What Does Coiled Tubing Drilling (CTD) Mean?
Coiled tubing drilling (CTD) is a trenchless technique used for drilling re-entry wells, new shallow wells, deepening conventional wells and for drilling under-balanced. Complex CTD operations, including directional drilling and cased completions, require pipe handling equipment, large diameter coiled tubing, fluid handling equipment for mixing, cleaning and recirculating, provisions for handling long bottom hole assemblies (BHA) and blowout preventer (BOP) stacks. CTD is commonly used in existing wellbores for re-entry drilling or sidetracking through the production tubing.
Coiled tubing drilling is also used in combination with rotary drilling rigs for drilling a simple well bore and using CTD for penetrating into the desired zone.
Trenchlesspedia Explains Coiled Tubing Drilling (CTD)
Coiled tubing drilling units can handle drilling new shallow wells with diameters up to 8 1/2" and depth up to 5000 to 6000 feet. In soft formations the bore diameter may reach up to 12 1/4 inches but the casing size is limited to the size of the casing used for final production which is 3 1/2 inches.
For simple CTD operations fewer rig loads and therefore a smaller location than conventional rigs is required making it a good option for areas that have environmental requirements, such as through national parks, jungles etc. Coiled tubing drilling can also be used for clean out, well bore perforation and for retrieving or replacing downhole equipment.
Advances in CTD also allow for real-time downhole measurements which can be used for logging and treatment of wellbores. However; CTD is not viable for every drilling or production enhancement project and the geographical, technical and economic aspects of each project should be studied in detail before considering using coiled tubing drilling.