CPC Main Group
E21B 37/00 Methods or apparatus for cleaning boreholes or wells (E21B21/00 takes precedence)
4 direct subcodes
Child Classifications
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- E21B 37/02 Scrapers specially adapted therefor
- E21B 37/06 using chemical means for preventing or limiting the deposition of paraffins or like substances
- E21B 37/08 cleaning in situ of down-hole filters, screens, or gravel packs (E21B37/06 takes precedence)
- E21B 37/10 Well swabs