ABSTRACT
This chapter deals with the three basic flushing systems most widely used in water-well drilling, namely: air, foam/polymer injection and mud. The cleaning of the hole is the most important single factor in drilling, as an inadequate system which does not clean the hole will cause the greatest of problems. An air compressor of about 350cfm capacity at a pressure of about 150 psi will really drill some very big holes. Foam/polymer injection will clean the hole efficiently, irrespective of annular velocity in almost all conditions. Foam/polymer injection will clean the hole efficiently, irrespective of annular velocity in almost all conditions. Mud not only cleans the hole, it also cools the bit, lubricates it and stabilizes the hole. There are three types of mud pump in general: centrifugal pumps, positive displacement pumps and screw type pumps. Centrifugal pumps, sometimes known as rotary pumps, are designated by the diameters of the inlet, outlet and impeller.
