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Porosity that is not considered "effective porosity" includes water bound to clay particles (known as bound water) and isolated "vuggy" porosity (vugs not connected to other pores, or dead-end pores). The effective porosity is of great importance in considering the suitability of rocks or sediments as oil or gas reservoirs, or as aquifers.
The porosity is a measure of the total pore space in the soil. This is defined as a fraction of volume often given in percent. The amount of porosity in a soil depends on the minerals that make up the soil and on the amount of sorting occurring within the soil structure.
Connected porosity is more easily measured through the volume of gas or liquid that can flow into the rock, whereas fluids cannot access unconnected pores. Porosity is the ratio of pore volume to its total volume. Porosity is controlled by: rock type, pore distribution, cementation, diagenetic history and composition. Porosity is not controlled ...
Φ T = Total porosity (PHIT), which includes the connected and not connected pore throats. Φ e = Effective porosity which includes only the inter-connected pore throats. V b = bulk volume of the rock. Key equations: V ma + V cl + V fw + V hyd = 1 Rock matrix volume + wet clay volume + water free volume + hydrocarbon volume = bulk rock volume [20]
Specific yield, also known as the drainable porosity, is a ratio, less than or equal to the effective porosity, indicating the volumetric fraction of the bulk aquifer volume that a given aquifer will yield when all the water is allowed to drain out of it under the forces of gravity: = where
Permeability is typically determined in the lab by application of Darcy's law under steady state conditions or, more generally, by application of various solutions to the diffusion equation for unsteady flow conditions. [8] Permeability needs to be measured, either directly (using Darcy's law), or through estimation using empirically derived ...
Porosity, , is the ratio of volume of voids to the total volume, and is related to the void ratio: = = + = + Degree of ... From the effective stress equation, the ...
A force balance equation known as Washburn's equation for the above material having cylindrical pores is given as: [1] ... Porosity; Wood's metal, ...