Abstract: An electric downhole heating system for formation heat treatment in the field of oil and gas production contains a separate wiring chamber, heating chamber, and cooling chamber, the latter being inserted between the wiring chamber and the heating chamber. The heat treatment is carried out by inserting the heater in a borehole to be treated. A gas, preferably nitrogen or air, is brought to the heater with a hose or tube. The gas flows through the wiring chamber and cooling chamber, and is heated by following a tortuous path in the heating chamber before it is expelled from the heater.

Abstract: A batch method of in situ steam generation for steamflooding which comprises injecting hydrocarbons into an upper zone of the formation to serve as fuel for in situ combustion, injecting oxidant into the lower zone causing at least a portion of the oxidant to contact and combust with the injected hydrocarbons, injecting water into the upper zone to be converted into steam by the hot formation, followed by ceasing oxidant injection, injecting a non-oxidant material into the lower zone so that the combustion zone does not approach the wellbore, and generating a steam front to drive formation hydrocarbons towards at least one production well.