CT drilling has a number of undisputable advantages, which provided for its rapid development. In the first place, this is an opportunity of underbalanced drilling of the whole well or some certain sections of the borehole. It allows for:

1. Destroying O&G and all underlying porous formations, which may contain oil or gas, when the pressure in the well is lower than that in the formation. It prevents the possibility of penetration of drilling mud and its particles into the formation and rules out the possibility of filtering off filtrate from the solution. It guarantees the preservation of the natural collecting properties of the formation and prevents the reduction of future debits of oil and gas.

2. Revealing and thorough studying of all O&G prospective horizons along the well section even during the drilling process, which is especially important for exploration.

3. Lifting more authentic representative core.

4. Defining water formations and interstratified layers occurring in the section, studying the nature of water influx and formation pressure.

5. Relatively fast lifting of the particles of drilled rock up to the surface (there is no such delay in their lifting in the annulus like during conventional drilling). That is why the interpretation of the geological well log according to rock cuttings is very precise.

6. Sharp raise of technical and economic performance of the bit run (bit run drilling rate may be multiplied) due to lesser depression and wearing out of the formation breaking tools as well as better treating of the bottomhole from the drilled cuttings.

7. Identifying Production Index for all promising horizons in time.

8. Excluding absorption of the sludge during drilling in abnormally low pressure, etc.

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