Hydraulic fracturing - QGC

A mixture of water and sand ispumped back into the well.Increasing flow ratesExploration and appraisal wells are drilled todetermine whether a coal seam holds commercialquantities of natural gas.These wells help us to understand the permeabilityof the coal, or the rate at which fluid or gas can passthrough the coal, and gauge the production capabilityof a particular area underground.Wells with higher flow rates of gas are typically moreefficient and productive than wells with lower flowrates.If the flow of water or gas to the surface is low,hydraulic fracturing may be used to stimulateproduction.QGC uses high-pressure pumps to inject a mixture ofwater and sand back into the well. The coal seamwater required for hydraulic fracturing is normallystored next to the well in temporary ponds that areabout 2500m 2 .The force of the water makes tiny cracks in the coalwhich are then held open by the sand particles,allowing the gas to more freely flow to the surface.This process can increase the productivity of a wellby two or three times compared to production ratesbefore fracturing.A clear benefit from hydraulic fracturing is areduction in the number of wells drilled in aparticular location.The United States Environmental Protection Agencyhas studied the impacts of hydraulic fracturing. In2004, it concluded that while thousands of wells arefractured annually in the United States the techniqueposed little or no threat to underground supplies ofdrinking water.A full copy of the EPA’s report, Evaluation of Impactsto Underground Sources of Drinking Water byHydraulic Fracturing of Coalbed Methane Reservoirs, isavailable via the agency’s website, www.epa.govHigh-pressure pumps inject the fracturing fluid back intowells to open tiny cracks in the coal seam.