Feasibility study for the use of kinetic hydrate inhibitors in deep-water drilling fluids

The feasibility of using kinetic hydrate inhibitors (KHIs) in deep-water water-based drilling fluids to give added subcooling protection has been investigated. A range of neutral, anionic, or cationic commercial and noncommercial KHls were first tested for their compatibility with highly saline drilling fluids. Thereafter, the most suitable products were tested as KHIs in a sapphire cell arrangement at pressures up to 300 bar and temperatures down to 0.9 degrees C. Experiments with the best inhibitors were also carried out in the presence of two types of clay to represent drilling cuttings with different activity and in simulated shut-in conditions. The conclusion was that some KHIs, particularly neutral or anionic polymers, could be used in drilling fluids if the activity of the clay/cuttings is low, probably because of negligible adsorption of the KHI polymer onto the clay/cuttings. It was also shown that pressure and not just subcooling is an important factor in determining the performance of a KHI.