The more usual (generic) German term is "Stützmittel".

"Sized particles mixed with fracturing fluid to hold fractures open after a hydraulic fracturing treatment. In addition to naturally occurring sand grains, man-made or specially engineered proppants, such as resin-coated sand or high-strength ceramic materials like sintered bauxite, may also be used. Proppant materials are carefully sorted for size and sphericity to provide an efficient conduit for production of fluid from the reservoir to the wellbore."
See www.glossary.oilfield.slb.com/Display.cfm?Term=proppant

Plenty more references in the given context.