E FIXED CONSTRUCTIONS
E21 EARTH OR ROCK DRILLING; MINING
E21B EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
E21B43/00 Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
E21B43/25 Methods for stimulating production
E21B43/26 by forming crevices or fractures
E21B43/2607 Surface equipment specially adapted for fracturing operations