Characterization οf Sandstone Pore Network using Mercury Porosimetry, Helium Porosimetry and Scanning Electron Microscopy (original) (raw)
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Comparison of Mercury Porosimetry and X-Ray Microtomography for Porosity Study of Sandstones
Acta Geodynamica Et Geomaterialia, 2012
Sandstones have been widely used as a building material since the medieval time all around the Europe. Porosity is one of the main factors affecting the resistance to weathering processes and consequently to the changes of mechanical and physical properties of these stones. Rock material is generally negatively influenced especially during the winter period when frost action takes place. Effect of salt crystals and ice formation depends on the character of pore space, including the pore size distribution. Mercury porosimetry is well known method which provides information about porosity and pore size distribution of samples, but as any other method, it has its own limitations. X-ray microtomography can be used as a complementary method enabling another "view" into the pore space. Main aim of this paper has been to provide the information about the use of these two mentioned methods and comparison of obtained results, within the study of sandstone weathering. The research was focused on two commonly used Czech Cretaceous sandstones-Hořice and Božanov. The stones were exposed to the accelerated durability test which is based on the meteorological data measured in Prague winters from 1998 to 2008. There were described the changes in the area of pores diameters > 5 μm. Use of mercury porosimetry together with X-ray microtomgraphy enabled more detailed understanding of the processes inside the stone structure.
2015
Various techniques have been developed over the years for characterizing pore structure beyond a simple visual description. These tests provide qualitative data for both reservoir evaluations in the short run and reservoir simulation in the long run. In this study, mercury porosimetry (MP), low field (2MHz) nuclear magnetic resonance (NMR) relaxometry, centrifuge drainage tests and flow tests were run on 11 plugs of a mix of sandstones, limestones, dolomites and chalk. Initially, a representative elemental volume (REV) which uses pore size distribution (PSD) data and porosity to simulate the pore network is discussed. The model is later used to predict permeability and predictions were compared with gas flow measurements. NMR and centrifuge data are coupled to derive capillary pressure curves and the results are compared with MP derived capillary curves. The results indicate that there is significant difference between the two capillary curves based on the degree of heterogeneity of...
Pore-throat characterization in highly porous and permeable sandstones
Aapg Bulletin, 2009
Several methods have been developed to characterize the pore spaces in sandstone reservoirs using data on the porethroat-size distribution obtained from mercury injection tests. The Winland equation, the threshold pressure, the displacement pressure, and Pittman's equation are mostly used for this purpose to delineate the stratigraphic traps and seals.
Modern Applied Science, 2017
Understanding geological features with engineering aspect has been done by previous studies and remains attractive by both geologists and engineers. This study employed data of a total of one hundred and seventy-nine (179) sandstone samples obtained from the Middle Miocene to Late Miocene Balikpapan Formation in Kutai Basin, Indonesia. The data includes thin section porosity, scanning electron microscope (SEM), x-ray diffraction (XRD), and capillary pressure (Pc). All samples are mainly dominated by quartz with additional rock fragment and feldspar, and additional component such as plagioclase, heavy minerals, occasional carbonaceous materials, micas and opaque minerals. Detrital clays, pseudomatrix and laminated clays occurred locally in minor quantity. Porosity ranges from 6 to 28.8.9%, whereas permeability ranging from 0.02 and 4,718 mD. This study investigates the relationship of microscopic geological features with pore geometry and pore structures. Kozeny equation and Leverette's J-Function are implemented to characterize the pore geometry and structure in correlation with microscopic geologic features. The main findings of the study are that: i) combination of quartz content, texture, clay content, and the diagenetic history of quartz cementation strongly relates to both pore geometry and structure of the sandstone samples, ii) the content of cements does not show a systematic effect on either pore geometry or pore structure, and iii) in general, for all the sandstone samples employed here, the higher quartz and lower clay contents tend to give both a larger pore geometry and lower pore structure in terms of pore tortuosity.
