Αποτελέσματα Αναζήτησης
Used in geology, hydrogeology, soil science, and building science, the porosity of a porous medium (such as rock or sediment) describes the fraction of void space in the material, where the void may contain, for example, air or water.
The key properties of interest include lithology (e.g., mineralogy, grain fabric), water saturation, porosity, permeability and density. Three broad categories of measurements are typically made, (a) on core or crushed rock, (b) within the bore hole via well logging tools and (c) seismic.
The porosity of earth materials originates during two phases: 1) during the deposition of sediments, lithification or cooling of crystalline rock; and 2) after deposition as the earth material is exposed to other conditions such as compaction, weathering, fracturing and/or metamorphism.
19 Νοε 2021 · Due to pore volume decrease with depth, sedimentary rocks possess three types of compressibility: bulk, matrix and pore volume compressibility. Density of rocks varies by density of constituting minerals and total porosity, and may be calculated as an arithmetic mean.
Generally, unconsolidated materials have higher porosities (20 to 55%) than consolidated sediments and igneous and metamorphic rocks. Though, some consolidated sedimentary rocks; and weathered and/or fractured igneous and metamorphic rocks can also have high porosities.
Effective porosity can be determined at the laboratory scale when sediment and rock samples of a given volume are dried and then the pore spaces are filled with water (Figure 8). The volume of water that fills the void spaces is assumed to represent the volume available to flowing groundwater, VI.
1 Μαΐ 2016 · We review the technological means, both sample preparation and imaging methodologies, that underpin current models for porosity evolution in sedimentary rocks and that serve efforts to extend this understanding to pore systems in the fine-grained sedimentary rocks known as mudstones or shales.
