Shale adhesion force measurements via atomic force microscopy (original) (raw)
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Energies, 2019
While the effect of polar-oil component on oil-brine-carbonate system wettability has been extensively investigated, there has been little quantitative analysis of the effect of non-polar components on system wettability, in particular as a function of pH. In this context, we measured the contact angle of non-polar oil on calcite surface in the presence of 10,000 ppm NaCl at pH values of 6.5, 9.5 and 11. We also measured the adhesion of non-polar oil group (–CH3) and calcite using atomic force microscopy (AFM) under the same conditions of contact angle measurements. Furthermore, to gain a deeper understanding, we performed zeta potential measurements of the non-polar oil-brine and brine-calcite interfaces, and calculated the total disjoining pressure. Our results show that the contact angle decreases from 125° to 78° with an increase in pH from 6.5 to 11. AFM measurements show that the adhesion force decreases with increasing pH. Zeta potential results indicate that an increase in p...
Scientific reports, 2015
Core flood and field tests have demonstrated that decreasing injection water salinity increases oil recovery from sandstone reservoirs. However, the microscopic mechanism behind the effect is still under debate. One hypothesis is that as salinity decreases, expansion of the electrical double layer decreases attraction between organic molecules and pore surfaces. We have developed a method that uses atomic force microscopy (AFM) in chemical force mapping (CFM) mode to explore the relationship between wettability and salinity. We functionalised AFM tips with alkanes and used them to represent tiny nonpolar oil droplets. In repeated measurements, we brought our "oil" close to the surface of sand grains taken from core plugs and we measured the adhesion between the tip and sample. Adhesion was constant in high salinity solutions but below a threshold of 5,000 to 8,000 ppm, adhesion decreased as salinity decreased, rendering the surface less oil wet. The effect was consistent, ...
Mapping of adhesion forces on soil minerals in air and water by atomic force spectroscopy (AFS)
Journal of adhesion science and …, 2003
The adhesion force between an atomic force microscope (AFM) tip and sample surfaces, mica and quartz substrates, was measured in air and water. The force curves show that the adhesion has a strong dependence on both the surface roughness and the environmental conditions surrounding the sample. The variability of the adhesion force was examined in a series of measurements taken at the same point, as well as at different places on the sample surface. The adhesion maps obtained from the distribution of the measured forces indicated regions contaminated by either organic compounds or adsorbed water. Using simple mathematical expressions we could quantitatively predict the adhesion force behavior in both air and water. The experimental results are in good agreement with theoretical calculations, where the adhesion forces in air and water were mostly associated with capillary and van der Waals forces, respectively. A small long-range repulsive force is also observed in water due to the overlapping electrical double-layers formed on both the tip and sample surfaces.
Frontiers in Earth Science, 2023
Shales are composed of minerals and organic matter, whose individual properties are essential to determining the rock's macroscopical deformation and strength. Scanning electron microscopy combined with electron energy dispersive spectroscopy (EDS) has been extensively used to evaluate composition, while peak-force atomic force microscopy (AFM) has been used on the determination of elastic modulus with nanometric resolution. Still, there is a need for tools to conduct an in-depth study of the minerals' tribomechanical properties. Atomic force microscopy is a tool that can contribute to these studies, as it can simultaneously measure the tribomechanical properties and identify the phases. In this work, we propose using atomic force microscopy and energy dispersive spectroscopy to identify the shale components and to measure the in situ tribomechanical properties from the different phases. Friction images between the atomic force microscopy tip and the surface were acquired as a function of load. Minerals and organic matter were later identified by colocalized energy dispersive spectroscopy mapping. Then, the frictional characteristics of the major shale constituents were obtained by adjusting the Derjaguin-Muller-Toporov model to the selected components. Moreover, the identification of the different phases was performed. The results show that friction at the nanometer scale was observed to be higher for organic matter than for any other shale constituent, while shear strength was observed to be higher for quartz and lower for organic matter. These characteristics were used to differentiate shale constituents. It is shown that a careful comparison of friction can be used to differentiate the sulfite pyrite, tectosilicates (quartz, andesine, and albite), phyllosilicate biotite, and organic matter. The presented methodology gives novel information on friction properties in the nanoscale that are comparable to available centimetric characterization techniques contributing to the understanding of rock strength.
