Abstract: An oil field production chemical, especially a scale inhibitor, is in the form of particles thereof carrying a coating e.g. of a dispersing agent. The coating may be polymeric such as an oligomeric polyacid polyester, a polymeric alkoxylated alcohol or a fatty acid polyamine condensate or it may also be a surfactant and may be used in the form of a suspension in an inert oil, such as diesel oil or kerosene which may be injected into a subterranean formation to inhibit the formation of deposits, e.g. scale in oil wells over a longer period than compounds free of the coating.

Abstract: An apparatus for producing an extrudate (e.g., water-dispersable extruded rod-shaped granules) from an extrudable powder-based material (e.g., a finely-divided water-insoluble powder) includes a hopper for the extrudable material having at least one extrusion aperture at its lower end, a rotatable extruder tool at or near the lower end of a first drive shaft for forcing the extrudable material through the aperture(s) and a rotatable feeder at or near a lower end of a second drive shaft for feeding the extrudable material to the extruder tool. The first drive shaft is rotatably mounted within the second drive shaft by axially displaced bearings, the second drive shaft being mounted within a fixed bearing housing by further axially displaced bearings. Drive motors are connected by respective drive trains to the upper ends of the first and second drive shafts, respectively.