{HEAD ~ Wellbore WB} contains {TAIL ~ a conventional drill pipe DP} extending from the surface S to the lower end of the wellbore 
contains
{ HEAD ~ Wellbore WB } contains { TAIL ~ a conventional drill pipe DP } extending from the surface S to the lower end of the wellbore
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH