RIASSUNTO
Abstract
Introduction
Strong LNG demand, both here in Australia and overseas, fuelled by worldwide transition to a low carbon economies is driving unprecedented growth in coal seam gas (CSG) exploration and development of east coast resources, not to mention the other conventional gas resources around Australia. With this accelerated growth in demand for gas, particularly with the onshore CSG production, comes the matter of the associated environmental affects and the need for socially responsible environmental management and mitigation of impacts.
Why do I single out the CSG industry in this regard - after all the oil and gas industry has been the subject of considerable environmental regulation during the many decades of production in this country, and has a very proud record in doing the right thing.
This paper relates specifically to one unique attribute associated with the production of CSG, namely the need to extract groundwater from the gas production wells in order that they be depressurised as a precursor to gas release. Pumping groundwater from of the coal seam ‘aquifers' targeted for the resource reduces the hydraulic pressure to the point that the adsorption bonds holding the methane to the surfaces of the coal cleats (or micro-fractures) are reversed and the gas moves into the gaseous phase, and is hence available to flow to the well under the prevailing hydraulic gradients. Typically, a CSG well is pumped for its groundwater, producing its peak flows early in the life of the well, with flows of water tapering off with time, as gas flows increase and peak some years into its life.