How does STABView evaluate the risk of borehole collapse while drilling?
STABView has two primary models for evaluating borehole collapse risk. Both of these models assess the mechanical integrity of the rock around the circumference of the borehole. STABView’s 2D model evaluates the size of the zone of yielded rock around the borehole using the theory of elastoplasticity, including pore pressures effects during over- or underbalanced drilling. This model is useful for vertical wells, or for horizontal wells that are approximately parallel to either the maximum or minimum horizontal in-situ stress. STABView’s elastic 3D model evaluates the bottomhole pressure or equivalent circulating density (ECD) at which shear yielding initiates on the borehole wall using linear elastic theory. When calibrated based on drilling experience for offset wells, this model has been shown to reliably predict the bottomhole pressure (or ECD) at which catastrophic hole collapse will occur.
