Effective porosity

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

Evaluation of spatial distribution of hydraulic conductivity using effective porosity data

Abstract: The use of spatial distribution of effective porosity (Φe) to estimate the distribution of saturated hydraulic conductivity (K2) is evaluated on five new soils and on a combination of soils. The K2 is related to Φe by a generalized Kozeny-Carman equation. This equation is then combined with scaling

Porosity and bulk density of sedimentary rocks

Abstract: More than 900 items of porosity and bulk density data for sedimentary rocks have been tabulated Most of the data are from the more accessible American, British, German, and Swiss literature The number of porosity determinations per item ranges from 1 to 2,109 The tabulation reflects the fact that more porosity than bulk density data are availabl_e for sedimentary rocks

Estimation of saturated hydraulic conductivity of soils from particle size distribution and bulk density data

Abstract: Since laboratory and field measurement of soil hydraulic properties is time consuming and subject to large error, numerous models have been proposed to predict soil hydraulic properties from easily measurable soil properties such as particle size distribution, bulk density, effective porosity and carbon content. In this study a multiple linear regression model was developed to predict the saturated hydraulic conductivity of soils from their particle size distribution and bulk density data. Published data from 350 soil core samples of varying soils from different sources were used to develop the model. Stepwise regression selected the best model for prediction of soil hydraulic conductivity (R2 = 0.68, P < 0.0001) from the independent parameters of silt, clay, and bulk density. Additional field measured data were collected to test and validate the model using several statistical evaluation procedures. Based on the statistical evaluation criteria, the model performed fairly well and gave a satisfactory validation versus the field measured data.

Sandstone diagenesis and porosity modification during basin evolution

Abstract: The properties of sandstones as potential reservoirs and shales as source rocks depend on primary facies relationships and diagenesis. Porostiy loss due to mechanical compation and pressure solution is essentially a function of grain parameters (sorting, packing and composition) and net overburden stress. The porosity loss can be predicted to a certain extent. The importance of secondary porosity caused by dissolution of framework grains and cements has been fully recognized. The discussion has focused on the processes causing such dissolution and to what extent it can cause net increase in porosity. The most critical factor in clastic diagenesis is the nature of porewater flow and the degree of mass transfer taking place as a result of this. In the North Sea reservoir rocks, petrographic and geochemical evidence suggest that most of the leaching of feldspar and mica resulting in the formation of kaolinite occurred early during fresh wather flushing. Recent calculations indicate that »acids« derived from source rocks are inadequate to explain the secondary porosity observed in reservoir rocks. Mathematical modelling suggests that thermal convection is of limited importance in sedimentary basins, except where there are high lateral changes in geothermal gradients. Evidence from porewater geochemistry suggests that porewaters in sedimentary basins are often stratified or compartmentalized in a way which is inconsistent with large scale convection or compactional flow, making it necessary to assume that diagenetic reactions are relatively isochemical during deeper burial. A better understanding of the diagenetic reactions will help us to improve our predictions about porosity/depth relations, pore size, and pore geometry distribution in reservoir rocks. Porosity depth trends from offshore Norway and published data from other basins are discussed. Empirical linear best fit lines are found to illustrate the relationship quite well for depths between one and five km. Within a specific region, the linear porosity gradient is a function of mineral composition and of temperature and pressure gradients. Primary porosity tends to be best preserved in sandstones with high proportions of stable grains (e. g. in quartz arenites) down to about 3 or 4 km. At greater depth, porosity loss is accelerated due to increased pressure solution. Secondary and primary porosity adjacent to feldspar grains then tends to be selectively preserved relative to primary pores between quartz grains.