sjavadi

• Dziadkowiec, Joanna; Ban, Matea; Javadi, Shaghayegh; Jamtveit, Bjørn & Røyne, Anja (2021). Ca2+ ions decrease adhesion between two (104) calcite surfaces as probed by Atomic Force Microscopy. ACS Earth and Space Chemistry. 5(10), s. 2827–2838. doi: 10.1021/acsearthspacechem.1c00220. Fulltekst i vitenarkiv Vis sammendrag

  Solution composition-sensitive disjoining pressure acting between the mineral surfaces in fluid-filled granular rocks and materials controls their cohesion, facilitates the transport of dissolved species, and may sustain volume-expanding reactions leading to fracturing or pore sealing. Although calcite is one of the most abundant minerals in the Earth’s crust, there is still no complete understanding of how the most common inorganic ions affect the disjoining pressure (and thus the attractive or repulsive forces) operating between calcite surfaces. In this atomic force microscopy study, we measured adhesion acting between two cleaved (104) calcite surfaces in solutions containing low and high concentrations of Ca2+ ions. We detected only low adhesion between calcite surfaces, which was weakly modulated by the varying Ca2+ concentration. Our results show that the more hydrated calcium ions decrease the adhesion between calcite surfaces with respect to monovalent Na+ at a given ionic strength, and thus Ca2+ can sustain relatively thick water films between contacting calcite grains even at high overburden pressures. These findings suggest a possible loss of cohesion and continued progress of reaction-induced fracturing for weakly charged minerals in the presence of strongly hydrated ionic species.

• Javadi, Shaghayegh & Røyne, Anja (2018). Adhesive forces between two cleaved calcite surfaces in NaCl solutions: The importance of ionic strength and normal loading. Journal of Colloid and Interface Science. ISSN 0021-9797. 532, s. 605–613. doi: 10.1016/j.jcis.2018.08.027. Fulltekst i vitenarkiv Vis sammendrag

  The mechanical strength of calcite bearing rocks is influenced by pore fluid chemistry due to the variation in nano-scale surface forces acting at the grain contacts or close to the fracture tips. The adhesion of two contacting surfaces, which affects the macroscopic strength of the material, is not only influenced by the fluid chemistry but also by the surface topography. In this paper, we use Atomic Force Microscope (AFM) to measure the interfacial forces between two freshly cleaved calcite surfaces in CaCO3-saturated solutions with varying NaCl concentration. We show that calcite contacts become stronger with increasing NaCl concentration (> 100 mM), as a result of progressively weaker secondary hydration and increasing attraction due to instantaneous ion-ion correlation. Moreover, we discuss the effect of normal applied force (Fn) and surface roughness on the measured adhesion forces (Fad). We show that the measured pull-off force (adhesion) is linearly correlated with the magnitude of Fn, where an increase in applied force results in increased adhesion. This is attributed to a larger number of contacting surface asperities and thus increase in real contact area and the contact-bond strength. We discuss that the possible variation in local topography at contacts, together with strong dependence on ionic strength of the solution, can explain the inconsistent behavior of calcite rocks in NaCl solutions.

• Dziadkowiec, Joanna; Javadi, Shaghayegh; Bratvold, Jon E.; Nilsen, Ola & Røyne, Anja (2018). Surface Forces Apparatus Measurements of Interactions between Rough and Reactive Calcite Surfaces. Langmuir. ISSN 0743-7463. 34((25)), s. 7248–7263. doi: 10.1021/acs.langmuir.8b00797. Fulltekst i vitenarkiv Vis sammendrag

  Nm-range forces acting between calcite surfaces in water affect macroscopic properties of carbonate rocks and calcite-based granular materials, and are significantly influenced by calcite surface recrystallization. We suggest that the repulsive mechanical effects related to nm-scale surface recrystallization of calcite in water could be partially responsible for the observed decrease of cohesion in calcitic rocks saturated with water. Using the Surface Forces Apparatus (SFA), we simultaneously followed the calcite reactivity and measured the forces in water in two surface configurations: between two rough calcite surfaces (CC), or between rough calcite and a smooth mica surface (CM). We used nm-scale rough, polycrystalline calcite films prepared by Atomic Layer Deposition (ALD). We measured only repulsive forces in CC in CaCO3-saturated water, which was related to roughness and possibly to repulsive hydration effects. Adhesive or repulsive forces were measured in CM in CaCO3-saturated water depending on calcite roughness, and the adhesion was likely enhanced by electrostatic effects. The pull-off adhesive force in CM became stronger with time and this increase was correlated with a decrease of roughness at contacts, which parameter could be estimated from the measured force-distance curves. That suggested a progressive increase of real contact areas between the surfaces, caused by gradual pressure-driven deformation of calcite surface asperities during repeated loading-unloading cycles. Reactivity of calcite was affected by mass transport across nm to µm-thick gaps between the surfaces. Major roughening was observed only for the smoothest calcite films, where gaps between two opposing surfaces were nm-thick over µm-sized areas, and led to force of crystallization that could overcome confining pressures of the order of MPa. Any substantial roughening of calcite caused a significant increase of the repulsive mechanical force contribution.

