Primary drainage

The estimation of flow functions from an actual experiment is reported next. A multi-rate primary drainage experiment was conducted on a Texas Cream limestone sample. Hexadecane was used as the oleic phase and deuterium oxide (D20) was used as the aqueous phase. Protons are imaged, so only the oil phase is observed. The pressure drop data, production data and saturation data are shown in Figures 4.1.11-... 

Fig. 4.1.11 Calculated and measured pressure-drop data in a multi-rate primary drainage experiment on the Texas Cream limestone sample (Reprinted with permission for [34]).

The superior vena cava (SVC) is the primary drainage vein for blood return from the head, neck, and upper extremities. It is a relatively thin-walled vein that is particularly vulnerable to obstruction from adjacent tumor invasion or thrombosis. The obstruction leads to elevated venous pressure, although collateral veins partially compensate. This is one reason for the relatively slow onset of the classic symptoms of SVCS. In fact, 75% of patients have signs and symptoms for more than 1 week before seeking medical attention.15... 

Since water must be forced into a dry GDM regardless of PTFE-content, water is effectively the non-wetting phase. This process has the characteristics of primary drainage, for which invasion percolation30 is an adequate model.6,31 Invasion percolation describes... 

Figure 10 displays the steady state invading liquid water fronts corresponding to increasing capillary pressures from the primary drainage simulation in the reconstructed CL microstructure... 

Figure 10. Advancing liquid water front with increasing capillary pressure through the initially air-saturated reconstructed CL microstructure from the primary drainage simulation.

Figure 12. 2-D phase distribution maps on several cross-sections along the GDL through-plane direction from the primary drainage simulation.

The primary drainage and steady-state flow simulations, described in the earlier section and typically devised in the petroleum/reservoir engineering applications,53 54 58,60 were deployed to evaluate the capillary pressure and relative permeability relations as functions of liquid water saturation, respectively. 

Lambiase, R.E., Deyoe, L., Cronan, J.J., Dorfman, G.S. Percutaneous drainage of 335 consecutive abscesses results of primary drainage with 1-year follow-up. Radiology 1992 184 167-179... 

Primary Drainage - Water Wet O Primary Drainage - Intermediate Wet A Primary Drainage - Organic Wet... 

Figure 5. (a) Primary drainage and (b) primary imbibition two-phase (water/PCE) capillary pressure-saturation curves for water-, intermediate-, and... 

The core samples were flooded with CO for several hours and saturated with brine under vacuum. To insure complete saturation and stabilization of absolute permeability each core was flooded with at least 300 pore volumes of brine while a back pressure of 500 psi was always imposed against the flow. For all the cores primary drainage was completed by displacement. Oil was pumped with a rate of 2 cc/min for 150 pore volumes. The water saturation at this stage was considered irreducible. Tables 2 through 4 each show the types of experiments, the order in which they have been conducted, and the end points of each experiment for core number 1 to 3 respectively. The displacement experiments conducted with a rate lower than 2 cc/min, were followed by a bump after the pressure drop and production was stabilized. For these experiments, the end point relative permeabilities and water saturation after the bump, and the average water saturation before the bump are shown. Steady state experiments were only conducted on Core No. 1. These experiments... 

Area under primary drainage curve A2—Area under imbibition curve A —Area under secondary drainage curve Wettability index,... 

For the numerical setup for a primary drainage simulation in the LBM fiumework, a non-wetting phase (NWP) reservoir is added to the porous structure at the fi ont end and a wetting phase (WP) reservoir is added at the back end." These two end reservoirs added to the porous structure in the through-plane (i.e. thickness) direction are composed of void space. It should be noted that for the primary drainage simulation in the typical hydrophobic PEMFC porous structures, liquid water is the NWP and air is the WP. Fixed pressure boundary conditions, which are equivalent to... 

Primary drainage and waterflood capillary pressures and relative permeabilities are determined from multiphase flow simulations based on the pore network. Flow simulation input parameters are set according to expected wettability conditions (Kalam, 2006, 2012). Kalam (2012) lists the following properties ... 

Network-based flow relations capillary pressure as a functiOTi of water saturation, relative permeability as a function of water saturatiOTi, Resistivity Index as a function of water saturation, and corresponding saturation exponent n for both primary drainage and imbibition cycle. 

Volotkin, Y., Looyestijn, W.J., Slijkerman, W.F.J., Hofman, J.P., 2001. A practical approach to obtain primary drainage capillary pressure curves from NMR core and log data. Petrophysics 42, 334-342. July-August. 

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