Recently geomechanical analysis plays an important role in drilling process. Therefore, formation pore pressure study is essential to design suitable mud weight characteristics for safe drilling operations. Accurate prediction of fluid pressure in formation pore space impacts not only the safety of the drilling operation, but also the time and expense of drilling, as well as the condition of the formation for testing and production.

The Sarir Oil Field in Libya is regarded one of the most important oil resources in the Sirt Basin. The major reservoir of the Sarir Oil Field is the Upper Jurassic–Lower Cretaceous Nubian Sandstone, which is composed of sandstone interbedded with shales. This study presents pore pressure prediction of the Nubian Sandstone reservoir by using Eaton’s method calibrated by Repeat Formation Tester (RFT) for two wells. In order to predict pore pressure in subsurface rocks, Eaton’s resistivity and acoustic methods were further improved utilizing depth-dependent normal compaction equations. These customized procedures offer a much-improved method of managing compaction trendlines. The studied wireline log records revealed the trend of the Nubian reservoir pore pressure, which led to better design of the optimum drilling mud weight requirements. The results show a high correlation with the calibrated RFT measurements.