| Bentonite | Provides viscosity and gel strength, and helps form a filter cake that limits fluid loss. | Water-based drilling fluids, particularly freshwater and low-solids systems. | Viscometer readings, yield-related properties, filtration, moisture, and particle-size checks. | Usually supplied as a dry powder; protect from moisture and contamination during storage. |
| Barite | Increases drilling-fluid density to help manage formation pressure. | Weighting water-based or oil-based drilling fluids. | Specific gravity, particle-size distribution, moisture, and relevant impurity checks. | High-density mineral powder; settling and suspension performance depend on the complete fluid formulation. |
| Polyanionic Cellulose (PAC) | Helps control filtration and can contribute to viscosity in water-based fluids. | Water-based systems where fluid-loss control and shale inhibition support are required. | Viscosity, filtration performance, moisture, and solution behavior under specified test conditions. | Available in grades with different viscosity and fluid-loss characteristics; follow supplier mixing guidance. |
| Carboxymethyl Cellulose (CMC) | Acts mainly as a viscosifier and fluid-loss-control polymer. | Freshwater and other compatible water-based drilling-fluid systems. | Viscosity, filtration, moisture, and consistency between production batches. | Dry powder that should be dispersed thoroughly to reduce lumping during hydration. |
| Starch | Reduces fluid loss by helping build a low-permeability filter cake. | Water-based fluids, including systems used where filtration control is needed. | Fluid-loss performance, solubility or dispersion, moisture, and microbial stability where relevant. | Performance can be affected by temperature, salinity, and the selected starch treatment. |
| Xanthan Gum | Provides viscosity and suspension capacity, especially at low shear rates. | Water-based fluids requiring improved cuttings transport or suspension of weighting material. | Rheology, hydration, moisture, and performance in the intended water chemistry. | Mixing order and adequate hydration can affect the final rheological response. |
| Lignosulfonate-Based Thinner | Deflocculates or thins drilling fluids, helping adjust rheology. | Selected water-based muds, subject to system chemistry and operating conditions. | Rheological response, pH, solids content, and compatibility with the fluid system. | May be supplied as a powder or liquid; suitability depends on temperature and formulation. |
| Sulfonated Asphalt | Can help control filtration and reduce shale-related problems in compatible systems. | Water-based drilling fluids designed for wellbore stability and fluid-loss management. | Dispersibility, filtration performance, moisture, and compatibility with other additives. | Formulations vary; confirm compatibility with salinity, pH, and other mud components. |
| Partially Hydrolyzed Polyacrylamide (PHPA) | Provides polymeric inhibition and can support encapsulation of drilled solids. | Polymer-based water drilling fluids and selected low-solids systems. | Viscosity, polymer concentration, hydration, and performance in the target water chemistry. | Use controlled mixing and avoid conditions that can degrade polymer performance. |
| Calcium Carbonate | Serves as a weighting and bridging material; it is acid-soluble under suitable conditions. | Drilling and completion fluids where particle-size selection and cleanup requirements matter. | Particle-size distribution, density, purity, moisture, and suspension behavior in the fluid. | Available in different particle-size ranges; selection should match the formation and bridging objective. |