The graphs show that fluid density , increasable with the effective circulating fluid slurry density in excess of the subterranean strata pore pressure , must be maintained to prevent ingress of unwanted subterranean substances into said circulated fluid slurry and pressured {HEAD ~ caving} of {TAIL ~ rock} from the walls of the strata passageway 
The graphs show that fluid density , increasable with the effective circulating fluid slurry density in excess of the subterranean strata pore pressure , must be maintained to prevent ingress of unwanted subterranean substances into said circulated fluid slurry and pressured { HEAD ~ caving } of { TAIL ~ rock } from the walls of the strata passageway
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