NOVELTY - The method involves acquiring information relating to a human-made downhole feature using a treatment tool (10) positioned in a borehole (12). A condition e.g. phase condition, relating to the downhole feature is estimated based on the acquired information. The downhole feature is treated using additive applied by the treatment tool. A change in the condition of the downhole feature is estimated after the treatment of the downhole feature. The treatment tool is positioned in the borehole. The treatment tool is kept in the borehole while the condition is estimated.    USE - Method for treating a human-made naturally occurring downhole feature e.g. hydrocarbon bearing subsurface formation, fluid (all claimed) such as liquid hydrocarbon, gaseous hydrocarbon, brine and water, rock, earth, soil, wellbore tubular such as casing, liner and production tubing, production device, intelligent well completion device, anchor, sand screen, valve and packer, associated with a borehole e.g. hydrocarbon producing well, geothermal well and groundwater well, utilized in oil and gas industry for offshore or subsea applications.    ADVANTAGE - The method enables providing enhanced additive treatment systems. The method enables the treatment tool to be used to cost-efficiently isolate and treat specific zones in a single trip, thus minimizing scale deposition or scale squeeze. The method enables a treatment system to monitor treatment to evaluate treatment effectiveness. The method enables distributing sensors at and around a region in which the additive is being applied to increase accuracy and resolution of the information acquired by the sensors.    DETAILED DESCRIPTION - The additive is selected from a group consisting of an additive formulated to adjust a formation parameter, an additive formulated to adjust a chemical property, an additive formulated to adjust a fluid property, a corrosion inhibitor, gas, liquid, gel, plasma, solid acid, magnetorheological fluid, proppant, gravel, cement and resin. An INDEPENDENT CLAIM is also included for an apparatus for treating a downhole feature.    DESCRIPTION OF DRAWING(S) - The drawing shows an elevational view of a treatment tool.    Treatment tool (10)    Borehole (12)    Sensors (20, 21)    Flow line (24)    Communication line (26)