Waxy Crude Oil Restart: Mechanical Properties of Gelled Oils

Abstract

Abstract In case of a prolonged shutdown and an inopportune cooling, the crystallization of a crude oil takes place and hinders the production of these petroleum products. Because of the gel-like network formed by the crystals entrapping the oil, a restarting pressure is required to start-up flow. In order to predict the necessary pressure, the restart process and the corresponding mechanical behavior of the gelled oil must be assessed. In this paper, a set of two experimental approaches is presented and discussed in relationship with the restart process. The solid-like behavior of the gelled bulk oil was investigated thanks to a set of mechanical test cells. The rheological behavior of the gelled waxy crude oil was studied with a vane test apparatus and a controlled-stress rheometer. Eventually, the two experimental methods gave complementary and converging results revealing how a crude oil stuck inside a pipeline would react during a restarting operation. They help the understanding of the physical mechanism of the flow restart and release the data required for prediction.