A method has been developed that allows the estimation of porosity as a function of reservoir depth in high vertical relief fields. Porosity is known to decrease as net overburden pressure increases. This porosity reduction in turn leads to large reductions in reservoir permeability, the end result being a significant reduction in productive pore volume, net pay, and well productivity. The Eastern Overthrust Fields in Venezuela’s El Furrial Trend produce from thick Miocene to Cretaceous sandstones and have very large hydrocarbon columns (two to three thousand feet is not unusual). Therefore, significant deterioration in pay quality is observed in the downdip areas. Using data from wells drilled in the Repsol/YPF Quiriquire Block, we observed that it was difficult to understand the true nature of the reservoir sands because the data was distorted by reservoir compaction in downdip wells. A method was developed to eliminate the distortion introduced by depth and overburden stress in porosity logs. This technique allows the well data to be interpreted as if all the wells had been drilled at a common datum. Once the undistorted data is interpreted and contoured, the data is re- shifted up or down using a depth grid map. Reservoir property grid maps can be prepared which better represent the sandstone properties at the depth at which they are found today. These maps can then be used in reservoir simulators to match and predict reservoir volumes and performance. The proposed method is most useful in development situations where there is sparse well control. Therefore, our first application has been in the Repsol/YPF operated Tropical Field, a 1998 discovery. Using this method, we prepared a reservoir description that depicts undrilled downdip areas much more accurately than would be possible using conventional methods. The new method resulted in large changes in our estimates of hydrocarbons in place and reserves and significantly impacted future development plans.