A Review of Recent Research on Contamination of Oil Well Cement with Oil-based Drilling Fluid and the Need of New and Accurate Correlations

Abstract

Drilling fluids and oil well cement are important well barriers. Their compatibility affects the long-term integrity of the well. The mixing of drilling fluid with the oil well cement causes contamination of oil well cement. If the contamination is due to diesel/oil-based drilling fluid (OBF) it adversely affects the rheological and mechanical properties of oil well cement—in other words, the long-term integrity of the well. An initial study on OBF contamination of oil well cement was carried out two decades ago. In recent years, several research projects were carried out on the same topic to understand the reason for changes in the properties of oil well cement with OBF contamination. This literature review shows that using OBF eliminates several drilling problems, as the long-term integrity of the well depends on the amount of OBF contamination in the cement slurry. This paper compares the experiments performed, results and conclusions drawn from selected research studies on OBF contamination of oil well cement. Their shortcomings and a way forward are discussed in detail. A critical review of these research studies highlights the need for new and accurate correlations for OBF-contaminated oil well cement to predict the long-term integrity of wells.

Keywords

• contaminated cement slurries
• oil well cement
• diesel-based mud
• oil-based mud (OBM)