Over the past few years, there has been a surge of interest in using Australia's coalbed methane (CBM) resources to produce liquefied natural gas (LNG) for export, taking advantage of increasing prices and growing global demand for gas. Principally in Queensland, the second largest state, situated in the northeast of the country, there has been significant investment by a number of companies to secure footholds in this resource play. By December 2008, seven proposals for LNG plants had been announced, most involving partnerships between Queensland companies with coal seam gas resources and international petroleum companies.
Most exploration and appraisal CBM wells are tested to determine pressures and coal seam deliverability. As the majority of wells cannot flow to surface naturally, closed chamber tests are conducted, most often in open hole. An alternative testing method employed by a number of operators in Australia over the past 2 years has been the dual packer module of wireline formation testers. Although wireline packers provide a cost-effective and an efficient way of obtaining high-quality pressure transient data sets, they are limited to relatively small test intervals. A new, innovative approach enables testing coal seams of up to 15 m in thickness using wireline formation testers. The new wireline formation testing configuration offers several benefits over conventional drillstem tests (DST) for this application, including rig-time savings. Another benefit of the new technique is the broad range of drawdown and inflow rates, extending coverage from very low- to high-permeability coals. Additional applications used in the field include step-rate tests, the results of which have been applied to assess and rank different coal seams across a number of fields and coal types.