A method for forming a wellbore in a heated formation includes flowing liquid cooling fluid to a bottom hole assembly in a wellbore in a heated formation. At least a portion of the liquid cooling fluid is vaporized at or near a region to be cooled. Vaporizing the liquid cooling fluid absorbs heat from...http://www.google.de/patents/US20090194329?utm_source=gb-gplus-sharePatent US20090194329 - METHODS FOR FORMING WELLBORES IN HEATED FORMATIONS
