دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: drill pipe, tubing, sucker rods, and so forth with the diameter near the top of the well larger than the diameter below.

n: A string of drillpipe or casing that consists of two or more sizes or weights.

a tubing string with more than one tubing size. Normally the smallest pipe is on bottom with larger sizes toward the top. The sizes are set to minimize flowing friction and keep the velocity above the critical level to lift fluid.