The evaluation of the compressibility module of the formation is a key element for the environmental monitoring and the "reservoir management". The trend of this formation parameter is evaluated by knowing the pore pressure and the soil compaction all along the reservoir exploitation time. A new technology to measure in real time the compaction of the formation during reservoir exploitation has then been developed and is herein described. Main advantage of the presented technology is the possibility to continuously carry out such a measurement without stopping the production. The operating principle is based on the measurement of the displacement with respect to the casing of two metallic targets fixed in the formation at two different depths. The vertical distance between the targets is in the order of about 10 m, which is the typical length of casing elements. Assuming the casing very stiff, the difference between the vertical displacements of the targets provides the measurement of formation compaction. The vertical displacement of the metallic targets is gathered by means of electromagnetic sensors installed within the casing wall before its installation in the borehole. The metallic targets shall be introduced in the formation during the drilling operations before the well completion, using a suitable tool specifically developed for this application. The tool will be lowered inside the casing applying wire-line equipment and procedure. First, the tool will drill the hole in the casing and formation, then the metallic target will be inserted at a distance of about 100 mm from the casing wall

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