Copyright 2016, Society of Petroleum Engineers. Attempts have been made in the past to use uphole motor in extending the reach of coiled tubing in directional wellbores, but these efforts were not successful because of poor design. We have designed a workable configuration suitable for coiled-tubing and conventional drillpipe operations. In addition, we have developed a procedure for selecting the required uphole motor size, rotating tubular dimensions, and circulation rate based on surface pump and tubular-buckling constraints. The configuration of the drillstring is highly sensitive to the flow and drilling parameters. And the rotating length function was derived using soft-string torque and drag model. The motor winding ratio and flow rate were made the independent variables of the rotating length and surface pump pressure functions. Based on available surface pump pressure, flow coefficient, and turbulence flow index constraints, the optimum uphole motor configuration and flow rate were determined. From the numerical tests conducted, it is evident that the tecnhlogy is viable and cheap. The technique can significantly increase the reach of tubular in the lateral sections of the wellbore. Furthermore, combining the uphole motor with the articulated tractor system, greater reach is achievable.
