Interim Report on Pressure Effect on Waxy-Crude Pipeline-Restart Conditions Investigated by a Model System

Abstract

Summary A comprehensive review of literature concerning wax crystallization, deposition, and gelation, as well as the yielding behavior of waxy crude gels during pipeline restart is presented. Detailed experimental investigation of the temperature and pressure effects on gel strength is carried out. Influence of testing temperature on gelation kinetics is studied using a controlled stress rheometer (CSR), and the data is analyzed by applying a modified Avrami model for isothermal crystallization. The effect of system pressure on restart conditions is studied using a model pipeline system. It is observed that this system provides the best reproducibility of yield pressures. The model pipeline results are compared with the yield point tests obtained on a CSR. The results of the experimental work reported in this paper suggest that weaker gels may be formed at higher shut-in pressures, which is a favorable condition for pipeline restarting operations.