101New Generation Glycol Drilling Fluids System for Drilling of Water-Sensitive Formations


Intensified concerns about hazardous environmental effects of conventional oil-based mud (OBM) in Iranian offshore oil fields motivated drilling companies in Iran to search for a suitable substitution.  Water based drilling fluid (WBDF) is relatively a qualified class of drilling fluids that can combine the technical advantages of OBM. Glycol is a type of water fluid and is counted as one of the highest prospects for extensive use in Iran due to its availability and lower cost, compared to other types of drilling fluids.

In this study, feasibility of utilizing innovative formulations of water based drilling fluid (WBDF) was investigated mostly based on local products. Suitable formulations for PBM at desired operational ranges of temperature, mud weight and glycol and water ratio (G/W) were developed and optimized. In addition, Rheological properties and electrical stability of the systems were measured. Stability of each mud system under down-hole conditions was examined and their filtration characteristic was determined by means of a filter press. Furthermore, Shale recovery was evaluated and the effects of possible contaminants in the system were also studied. Confirmation of the obtained results was conducted by comparison of Glycol-based mud with similar conventional oil based packages.

From technical points of view, laboratory results indicate that conventional muds can be replaced with Glycol-based mud in Iranian offshore fields since it suppresses environmental concerns, is tolerable to contaminant and can provide advantages of OBM with reasonable cost. Comparisons of WBM with OBM show that rheological properties and shale recovery were approximately identical, while Glycol based mud represented higher electrical stability and lower filtration rate.

Keywords:  Glycols, water based drilling fluid (WBDF), Shale Inhibition, Lubricity, Reactive Shale.

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