Field testing results of downhole scale inhibitor injection

The first field tests on the addition of scale inhibitors to geothermal brines were carried out in Italy between 1981 and 1985 at Cesano and at Latera. A long-term experiment was recently performed in the Latera 2 well to check the feasibility of the downhole inhibitor injection technique as a reliable solution to the carbonate scaling problem. A plastic-lined injection pipe was used to solve the corrosion problems caused by the inhibitor itself. Two different scale inhibitors have been tested down to minimum concentrations of 10 ppm. Downhole injection was performed at about 750 m depth using a 4.6 mm OD flexible pipe freely lowered in the 9″5/8 casing and with total flow rates of 300 t/h for three months.