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function of the pressure and the volume of the fluid injected at the bottom of the drillstring.

*    To execute CPTWD tests at different penetration ratę, within 1 and 2 cm/s, and compare the results

*    Broad comparison between the penetrometric results and those obtained with other testing methodologies “in situ” (field vane test, SPT, etc) and in laboratory (where possible).

*    To compare, when feasible, and economically possible, the penetrometric results obtained at great depth. For instance, comparing the CPTWD data with other penetrometric tests (wire linę CPT down-hole used for offshore surveys) or penetrometric tests carried out with pre-drilled holes.

*    To evaluate not only with “in situ” tests, but also with laboratory tests and/or with the help of mathematic models, the influence of the rotation and fluid injection on the penetrometric data. In this way, it would be possible to calibrate, in a morę scientific way, the MWD parameters.

*    Since, for the First time, it is possible to compare results of MWD and CPTU from the same soil mass, there should be a possibility to carry out accurate calibrations of the drilling parameters and to get morę objective and reliable data and possible correlations between the MWD and CPTU in soft soil.

*    In case the CPTWD is evaluated in sufficiently documented and monitored cases, there is hope for the verification throughout "back-analysis", of the data obtained

5 POSSIBLE APPLICATIONS

The following are possible cases where the use of the CPTWD system could be competitive in relation to the traditional type of survey:

*    Sites with altemating layers of non penetrable soil (i.e. gravel, cemented sands) and penetrable intervals of geotechnical interest (Ref. 4).

*    Presence of compact overburden with subsequent penetrable layers.

*    Geotechnical deep drilling (in particular the OFFSHORE drillings) where the cost/production ratio is important.

*    Unavailability of the static penetrometer rig, providing the possibility to carry out static penetrometric tests with any kind of drillrig, at least at conventional depths .

*    Geotechnical and environmental deep drillings: - at the end of the c.c.drilling/CPTWD, it is possible to install a piezometer and/or geotechnical instrumentation inside the bored hole.

*    Deep surveys and main presence of sandy soils in which it is not possible to withdraw sufficiently undisturbed samples and the normal tests in situ (i.e. SPT) would not be economically efficient or reliable.

*    The opportunity to have a morę complete data matrix than with a normal penetrometer, which allows other kinds of interpretations. In particular, the fact of having in the same row (every 2 cm) the data of: Q_c, F_s, U2, U3, thrust, torąue, ratę of penetration, RPM, volume of injected fluid.

6 CONCLUSIONS

The CPTWD method lends itself to futurę improvements and developments, not only from a practical point of view, but also in a theoretical and interpretative area. The same generał principle can be used for the implementation of other kind of tests with other kind of sensors, even when the “continuous” (that is, simultaneously with the drilling process) process to obtain the data is prerogative to the static penetrometric test.

Still, with the idea of adapting other instruments to a core barrel wire-line, the time has been reached for the studying of further applications complementary to the CPTU test, for example:

*    down hole wire-line field vane test. In contrast to CPTWD, this type of test is "discontinuous", that is, it is not possible to carry out scissometric tests during the drilling.

*    execution of tests with Permeameter and sampling of fluids. Such applications has already been performed by NGI (Norwegian geotechnical institute) for the execution of offshore tests: a wire-line application of a Permeameter and gas sampler at great depth (D.G.S.: deep gas sampler) has been implemented by the NGI essentially for the petroliferous/oil drilling, but it is also applicable at