Genesis of mud volcanoes in sedimentary basins: A solitary wave-based mechanism

Abstract

Mud volcanoes represent the ground surface morphological expression of highly focused fluid flow inside sedimentary basins. Sedimentary basins show usually the presence of overpressured compartments encapsulated by low-permeability bounds (seals), which can have different origins (capillary barriers with high entry capillary pressure, diagenetically sealed formations...). A mud volcano can be formed in response to the hydrofracturation of such a permeability barrier. When introducing the pressure dependence of permeability in poroelasticity, the theory predicts the upsurge of fluid pressure fronts after the hydrofracturation of the seal (initial shock). These fronts take the form of hydro-mechanical non-linear shock waves, which are solutions of a Bürgers-type equation. These (solitary) waves are associated with an upsurge of pore water, which depends on the pore fluid pressure gradient carried up with the waves. The arrival of these waves at the ground surface can generate mud volcanoes-type features with spots of highly focused flow.