SUCKER RODS STRING DESIGN – RODS FATIGUE BEHAVIOR INTERPRETATION USING GOODMAN DIAGRAM

Abstract

"During the standard pumping of an oil well, the sucker rods are subjective to alternative stress (tensile and compression). Certain steel grades have different behavior, taking into consideration their mechanical properties, like tensile strength. While most operators consider that, the higher the ultimate tensile strength (UTS) of a material is, it will behave better when subjected to loads. This paperwork shows that, comparing three different steel grades, they may have different results on the Goodman diagram, than expected. We are going to show that, even the steel grades have the same tensile strength (115 ksi), when calculating the %Goodman, the steel have different behavior, and this results from the manipulation of coefficients “A” and “b” involved in the formula, that each sucker rods manufacturer validates. "