Effective porosity

About: Effective porosity is a research topic. Over the lifetime, 1199 publications have been published within this topic receiving 26511 citations.

Nanoscale Accessible Porosity as a Key Parameter Depicting the Topological Evolution of Organic Porous Networks.

Abstract: A significant part of the hydrocarbons contained in source rocks remains confined within the organic matter-called kerogen-from where they are generated. Understanding the sorption and transport properties of confined hydrocarbons within the kerogens is, therefore, paramount to predict production. Specifically, knowing the impact of thermal maturation on the evolution of the organic porous network is key. Here, we propose an experimental procedure to study the interplay between the chemical evolution and the structural properties of the organic porous network at the nanometer scale. First, the organic porous networks of source rock samples, covering a significant range of natural thermal maturation experienced by the Vaca Muerta formation (Neuquen Basin, Argentina), are physically reconstructed using bright-field electron tomography. Their structural description allows us to measure crucial parameters such as the porosity, specific pore volume and surface area, aperture and cavity size distributions, and constriction. In addition, a model-free computation of the topological properties (effective porosity, connectivity, and tortuosity) is conducted. Overall, we document a general increase of the specific pore volume with thermal maturation. This controls the topological features depicting increasing accessibility to alkane molecules, sensed by the evolution of the effective porosity. Collectively, our results highlight the input of bright-field electron tomography in the study of complex disordered amorphous porous media, especially to describe the interplay between the structural features and transport properties of confined fluids.

Characterizing Porosity and Diffusive Properties of Monolithic Cement-Based Solidified/Stabilized Materials

Abstract: This paper presents the application of a single reservoir diffusion test to determine both the effective porosity of a soil-cement matrix and the diffusivity of tritium through saturated, monolithic, cement solidified/stabilized wasteforms. Testing was performed on a laboratory mixture of cement paste, sand, and kaolinite. The influence of porosity on the proper interpretation of the diffusion tests was examined. Results of tests on three replicate specimens were consistent and indicate effective porosities of 0.26 to 0.28 and effective diffusive coefficients of 2.5 × 10−10 to 3.0 × 10−10 m2/s. The effect of curing time is discussed. Products of the effective diffusion coefficients and porosity (neDe) decreased by 22 % from specimens cured for 14 days to specimens cured for 28 days prior to testing while from 70 to 126 days of curing neDe only changed by 8 %. This suggests that curing should be carried out for greater than 70 days prior to conducting these tests.

Examination of surface-NMR within an integrated geophysical survey in Nauen, Berlin

Abstract: A combined geophysical survey has been conducted at the test site Nauen near Berlin, prospecting a shallow aquifer in fluvial sediments bordered by glacial till. Some of the geophysical results have been reported earlier [1]. Comprehensive investigations of geoelectric sections and depth-soundings as well as georadar profiles were interpreted to describe subsurface conditions. The structure of the dipping glacial till is well recognisable up to a depth of 13 m. The sandy sediments above represent the aquifer with the water table at a depth of about 2 m. The radar velocities and resistivities from Block-Inversion of geoelectric sections have been used to derive hydrological parameters. The aquifer is accordingly determined to have a porosity around 24 % and a water content of 5 % in the vadose zone. At the main profile, five SNMR soundings have been carried out in order to compare the results with those from conventional geophysical methods. Inversion results show mobile water contents of less than 20 % in the first few meters of the vadose zone, increasing rapidly to 30 %. This means an aquifer with an effective porosity of at least 30 % plus adhesive water content. Decreasing water contents below 15-18 m relate to the glacial till which has low permeability and less mobile water. Increasing water contents in larger depth again to values above 30 % indicates another aquifer which is not verified with other methods yet. The decay times within the aquifer are generally about 150-250 ms and correspond in average to medium sands [2]. However, in detail they are somewhat ambiguous.