Factors Influencing the Cold Transportation Process of Waxy Shale Oil

Abstract

During the cold flow transportation (cold transportation) process of waxy crude oil, when the transportation temperature is below the wax precipitation point, wax deposition and pipe congealing phenomena can easily occur, affecting the safety of the transportation pipeline. By analyzing the microscopic wax crystal structure and size in the oil matrix under the cold transportation conditions of waxy shale oil, studying the rheological change rules of congealed oil during cold transportation, and combining basic physical properties with annular wax deposition simulation, a wax deposition kinetic model is developed. This model predicts the wax deposition rate and proposes safe transportation conditions and pipe cleaning requirements for cold transporting waxy shale oil. The results show that under cold transportation conditions, waxy shale oil forms needle-shaped microcrystalline wax with a length of less than 2 µm. Shear forces can disrupt the stable congealed oil structure and improve its rheological properties. Decreasing the initial temperature of cold transport helps reduce the yield stress of congealed oil. The kinetic model predicts a maximum wax deposition rate of no more than 0.23 mm/d. These findings can provide technical guidance for a flow safety design of the cold transportation process for waxy shale oil.