What Does Saltwater Drilling Fluid Mean?
Saltwater drilling fluid or saltwater mud is a water-based mud containing dissolved sodium chloride or NaCl as the major component. They are used in particular drilling conditions such as for shale inhibition, for drilling through salt formations and to prevent the accumulation of hydrates around sub-sea wellheads and equipment.
HIgh-density brine such as calcium chloride, calcium bromide, zinc bromide, and potassium and cesium formate can be used to formulate low solids systems.
Trenchlesspedia Explains Saltwater Drilling Fluid
Saltwater drilling fluid finds primary use in drilling through salt strata that is prone to dissolution when other types of drilling fluids are used. In salt zones that have high temperatures and are plastic, the wellbore can close in unless the maintained mud weight is extremely high. Polymers and salt particles are used in saturated salt water muds to bridge over permeable production zones.
The saltwater drilling fluid may also contain undissolved salts to increase its density or to act as a bridging agent over permeable zones. Undissolved salts can help increase the density beyond 10 lbm/gal to 13 lbm/gal.
Other additives include xanthan gums for hole cleaning, starch and starch derivatives for fluid loss control, attapulgite and sepiolite for lifting cuttings, bentonite, caustic soda/ potash, polyanionic cellulose, lignosulfonate, lignite, corrosion inhibitor, and defoamers.