Leak-off test

The leak-off test (LOT) is routinely used to verify that the cement and formation being tested can withstand predicted wellbore pressures and that it’s safe to drill to the next casing point, but there are several sources for uncertainty in the result. Thermal and/or compressive effects in the system, high gels or shear-thinning fluid effects, and permeable formation effects can all conspire to mask the leak-off point that rig teams are trying to accurately determine.