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Tor Austad - One of the best experts on this subject based on the ideXlab platform.
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wettability alteratIon and improved oil recovery by spontaneous imbibitIon of seawater into chalk impact of the Potential Determining Ions ca2 mg2 and so42
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2007Co-Authors: Peimao Zhang, Medad T Tweheyo, Tor AustadAbstract:Abstract Carbonate wettability is dictated by the surface chemistry related to stability of the water film between the oil phase and the rock surface. It has been verified, both in the field and laboratory, that seawater is an excellent injectIon fluid to enhance the oil recovery from fractured chalk. The objective of different papers in this series has been to understand the chemistry for improved spontaneous imbibitIon of seawater into low permeable chalk at low water wetness. Improved spontaneous imbibitIon of water will take place if the chalk becomes more water-wet during the productIon phase. The Potential Determining Ions present in seawater, Ca2+ and SO42−, have great influence on the surface charge of chalk, which can modify the wettability during water injectIon. In the present study, it was verified that Mg2+ is another strong Potential Determining Ion towards chalk, which can increase the positive surface charge density. At high temperatures, Mg2+ can even substitute Ca2+ from the chalk surface, and the degree of substitutIon increased as the temperature increased. The interplay between the three Potential Determining Ions: Ca2+, Mg2+ and SO42− and the chalk surface with the aim to improve the water wetness of biogenic chalk, was studied from a spontaneous imbibitIon point of view. To improve water wetness, SO42− must act together with either Ca2+ or Mg2+. In both cases, the efficiency increased as the temperature increased. The water wetness of chalk can be improved if some of the carboxylic material adsorbed onto the chalk surface is displaced. A chemical mechanism discussing the mutual interactIon between the Potential Determining Ions and the chalk surface is proposed.
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new wettability test for chalk based on chromatographic separatIon of scn and so42
Journal of Petroleum Science and Engineering, 2006Co-Authors: Skule Strand, Dag Chun Standnes, Tor AustadAbstract:Abstract Wettability, water-wetness or oil-wetness, is usually defined in terms of the method used to determine the wetting state of a porous medium. In the Amott test, which is most frequently used for porous media, the wetting indices of water and oil are determined by the extent of spontaneous imbibitIon of water and oil from the state of the corresponding residual fluid saturatIons of the core. Thus, the Amott fluid wetting index reflects the Potential capillary energy associated with the spontaneous imbibitIon process, which results in a very insensitive way to detect wetting alteratIons close to neutral conditIons. Unfortunately, the natural wetting state of many carbonate reservoirs is close to neutral conditIons or preferential oil-wet. In this paper, the wetting state of porous chalk is characterized by the fractIon of surface area covered by one of the two fluids, i.e. water or oil. As the new wettability test is based on the chromatographic separatIon of two water-soluble components, i.e. a tracer, SCN − , and a Potential Determining Ion towards chalk, SO 4 2− , the fractIon of the surface area covered by water was decided to represent the new wetting index. Using a chalk core at residual oil saturatIon, the area between the effluent curves for SCN − and SO 4 2− is proportIonal to the area contacted by water during the flooding process. The ratio between this area and the corresponding area obtained from a completely water-wet core will give a water index between 0 and 1, representing completely oil-wet and completely water-wet conditIons, respectively. The method is excellent to be used close to neutral conditIon, which will give a wetting index of 0.5. Experimental results are presented for two different chalks at different wetting conditIons. Furthermore, the change in the Zeta-Potential of the chalk surface over the dispersIon zone of SO 4 2− is visualised by a gradient in the Ca 2+ concentratIon in the same regIon.
Peimao Zhang - One of the best experts on this subject based on the ideXlab platform.
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wettability alteratIon and improved oil recovery by spontaneous imbibitIon of seawater into chalk impact of the Potential Determining Ions ca2 mg2 and so42
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2007Co-Authors: Peimao Zhang, Medad T Tweheyo, Tor AustadAbstract:Abstract Carbonate wettability is dictated by the surface chemistry related to stability of the water film between the oil phase and the rock surface. It has been verified, both in the field and laboratory, that seawater is an excellent injectIon fluid to enhance the oil recovery from fractured chalk. The objective of different papers in this series has been to understand the chemistry for improved spontaneous imbibitIon of seawater into low permeable chalk at low water wetness. Improved spontaneous imbibitIon of water will take place if the chalk becomes more water-wet during the productIon phase. The Potential Determining Ions present in seawater, Ca2+ and SO42−, have great influence on the surface charge of chalk, which can modify the wettability during water injectIon. In the present study, it was verified that Mg2+ is another strong Potential Determining Ion towards chalk, which can increase the positive surface charge density. At high temperatures, Mg2+ can even substitute Ca2+ from the chalk surface, and the degree of substitutIon increased as the temperature increased. The interplay between the three Potential Determining Ions: Ca2+, Mg2+ and SO42− and the chalk surface with the aim to improve the water wetness of biogenic chalk, was studied from a spontaneous imbibitIon point of view. To improve water wetness, SO42− must act together with either Ca2+ or Mg2+. In both cases, the efficiency increased as the temperature increased. The water wetness of chalk can be improved if some of the carboxylic material adsorbed onto the chalk surface is displaced. A chemical mechanism discussing the mutual interactIon between the Potential Determining Ions and the chalk surface is proposed.
