Permeability profile

Marquis [86] described a method of enhancing the permeability profile of an oil-bearing formation during the injection of a foam-forming composition or a... 

Fig. 3.4 Permeability profiles for (a) warfarin (acid), (b) propranolol (base) and (c) morphine (ampholyte) based on a BBB PAMPA model (plON) composed of animal brain extract of lipids. The data (unpublished) were analyzed with the pCEL-X program (plON), with the refined parameters indicated in the three frames. In all three cases, there was evidence for the permeation of charged...

Once the precipitate is formed in the larger pores, the subsequent fluid flow will be diverted to relatively smaller pores, thereby increasing the sweep efficiency. Additional experimental work with a series of connected cores suggested that the permeability profile can be successfully modified. However, pH control plays a critical role in the propagation of the chemical precipitation reaction [48]. 

D. H. Hoskin, T. O. Mitchell, and P. Shu. Oil reservoir permeability profile control with crosslinked welan gum biopolymers. Patent US 4981520, 1991. 

Avdeef, A., High-throughput measurements of permeability profiles, in van de Waterbeemd, H. Lennemas, H. Artursson, P. (eds.), Drug Bioavailability. Estimation of Solubility, Permeability, Absorption and Bioavailability Wiley-VCH Weinheim, 2003 (in press)... 

The determination of the evolution of the permeability of these rocks during acidizing is necessary when attempting to predict the evolution of the skin (Equation 2). Previous studies (6) have tried to model the shift of the pore size distribution due to acid attack. Then, permeability profiles were computed by integrating the contributions to the overall flow of each of the rock pores, all over the considered volume of rock. The main limitation of this method lies in the disregarding of the spatial correlation between rock pores. 

Another approach of the problem has been proposed recently (9). Based on a comprehensive experimental study, it considers that wormholes have an almost infinite conductivity in comparison with the original pores of the rock. Consequently, a fair approximation of the permeability profile of an acidized piece of rock of length L is a step function. From its inlet up to almost the tip of the wormholes, the permeability is infinite. In the rest of the rock, it is equal to the original one, i.e. ko, and the overall permeability of this core becomes ... 

Injecting acid in such an interval produces wormholes in the nearwellbore region, which is damaged, so that the acid flow only takes place in the clean primary porosity of the rock. This superposes to the original step function of the permeability profile a second, similar function, stating that the acidized profile now includes in the vicinity of the wellbore, from rw up to re, a zone of infinite conductivity... 

Figure 1 Permeability profile in a damaged double porosity reservoir during acidizing. rw wellbore radius, re wormholes penetration, damage radius, kptp undamaged reservoir permeability (total contribution of both primary and secondary porosities), kPP damaged permeability (primary porosity contribution only).

Class III High Low Same as Class I. Correlation will depend on intestinal permeability profile along the gastrointestinal tract. 

As such, VolSurf affords much structural information of use in designing compounds with optimal permeability profile, and in defining an ideal property space in similarity searches. 

Avdeef A (2002) Eligh-throughput measurement of permeability profiles. In Van de Waterbeemd H, Lennernas H, Arturrson P (Eds) Drug Bioavailability— Estimation of Solubility, Permeability and Absorption. Wiley-VCH, Weinheim, pp 46-70. 

Gyurosiova, L., Laitinen, L., Raiman, J., et al. Permeability profiles of M-alkoxy-substituted pyrrolidinoethylesters of phenylcarbamic acid across caco-2 monolayers and human skin. Pharm. Res. 19(2) 162-168, 2002. 

Figure 11.18 Comparison of methane conversion as a function of the molar fraction of oxygen in the total feed in two reactors using porous membranes with a uniform permeability and a decreasing permeability profile at 750 C and a total flowrate of 172 standard cm /min (open circles represent the membrane with a decreasing permeability along its length and open squares represent the membrane with a uniform permeability) (Coronas et al., 1994J...

The chemical structure of a drug determines its solubility and permeability profiles. In turn, the concentration at the intestinal lumen and the permeation of the drug across the intestinal mucosa are responsible for the rate and extent of absorption.39 Unfavorable physicochemical properties have been a limiting factor in the oral absorption of peptides and peptidomimetics.40 The structural factors involved in the permeation of peptides will be described here. 

Figure 4 Plots of predicted permeability with depth at the Amherst Test Site, CPTU-I. Permeability profiles are determined from the data pairs (a) Bq-Qt, (b) Fr-Qt, and (c) Bq-Fr to recover magnitudes of Kp.

Figure 9.7 Effective permeabilities for some weak acids, as measured by PAMPAs at three different pH values. pAa values for the acids are shown in parentheses. (Reproduced with permission from Avdeef, A., High-throughput Measurement of Permeability Profiles , Chapter 3 in Drug Bioavailability, van de Waterbeemd, H., Lennernas, H., Artursson, P., Eds. (Wiley-VCH Verlag GmbH Co. KGaA) p. 53, copyright 2003).

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