Electromagnetic Devices (EMDs) have been used for scale management in the field. The proposed mechanism for their function is that the device imparts an electromagnetic pulse that provides sufficient energy to cause homogeneous nucleation, resulting in the formation of very small particles (5-8 microns) which pass through the production system, preventing heterogeneous nucleation and deposition. This paper summarises an experimental programme to examine the proposed mechanism of operation of the EMD under controlled laboratory conditions. Flow experiments were performed under ambient conditions using a mixed North Sea Seawater (NSSW) / Nelson Forties Formation Water (NFFW) scaling system. Experiments were performed with the EMD active and compared to baseline experiments where the EMD was inactive, to assess if the device impacted the scaling process.
A full quantitative assessment for each experiment was performed including; assessment of the mass of scale deposited and its location, full effluent analysis by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP) and effluent sample filtration for solids content, morphology using Environmental Scanning Electron Microscopy / Energy Dispersive X-ray (ESEM/EDX) analysis and particle size distribution (PSD). From the experiments performed, it was found that the device impacted the scale deposition process in comparison to when it was not activated. Results indicated that although a similar amount of scale is lost from solution, less deposit was collected in the test apparatus itself. The precipitate in the effluent samples (which had passed through the apparatus) was found to have a mean particle size in the region of 10 microns, with a significant proportion of the distribution of particles below 1 micron; this was confirmed by ESEM/EDX and PSD. A further particle distribution range was identified as less than 0.22 microns. This material (10-20% of that injected) passed through the 0.22 micron filter used to collect the solid, but was accounted for when the experimental procedure was adapted.
The results from this study indicate that under the conditions used, the EMD has an impact on the scaling process resulting in homogeneous nucleation of smaller scale particles that are transported through the apparatus. This supports the mechanism reported previously and provides a greater understanding to how such devices work in the field.