Browsing by Author "Jian, Guoqing"

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    Characterizing adsorption of associating surfactants on carbonates surfaces
    (Elsevier, 2018) Jian, Guoqing; Puerto, Maura; Wehowsky, Anna; Miller, Clarence; Hirasaki, George J.; Biswal, Sibani L.
    HYPOTHESIS: The adsorption of anionic surfactants onto positively charged carbonate minerals is typically high due to electrostatic interactions. By blending anionic surfactants with cationic or zwitterionic surfactants, which naturally form surfactant complexes, surfactant adsorption is expected to be influenced by a competition between surfactant complexes and surfactant-surface interactions. EXPERIMENTS: The adsorption behavior of surfactant blends known to form complexes was investigated. The surfactants probed include an anionic C15-18 internal olefin sulfonate (IOS), a zwitterionic lauryl betaine (LB), and an anionic C13-alcohol polyethylene glycol ether carboxylic acid (L38). An analytical method based on high-performance liquid chromatography evaporative light scattering detector (HPLC-ELSD) was developed to measure three individual surfactant concentrations from a blended surfactant solution. The adsorption of the individual surfactants and surfactant blends were systematically investigated on different mineral surfaces using varying brine solutions. FINDINGS: LB adsorption on calcite surfaces was found to be significantly increased when blended with IOS or L38 since it forms surfactant complexes that partition to the surface. However, the total adsorption of the LB-IOS-L38 solution on dolomite decreased from 3.09 mg/m2 to 1.97 mg/m2 when blended together compared to summing the adsorption values of individual surfactants, which highlights the importance of mixed surfactant association.
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    Evaluating the Transport Behavior of CO2ﾠFoam in the Presence of Crude Oil under High-Temperature and High-Salinity Conditions for Carbonate Reservoirs
    (American Chemical Society, 2019) Jian, Guoqing; Zhang, Leilei; Da, Chang; Puerto, Maura; Johnston, Keith P.; Biswal, Sibani L.; Hirasaki, George J.
    An amine-based surfactant, Duomeen TTM, was evaluated for foam flooding in carbonate rock at high temperature (120 °C), high salinity (22% total dissolved solids), and CO2–oil miscible conditions. We demonstrate enhanced oil recovery by utilizing CO2 foam under miscible conditions in the presence of crude oil. The foam was generated in situ by both co-injection and surfactant alternating gas injection modes. Foam transport and propagation were characterized as a function of the foam quality, shear rate, permeability, surfactant concentration, and method of injection. Finally, we utilize the experimental results to obtain the parameters for the STARS foam model by optimizing multiple variables related to the dry out, shear thinning, and surfactant concentration effects on foam transport. Enhanced oil recovery utilizing CO2 foam under miscible conditions in the presence of SMY crude oil was able to decrease oil saturation to 3.0%. It was also determined that significantly more injected pore volumes were required for the foam to reach the steady state in the presence of SMY crude oil. A foam simulation process in a heterogeneous reservoir is conducted applying the parameters obtained. The TTM CO2 foam generated significantly reduces the mobility of CO2 in the high permeability layers, which results in an improved swept volume in the low permeability zone that significantly improves oil recovery when epoil = 1 and fmoil = 0.5. Oil saturation parameters play important roles in the effectiveness of CO2 foam: large epoil and small fmoil will reduce the efficiency for TTM CO2 foam.
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    Two-Step Adsorption of a Switchable Tertiary Amine Surfactant Measured Using a Quartz Crystal Microbalance with Dissipation
    (American Chemical Society, 2019) Chen, Yi-Lin; Zhang, Leilei; Song, Jin; Jian, Guoqing; Hirasaki, George; Johnston, Keith; Biswal, Sibani Lisa
    The adsorption of a switchable cationic surfactant, N,N,N′-trimethyl-N′-tallow-1,3-diaminopropane (DTTM, Duomeen TTM), at the silica/aqueous solution interface is characterized using a quartz crystal microbalance with dissipation (QCM-D). The adsorption isotherms reveal that changes in the solution pH or salinity affect surfactant adsorption in competing ways. In particular, the combination of the degree of protonation of the surfactant and electrostatic interactions is responsible for surfactant adsorption. The kinetics of adsorption is carefully measured using the real-time measurement of a QCM-D, allowing us to fit the experimental data with analytical models. At pH values of 3 and 5, where the DTTM is protonated, DTTM exhibits two-step adsorption. This is representative of a fast step in which the surfactant molecules are adsorbed with head-groups orientated toward the surface, followed by a slower second step corresponding to formation of interfacial surfactant aggregates on the silica surface.