Many non-chemical treatment devices claim to control or reduce scaling by produced fluids. Obtaining controlled test data in the field is very difficult. Some controlled laboratory testing procedures for calcium carbonate and calcium sulphate dihydrate (gypsum) scaling are presented, together with sample results for treatment of supersaturated brines passed through a 13,500 Gauss field from an electromagnet, and a pair of dummy and magnetic tools for downhole application. Neither treatment had a significant effect on the amount of scale deposited, the morphology of the scale, and the turbidity of the mixed brines, over a wide range of supersaturations in the carbonate scaling system chosen. In a more limited study of the calcium sulphate system, significant differences were found between treatments with the magnetic and non-magnetic tools. However, in one experiment the magnetic tool increased the amount of deposit, while in a second identical one it decreased it. It is suggested that this inconsistency may be linked to random scale nucleation processes rather than any effect of an applied magnetic field.
Keywords: scale, scale control, calcium carbonate, calcium sulfate, non-chemical devices, magnetic fields, nucleation, laboratory testing methods