Tuesday, 14 November 2017

Drilling Casing Flotation Equipment With PDC Bits



General Considerations


  • It is now possible to drill out casing flotation equipment with PDC bits using rotary or turbine drilling techniques. This eliminates the need to perform a separate casing clean-out trip. This will only be attempted if the next section of open hole is suited to PDC drilling
  • On exploration/appraisal wells, when the nature of the formations are uncertain, it may be advisable to drill out the float equipment and open hole with a re-run or repaired PDC bit in the first instance.
  • It must be certain that there is no junk, such as rock bit teeth or side coring bullets, lying below the casing shoe. The risk of casing accessories producing junk must also be taken into consideration. 
  • Beware of damaging a PDC bit where there is a high dogleg in the shoe track.
  • It is advisable to use a PDC bit with a minimum of PDC cutters on the gauge area. Gauge cutters, if present, should be of the flat profile type rather than the circular profile type in order to avoid damage while rotating in the casing.
  • Casing float equipment must be thread locked to overcome the greater right hand torque produced by the PDC cutting action.
  • Consideration should be given to usage of non-rotating float and plugs.
Disqus Comments