Geomechanical characterisation of organic-rich calcareous shale using AFM and nanoindentation
Rock Mechanics and Rock Engineering, 2020
The geomechanical integrity of shale overburden is a highly significant geological risk factor for a range of engineering and energy-related applications including CO$$_22storageandunconventionalhydrocarbonproduction.Thispaperaimstoprovideacomprehensivesetofhigh−qualitynano−andmicro−mechanicaldataonshalesamplestobetterconstrainthemacroscopicmechanicalpropertiesthatresultfromthemicrostructuralconstituentsofshale.Wepresentthefirststudyofthemechanicalresponsesofacalcareousshaleoverlengthscalesof10nmto1002 storage and unconventional hydrocarbon production. This paper aims to provide a comprehensive set of high-quality nano- and micro-mechanical data on shale samples to better constrain the macroscopic mechanical properties that result from the microstructural constituents of shale. We present the first study of the mechanical responses of a calcareous shale over length scales of 10 nm to 1002storageandunconventionalhydrocarbonproduction.Thispaperaimstoprovideacomprehensivesetofhigh−qualitynano−andmicro−mechanicaldataonshalesamplestobetterconstrainthemacroscopicmechanicalpropertiesthatresultfromthemicrostructuralconstituentsofshale.Wepresentthefirststudyofthemechanicalresponsesofacalcareousshaleoverlengthscalesof10nmto100\upmu$$ μ m, combining approaches involving atomic force microscopy (AFM), and both low-load and high-load nanoindentation. PeakForce quantitative nanomechanical mapping AFM (PF-QNM) and quantitative imaging (QI-AFM) give similar results for Young’s modulus up to 25 GPa, with both techniques generating values for organic matter of 5–10 GPa. Of the two AFM techniques, only PF-QNM generates robust results at higher moduli, gi...
Adhesion force imaging in air and liquid by adhesion mode atomic force microscopy
Applied Physics Letters, 1994
A new imaging mode for the atomic force microscope (MM), yielding images mapping the adhesion force between tip and sample, is introduced. The adhesion mode AFM takes a force curve at each pixel by ramping a piezoactuator, moving the silicon-nitride tip up and down towards the sample. During the retrace the tip leaves the sample with an adhesion dip showing up in the force curve. Adhesion force images mapping parameters describing this adhesion dip, such as peak value, width, and area, are acquired on-line together with the sample topography. Imaging in air gives information on the differences in hydrophobicity of sample features. While imaging a mercaptopentadecane-gold layer on glass in demineralized water, the adhesion force could be modulated by adding phosphate buffered saline.
Journal of Contaminant Hydrology, 2009
The objective of this study was to determine if there is a nanoscale surface film on aquifer-like materials exposed to deep groundwaters, as has previously been found on surfaces exposed to surface and soil waters. Such surface films will modify surface properties that are so important in determining the mobility of many groundwater pollutants. Muscovite mica was used because a) it is a good analogue for the main sorbing phases of many clastic aquifers and b) its cleavage planes are atomically flat allowing high resolution imaging. Freshly-cleaved muscovite plates were exposed to groundwater from a sandstone aquifer for 30 min, and surface properties (morphology, coverage, roughness and tip-substrate force interactions) were measured using atomic force microscopy (AFM). A patchy surface film of several nanometres in depth, incorporating larger separate particles, was found on the mica surface. This film was associated with significantly increased roughness values and AFM probe-sample interaction forces compared with pure water and inorganic (synthetic groundwater) solution controls. Although the results reported are preliminary in nature, if confirmed, such films are likely to affect sorption reactions, surface-facilitated redox interactions, non-aqueous phase liquid wetting angles, and colloid-pathogen-rock attachment, and will thus be of importance in understanding natural attenuation and migration of dissolved, non-aqueous and particulate phases in groundwaters.
Effect of dilute acid treatment on adhesion properties of Longmaxi black shale
Petroleum Science
Properties of shale in an acid environment are important when acid or CO2 is injected into geologic formations as a working fluid for enhanced oil and gas recovery, hydraulic fracturing and reduced fracture initiation pressure. It has previously been shown that acid fluids can enhance the formation conductivity and decrease the hardness of shale. However, less is known about the effect of dilute acid on the adhesion properties of shale. In the study, shale samples are characterized in detail with advanced analysis. Adhesion properties of shale via dilute acid treatment were revealed by atomic force microscopy (AFM) for the first time. Results indicate that acid treatment can greatly enhance adhesion forces of the shale surface. After acid treatment, the average adhesion forces show a platform-like growth with an increase in loading force. Through analysis of results from AFM, scanning electron microscopy, and X-ray diffraction, we affirm that the enhanced adhesion forces are mainly ...
Nanoscale geochemical and geomechanical characterization of organic matter in shale
Nature communications, 2017
Solid organic matter (OM) plays an essential role in the generation, migration, storage, and production of hydrocarbons from economically important shale rock formations. Electron microscopy images have documented spatial heterogeneity in the porosity of OM at nanoscale, and bulk spectroscopy measurements have documented large variation in the chemical composition of OM during petroleum generation. However, information regarding the heterogeneity of OM chemical composition at the nanoscale has been lacking. Here we demonstrate the first application of atomic force microscopy-based infrared spectroscopy (AFM-IR) to measure the chemical and mechanical heterogeneity of OM in shale at the nanoscale, orders of magnitude finer than achievable by traditional chemical imaging tools such as infrared microscopy. We present a combination of optical microscopy and AFM-IR imaging to characterize OM heterogeneity in an artificially matured series of New Albany Shales. The results document the evo...