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