Apparatus for plugging a blast hole in an in situ oil shale retort or the like

摘要

A plugging apparatus is provided to reliably plug a bottomless blast hole in underground oil shale retorts and oil and gas wells. The plugging apparatus has a special electrically powered sequencer which automatically lowers and releases a bag of cementatious slurry, supported by a drainpipe-reinforced concrete disc, from a canister to form a composite blasting plug in the blast hole.