Capillary Pressure
1. Since, the order by which displacement sequences occur in a petroleum reservoir remains primarily governed by the values of pore-scale ‘threshold capillary pressure’ (the minimum entry pressure required to initiate the displacement of a defending-phase by an invading-phase from the center of an element, i.e., pore or throat), would it remain feasible to estimate ‘threshold capillary pressure’ @ laboratory-scale using experiments associated with actual pore geometries, having both non-uniform wettability and multi-phase fluids (water, oil & gas), and not estimating capillary pressures in a system of capillary tubes consisting of idealized geometrical cross sections with the corresponding pore-size distribution?
2. Whether the calculation of capillary pressures as well as the prediction of fluid configurations within irregular pore shapes would remain feasible with SEM in the absence of physical constraints such as pore boundaries of asymmetrical shape; or, pore boundaries with non-uniform wettability (and leading to a thermodynamically inconsistent scenario, where Mayer, Stowe and Princen theory based on a free energy balance between the fluid and solid phases within a reservoir cannot be applied)?
3. If the three‐dimensional (3‐D) pore network controls the distribution of the fluids in a petroleum reservoir, but once a fluid gains access to a given pore, it is the local and the threshold capillary pressures of the displacement that determine whether the displacement in that pore will take place or not, then, would it remain feasible to compute the actual threshold capillary pressure having complex displacements (unlike piston-like displacements) using actual irregular pore geometries @ laboratory-scale using experiments?
4. Under what circumstances, in a real field petroleum reservoir, whether the fluid configuration can be considered to remain to be thermodynamically favorable, upon minimizing the free energy of the system?
Also, whether the total Helmholtz free energy would always remain to be linearly proportional to the ‘interfacial tension between fluid phases’ (equal to the work done per unit increase in interfacial area) and the pressure of the fluid phase?
If not, then, how could we assume the reservoir to be a closed system, whereby, the reservoir @ a constant temperature and @ a fixed total volume is supposed to be at equilibrium upon minimizing Helmholtz free energy?