The disclosure concerns methods for heating a subsurface formation using an electrical resistance heater. Preferably, the subsurface formation is an organic-rich rock formation, including, for example, an oil shale formation. The method may include providing an electrically conductive first member in a wellbore in a subsurface fornation, an electrically conductive second member in the wellbore, and an electrically conductive granular material in the wellbore. The granular material is positioned so as to provide an electrical connection between the first member and the second member. An electrical current is established across the first member, the granular material and the second member so as to generate resistive heat within the granular material. The surrounding subsurface formation is thereby conductively heated so as to cause formation hydrocarbons in the formation to be heated, and in some cases, pyrolyzed to form hydrocarbon fluids.