Browsing by Author "Paudyal, Samiridhdi"

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    Observations of CO2 Corrosion-Induced Carbonate Scale Formation and Inhibition on Mild Steel
    (SPE, 2022) Li, Wei; Dai, Zhaoyi; Wang, Xin; Ko, Saebom; Paudyal, Samiridhdi; Yao, Xuanzhu; Leschied, Cianna; Shen, Yu-Yi; Pimentel, Daniel; Kan, Amy T.; Tomson, Mason
    Aqueous CO2-containing environment is ubiquitous in oil and gas production. Carbonate scales (e.g., calcite) tend to form in such an environment. Meanwhile, the CO2 corrosion of mild steel infrastructure may result in corrosion-induced scales including siderite (FeCO3). Previously, siderite was generally treated as a corrosion problem rather than a scale problem. However, the relationship between the corrosion-induced scale and other metal carbonate scales on the steel surface is unclear. For example, how does siderite influence calcite deposition on the mild steel? In this study, the mild steel corrosion and mineral carbonate scaling behaviors were investigated simultaneously in the presence of various cations such as Ca2+ and Mg2+. We observed a two-layer scale structure on the mild steel surface under simulated oilfield conditions. The inner layer is an iron-containing carbonate scale such as ankerite or siderite, while the outer layer is calcite. In addition, calcite deposition at a very low saturation index was observed when the inner layer was present. Furthermore, a common scale inhibitor [diethylenetriaminepentakis(methylenephosphonic acid) or DTPMP] can effectively mitigate calcite, siderite, and ankerite formation on the steel surface, but meanwhile, aggravate the steel corrosion because of the absence of protective scale layers.
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    Prediction Models of Barite Crystallization and Inhibition Kinetics: Applications for Oil and Gas Industry
    (MDPI, 2021) Dai, Chong; Dai, Zhaoyi; Zhao, Yue; Wang, Xin; Paudyal, Samiridhdi; Ko, Saebom; Kan, Amy T.; Tomson, Mason B.
    Barite is one of the most common mineral scales in the oilfield and its formation can sequester toxic strontium (Sr) and radium (Ra). Various scale inhibitors are widely used to inhibit its formation. The inhibition efficiencies of 18 common inhibitors were tested using an improved kinetic turbidity method over broad oil and gas production conditions. A theoretical and a semi-empirical barite crystallization and inhibition model were developed for the 18 most used scale inhibitors. Both models can work under a broad range of production conditions and are carefully reviewed against all available experimental data. These models have shown wide applications in industrial operations, field testing, and laboratory testing. Using the new models and testing method, a novel fast inhibitor performance testing method was proposed and validated. Furthermore, the barite crystallization and inhibition models also work well to predict the inhibition performance of mixed inhibitors. This study not only advanced barite scale inhibition in an efficiency and low-cost way during oil and gas production, but also provided new insights on understanding the fate and transport of toxic Sr and Ra.