An assembly for drilling a deviated borehole includes a bottom hole assembly
connected
to a string of coiled tubing and includes a bit driven by a downhole motor powered
by drilling fluids. A surface pump pumps the drilling fluids downhole through a
cross valve to provide a first path directing drilling fluids down the coiled tubing
flowbore and a second path directing drilling fluids down the annulus. The bottom
hole assembly has a downhole valve allowing flow between the flowbore and the annulus.
A first flow passageway directs drilling fluids down the coiled tubing flow bore
and then up the annulus and a second flow passageway directs drilling fluids down
the annulus and the up the flowbore. The bottom hole assembly includes a subsurface
pump capable of pumping drilling fluids from the second fluid passageway to the
surface. The bottom hole assembly includes an electric motor to rotate the subsurface
pump and the motor is provided with power conduits embedded in a wall of the coiled
tubing. Another subsurface pump may be provided, such that the subsurface pumps
pump drilling fluid with cuttings to the surface and/or pump clean drilling fluids
into the downhole motor to aid drilling.