TECHNICAL CHALLENGES IN THE DEVELOPMENT OF UNCONVENTIONAL GAS RESOURCES IN AUSTRALIA

Abstract

Unconventional gas resources, defined as low- permeability sandstone, coal seam and naturally- fractured shale gas reservoirs, represent a huge potential resource for future natural gas supply in Australia and around the world. Because low individual well-production rates are often the norm, unconventional reservoir development may involve the drilling of hundreds of wells to make the economics attractive. Thus, careful planning, sound development strategies and cost control are critical for project success.

Virtually all unconventional gas resources must be stimulated to be economic; stimulation costs are often the most significant amount of the total well expenditure. Thus, a cost-effective method for reservoir characterisation and fracture treatment optimisation is required. Because of marginal economics, techniques used to analyse the process and results are often oversimplified; this can lead to confusing or inadequate descriptions of the complex behavior of a hydraulically-fractured, low- permeability reservoir and in some cases bad development decisions. Detailed data collection programs and fracture treatment optimisation strategies are essential to adequately address the technical issues involved in unconventional reservoir development.

Besides the technical challenges associated with unconventional gas development, good forethought is necessary as to the planning and execution of the overall project. The development scenarios for coal seam and low-permeability sandstone gas resources are highly statistical and succeed or fail based on the average performance of the group of wells within the project. Following proven guidelines and methods during development while integrating key technologies into the planning and optimisation process are essential for success in unconventional reservoir development.