The Effects of Miscible CO₂ Injection on Oil Biomarker Parameters

Abstract

The purpose of this research was to study the effect of CO₂ injection on the geochemistry of crude oil in order to determine the probability of using geochemical parameters for monitoring CO₂ injection. In this process, four oil samples from different offshore oil fields were collected, synthetic steady state oil reservoir (porous media) were made by slim tube apparatus, then CO₂ injection process was done in different pressures. Various geochemical analyses were also carried out on the injected oil before and after the injection. The results show that the bulky changes on oil sample by CO₂ injection. CO₂ injection is more likely to precipitate complex and large molecules such as asphaltenes-resins and also large normal alkanes. In this case, the percentage of aromatic molecules was increased during injection. In general view on chromatograms, the height and abundance of all saturated compound peaks after CO₂ injection were significantly decreased. However, biomarker analysis shows that CO₂ injection has a tendency to change source and maturity biomarker parameters.

Keywords:

• CO₂ injection
• asphaltene precipitation
• oil geochemistry
• saturated biomarkers
• aromatic biomarkers