Casing Drilling

What is casing drilling?

Casing Drilling, an innovative process for simultaneously drilling and casing a well, is emerging as viable technology for the twenty-first century. The concept builds upon experience gained drilling liners to bottom in troublesome holes. With the advent of dependable top drive systems, wireline retrievable bottom hole assemblies, PDC bits, and high torque connections, it is possible to simultaneously drill and case a complete well using casing as the drill-string.

Development of casing drilling technology

Drilling with casing has proven to be an effective method of reducing drilling costs and solving drilling problems. Most of the current casing drilling activity is focused on drilling vertical wells, but interest in directional wells is increasing as the benefits of casing drilling in straight holes are
demonstrated. A directional casing drilling system has been run sufficiently to prove that directional drilling with casing can be practical with casing sizes from 5-1/2” to 13-3/8”. The system uses a wireline retrievable directional drilling assembly, positioned in the lower end of the casing, to replace the conventional directional tools used when drilling with drill pipe. These tools have been used to drill to inclinations greater than 90 degrees and have been retrieved and re-run at inclinations ranging from vertical to horizontal. The directional casing drilling system can be used for a broad range of directional applications to capture the proven advantages of casing drilling that have been demonstrated for vertical wells.

Note: Casing Drilling is a trademark of Tesco Corp

From the Tesco Corp Website

The CASING DRILLING® process uses standard oilfield casing to drill the well and then leaves it in place to case the well. This process makes it possible to speed up drilling 20 to 30 percent or more, by eliminating drill-string tripping and the problems associated with it. Drill bits and other downhole tools are lowered and retrieved via wireline inside the casing and latched to the bottom-most joint of casing. This safer and more efficient process will change forever how wells are drilled. Almost any drilling rig can be adapted to use TESCO's CASING DRILLING® technology. Rigs with existing top drive systems are readily converted, either permanently or temporarily, by installing a wireline system for running and retrieving the drilling tools. Portable TESCO Top Drive Drilling Systems can be easily installed on rigs without top drives. Converted rigs lose none of their conventional capabilities.

CASING DRILLING® delivers all of the functionality of conventional drillpipe drilling, including:

• Vertical or directional;
• Steerable motor assemblies
• Rotary steerable systems;
• Logging while drilling;
• Coring;
• Retrievable or non-retrievable systems.

Benefits of the CASING DRILLING® Process

For operators, CASING DRILLING®:

• Reduces drilling time and lowers costs
• Improves wellsite safety and well control
• Reduces unscheduled events
• Provides a quicker return on investment
• Lessens environmental impact
  

For drilling contractors, CASING DRILLING®:

• Eliminates the need for drillpipe and drill collars
• Eliminates the need for double and triple masts and heavy setback areas
• Makes rig moves easier
• Reduces labour requirements
• Reduces fuel consumption and wear on equipment
• Lessens the chance of pipe-handling incidents
• Lowers capital requirements
  

For service companies, CASING DRILLING®:

• Opens up a new service market
• Provides an additional application for existing tools and an opportunity to develop new tools to gain market share
• Extends tool life by protecting tools during running and retrieval
• Reduces time and risk in recovering from down-hole tool failure