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Stator Elastomers The effects of different drilling fluids and fluid additives on Navi-Drill stator elastomers is the subject of continuous investigation at Baker Hughes INTEQís Drilling Systems Engineering Departments in Celle, Germany and in Houston, Texas. Detailed records of drilling fluid effects on various types of elastomer compounds are filed in a database.

The main concerns are synthetic-base drilling fluids (e.g., ester oils) and mineral oil-base (e.g., diesel oil) muds. The elastomers typically used for Navi-Drill stator linings are based on high-grade synthetic nitriles that exhibit good resistance to synthetic oil-base and water-base drilling fluids

The interaction between elastomer and drilling fluid can lead to swelling and loss of physical properties, e.g., hardness or elongation. Also, shrinkage (leading to an increased hardness) is observed sometimes. Swelling will increase the rotor stator interference and cause a higher strain and heat build-up in the elastometer. This increased specific loading of the elastomer finally leads to ìchunkingî - cracks and a fracture of the stator elastomer

Diesel-based drilling fluids have been, to a large extent, displaced by low toxicity mineral oils or synthetic fluids. Although the synthetics usually contain no aromatics, they often have an adverse effect on stator elastomers. Pre-job testing of drilling fluid and elastomer compatibility is recommended where no previous experience (see BHI-database) has been logged. This service can be provided on request by our in-house laboratory.