CPC Subgroup
E21B 37/08 cleaning in situ of down-hole filters, screens, or gravel packs (E21B37/06 takes precedence)
Full Title
Methods or apparatus for cleaning boreholes or wells (E21B21/00 takes precedence) > cleaning in situ of down-hole filters, screens, or gravel packs (E21B37/06 takes precedence)