Medad T Tweheyo - One of the best experts on this subject based on the ideXlab platform.
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wettability alteratIon and improved oil recovery by spontaneous imbibitIon of seawater into chalk impact of the Potential Determining Ions ca2 mg2 and so42
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2007Co-Authors: Peimao Zhang, Medad T Tweheyo, Tor AustadAbstract:Abstract Carbonate wettability is dictated by the surface chemistry related to stability of the water film between the oil phase and the rock surface. It has been verified, both in the field and laboratory, that seawater is an excellent injectIon fluid to enhance the oil recovery from fractured chalk. The objective of different papers in this series has been to understand the chemistry for improved spontaneous imbibitIon of seawater into low permeable chalk at low water wetness. Improved spontaneous imbibitIon of water will take place if the chalk becomes more water-wet during the productIon phase. The Potential Determining Ions present in seawater, Ca2+ and SO42−, have great influence on the surface charge of chalk, which can modify the wettability during water injectIon. In the present study, it was verified that Mg2+ is another strong Potential Determining Ion towards chalk, which can increase the positive surface charge density. At high temperatures, Mg2+ can even substitute Ca2+ from the chalk surface, and the degree of substitutIon increased as the temperature increased. The interplay between the three Potential Determining Ions: Ca2+, Mg2+ and SO42− and the chalk surface with the aim to improve the water wetness of biogenic chalk, was studied from a spontaneous imbibitIon point of view. To improve water wetness, SO42− must act together with either Ca2+ or Mg2+. In both cases, the efficiency increased as the temperature increased. The water wetness of chalk can be improved if some of the carboxylic material adsorbed onto the chalk surface is displaced. A chemical mechanism discussing the mutual interactIon between the Potential Determining Ions and the chalk surface is proposed.
Masahiro Yamamoto - One of the best experts on this subject based on the ideXlab platform.
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electrocapillarity at the nonpolarized interface between the aqueous solutIon and the room temperature molten salt composed of 1 octyl 3 methylimidazolium bis pentafluoroethylsulfonyl imide
Physical Chemistry Chemical Physics, 2004Co-Authors: Takashi Kakiuchi, Fumiko Shigematsu, Takuya Kasahara, Naoya Nishi, Masahiro YamamotoAbstract:The interfacial tensIon between the room-temperature molten salt (RTMS, also called Ionic liquid) composed of 1-octyl-3-methylimidazolium bis(perfluoroethylsulfonyl)imide (C8mimC2C2N) and the aqueous solutIon containing 1-octyl-3-methylimidazolium chloride or lithium bis(perfluoroethylsulfonyl)imide has been measured as a functIon of the compositIon of the aqueous phase. The phase–boundary Potential calculated for this non-polarized interface from the solutIon compositIon enables us to construct the corresponding electrocapillary curve, which shows a parabolic shape with respect to the variatIon of the phase–boundary Potential over 300 mV. C8mim+ Ions specifically adsorb at the interface. Switching of the Potential-Determining Ion from C8mim+ to C2C2N− causes a jump of more than 160 mV in the Potential at the outer Helmholtz plane on the aqueous side of the interface.
André Nonat - One of the best experts on this subject based on the ideXlab platform.
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C-S-H/solutIon interface: Experimental and Monte Carlo studies
Cement and Concrete Research, 2010Co-Authors: Christophe Labbez, Isabelle Pochard, Bo Jönsson, André NonatAbstract:The surface charge density of C-S-H particles appears to be one of the key parameters for predicting the cohesIon strength, understanding the Ion retentIon, the pollutant leakage, and admixture adsorptIon in hydrated cement pastes. This paper presents a Monte Carlo simulatIon of the surface-Ions interactIons that permits the predictIon of surface charge density (σ), electrokinetic Potential (ζ) and Ions adsorptIon of mineral surfaces in equilibrium with a given electrolyte solutIon. Simulated results are compared to experimental data obtained by titratIon, electrokinetic Potential measurements and Ions uptake in the case of C-S-H suspensIons. An excellent agreement is found between simulated and experimental results. The wide spread idea that calcium is a Potential Determining Ion in cement paste systems appears to be incorrect. Instead, the pH controls the charging behaviour of C-S-H nano-particles. This paper also shows to what extent the electrostatic interactIons contribute to the measured Ca/Si ratio.