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