Pore Size Distribution Of Porous Media Research Articles

Estimation of shale pore-size-distribution from N2 adsorption characteristics employing modified BJH algorithm

Accurate pore-size-distribution (PSD) is the key to comprehending porous media and shale rock characteristics. There are multiple methods for calculating the PSD of porous media. The Barrett–Joyner–Halenda (BJH) method is the most widely used and simplest calculation, and therefore, this study focus on the BJH algorithm to discuss the accurate shale PSD based on N2 adsorption characteristics. Despite conducting more than a hundred experiments there are certain phenomena for which the calculated pore volume is smaller than the actual pore volume. Therefore, we combined the Brunauer–Emmet–Teller (BET) multilayer adsorption theory and Halsey adsorption equation to analyze the capillary evaporation and desorption demarcation points in the desorption isotherm of each shale sample, and a modified PSD calculation model was established. In addition, we applied the modified BJH algorithm to a homogeneous silicon material with the pore radius known, for calculating the theoretical pore radius and subsequently the pore radii; this allowed determining the correctness of the modified algorithm. The calculation error was approximately 5% that indicated the accuracy of this algorithm. Therefore, this study could provide meaningful insights into the accurate PSD calculation and gas-in-place estimation in shale nanoporous media.

A permeability-change relationship in the dryout zone for CO2 injection into saline aquifers

Injectivity is critical for injection of CO2 into saline aquifers. Previous model studies indicate that injectivity can be impaired by salt precipitation near the injection well. These results are largely determined by the relationships between permeability and salt precipitation. In this study, we develop a new relationship for permeability change owing to salt precipitation near a CO2 injection well. This relationship differs from previous relationships in that it considers the fact that the salt precipitation occurs only in pore space occupied by brine during the precipitation process, and in that it is based on well-established relative-permeability relationships for two-phase flow in porous media. Using this relationship, we can link permeability change to the effects of saturation in a CO2–brine system and the pore-size distribution of porous media. Its usefulness is demonstrated by the good agreement between predicted results and observations from a laboratory experiment. The developed methodology, in principle, can also be applied to other two-phase flow systems involving chemical-reaction-induced permeability changes.

An Image-Based Method for Obtaining Pore-Size Distribution of Porous Media

This purpose of this investigation is to develop a new method for obtaining pore-size distribution (PSD) and other pore parameters from inner structure images. This method can be summarized into four key procedures to realize its functionality. A MATLAB program was composed to make the method applicable for image analysis. Image tests on wastewater biofouling layer samples showed the validity and feasibility of the method for analyzing intrinsic porous structures. The structural information obtained by this method can facilitate the understanding of transport phenomena, e.g., water flow and species diffusion inside porous structures.