When is a Leak-Off Test (LOT) performed?

A Leak-Off Test (LOT) is performed after drilling out the casing shoe and entering a new formation to determine the integrity and pressure of the formation being targeted for drilling. This test helps in assessing the formation's ability to withstand drilling pressures without fluid loss, which is critical to ensuring that the well is safe to proceed. By conducting the LOT at this point, operators can gather essential data regarding the pressure gradient and mechanical properties of the newly encountered formation.

Performing the LOT at this stage is vital because it can help prevent well control issues that might arise from conditioning the wellbore before continuing drilling operations. The test informs operators about the formation's capacity to hold pressure and ensures that the drilling plan is adjusted accordingly to avoid any potential blowout or ineffective drilling conditions.

Other options present stages that are not suitable for conducting a Leak-Off Test. For instance, carrying out a LOT before drilling out the casing shoe would not provide accurate formation data, as the formation has not yet been accessed. Conducting it during the initial drilling stages wouldn't be effective either, since the formation has not been adequately evaluated yet. Finally, performing a LOT after the well has been completed would not provide valuable information for ongoing operations, as the well should have been evaluated prior to