Coiled Tubing Drilling is best suited for under-balanced operations because it is a “closed-loop” system. A “closed-loop” system does not require the formation to be put in an over-balanced state at anytime during the operation and because drilling mud is not required, there is no skin or near well-bore damage caused. The CTD is designed to operate on a wide variety of E-Line and TEC line options. The system is ideal for narrow and low pressure formations but can be run in basically any formation or pressures.