Changing the Safe Drilling Window With Invert Emulsion Drilling Fluids

摘要

Often the range in drilling-fluid densities required to prevent hole collapse without fracturing the wellbore (i.e., the safe drilling window) is narrow. This often is the case for wells having high deviation angles, and is of particular concern in extended-reach-drilling (ERD) wells. With increasing stepouts, the drilling equivalent circulating density (ECD) continues to climb with increasing measured depth (MD) while the true-vertical depth (TVD) remains fairly constant.