowing back unassisted and gas was flaring at low surface flowing pressures. This was the first successful, post-frac gas flows from a multistage, fracture stimulated, laterally drilled, shale gas well in Australia.
This paper details the data collected in the vertical pilot well and observations and implications of in situ stress magnitudes and varying natural fracturing azimuths had on the drilling and subsequent hydraulic fracturing treatment of the lateral wellbore. In addition, we will present our recommendations for future well targeting and treatment strategies for this area and recommendations for shale gas exploration and appraisal in other frontier basins.
