How to drill a smooth medium-radius well

Any operator that has attempted a medium-radius well probably has experienced sticking problems while building hole angle. Such sticking problems could noticeably decrease penetration rate or even cause the loss of the well. Sticking problems are discussed in this article. They may result from sloughing shales, ledging, differential sticking or any routine problems occurring in conventional directional and vertical drilling. In addition, downhole sticking can be caused by using conventional-type stabilizers on medium-radius, nonrotating assemblies. Although conventional stabilizers efficiently centralize and control the drillstem when rotating, they quickly become a liability when sliding. High point contact loads and interference with the wellbore will produce sticking and uneven weight transmission to the bit, which is frequently manifested in reduced penetration rates, even with more conventional steerable assemblies. The author proposes that stabilization should be avoided on medium-radius, nonrotating assemblies.