• The principal objective of the research on electrostatic charging is to improve our understanding of why powders get charged, how it can be controlled and avoided when it is undesirable, and enhanced when it is desired. Electrostatic powder coating has been investigated, and a considerable activity was the investigation of how electrostatic attractive forces between oppositely charged particles could be used to achieve ideal and stable mixtures of different powders.

• Magnetic shielding due to magnetic particulate solids in drilling fluids: The magnetic properties of a drilling fluid are known to vary significantly, depending on the mineralogical composition of the weight material such as dolomite, magnetite in the drilling fluid, or / and the magnetic contamination (mainly iron of steel etc.) during the handling process of the drilling fluid involving particulate solids in dry condition or slurry. It has been established that magnetic properties in the drilling fluid shield the Earth’s magnetic field measured by the magnetic sensors present in MWD directional tools (see Figure), and contribute significantly to errors in directional surveying of wellbores. Magnetic shielding degrades the borehole position accuracy.

Fig. Shielded magnetic field as a function of time for different concentrations of magnetite powders.