Two different crude oils with significantly different physical properties, South Pelto Crude Oil and Garden Banks Condensate, were studied extensively in the small-scale flow loop of Tulsa University Paraffin Deposition Projects. A total of eight oil-water deposition tests, two single-phase deposition tests, and two inversion point tests were successfully conducted. Four different water cuts were selected for each fluid. The deposit thickness showed a decreasing trend with increasing water cuts for both the South Pelto oil and Garden Banks condensate tests. In contrast to South Pelto's water continuous results, which showed no deposit, a Garden Banks condensate test with 85% water cut did generate a very thin and hard deposit film. This result indicates that there has to be a different deposition mechanism than the ones based on conventional diffusion theory. A reduction in Reynolds number caused by the increased apparent viscosity of the mixture also resulted in a lower paraffin content of the deposits. The volume fraction of water in the deposit is lower than the initial water cut of the mixture for both fluids. Garden Banks showed less water fraction in the deposit compared to South Pelto. Couto's (2004) preliminary oil-water paraffin deposition model was validated against experimental data. Several modifications are proposed to account for water concentration in the deposit and changes in the diffusion coefficient for water dominated flows. Model predictions agree fairly well with experimental data acquired in this and previous studies. Introduction When the bulk oil temperature is higher than the pipe wall temperature which is below wax appearance temperature (WAT), there will be a dissolved wax concentration gradient between the bulk oil and pipe wall. This concentration gradient will result in diffusion of dissolved wax molecules towards the pipe wall and later crystallization and deposition of waxes. This continuous deposition process reduces the effective flow area of the pipe and may eventually result in complete blockage. Paraffin deposition can be a very costly and dangerous problem in the oil industry. It can affect single wells, and transportation pipelines that are critical to the safe supply of oil to processing facilities. Most paraffin deposition studies conducted to date have focused on single-phase oil and oil-gas two-phase flow. Nevertheless, the presence of water along with the oil is increasingly common in everyday field operations. A literature review showed that the paraffin deposition process is not well understood for oil-water flow conditions. Very few studies have been conducted to investigate the effects of water on the deposition process. A series of single-phase oil and two-phase oil-water deposition experiments using South Pelto Crude Oil and Garden Banks Condensate have been conducted to investigate the effect of water on crude oil paraffin deposition process under flowing conditions. Based on the results of the experimental study, Cuoto's (2004) oil-water deposition model was improved. The test facility used in this study is the Small Scale Test Loop of Tulsa University Paraffin Deposition Projects (TUPDP) consisting of three test sections with different pipe diameters.

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The scaling properties of turbulent flows are well established in the inertial sub-range. However, those of the synoptic-scale motions are less known, also because of the difficult analysis of data presenting nonstationary and periodic features. Extensive analysis of experimental wind speed data, collected at the Mauna Loa Observatory of Hawaii, is performed using different methods. Empirical Mode Decomposition, interoccurrence times statistics, and arbitrary-order Hilbert spectral analysis allow to eliminate effects of large-scale modulations, and provide scaling properties of the field fluctuations (Hurst exponent, interoccurrence distribution, and intermittency correction). The obtained results suggest that the mesoscale wind dynamics owns features which are typical of the inertial sub-range turbulence, thus extending the validity of the turbulent cascade phenomenology to scales larger than observed before.

The probability density function (PDF) of the time intervals between subsequent extreme events in atmospheric Hg0 concentration data series from different latitudes has been investigated. The Hg0 dynamic possesses a long‐term memory autocorrelation function. Above a fixed threshold Q in the data, the PDFs of the interoccurrence time of the Hg0 data are well described by a Tsallis q‐exponential function. This PDF behavior has been explained in the framework of superstatistics, where the competition between multiple mesoscopic processes affects the macroscopic dynamics. An extensive parameter μ, encompassing all possible fluctuations related to mesoscopic phenomena, has been identified. It follows a χ2 distribution, indicative of the superstatistical nature of the overall process. Shuffling the data series destroys the long‐term memory, the distributions become independent of Q, and the PDFs collapse on to the same exponential distribution. The possible central role of atmospheric turbulence on extreme events in the Hg0 data is highlighted.