Upgrading of heavy crude oils: Castilla

Oil resources similar to WTI and Brent crude oils are dwindling, so heavy and extra-heavy crude oils, and bitumen must be used to meet the growing demand for fuels. The vast majority of the world's refineries are not suitable for processing these types of feed stock, so upgrading processes are required to make synthetic crude oils from those resources compatible with the equipment installed. By its viscosity Castilla crude oil is not classified as an extra-heavy crude oil, as even on surface it flows. However, it has 45.6 wt.% of vacuum bottoms and high concentrations of Conradson Carbon (CCR of 34 wt.%) and metals (nickel and vanadium content of 928 ppm) within it. This article presents various alternatives for the upgrading of the crude Castilla, using as raw material crude oil free of lights (199 degrees C+), reduced crude (370 degrees C+) and vacuum bottoms. The technologies used in the studied scheme were visbreaking (VBK), delayed coking (DC), solvent deasphalting (DAF), hydrotreating and distillation. The studies were conducted at pilot plant scale and the analysis of the products was done using standard techniques such as ASTM. Among the outstanding results we have the operational scheme of the vacuum bottoms Visbreaking, but this is not a typical Visbreaking process because the coke production was 8.2 wt.%. A furnace with some characteristics of a DC furnace, and a pair of soakers that function as coking drums should be used to avoid coke deposition within the internal walls of the coils. This is an innovative technology that sits between visbreaking and delayed coking. (C) 2012 Elsevier B.V. All rights reserved.