Flow assurance methods for transporting heavy and waxy crude oils via pipelines without chemical additive intervention

Abstract

Most of the unconventional fossil fuel reserves consist of heavy crude oil. Crude oil is transported through pipelines, land, and cargo tankers. It loses its ability to flow below its pour point. Therefore, crude oil needs to be heated above its pour point, or it requires some mechanism to reduce viscosity and improve the flow in pipeline transportation. The flow assurance methods depend on the types and attributes of crude oil. Saturates, aromatic, resin and asphaltenes are the main constituents, and their composition and proportion define crude oil's properties. Higher molecular weight components, such as waxes, resins, and asphaltenes cause high viscosity in crude oil. Chemical additives are the commonly used method to reduce viscosity. However, recent advancements in non-chemical treatment methods for heavy and waxy crude oil provide an opportunity for flow assurance in pipeline transportation. These methods include dilution and emulsification, annular and core flow, thermal and electrical heating, ultrasonic and microwave treatment, solar heating, electromagnetic field conditions, thermochemical heat treatment, and plasma heating. However, these techniques have certain advantages and disadvantages depending on the characteristics of the crude, the applicability of technology, and economic considerations. A combination of two or more techniques for viscosity reduction is more suitable for flow assurance in pipeline transportation.