The Application of In-Situ Stress Measurement and Numerical Stress Analysis to Coalbed Methane Exploration in Australia

Abstract

Abstract Exploration for coalbed methane in Australia has evolved over the past few years to a point where the focus is very largely on the targeting of regions of relatively higher permeability. Gas content has generally been found to be adequate enough to encourage commercial development. Permeability has, however, often been found to be too low by comparison with overseas experience to suggest commercially viable gas production rates. The unravelling of an understanding of coal permeability and its relationship to the geological environment is being helped by the application of in- situ stress measurement (conducted in coal and associated sediments) and numerical stress aiialysis. Knowledge of the in-situ stress field becomes a means by which to quantify the relationship between coal permeability and the related structural geological framework, leading ultimately to a better basis to guide the development of exploration strategies. This paper describes the results of in-situ stress measurements conducted in a number of coalbed methane exploration holes in the Sydney Basin and associated stress analyses conducted to examine the influence of in-situ stress and geological structure on coal seam permeability as measured by well test.