Technology Applied to Extend the Drilling Reach of a Platform Workover Rig

Abstract The term "Extended Reach Drilling" refers to drilling operations conducted beyond the normal reach of drilling facilities. Typical problems associated with this type of operation are torque & drag limitations, wellbore stability, mud rheology and solids control and directional well design1,2,3. Such problems are particularly challenging to the CACT Operators Group due to limited platform rig size and platform deck space. These problems are further compounded by the fact that no spare well slots are available on the platforms, so all new platform drilling operations are sidetracks. This results in tortuous 3-dimensional well profiles that generate high levels of drilling torque and drag, disproportionate to the measured depth. The well planning and drilling practices used to drill these wells are very similar to those used in ultra-long extended reach wells and reflect the challenging nature of platform sidetrack operations. This paper describes the challenges that are faced during development of the well plans and details the methods that are later used while drilling the sidetrack wells. Case histories with actual field data will show how the applications of the following new or emerging technologies have been applied successfully in the sidetrack program. Borehole Stability Modeling was used to identify areas where the potential for borehole breakout and fluid losses (lost circulation) existed, so that plans could be made to avoid these problems. Real Time Downhole Data Measurements were used to provide instantaneous information on drilling conditions in order to avoid the problems experienced in previous wells. PDC bit designs, featuring low torque cutting structures to improve bit steerability were successfully applied on several recent sidetrack wells.