Abstract: Embodiments comprise a method of removing material at a well, involving progressively jetting heat along a helical path to heat a target material for removal. Embodiments of the method comprise material removal from a downhole well element, involving running in a downhole assembly with a downhole heating device comprising a fuel towards a target location. For example, such embodiments provide an alternative method for the removal of wellbore tubulars, using a rapid oxidation process to significantly alter the physical state of the tubular well element and reduce it to an oxide deviate, thereby facilitating an area where a more conventional barrier can be installed in the wellbore.