화학공학소재연구정보센터
Energy & Fuels, Vol.33, No.11, 10756-10764, 2019
Effect of Emulsified Water on Gelled Pipeline Restart of Model Waxy Crude Oil Cold Flows
Recent work has shown the promise of cold flow technology for transporting waxy crude oils below their wax appearance temperatures. The thermal flux that results due to the difference between the temperature of the transported oil and the ambient is minimized in the implementation of cold flow, thus significantly lowering wax deposition on pipeline walls. Restarting pipelines carrying waxy oils under cold flow conditions is an important consideration. In previous work from our laboratory, we have shown that gelled pipeline restart pressures for water-free systems are significantly lower for pipelines shut down starting from pre-established cold flow conditions in comparison to pipeline shutdown starting from hot flow conditions. In this paper, we examine the applicability of this conclusion when varying amounts of emulsified water are present within the oil. We investigate model oils containing 7.0 wt % wax, with water cuts ranging from 0 to 60 wt %. Restart studies were conducted in a bench-scale, 0.4 in. diameter, 4 ft long flow loop. The pressure required to restart the gelled pipeline decreases with a decrease in the cold flow shutdown temperature and with an increase in the water content. Complementary rheological measurements show that the presence of water reduces the yield stress of model waxy crude oil gels.