A FAST, SMOOTH CURVE IS THE KEY TO A SUCCESSFUL, UNCONVENTIONAL WELL. THE NEW 7’’ CD-AST DRILLING TOOL IS DESIGNED TO OPTIMIZE THE ROCK-CUTTER INTERFACE UNAFFECTED BY THE CURVATURE AND THEN GO ON TO DRILL THE LATERAL SECTION AS EFFECTIVE IN THE SAME RUN. THIS IS ACHIEVED THROUGH AN ARTICULATED TOOL-BODY THAT IS STIFF ENOUGH TO CONVEY THE REQUIRED FORCE BUT ALSO FLEXIBLE ENOUGH TO TRACK THE MOST AGILE 3D STEERING SYSTEMS AT FAST RPM.
For moderate curvatures, the counter force assisted 6 ¾” XC-AST tool equipped with flex joints top and bottom is an alternative to the 7” CD-AST.
The graph above shows the hours of Safe Service versus curvature for both configuration alternatives. *The graph represents the tools with flex-joints top and bottom as shown in the illustration. The flex joints are supplied by Tomax unless already incorporated in the BHA.
Note that the figure for curvature is absolute, so local bends must be included. In other words, a good safety margin for the curvature is recommended. For tripping (non-rotating), fatigue is not an issue.