7-inch Casing While Drilling CWD With Retrievable Bottom Hole Assembly BHA

Abstract

Casing drilling technology, as an alternative to conventional drilling, has been known for a long time. This method is mainly used for wells with geological complications, such as lost circulation or wellbore instability of various nature. By using drilling on a string for a section or part of it, the problem interval is immediately cased, eliminating the time spent on additional operations, such as pulling the bottom hole assembly (BHA), wiper trips and running the casing. Thus, this allows to reduce the time for well construction, reduces the risk of accidents and non-productive time associated with the complication zone. Casing drilling has become widely for drilling vertical surface conductors and technical casing with a drillable shoe, as well as for drilling with retrievable BHA in inclined sections for 324- and 245-mm casing. The aim of this work was to perform directional drilling on a 178mm production casing in an interval where the client had geological problems associated with running casing due to a zone of rock collapse. The uniqueness of the task lies in the fact that no one in the world has yet performed drilling on a casing with a building inclination and landing into a horizontal plane. It was necessary to follow the designed well trajectory, to build inclination from 67 to 85 degrees with the planned dogleg severity of 1 degree / 10m.