Unusual Overpressured Formation Revealed by Integrated Analysis of Lwd, Drilling, Mud Logging and Wireline Data

An integrated analysis of LWD, drilling, Mud Logging and wireline data offered a possible explanation for the presence and behavior of an overpressured sand reservoir located at 1704 m depth in an exploration well drilled in the Getic Depression (Romania). The upper part (seal) of this formation blasted during drilling leading to the expulsion of 10 m3 of reservoir fluids (brine and dissolved gas). It can be assumed that the reservoir seal consists of hardened siltstone formed by diagenetic processes after a rapid shallow marine transgression – regression sedimentary cycle in this area created the reservoir itself.

Prior to this analysis, an explanation for the presence of the overpressured zone did not exist. As such, it could continue to pose threats to budgets and personnel safety. The unique combination of LWD and wireline data in this well combined with the standard mudlogging and drilling data resulted in the perfect blend of information to ascertain the geological reason for the overpressure occurrence.