Directional Drilling with Casing

SummaryCasing while drilling (CwD) has proven to be an effective method of reducing drilling costs and solving drilling problems. Most of the current CwD activity focuses on drilling vertical wells, but interest in directional wells is increasing as CwD benefits in straight holes are demonstrated.A directional CwD system has been run sufficiently to prove that directional drilling with casing is practical with casing sizes from 7 to 133/8 in. The system uses a wireline-retrievable-directional-drilling assembly (positioned atthe lower end of the casing) to replace the conventional directional tools used when drilling with drillpipe. These tools have been used to drill to inclinations greater than 90° and have been retrieved and rerun at inclinations ranging from vertical to horizontal.Directional CwD can be used for a broad range of directional applications to capture proven advantages demonstrated in vertical wells.