The polymers can be added to bentonite-based muds to prevent and reduce swelling of clay layers. They allow selective flocculation, it means that the clay cuttings in mud are not diluted and therefore can be easily removed with cleaning system. Polymers reduce coefficient of friction and torque and prevent sticking of drilling tools.
Inhibited muds are mainly used for drilling in shale and clay. During drilling in these layers inhibited systems are characterized (compared with standard drilling fluid with the same solid content) by:
- Low viscosity
- Low shear strength
- High tolerance to cuttings
- High resistance to pollution