ANALYSIS OF ROCK MECHANICAL PARAMETERS FROM WELL LOG DATA AND DIPOLE SHEAR SONIC IMAGER - APPLICATION TO ALGERIAN SAHARA 'ALGERIA'

摘要

The use of 'DSI' (Dipole Shear sonic Imager), in the Tin Fouye Tabankort area in Algeria allowed the exploitation of the rock mechanics properties in the field of drilling having for objective determination of the margin of ability of the well. The tool 'DSI' has a considerable advantage by its application which makes it possible to combine the technology of monopole and of dipole and to offer an effective method for the determination of the acoustic dynamic mechanical properties in-situ. The practical results of this study showed that: 1 - The phenomenon of BIOT is less when the medium is impermeable, 2 - There is a significant effect of the petrophysic properties on the mechanical properties expressed by the effect of the coefficient of BIOT on the variation of the values of the density of mud. The beach of variation of the stability of the well obtained starting from the tool 'DSI' lies between the values 1.40 g/cc and 1.80 g/cc. On the other hand the results obtained by the application of Leake-off test and the successive increase in the density of mud vary from 1.50 g/cc with 1.90 g/cc. With the base of these results, it is necessary to note that the result obtained by tool DSI is almost closer than the practical methods and the percentage of error obtained by the application of this tool is due to the difference between the dynamic and static mechanical properties. The finality of this study is to determine a field of application of this new technique in the study of the stability of the well during drilling.