Permeability (earth sciences)

About: Permeability (earth sciences) is a research topic. Over the lifetime, 15424 publications have been published within this topic receiving 288535 citations.

Assessment of the Surface Permeation Properties of Recycled Aggregate Concrete

Abstract: The water permeability, air permeability and surface permeability of recycled aggregate concrete (RAC) are compared with those of a control concrete made with natural aggregate. The study shows that the permeation properties of RAC depend on mix-design, conditions of curing and drying of samples. Relationships between permeability and other physical characteristics of concrete such as water absorption capacity and diffusivity are discussed. According to the criteria existing for ordinary concrete made with natural aggregate, RAC could be classified as being of moderate quality rather than poor quality. The testing methodology shows that some of the techniques used to measure the permeability of RAC need to be modified in order with the distinctive characteristics of this material.

Multiscale, Multiphysics Network Modeling of Shale Matrix Gas Flows

Abstract: We present a pore network model to determine the permeability of shale gas matrix. Contrary to the conventional reservoirs, where permeability is only a function of topology and morphology of the pores, the permeability in shale depends on pressure as well. In addition to traditional viscous flow of Hagen–Poiseuille or Darcy type, we included slip flow and Knudsen diffusion in our network model to simulate gas flow in shale systems that contain pores on both micrometer and nanometer scales. This is the first network model in 3D that combines pores with nanometer and micrometer sizes with different flow physics mechanisms on both scales. Our results showed that estimated apparent permeability is significantly higher when the additional physical phenomena are considered, especially at lower pressures and in networks where nanopores dominate. We performed sensitivity analyses on three different network models with equal porosity; constant cross-section model (CCM), enlarged cross-section model (ECM) and shrunk length model (SLM). For the porous systems with variable pore sizes, the apparent permeability is highly dependent on the fraction of nanopores and the pores’ connectivity. The overall permeability in each model decreased as the fraction of nanopores increased.

Grain Size Distribution and Its Effect on The Permeability of Unconsolidated Sands

Abstract: Since permeability is the measure of the ease with which water moves through aquifer material, certain relationships must exist between permeability and the statistical parameters that describe the grain size distribution of the porous mediums. Experimental studies to investigate these relationships consisted of systematic variation of the values of the statistical parameters and evaluation of the corresponding permeabilities of the samples. The parameters investigated included measures of the average size, dispersion, skewness, peakedness, and modality of the sample distributions. Several graphs were developed that related permeability to the various statistical parameters. On the basis of these plots a group of curves was defined to predict laboratory permeability values for aquifer samples with random statistical distribution. This set of prediction curves incorporated only the average size and dispersion, because these parameters best described the relationship between permeability and the grain size properties of the porous mediums. These prediction curves were then used to determine the laboratory permeability coefficients for a group of samples obtained from a natural aquifer, and the results were compared with actual permeability values obtained from laboratory tests.

Pore Distribution and Permeability of Silty Clays

Abstract: This investigation utilizes pore size distribution measurements to examine the relationship between permeability and compactive variables for laboratory compacted clayey silts. Closed-system falling head permeability tests under back pressure were performed on each of the compacted samples. Freeze drying was successfully used to dehydrate specimens prior to pore size measurements. The mercury intrusion technique was used to determine the pore size distribution. The pore size distributions of the soils tested were bimodal with a large pore mode occurring between 10 μ and 1 μ and a small pore mode occurring at 0.1 μ. Varying the compaction variables produced changes in the size and frequency of the large pore mode, but caused no change in the pore size distribution about the small pore mode for a given soil type. Three theoretical permeability models that relate pore size distribution parameters to permeability were generated. These parameters were successfully used to determine empirical permeability prediction equations for the soils tested.