Se alle arbeider i NVA

• Dziadkowiec, Joanna; Javadi, Shaghayegh; Ban, Matea; Jamtveit, Bjørn & Røyne, Anja (2022). Ion-dependent adhesion between calcite surfaces. Fulltekst i vitenarkiv
• Dziadkowiec, Joanna; Ban, Matea; Javadi, Shaghayegh; Jamtveit, Bjørn & Røyne, Anja (2021). Ion-specific adhesion between brittle calcite surfaces. Fulltekst i vitenarkiv
• Dziadkowiec, Joanna; Javadi, Shaghayegh & Røyne, Anja (2019). Contacts between reactive surfaces. Fulltekst i vitenarkiv
• Dziadkowiec, Joanna; Javadi, Shaghayegh; Bratvold, Jon E.; Nilsen, Ola & Røyne, Anja (2018). Adhesive and repulsive forces between calcite surfaces. Fulltekst i vitenarkiv
• Javadi, Shaghayegh; Dziadkowiec, Joanna; Røyne, Anja; Bratvold, Jon E.; Nilsen, Ola & Hiorth, Aksel (2018). Synthetic CaCO3 surfaces in aqueous solutions – AFM and Surface Force Apparatus (SFA) measurements. Fulltekst i vitenarkiv
• Dziadkowiec, Joanna; Javadi, Shaghayegh; Bratvold, Jon E.; Nilsen, Ola & Røyne, Anja (2018). Nucleation in solution confined between reactive surfaces can generate long-range repulsive forces. Fulltekst i vitenarkiv
• Javadi, Shaghayegh (2017). Interaction forces between two calcite surfaces as a function of ionic strength in NaCl solutions. Fulltekst i vitenarkiv
• Javadi, Shaghayegh; Røyne, Anja & Hiorth, Aksel (2017). AFM study of the adhesion of calcite surfaces in NaCl solutions. Fulltekst i vitenarkiv
• Dziadkowiec, Joanna; Javadi, Shaghayegh; Bratvold, Jon E.; Nilsen, Ola & Røyne, Anja (2017). Interactions between reactive CaCO3 surfaces in aqueous solutions -Surface Forces Apparatus measurements. Fulltekst i vitenarkiv
• Røyne, Anja; Javadi, Shaghayegh & Dziadkowiec, Joanna (2017). Nanoscale forces between calcite surfaces and how they relate to fracturing and friction. Fulltekst i vitenarkiv
• Dziadkowiec, Joanna; Javadi, Shaghayegh & Røyne, Anja (2017). Surface Forces Apparatus measurements of interactions between rough and reactive calcite surfaces. Fulltekst i vitenarkiv
• Javadi, Shaghayegh; Røyne, Anja & Hiorth, Aksel (2016). Interaction between two calcite surfaces, in nano-scale, as a function of fluid composition. Fulltekst i vitenarkiv Vis sammendrag

  As one part of the Enhanced oil recovery (EOR) techniques, the injection of fluid into chalk reservoirs, specifically in the North sea, has been of interest for several years. Despite extensive research in this field, there are still many questions left to be answered. One such question is the compaction of chalk reservoirs as the impact of fluid injection. The cause of this process is not fully understood, but it is believed that the microscopic origin of this effect could reveal the secrets behind this phenomenon [1]. Recent experimental and theoretical works have shown, e.g., [1] & [2], that the mechanical strength of chalk rocks behave dependently on the chemistry of pore fluid. In particular, it may be the interfacial nano-forces near the grain boundaries that are responsible for mechanical behavior of two interacting calcite-bearing rocks. In this work, we present an experimental study, in which the hydration re- pulsion between two calcite surfaces is measured. We have developed an experimental method using Atomic Force Microscope (AFM), in which a tip- less AFM cantilever is glued to a calcite fragment, from a freshly cleaved calcite crystal [3]. We then investigate the interaction between these two cal- cite grains in a fluid cell containing salt water. We show the effect of ionic compound, ionic strength and salinity on the hydration short-range forces be- tween calcite surfaces over the time. The result of this study can help us to understand the mechanism behind the chalk-liquid interactions and so-called chalk water weakening due to water adsorption on calcite surfaces. Figure 1 shows a simple sketch of the AFM-tip modification (left), and a SEM image of one of the calcite grains attached to the AFM cantilever (right).

