Topic
Effective porosity
About: Effective porosity is a research topic. Over the lifetime, 1199 publications have been published within this topic receiving 26511 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: The relative merits of model complexity and types of observations employed in model calibration are compared in this article, where an existing groundwater flow model coupled with an advective transport simulation of the Salt Lake Valley, Utah (USA) is adapted for advctive transport, and effective porosity is adjusted until simulated tritium concentrations match concentrations in samples from wells.
Abstract: The relative merits of model complexity and types of observations employed in model calibration are compared An existing groundwater flow model coupled with an advective transport simulation of the Salt Lake Valley, Utah (USA), is adapted for advective transport, and effective porosity is adjusted until simulated tritium concentrations match concentrations in samples from wells Two calibration approaches are used: a “complex” highly parameterized porosity field and a “simple” parsimonious model of porosity distribution The use of an atmospheric tracer (tritium in this case) and apparent ages (from tritium/helium) in model calibration also are discussed Of the models tested, the complex model (with tritium concentrations and tritium/helium apparent ages) performs best Although tritium breakthrough curves simulated by complex and simple models are very generally similar, and there is value in the simple model, the complex model is supported by a more realistic porosity distribution and a greater number of estimable parameters Culling the best quality data did not lead to better calibration, possibly because of processes and aquifer characteristics that are not simulated Despite many factors that contribute to shortcomings of both the models and the data, useful information is obtained from all the models evaluated Although any particular prediction of tritium breakthrough may have large errors, overall, the models mimic observed trends
3 citations
15 Apr 2005
TL;DR: There are two types of porosity: primary and secondary porosity as discussed by the authors : primary porosity, such as pores between sand grains, is created when rocks are formed, and the shape, sorting, and packing of grains determine primary poreosity.
Abstract: The occurrence, movement, and storage of groundwater are controlled by geology. The geologic factors that control groundwater are petrography, stratigraphy, structure, geomorphology, lithology, and thickness. The petrography of a given rock type controls the porosity and permeability. Porosity defines the storage capacity of an aquifer. There are two types of porosity: primary and secondary. Primary porosity, such as pores between sand grains, is created when rocks are formed. The shape, sorting, and packing of grains determine primary porosity. Sedimentary rocks are poorly sorted when the grains are not the same size creating spaces between the larger grains that are filled by smaller grains. Secondary porosity such as joints, fractures, and solution opening, is formed after the rock has been deposited. The number and arrangement of fracture openings and the degree to which they are filled with fine-grained material control secondary porosity.
Keywords:
confined aquifer;
unconfined aquifer;
aquifer;
continuing zone
3 citations
TL;DR: In this paper, the distribution of porosity and permeability enhancement in hydrocarbon reservoirs can be predicted by integrating the generation of carboxylic acids, phenols, mineral oxidants, and liquid hydrocarbons in time-temperature space.
Abstract: Predicting the distribution of porosity and permeability enhancement in hydrocarbon reservoirs can be achieved by integrating the generation of carboxylic acids, phenols, mineral oxidants, and liquid hydrocarbons in time-temperature space. Such predictive models can be constructed by linking data from oil-field water chemistry, source rock geochemistry, clay mineralogy, clastic diagenesis, thermal modeling and basin analysis. The detailed organic and inorganic geochemistry and the thermal scenarios used in the time-temperature analysis must be basin specific. Predictive time-temperature models using kerogen-specific kinetic parameters have been developed for two tectonic settings: rift or "pull-apart" basins, and intermontane or "Laramide" basins. From these integrated reconstructions, the optimum conditions and capacity for porosity and permeability enhancement can be predicted. The optimum conditions for porosity and/or permeability enhancement are: (1) short migration distances, (2) rapid evolution from organic solvent generation to the liquid hydrocarbon window (thermal environments associated with crustal attenuation or overpressuring could cause such perturbations), (3) adequate fluid flux (organic acids are highly water soluble), and (4) available conduits in potential reservoir rocks (fractures, unconformities, or preserved original porosity). End_of_Article - Last_Page 868------------
2 citations
TL;DR: In this article, a mathematical solution for outdiffusion from a porous cylinder was developed by applying a corrected form of Fick's second law for a case where part of the pores are so-called dead-end pores.
Abstract: The nature of diffusivity and porosity in rock was studied as a function of various parameters. The phenomena of main interest were dead-end porosity, ion-exclusion and sorption. The rock types studied were rapakivi granite, granite and gneiss, and tracer techniques with 36 Cl, 22 Na + and 3 H (HTO) were used as a research method. A mathematical solution for outdiffusion from a porous cylinder was developed by applying a corrected form of Fick's second law for a case where part of the pores are so-called dead-end pores. With this model the theoretical curve could be closely fitted to the measured values. It was found that the rock-capacity factor is an increasing function of the ionic concentration of the solution in the case of Cl indicating ion-exclusion, while the opposite is true in the case of Na + indicating ion-exchange type sorption. The effective diffusion coefficient was also found to vary as a function of the salinity in the case of 36 Cl. In the case of 22 Na, the effect was opposite and weaker. The diffusion of tritium through the rock samples was clearly higher than the diffusion of 36 Cl. Part of the difference is explained by the smaller effective porosity for 36 Cl. The rest can probably be explained by the steric effects on the chloride ion caused by the negatively charged pore surfaces in the narrow pores.
2 citations
TL;DR: In this paper, the authors present laboratory measurements and analysis of twenty UAE carbonates samples which include quantitative mineralogy, total and effective porosity, permeability and compressional and shear wave velocities as a function of effective pressure and saturation.
Abstract: Summary We present laboratory measurements and analysis of twenty UAE carbonates samples which include quantitative mineralogy, total and effective porosity, permeability and compressional and shear wave velocities as a function of effective pressure and saturation. Brine saturated compressional velocity dependence on porosity is twice that of shear waves. Compressional and shear wave velocities were measured when saturated with three different saturants, air, brine and dodecane. No evidence for shear weakening was found when care was taken to eliminate dissolution of the carbonate. In particular we were able to verify the Biot-Gassmann’s assumption of constant shear modulus regardless of saturation.
2 citations