Utilization of Mud Weights in Excess of the Least Principal Stress to Stabilize Wellbores: Theory and Practical Examples

摘要

In this paper, we address the theoretical possibility of drilling with mud weights in excess of the least principal stress for cases of par- ticularly high pore pressure or severe wellbore instability. Because lost circulation caused by hydraulic fracturing is to be avoided, we consider three critical wellbore pressures, p_(frac), p_(link), and p_(grow). Tensile fractures initiate at the wellbore wall at p_(frac), link up to form large axial fractures that are subparallel to the wellbore axis at p_(link), and propagate away from the wellbore at p_(grow). It is obvious that lost circulation cannot occur if the wellbore pressure during drilling is below p_(frac).