• Javadi, Shaghayegh (2016). Interaction forces between two calcite surfaces as a function of fluid composition. Fulltekst i vitenarkiv Vis sammendrag

  Upon interaction between two calcite crystals in the presence of fluid, repulsion and attraction forces are generated by the confined fluid film at the interface. It has been shown that these nano-scale forces impact the mechanical behavior of calcite-bearing rocks, e.g., [1] & [2]. The long-term deformation of calcite rocks induced by chemical mechanisms, such as dissolution and growth, occurs in the presence of pore fluid. This makes the interaction analysis more complicated [3]. We therefore need to find out not only the responsibility of chemistry fluid on mechanical behavior of calcite, but also to what extent calcite crystals grow or dissolve in pore fluid. Since calcite is the main component of chalk, the result of this study describes the compaction caused by injecting water into chalk reservoirs [1], through the Enhanced Oil Recovery (ERC) projects. In this work, we present an experimental method to study the interfacial forces between two calcite crystals in fluid, in nano-scale. We observed that changing the chemistry of pore fluid, will change the adhesion properties of calcite. In order to measure the adhesion force, we have developed a method using Atomic Force Microscopy (AFM) [3]. Through this method we investigate the nano-scale repulsion and attraction forces between two calcite grains in a liquid cell that are moving towards or apart from one another. Analyzing this experimental data gives us the adhesion force between two calcite grains for variation of ionic compound, ionic strength and salinity. The measured adhesion force depends on the area of contact, which is in turn affected by growth and dissolution of the crystal surfaces. We show that the short-range forces between calcite surfaces in salt water vary extensively as a function of fluid composition and time.

• Røyne, Anja; Bergsaker, Anne Schad; Javadi, Shaghayegh; Dziadkowiec, Joanna; Bratvold, Jon E. & Nilsen, Ola (2016). The role of surface forces and confined fluid films in the slow deformation of rocks. Fulltekst i vitenarkiv
• Javadi, Shaghayegh; Røyne, Anja & Hiorth, Aksel (2015). Experimental investigation of nano-scale interaction between two calcite grains. Fulltekst i vitenarkiv
• Javadi, Shaghayegh; Røyne, Anja & Hiorth, Aksel (2015). Experimental investigation of the effect of fluid chemistry on adhesive properties of calcite surfaces. Fulltekst i vitenarkiv
• Røyne, Anja & Javadi, Shaghayegh (2015). The role of surface forces in fluid-rock interactions. Fulltekst i vitenarkiv
• Røyne, Anja; Hassenkam, Tue; Bergsaker, Anne Schad & Javadi, Shaghayegh (2015). The role of nanoconfined fluid films in fracture propagation and healing. Fulltekst i vitenarkiv
• Røyne, Anja & Javadi, Shaghayegh (2019). Interaction between two calcite surfaces in aqueous solutions: Study of nano-scale interfacial forces using AFM and SFA. Universitetet i Stavanger. Fulltekst i vitenarkiv Vis sammendrag

  Carbonate-bearing rocks in the upper Earth’s crust are prone to continuous changes under influences of various physical and chemical processes. The macroscopic mechanical strength of carbonates is generally controlled by the cohesion between contacting grains at a molecular scale. These grains deform in contact regions due to the chemistry of pore fluid. The repulsive and attractive forces that perate at the grain contacts may be affected by the dissolution and recrystallization kinetics at the mineral-liquid interfaces. The processes by which the nano-scale interfacial forces are influenced by changing properties of the confined fluid are largely unknown. In this thesis, I investigate these processes and their possible contribution to the strength of calcite-bearing rocks and materials. The Atomic Force Microscope (AFM) and Surface Force Apparatus (SFA) are two powerful tools that provide an opportunity of direct observation of mineral reactions to the contacting fluid and measuring the surface forces at nano-scale in air and liquid environments. In this project, we perform an extended number of experiments using the AFM and SFA to improve our understanding of variation in interfacial forces linked to the strength of calcite and calcite-bearing rocks. In the AFM experiments, we bring an in situ fabricated calcite probe into contact with an opposing freshly cleaved calcite surface in a fluid cell containing aqueous solutions with varying chemical compositions. We also combine the AFM force measurements with a technique called inverse imaging, for in situ simultaneous characterization of the calcite probes. Based on these experiments, we discuss that the possible variation in local topography of contacts, together with a strong dependence on ionic strength of the solution, can explain the variation in strength of calcite rocks in aqueous solutions. With the SFA, we can perform in situ observations of the possible changes in the surfaces via light interferometry technique while measuring the interfacial interactions at nano-scale. At this scale, interactions between contacting surface asperities define the nature of interfacial forces, repulsive or attractive. We discuss how the crystal growth, dissolution and changes in surface roughness affect these interaction forces and their implications on the strength of calcite-bearing rocks.

Se alle arbeider i NVA