Since the re-introduction of silicate-based drilling fluids in the mid-1990's, there have been numerous papers written on the inhibitive and environmental properties of sodium and potassium silicate. While it is generally accepted that potassium or sodium based silicate drilling fluids will help mitigate metal corrosion, there appears to be very little written on the subject. With increasing steel prices and competition for drill pipe, operators are becoming more aware of the cost associated with metal corrosion.

This paper discusses the chemistry of sodium and potassium silicate as it relates to the protection of metals against corrosion. Aside from providing an alkaline environment, silicate is shown to deposit a protective film on various metal surfaces. Drill string corrosion coupons were used to gauge the amount of wear and corrosion while running potassium silicate-based drilling fluids in Western Canada. Gravimetric analysis confirmed that the rate of metal corrosion was minimal under a variety of drilling conditions.

Keywords:
Pipeline Corrosion, riser corrosion, silicate, flowline corrosion, drilling fluids and materials, Upstream Oil & Gas, Corrosion coupon, drilling fluid, Subsurface Corrosion, silicate concentration
Subjects:
Drilling Fluids and Materials, Production Chemistry, Metallurgy and Biology, Pipelines, Flowlines and Risers, Drilling fluid selection and formulation (chemistry, properties), Drilling fluid management & disposal, Materials and corrosion, Well Integrity, Subsurface corrosion (tubing, casing, completion equipment, conductor), Corrosion inhibition and management (including H2S and CO2)
Copyright 2007, Society of Petroleum Engineers
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