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