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Drilled formations are commonly invaded by drilling fluids during the drilling operations, and as a result, the rock pore system will have alterations that consequently alter the rock properties. The objective of this study is to investigate the impact of the most commonly used weighting materials in water-based mud (WBM) on the Berea Buff sandstone pore system and rock characteristics. Rock−mud interaction was imposed by using a customized high-pressure high-temperature filtration test cell under 300 psi differential pressure and 200°F temperature to simulate downhole conditions during drilling that affect the rock−mud interaction. Extensive lab analysis was accomplished to investigate the rock characteristic alterations in terms of rock porosity, permeability, pore size distribution, flow characteristics, resistivity, and acoustic properties. Ilmenite-WBM showed the maximum values (8.3 cm 3 filtrate volume and 7.6 mm cake thickness), while barite recorded the lowest filtrate volume (5.3 cm 3) and thickness (3 mm). Nuclear magnetic resonance profiles illustrated the changes in the rock pore system due to the dominant precipitation or dissolution effects. A general porosity reduction was recorded with all mud types that ranged from 4.2 to 9.9% for ilmenite and Micromax, respectively. The rock permeability showed severe damage after mud exposure and a reduction in the pore throat radius. After mud invasion, the rock electrical resistivity showed alterations based on the mineralogical composition of the weighting materials that replaced the saturated brine from the rock pores. Compressional wave velocities (V p) showed an increasing trend as V p of Micromax-WBM increased by 4.5%, while hematite-and ilmenite-WBMs recorded the minimum increase of 1.8%. A general reduction was found for shear wave velocities (V s); Micromax-WBM showed the highest V s reduction by 6.6%, while ilmenite-WBM recorded the minimum reduction of 1.8%. The pore system alterations are the main reason behind V p increase, where the rock lithology alterations controlled the V s changes. The study findings will add more for the rock logging interpretation and rock properties alterations after the mud exposure.
Multiscale Research on Pore Structure Characteristics and Permeability Prediction of Sandstone
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The random existence of many irregular pore structures in geotechnical materials has a decisive influence on its permeability and other macroscopic properties. The analysis and characterization of the micropore structure of the material and its permeability are of great significance for geotechnical engineering. In this study, digital images with different magnifications were used to examine the pore structure and permeability of sandstone samples. The image processing method is used to obtain binary images, and then, the pore size distribution method is used to calculate the pore size distribution. Therefore, based on the Hagen-Poiseuille formula, we get the prediction value of material’s permeability and compare it with the value obtained from mercury intrusion porosimetry (MIP). It is found that different microscopic images with different magnification and various statistical methods of pore size have a specific influence on the characterization of pore structure and permeability...
Arabian Journal of Geosciences, 2014
25.8 and 34.7 %, gas permeability 'k' varies from 0.14 to 6.92 μm 2 (very good to excellent rank), and the mean pore diameter 'D' varies between 3.9 and 25.7 μm (macro to mega pores). The study stated the applicability of the present equation and introduced a number of equations that could be used to calculate porosity, permeability, and pore radius in terms of grain elongation. The applicability of the present study has some limitations due to (1) cementation, (2) microporosity, and fracturing. The effect of cementation can be minimized by processing the grains and the surrounding cement statistically as a bulk ellipsoid unit, whereas the micropores/fractures can be measured by helium injection.
Comparison of computer image analysis with mercury porosimetry in sandstone porosity measurement
2001
Computer image analysis was used to determine porosity volume in sandstones from Upper Silesia and Jura Krakowsko-Czestochowska. Calibration of the data was made by comparison with the results of mercury injection capillary pressure methods. Image analysis can yield many useful parameters. This study obtained chosen size parameters and diameters of equivalent area circles, calculated for all samples after 100 partial observations. Results obtained by image analysis are close to those measured by mercury injection capillary pressure. They could complement standard mercury porosity measurements, and in some cases, replace them.
Pore structures and transport properties of sandstone
Transport in Porous Media, 1993
We report laboratory measurements of pore structure, capillarity, water permeability, and electrical conductivity on Fontainebleau sandstone specimens. Experimental equipment and techniques are described. Water permeability measurements were performed on saturated cores with a 100 MPa permeameter. Various combinations of pore and confining pressures were used and an effective pressure law was determined. In addition, electrical conductivity of samples saturated with KC1 brines was measured over a wide range of electrolyte conductivities (10-3 to 1 S m-1). The well-known relationship F = q~-" fits well our data, and empirical parameters such as the cementation exponent and tortuosity factor are derived. Differences between transport properties of the three types of sandstone are related to the microstructural characteristics of the pore network of each rock.
Porosity study of synthetic sandstones by non-destructive nuclear techniques
Materials Research, 2011
In this paper nuclear techniques were used to describe the structural characteristics of ceramic samples. These samples were produced mainly with silica to simulate sandstones. Three sets of samples with different characteristics were analyzed using gamma ray transmission to obtain point by point porosity and X-ray microtomography to obtain the porosity, for 2D sections and the scanned bulk, as well as the pore size distribution. The transmission results indicated total porosity values of 28.6 (4.5)% for the group of samples called ceramic I and 59.6 (2.1)% for ceramic II. The samples analyzed by microtomography achieved resolutions of 1.7, 0.6 and 1.3 µm for the ceramic I, II, and III samples, respectively. This analysis indicated average porosity values of 27.9 (1.4)% for ceramic I samples and 29.4 (1.2)% for ceramic III samples.