GEOPHYSICAL WELL LOGGING- A CONTRIBUTION TO THE FRACTURES CHARACTERIZATION

Abstract

The need of a proper reconstruction of faults and fracture systems crossed during the well drilling is one of the most important feature for the deep exploration of a geothermal reservoir.
The geophysical well logging have been always utilized for geological and stratigraphic determinations, for the measurement of the main physical characteristics in order to provide calibration parameters for the surface geophysical surveys and for a qualitative localization of fractured and potential productive layers. Recent and specialized techniques and sensors for the detection of geometrical-structural parameters are now widely used.

One of them, the Circumferential Borehole Imaging Log (CBIL), when utilized for potential fractured layers already tagged by other techniques (as acoustic Wave Forms), has been proved as very effective and detailed.

We applied a complete set of this techniques in a deep well of the Larderello-Travale geothermal field, and a detailed analysis and characterization of the fractures was performed. The standard well-testing procedure was also applied, in order to match the results from the different approaches. A satisfactory correspondence was achieved. A preliminary comparison between the geometrical parameters of the fractures and their productivity was also carried out.