Elucidating Kinetic, Adsorption and Partitioning Phenomena from a Single Well Tracer Method: Laboratory and Bench Scale Studies

Abstract

This study is aimed at giving some insights on kinetics, adsorption and partitioning of ethyl acetate during a single well tracer test. Synthetic formation water, an specific crude oil and a silicate-dolomite rock were used during experiments performed in laboratory and bench scale systems. Independent sets of experiments were designed to calculate the partition coefficient of ethyl acetate between the formation water and the oil, to develop a kinetic model for the hydrolysis of ethyl acetate, and to derive isotherm and kinetic models for the adsorption of ethyl acetate on the rock. These tracer experiments were evaluated at a concentration range (100–300 mmol.L−1) similar to that supposed to be used in the single well tracer method. All parameters determined from these experiments were validated describing observations from stirred batch and column systems, in which kinetic, adsorption and partitioning phenomena occurred at the same time. Pseudo-heterogeneous models, accounting for three phases namely the formation water, the rock and the oil, were applied to elucidate the interaction of the different mechanisms involved in these set-ups. Main results are summarized as follows: (i) partition coefficients (KEA) were apparent varying from ca. 5–8 because of thermodynamic constraints; (ii) kinetic models for the hydrolysis of ethyl acetate were developed under acid and basic conditions since at neutral ones there were negligible conversions; (iii) the combined Langmuir-Freundlich isotherm and the Langmuir kinetics were the most suitable models describing equilibrium and adsorption rate observations, respectively; (iv) the studied rock adsorbed significant amounts of ethyl acetate, leading to a maximum adsorption capacity (qEAm) of ca. 7.0 mmol.g−1 at studied operating conditions; (v) the adsorption kinetic model rather than the simplified isotherm model seems necessary to describe this phenomenon from the single well test evaluating ethyl acetate as the tracer; and (vi) partition, hydrolysis and adsorption parameters evaluated from independent experiments allowed us to describe observations from both stirred batch and column systems. These results disclose the importance of accounting for partition, hydrolysis and adsorption mechanisms in a single well method using ethyl acetate as the tracer.

Nanoconfined Liquid Phase Nanoextraction Based on Carbon Nanofibers

“…As expected for a single diffusion process, % extracted and % desorbed depends on time in a logarithmic scale . Furthermore, their values are statistically not different (α = 0.05) until 1800 s (30 min), while after this time, % desorbed underwent a sudden decrease.…”

“…As expected for a single diffusion process, % extracted and % desorbed depends on time in a logarithmic scale. 27 Furthermore, their values are statistically not different (α = 0.05) until 1800 s (30 min), while after this time, % desorbed underwent a sudden decrease. This behavior is due to the occurrence of a competing process that can be tentatively explained considering the possibility that the analyte is slowly and strongly adsorbed on the CNF surface, 28 inhibiting the successive release into the desorption solvent.…”

Análisis de la adsorción de un colorante en un material natural o sintético

“…Se puede obtener un modelo de isoterma lineal más simple a partir de la ec. 4.5 que se ha utilizado para evaluar la adsorción (Otero-López et al 2016):…”

“…11 se representan gráficamente los datos experimentales de las isotermas obtenidas a 20, 35 y 50 °C junto con las curvas teóricas ajustadas, pudiéndose observar que la reproducción del equilibrio de adsorción es muy buena mediante las ecuaciones de Langmuir, Freundlich y Langmuir-Freundlich. Cabe resaltar que los valores obtenidos del análisis de errores de la ecuación de Langmuir-Freundlich son casi cero, lo que sugiere que existe una sinergia entre la suposición de Langmuir y Freundlich, es decir, que la adsorción sea monocapa y multicapa, y la interacción entre las moléculas de RhB en la superficie de la ZN(Otero-López et al 2016). La capacidad de adsorción disminuye al incrementar la temperatura y los valores de 1/𝑛 inferiores a 1 muestran la naturaleza favorable de la adsorción de RhB sobre la ZN(Mane, Deo Mall, and Chandra Srivastava 2007).…”