Improving the oxidation behavior of heavy oil using copper stearate as a catalyst

Abstract

In-situ combustion is an effective thermal recovery process for heavy oils and natural bitumen. It is widely accepted what the success of an in-situ combustion depends on a stable combustion front. However, field and laboratory data show that combustion front is often unstable, which severely limits the wide application of in-situ combustion technique. The goal of this work is to develop oil-soluble metal-based catalyst to improve the combustion behavior of heavy oils, and thus achieve a stable combustion front. In this study, copper stearate was applied as a catalyst for improving oxidation of heavy oils. Its catalytic effect was evaluated in the absence and presence of alumina or silica by differential scanning calorimetry (DSC). The results showed that in all cases (crude oil + alumina + copper stearate and crude oil + silica + copper stearate) the oxidation behavior of the heavy oil was significantly improved. With the addition of copper stearate, reaction intervals were shifted into lower temperature range, especially for high-temperature oxidation, it was finished in a narrower temperature range with a higher heat release per unit mass. In high-temperature oxidation interval, coke combustion is the main reaction. This means that the existence of copper stearate greatly enhanced the combustion efficiency of coke, which thus can improve the stability of combustion front. In addition, it was found that copper stearate can also reduce onset temperature. All these results indicated that copper stearate has an immense potential for developing a stably self-sustained combustion front and simultaneously reducing the ignition temperature in a real in-situ combustion process.