A reliable, effective and accurate production simulator for the higher-pressure shales has yet to be developed and the often-conflicting predictions of current simulators have yet to be reconciled. Main production drivers have yet to be identified, differences between the various shale plays have yet to be delineated and a production analysis and projection tool is better than decline curve analysis and more accurate and faster than numerical simulators is still awaiting development.
It is widely recognized that gas is stored as free gas in the matrix pore space and as an adsorbate in organic material in the pores, the relative magnitudes varying with the pressure, the porosity and the TOC. Little, if any, gas is stored in the natural fractures. A fundamental requirement of a shale gas production model is that it addresses a sequence of processes from desorption, transport through a very tight matrix, and transport (perhaps two-phase) through fractures to the wellbore. We are addressing these issues by first assessing the geological and petro-physical differences between US shale plays and CBM plays as far as they impact gas productions.