Simultaneous hole enlargement with steerable motors, when compared to other type of operations, has unique challenges. These operations are typically associated to enhanced oil recovery projects such as cyclic steam stimulation (CSS) and steam assisted gravity drainage (SAGD) projects.
During motor steering, drill pipe cannot rotate; therefore, to drill and enlarge simultaneously, the tool must be located below the motor and above the bit. To steer the well, a motor bent is used to introduce side forces which deviates the wellbore – consequently the hole enlargement tool sustains side forces while reaming.
For many years, the only solution available in the market was to use eccentric equipment. The typical problems observed while drilling and enlarging with positive displacement motors and eccentric hole enlargement tools are:
Low drilling bit rate of penetration
Reduced directional responsiveness
Inconsistent hole size due to the dynamic competition between forces deviating and enlarging the borehole
Casing shoe drill out is complicated and dangerous
Halliburton provides solutions to steerable drilling challenges: