Referring to FIG 1, {HEAD ~ wellhead housing} 11 is {TAIL ~ a large tubular member} located at the sea floor 
is
Referring to FIG 1 , { HEAD ~ wellhead housing } 11 is { TAIL ~ a large tubular member } located at the sea floor
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH