reacting the oxidant and fuel in {HEAD ~ the oxidizers} to produce {TAIL ~ heat} to heat a portion of the formation; and 
reacting the oxidant and fuel in { HEAD ~ the oxidizers } to produce { TAIL ~ heat } to heat a portion of the formation ; and
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH