15 - Gravity driven flows in porous rocks: Effects of layering, reaction, boiling and double advection

Abstract

This chapter presents a hierarchy of models to describe gravity driven flows in porous rocks and the models account for a series of phenomena which can change the structure and spreading rate of the current. These include draining through the lower boundary of the formation or into a fracture intersecting the channel; reaction of the injected liquid with the formation that changes the permeability; boiling of the injected fluid as occurs in a superheated system; and the effects of thermal inertia in producing a range of double advective phenomena in currents driven by both temperature and salinity. Where possible, theoretical models are compared with laboratory data and some discussion about the implications of the modeling for field scale processes is included. The aim is to describe some of the physical controls on the gravity driven spreading of fluid through porous layers, accounting for the extra complications to the flow associated with rock-fluid interactions. The chapter presents a solution to describe the effects of draining from the end of the formation, as a model of draining into a fracture which bounds the porous layer. Also it expands the model and associated solutions to account for the motion of a gravity current moving through a high permeability layer, bounded below by a thin layer of much smaller permeability, but through which the current can eventually drain. An investigation of the effect of rock-fluid interactions is presented, focusing on the role of reactions between the injected liquid and the porous matrix the thermal inertia of flow in a porous layer.