A method for treating a tar sands formation includes providing heat from a first heater located between a steam injection well and a production well in a hydrocarbon containing layer. The first heater, the steam injection well, and the production well are located substantially horizontally in the layer. Heat is provided from a second heater horizontally offset from the first heater. The second heater is located vertically above an injection/production well and substantially horizontally in the layer. Steam is injected into the layer through the steam injection well after a selected amount of heat is provided from the first heater. Hydrocarbons are produced from the layer through the production well. Steam is injected and hydrocarbons are produced alternately through the injection/production well after a selected amount of heat is provided from the second heater.