| It is proved that down-hole torque and drag prediction is quite essential for engineering practice.The prediction results can be used to help decide the best casing running solution with minimum drag and torque to ensure the success of running casing to the designated position in the wellbore.This thesis studies previous prediction models for down-hole torque&drag,including mechanical models,determination of wellbore friction coefficient and control techniques,both domestic and abroad;In-depth analysis of main factors affecting casing running in horizontal wells,including well trajectory,well structure,drilling fluid property,wellbore cleanliness,stratigraphic lithology and the type and setting space of centralizers,is made;A prediction model which takes both buckling and bending of casing string into consideration is established.The model also covers the computation of viscous resistance of drilling fluid,determination of buckling and so on;A C# prediction program is designed with quantitative calculation and analysis performed using shale gas horizontal well field data and some meaningful results are concluded;A downholeactivated centralizer is designed,produced and tested using indoor experiment. |
