Analysis of overpressure generating mechanisms in different tectonic settings

Overpressure occurs at depth where formation fluid pressure exceeds hydrostatic pressure. A literature review of 56 overpressured basins out of &sim600 worldwide documented various overpressure generating mechanisms. Overpressure incidences are statistically analyzed by their hosting tectonic settings. The main mechanisms cited for those overpressured basins are disequilibrium compaction (&sim60%), hydrocarbon generation (&sim23%), tectonic compression (&sim14%) and diagenesis (&sim3%). The most common tectonic setting of surveyed basins with overpressured fluid conditions is the continental passive margin setting (&sim26%). Disequilibrium compaction is found to be the main overpressure generating mechanism in all tectonic settings. Basin age is an important variable to be considered because tectonic settings can change through time. The main contribution of this study is a table with percentages to be used in predicting possible overpressure generating mechanisms in a new or a reevaluated overpressured basin.