The Study on Low-Temperature Transportation of Waxy Crude Oil in Chemical Flooding Pipeline

Abstract At present, chemical flooding has become an important means to enhance oil recovery in Chinese oil fields. With the implementation of the “3060” carbon neutral policy, the low temperature transportation technology of high-water content crude oil has been implemented in major oil fields across China. However, there is a lack of research on low temperature transportation of crude oil in chemical flooding pipeline. In this paper, the rheometer and stirring method were used to study the rheological properties of oil-water mixtures of waxy crude oil in chemical flooding. The effect of hydrolyzed polyacrylamide (HPAM), petroleum sulfonate (PS) and HPAM/PS binary systems on the wall sticking of waxy crude oil during low temperature transportation was investigated by surface adhesion apparatus experiments for the first time. Finally, the interfacial tension (IFT) and contact angle (CA) of the chemical flooding oil/water/pipe wall system were measured by using a high-temperature and high-pressure optical contact angle measuring instrument. The interface wetting theory was used to deduce the adhesion mechanism of waxy crude oil during chemical flooding. The results showed that both HPAM and PS could advance the inversion point of the emulsion. Notably, the addition of HPAM after the inversion point increased the viscosity of oil-water mixture, whereas PS exhibited the opposite effect by decreasing it. Furthermore, the addition of HPAM increased the adhesion between oil droplets and pipe wall, consequently resulting in an elevation of the minimum safe transportation temperature (MSTT) in the range of 0 to 3°C. Conversely, the presence of PS correlated with a reduction in MSTT of 0 to 2°C. The simultaneous presence of both substances resulted in a mutual resistance phenomenon. The research results can provide theoretical guidance for low temperature transportation of waxy crude oil in chemical flooding pipeline.