Casing drilling has obvious advantages compared with conventional drill pipe drilling. It is a technical aspect of drilling engineering and it can bring huge economic benefits to oilfield operators. Casing drilling has the following characteristics:
1. Casing drilling uses standard oil well casing and allows drilling and casing operations to be performed simultaneously;
2. The bottom hole drilling tool assembly is installed at the lower end of the casing string, and can be quickly taken out through the inside of the casing with a wire rope. During the removal process, the mud can be continuously circulated;
3. Throughout the drilling process, keep the casing straight to the bottom of the well to improve the well control situation;
4. The casing is only drilled into the formation in one direction and no longer rises out. Unless it is confirmed that the well is dry after drilling, the last casing string may be taken out;
5. Casing drilling can continue to use many existing drilling technologies, such as directional drilling, cement injection, well logging, coring and well testing;
6. The main difference between the application of these technologies and the original is that instead of relying on the drill pipe, the drill bit is replaced by the wire rope.