Formation heat treatment is a process that has great potential as a method to increase the permeability of a formation; remove the damage caused during operations such as drilling, completions, and work-overs, and/or partially destroy the structure of clay in the near well-bore area. Published experimental work examining this technique confirms that, as a result of formation heating, blocking water can be vapourized, the clay structure may become dehydrated, the structure of the clays can be partially destroyed and, at temperatures above 600degrees C, microfractures can be generated in the sandstone. The few field studies utilizing this technique which have been reported list excellent results. However, the combination of high energy requirements and the use of specialized equipment makes the technique costly, so that its application in the field has not been accepted widely.