Autonomous electrical heating facility supplied by wind turbine for elimination of oil wellbore paraffin deposits
The article considers an autonomous electrical heating facility supplied by a wind turbine designed to eliminate paraffin deposits in an oil wellbore. Computer modeling of the facility is performed. Modeling results are verified with a laboratory simulation bench. Operating curves for various operating conditions are obtained. An optimal resistance of the heating cable is determined to ensure a maximal efficiency of the wind turbine, as well as the amounts of energy produced by the wind turbine with a constant load resistance and resistance control are compared.
Wax Deposition and Aging in Flowlines from Irreversible Thermodynamics
The development of waxy crude oil and some gas condensate fields can lead to serious operational problems because of solidification of the paraffin components of the fluid in flowlines. Many numerical models in the literature predict the thickness of the wax deposit. However, most of these models assume that the wax-oil (gel) deposit has a constant wax content. In this work, we analyze wax deposition in laminar flow regime to predict the thickness and the composition of the gel layer as a function of position and time. The wax-oil gel region is considered as a porous medium. The velocity field and the pressure drop are calculated from the Navier−Stokes equation in the liquid region and from a combined Darcy-type equation and the Navier−Stokes equation in the gel region. The wax amount is estimated as a result of a decrease in fluid temperature below the wax appearance temperature (WAT), counterdiffusion processes from thermal and molecular diffusions, and radial convection which occurs because of nonunifo...
An approach for simulation of paraffin deposition in pipelines as a function of flow characteristics with a reference to Teesside oil pipeline
Paraffin deposition is experienced in pipelines during transportation of oil when the oil temperature is cooled below its paraffin deposition temperature. The formed paraffin crystals in the bulk flow are believed to be transported by molecular, brownian diffusion and shear dispersion. Gravity settling mechanism in previous work in the authors` laboratory has been shown to contribute to the total paraffin deposition, however, to a lesser extent than the above mentioned mechanisms. The work done here demonstrates that the paraffin deposition by molecular diffusion mechanism is a dominant one. This is in agreement with other previous studies done on the paraffin deposition. In this study, however, experimental design was made to quantify this statement. The paraffin concentration gradient (dc/dr) is the driving force of the molecular diffusion mechanism (where r is the pipeline radius). In pipelines the cooling rate is one of many factors that affect the paraffin deposition profile. Equipment was designed to simulate the flow characteristics at pipeline pressure. A three dimensional model was developed for paraffin deposition rates at various flow regimes. The developed experimental approach and the designed equipment for simulating the pipeline conditions are presented in this paper.