Hauptnavigation

• About
• Team

Inhalt

Permeability experiments

Absolute permeability (k_abs, [m², Darcy])

Single-phase experiments to determine the absolute permeability of the mudstones are performed with a steady-state method. Constant fluid pressure is applied at the upstream side and the fluid volume forced through the sample was measured at the downstream side of the pressure cell. The pressure at the downstream side is atmospheric. Normal tap water as well as brine (100g NaCl/1l H2O) are used as fluid phases.

Effective permeability (k_eff, [m², Darcy])

If the capillary pressure is high enough to force the non-wetting fluid into the pore space the wetting fluid will be gradually displaced, thus the wetting fluid saturation will be reduced. The porous rock, now containing two different, immiscible fluids has an effective permeability to each fluid phase as a function of its fractional saturation. The ratio between the effective permeability (k_eff) and the absolute permeability (k_abs, single-phase flow) is called relative permeability (k_r), and is expressed in fractions of 1. Thus, Darcy's law can be rewritten for a system that contains two fluids:

The effective permeability (k_eff) to the gas-phase is determined by gas breakthrough experiments, a non-steady-state technique.