buoyant drill string sections 10 may be used for very long extended reach boreholes greater than approximately 6000 ft in horizontal length as required for the purposes of this invention any type of buoyant drill string may be used for example fig3 shows individual sections of drill pipe 31 with attached buoyancy modules 32 the buoyancy modules 32 may be i a buoyant foam material ii an inflatable bladder and iii a sealed chamber having a pressurized fluid of a predetermined density the pressurized fluid may be a liquid or a gas the buoyancy modules 32 may be integral with the drill pipe 31 to increase the relative stiffness of the sections 10 the buoyancy modules 32 may substantially increase the effective diameter of the drill string thereby increasing the flow velocities in the local annulus between the borehole and the drill string and improving the hole cleaning in that area in another embodiment see fig4 a drilling motor 40 is inserted in drill string 8 above the rotary steerable system 15 such that rotary steerable system 15 is attached to the output shaft of drilling motor 40 drilling motor 40 is a positive displacement motor actuated by the flow of drilling fluid through the motor 40 alternatively a fluid driven turbine motor not shown may be used such motors are know in the art and are not described here further drilling motor 40 may be used by itself or in conjunction with rotary table 4 to drive drill bit 17 in one mode rotary table 4 may be used to rotate drill string 8 at a relatively low speed for example 20 30 rpm while drilling motor 40 combined.