Crude oil is an important fossil resource that greatly impacts our industries and daily life. For crude oils, one of the most common way to transport oils from wellheads to downstream refineries is pipeline transportation. Over the last decades, much attention has been paid to study the flow properties of oils. Based on the theory of rheology, the flow behaviors of crude oils, i.e. shear-thinning, thixotropy, yield behavior, viscoelasticity, have been systematically studied. It is well established that the precipitation of wax crystals and aggregation of asphaltenes in crude oils at low ambient may be responsible for these complex flow behaviors of crude oils, and the safety of oil transportation and its efficiency are challenged thereby.
To improve the cold flow properties of crude oils, multiple methods have been developed regarding conventional heating, blending low-viscosity crude oil, adding pour point depressants (PPDs). These methods and the mechanisms of them have been studied by many researchers. In recent years, novel technologies including electrical treatment, electrical/magnetical heating, nano PPDs, etc, have been investigated. Compared with the conventional methods mentioned above, the new developed approaches show better flow-improving effects or consume much less energy and more environmentally friendly.
The scope of this special issue mainly focused on the study of flow properties of crude oils or their emulsions and the investigations of physical or chemical technologies to improve the flow properties of crude oils. Topic such as showdown and start-up of pipelines, rheology of crude oils or their emulsions, pigging of pipelines, electrorheology, the influence of asphaltenes and resins on oil flowability, new additives to improve cold flow properties of crude oils are also welcomed. The research described should possess novelty and be original work. The abovementioned technologies also include the description of facilities developed with novel strategies and are experimentally proven that is capable of improving flowability of crude oils.
Thus, the aim of this special issue is very clear: to shed light on better understanding of flow behaviors of crude oils, studying the flow assurance problems for crude oil pipeline transportation, and discussing novel methods and their mechanisms to improve cold flowability of crude oil.

Aims and Scope:

1. Crude oil transportation
2. Flow improving technologies
3. Rheology of crude oils
4. Flow assurance
5. Start-up of oil pipeline
6. Asphaltenes and resins