부산대학교 도서관

San Juan Basin, Fruitland Formation coalbed natural gas wells completed with open hole cavities using a controlled injection-blowout technique are often producing significantly greater gas and water rates than cased, hydraulically fractured wells in similar geologic environments. The cavity completion effectively connects the coal natural fracture system and the well. At the COAL Site, the pre-cavitation fluid productivity appeared to be controlled by the lower permeability butt cleat system. Post-cavitation productivity appears to be controlled by the greater permeability face cleat system. The 13 fold increase in gas productivity at the Site caused by the cavitation process is due to increased well-reservoir connectivity. The presence of the cavity is responsible only for a 60% increase in productivity. Formation damage was minimized by the lack of contact between the coal reservoir rock and drilling fluids. The near-cavity permeability appears to be temporarily increased during the cavitation operations. The near-cavity permeability increase is non-existent after extended production.