Seal capacity assessment is currently a mandatory step in Ecopetrol's offshore exploration workflow. The objective of this technique is to predict how close the formation pore pressure is to the fracture pressure - in order to foresee the potential risk of leakage by mechanical failure. Some relationships must be established: overpressure, hydrocarbon (HC) column heights and seal, since a reservoir under low effective stress will stand a lower buoyancy force and consequently a smaller HC column. Pore pressure and fracture pressure values were available from logs in 13 wells, while in 12 prospects those were estimated from interval velocities calibrated with leak off tests (LOT) and MDT data. In addition, two regimes were identified in the Caribe Sur area, a low overpressured regime and a highly overpressured one, the later coinciding with the presence of gas clouds and chimneys. One last conclusion is that HC columns rarely reach leak off pressure, suggesting that capillary leakage is reached before fracture failure occurs. Understanding of how, when and why pressure-related seal failure occurs is critical to avoid drilling dry holes. Keywords: Seal capacity, fracture pressure, pore pressure, hydrocarbon column, overpressure, effective stress.