Study On Reducing Viscosity Of Super Heavy Crude Oil With Supercritical CO₂

The viscosity super heavy oil with high asphaltene content, density and viscosity generally is greater than 10000mPa ? s, which leading to the pressure loss is very large when transporting the heavy crude oil. Do not use special treatment, it is impossible in the economic and technical to transport with conventional means, which seriously affected the exploitation and transportation of extra heavy crude oil. Supercritical CO2 with strong diffusion coefficient and better solubility can penetrate the internal heavy oil quickly. Inter force of heavy crude oil with supercritical CO2 change from liquid– liquid to liquid-gas, then the inter force declines .at the same time, the structure of asphaltene macromolecular is destroyed. So the viscosity of heavy crude oil declines and is beneficial to transportation. The technology has good performance, simple process and creativity, which is the forefront of research of heavy crude oil transportation topics.This paper researched the properties of super crude oil and supercritical CO2.The properties of CO2 solution and the affection of viscosity-reducing through experiment. Experimental study found that: the volume is bigger and the density is lower after CO2 soluting in heavy crude oil, so reducing the pressure loss of transportation. Viscosity-reducing rate can reach to 80% at the condition of 60-90℃,8-18MPa.the factors of affecting the viscosity reduction are temperature, dissolved gas-oil ratio and pressure. The optimal condition of transportation: 60℃, 18MPa, 130m3/m3 (GOR). Under the condition, the viscosity-reducing rate can reach to 95%.Based on the indoor experiment, an empirical formula is presented in the paper, which can calculate the saturated GOR and volume factor of Shengli Oilfield's super heavy oil dissolved with CO2, and it is important to the field application.