Risk of Wax Precipitation in Oil Well

• Published in: Natural resources research (New York, N.Y.) N.Y.), 2017, Vol.26 (1), p.67-73
• Main Authors: Struchkov, I. A., Rogachev, M. K.
• Format: Article
• Language: English
• Subjects: Asphaltenes; Chemical precipitation; Chemical treatment; Chemistry and Earth Sciences; Computer Science; Earth and Environmental Science; Earth Sciences; Flow rates; Flow velocity; Fossil Fuels (incl. Carbon Capture); Geography; Grain size; High pressure; Mathematical Modeling and Industrial Mathematics; Mineral Resources; Modelling; Oil and gas fields; Oil fields; Oil recovery; Oil wells; Oils & fats; Physics; Pressure drop; Simulation; Statistics for Engineering; Sustainable Development; Velocity; Waxes
• ISSN: 1520-7439; 1573-8981
• DOI: 10.1007/s11053-016-9302-7

The objective of this research is to simulate the impact of well operation conditions on wax precipitation in an oil sample, and to predict the wax-free well flowrate. Laboratory studies help producers to protect oil wells from potential problems. The maximum rise of simulated well operation conditions to in situ oil recovery leads to oilfield practice. The methods used for testing of oil sample were microscopy under high pressure with grain size analysis and light-scattering technique, which were conducted using laboratory equipment suited for investigations of reservoir fluids in conditions close to oilfield conditions. Experiments with modeling of temperature and pressure drop rates, flow velocity, and flow through time from downhole to wellhead were carried out. These experiments resulted in modeling of the relationship between functional pressure and wax appearance temperature (WAT), which is properly consistent with the Clapeyron–Clausius equation in a range of well operation conditions. Experimental simulation of well thermobaric operation conditions also resulted in definition of potential wax formation area in the tubing. Research data showed that WAT declines with increase in flow velocity and temperature, and pressure drop rates. Calculations demonstrated that an increase in flow velocity by 0.04 m/sec (equivalent to a well flowrate of 20 m 3 per day) leads to a decrease in wax formation depth of up to approximately 200 meters. Guidelines for slowdown of asphaltene–resin–paraffin particles formation in the well by chemical treatment are made.