Formation pore pressure in sedimentary basins is known to vary with depth. These variations are caused by one or more sedimentary, tectonic or diagenetic mechanisms. In Mesozoic basins of southern Tunisia, a detailed study has been carried out in order to characterize the regional pore pressure profile. The results show an over-pressure interval ranging from upper Triassic to lower Jurassic salts series.

The study of possible overpressure mechanisms allows us to conclude that the present-day overpressure can be explained by the active compressional tectonics that is affecting the North African margin. Nevertheless, other past overpressures have been interpreted from this study and have been attributed to different mechanisms. One of the most important paleo-overpressure mechanisms was gypsum dehydration. This diagenetic reaction has led to pore pressure approaching lithostatic pressure, demonstrated by hydraulic fractures and beef veins observed in fields.

In this study, we established a method based on a depth chart diagram enabling the identification of the likely mechanism involved in reservoir overpressure build-up and/or the prediction of a potential mechanism. This result could be important in the analysis of unexplored basins to predict the anticipated pressure profile and thereby reduce the risk of encountering unexpected overpressured zones and related drilling hazards. This method could be applied to other sedimentary basins with standard geological backgrounds.

已知沉积盆地中的地层孔隙压力随深度而变化。这些变化是由一种或多种沉积、构造或成岩机制引起的。在突尼斯南部的中生代盆地，为了表征区域孔隙压力剖面，已经进行了详细的研究。结果显示了从上三叠统到下侏罗统盐系的超压区间。

对可能的超压机制的研究使我们得出结论，目前的超压可以用影响北非边缘的活动挤压构造来解释。尽管如此，本研究已经解释了过去的其他超压，并归因于不同的机制。最重要的古超压机制之一是石膏脱水。这种成岩反应导致孔隙压力接近岩石静压，在田间观察到的水力裂缝和牛脉证明了这一点。

在这项研究中，我们建立了一种基于深度图的方法，能够识别涉及储层超压建立的可能机制和/或预测潜在机制。这一结果对于未勘探盆地的分析非常重要，可以预测预期的压力剖面，从而降低遇到意外超压区和相关钻井危险的风险。该方法可应用于具有标准地质背景的其他沉积盆地。