دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: a casing string with joints of various collapse resistance, internal yield strength, and tensile strength, designed for various depths in a specific well to best withstand the conditions of that well. In deep wens, high tensile strength is required in the top casing joints to carry the load, whereas high collapse resistance and internal yield strength are needed in the bottom joints. In the middle of the casing, average quality is usually sufficient. The most suitable combination of types and weights of pipe helps to ensure efficient production at a minimum cost.

n: A casing string made up of various different grades or weights of casing (sometimes referred to as a tapered string).

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.