Adsorption of crude oil components at mineral surfaces followed by quartz crystal micro-balance and contact angle measurements: The effect of oil composition, simulated weathering and dispersants

Improved knowledge of interactions between crude oil and solid surfaces is of great importance for understanding oil spill responses as well as oil spill behavior on land and in the near-shore environment. Here, the goal was to study how crude oils with various physicochemical properties interacted with model shoreline surfaces. In addition, the influence of simulated weathering and addition of dispersants was investigated for selected crude oils. A quartz crystal microbalance was used to follow the adsorption from 13 different crude oils on silica, aluminosilicate, and calcium carbonate surfaces, whereas the corresponding wettability alterations were followed by contact angle measurements. The polar crude oil components adsorbed in considerably higher amounts on the calcium carbonate surfaces than on the silica and aluminosilicate surfaces. The simulated weathering of oils resulted in increased adsorption onto both the silica and aluminosilicate surfaces, whereas it had a little effect on the calcium carbonate surface. The presence of dispersants generally reduced the amounts adsorbed on the surfaces. In the presence of seawater, the crude oil with a higher total acid number interacted strongest with the calcium carbonate surface.acceptedVersio

Adsorption of crude oil components at mineral surfaces followed by quartz crystal micro-balance and contact angle measurements: The effect of oil composition, simulated weathering and dispersants

Improved knowledge of interactions between crude oil and solid surfaces is of great importance for understanding oil spill responses as well as oil spill behavior on land and in the near-shore environment. Here, the goal was to study how crude oils with various physicochemical properties interacted with model shoreline surfaces. In addition, the influence of simulated weathering and addition of dispersants was investigated for selected crude oils. A quartz crystal microbalance was used to follow the adsorption from 13 different crude oils on silica, aluminosilicate, and calcium carbonate surfaces, whereas the corresponding wettability alterations were followed by contact angle measurements. The polar crude oil components adsorbed in considerably higher amounts on the calcium carbonate surfaces than on the silica and aluminosilicate surfaces. The simulated weathering of oils resulted in increased adsorption onto both the silica and aluminosilicate surfaces, whereas it had a little effect on the calcium carbonate surface. The presence of dispersants generally reduced the amounts adsorbed on the surfaces. In the presence of seawater, the crude oil with a higher total acid number interacted strongest with the calcium carbonate surface

Dynamic wettability alteration for combined low salinity brine injection and surfactant flooding on silica surface

Experimental results of dynamic contact angle measurements of low salinity brine and combined low salinity water and surfactant flooding (LSW–SF) on silica surface are presented in this study. Dynamic contact angle experiments were carried out for four crude oil samples with low salinity brines and combined low salinity and sodium dodecylbenzene sulfonate (SDBS) solutions. Similar measurements with the same ion strength in presence of different cations, Na+ and Ca2+, for low salinity injections and combined low salinity–SDBS solutions were also carried out to study the change in dynamic contact angles and wetting behavior. The presences of different cations change the initial contact angles in low salinity solution injections and show different dynamic behaviors in presence of different crude oils. The signs and values of the line tension to oil/water interfacial tension ratios have been calculated from the size dependence of the dynamic contact angle measurements on the silica coated quartz crystal microbalance sensors. Analysis indicates positive line tension values for low salinity brine systems and negative values for LSW–SF systems. Injection of surfactant solutions in presence of electrolyte prompts the spreading of the oil droplet over the surface, which is induced by interfacial tension gradient from the top of the oil droplet toward the contact line. The results indicated that spreading time, which is the required time for oil drop to gradually flatten out, is dependent on type of electrolytes and is a function of surface excess concentration of the surfactant

A predictive model for the wettability of chalk

Wettability is usually measured in special core analyses of limited plug samples according to typically costly and time-consuming procedures. For comparative purposes, wettability is considered an index. The two most frequently used wettability indices are the Amott–Harvey wettability index and the U.S. Bureau of Mines (USBM) index. The Amott–Harvey wettability index is linked to imbibition characteristics and the USBM index is associated with the area under capillary pressure curves. To provide a fast analytical method, a mathematical model for predicting the wettability of chalk is presented. The model is calibrated using experimental wettability data and subsequently applied to two wells in Danish chalk oil fields in the North Sea and to outcrop chalk samples. The model supplements traditional labor-intensive laboratory measurements and predicts water wettability variations with depth by modeling both depth and porosity dependencies; in addition, it provides estimates of the effects of the aging time and displacement temperature of chalk wettability measurements in the laboratory