In oil and gas industry, one of the solutions to improve productivity of oil and gas production is to remove scale formation in the near wellbore. Many treatment methods have been applied, however, the most common method is acid treatment. It is usually difficult to treat in the near wellbore of sandstone reservoirs with traditional acid system. As geologic information and past experience of acid treatment in the near wellbore at Vietsovpetro shown that two concerning problems are high temprature and secondary precipitation. New chemical system based on HEDP and NH4HF2 have shown important characteristic such as lower corrosion rate of production pipe, casing, and equipment in well high temperature condition, control of secondary precipitation after reaction, better penetration into reservoir, and better bond of reservoir wall after treatment.