In the tubular design of oil and gas wells, visualization of the loads and design limits (resistance over design factor) in a single 2D plot can help provide well designers a safety-factor overview of a particular string section. This plot is called a design limits plot (DLP). This paper illustrates the theoretical foundation and construction procedure of a new DLP, which is believed to more accurately represent safety factors.
The new DLP was built by plotting differential pressure, ΔP, vs. equivalent axial load Feq (= Fa +
A field example is presented that demonstrates the application of the new DLP for wellbore tubular design. It is shown that, for load cases in which counter-load pressures (which are defined as
Using the equivalent axial load instead of the axial force in the new DLP allows for better consistency with both the von Mises triaxial yield criterion and the