A quality control method for the preparation of dry compressed gas cylinder including passivating and/or preparing the compressed gas cylinder with the technique to be validated, filling the passivated/prepared compressed gas cylinder with gaseous carbon dioxide to a normal working pressure, wherein the gaseous carbon dioxide has a known .sup.18O isotope ratio, maintaining the pressurized gas cylinder at ambient temperature for a first predetermined period of time, and gradually emptying the pressurized gas cylinder, while simultaneously measuring the .sup.18O isotopic ratio, wherein a predetermined variation in the measured isotopic ratio of .sup.18O indicates a properly prepared cylinder.

A method for determining a relation between an initial saturation and a residual saturation in a first fluid in a porous sample, comprising the following steps saturating a porous sample with a second fluid; measuring a local volume of the second fluid in the porous sample; establishing a steady state profile of a saturation in the first fluid in the porous sample; generating a rise of a capillary ascension flow of the second fluid through the porous sample; during the capillary ascension flow, simultaneously measuring a local volume of the second fluid; and determining the relation between the initial saturation and the residual saturation based on the measured local volume.

The disclosure relates to methods for determining imbibition of hydraulic fracturing fluids into hydrocarbon-bearing formations. More specifically, the disclosure relates to laboratory methods for determining certain unconventional flow parameters to measure the imbibition over time of hydraulic fracturing fluids into a low-permeability hydrocarbon-bearing rock formation.

An isotope nuclear magnetic method for analyzing ineffective water absorption of rock pores includes steps of: saturating core pores of a core sample with a wetting phase fluid of water H.sub.2O, and obtaining a core T.sub.2 spectrum after being saturated with the water; re-saturating the core pores with a wetting phase fluid of heavy water D.sub.2O, and obtaining a rock baseline T.sub.2 spectrum; injecting fluorinated oil into the core sample saturated with the heavy water; injecting the water H.sub.2O, simulating a water injection process, and injecting the fluorinated oil, so as to analyze a content of immobile water and obtain a residual T.sub.2 spectrum, wherein a range formed by a difference between the residual T.sub.2 spectrum and the rock baseline T.sub.2 spectrum is an ineffective water absorption portion of the rock pores, and an ineffective water absorption amount is obtained.

The disclosure relates to methods for determining imbibition of hydraulic fracturing fluids into hydrocarbon-bearing formations. More specifically, the disclosure relates to laboratory methods for determining certain unconventional flow parameters to measure the imbibition over time of hydraulic fracturing fluids into a low-permeability hydrocarbon-bearing rock formation.

Disclosed is a method for determining moisture permeability of a textile. The method includes: a) providing at least one textile sample having a top surface and an opposed bottom surface, wherein at least a portion of the top surface is configured into a bowl shape for receiving a predetermined amount of a test liquid; b) introducing the predetermined amount of the test liquid into the bowl shape sample such that there is a minimum depth of the liquid contained above at least a portion of the top surface; and c) after a predetermined period of time, determining the moisture permeability of the textile sample by analyzing liquid penetration characteristics of any of the test liquid that may have permeated through the textile.

A method of constructing a model of permeation to mixtures of solvents of a multilayer polymer structure with n monolayers and its associated computer program. For example, selecting several initial compositions of solvent mixture E1 to Ey, carrying out a sorption measurement and a measurement of diffusion, discretizing said multilayer structure in space and time, estimating partial fluxes of each of the compounds of said composition of solvent mixture between each elementary slice of said multilayer structure, estimating on the one hand a maximal sorption ceiling of said downstream monolayer B and on the other hand the composition of solvent mixture at inlet of said downstream monolayer B, performing a mass balance from slice to slice as a function of time, adjusting the profile of concentrations, storing the concentration profiles and the partial fluxes obtained.

Mesoporous activated carbon having a mesopore structure of at least about 10%. In at least some embodiments, the activated carbon may be coconut shell-based. The enhanced activated carbon may have an intraparticle diffusion constant of at least about 40 mg/g/hr.sup.1/2.

A method for combined characterization of pore structure includes steps as follows. Firstly, CO.sub.2, N.sub.2 and high-pressure mercury intrusion porosimetry characterization curves are plotted based on actual measurement data, then, average values of the overlapping range of the CO.sub.2 and N.sub.2 characterization curves are calculated, and a function y.sub.i=(x) is fitted. Each pore volume y.sub.i corresponding to each pore diameter x.sub.i is calculated, and a curve is plotted with x.sub.i as a horizontal coordinate and y.sub.i as a vertical coordinate, thereby obtaining a characterization curve of the overlapping range between CO.sub.2 and N.sub.2 adsorptions. The same data processing is used to process the overlapping range data of the N.sub.2 and high-pressure mercury intrusion porosimetry characterization curves, to obtain the characterization curve between them. The characterization curves are spliced with the original CO.sub.2, N.sub.2, and high-pressure mercury intrusion porosimetry characterization curves to obtain a combined characterization curve.

Mesoporous activated carbon having a mesopore structure of at least about 10%. In at least some embodiments, the activated carbon may be coconut shell-based. The enhanced activated carbon may have an intraparticle diffusion constant of at least about 40 mg/g/hr.sup.1/2.