A new chromatographic approach for bitumen characterization and solvent concentration measurement

Solvents are co-injected with steam into oil sands for dilution and mobilization of bitumen. Solvent recovery and solvent content of the produced bitumen are important economic parameters for the evaluation of the perfor-mance of solvent-aided thermal recovery processes. Measurement of solvent in the produced streams is chal-lenging due to the component overlap between solvent and light components of bitumen. Additionally, the presence of water in the produced streams adds more complexity. This is due to the fact that the conventional solvent concentration measurement approaches rely on dewatering procedures that lead to significant solvent loss, making them incapable of accurate measurements. Currently, there is no established analytical method for the measurement of solvent fraction in bitumen-solvent blends. In this work, we have developed an analytical technique based on a combination of Gel Permeation Chromatography (GPC) and Gas Chromatography (GC) to fully characterize complex mixtures of bitumen and solvent and measure the solvent content of the production streams. The developed technique is validated using a known standard reference oil. The developed method was also applied for measuring solvent in the mixture of bitumen/solvent and bitumen/solvent/water mixtures. An average deviation of +/- 0.16 was obtained for the solvent content of samples with different water content. It was shown that the proposed method is capable of measuring the solvent content of the produced bitumen in the absence and presence of water, eliminating the error in measurements due to solvent loss associated with dewatering procedures.

Automated summary

Solvents are injected with steam into oil sands to dilute and mobilize bitumen. However, measuring the solvent content in the produced streams is challenging due to component overlap and the presence of water. In this study, an analytical technique based on GPC and GC was developed to fully characterize complex mixtures of bitumen and solvent and accurately measure the solvent content in the production streams.