Geomechanical Log Deduced from Porosity and Mineralogical Content

Abstract : The "geomechanical log" research project aims at estimating rock mechanical properties from a set of models, whose input data can be deduced from drilling logs and measurements on core samples (if these are available). The key point is to focus on defining relatively general and easy to handle models. In this paper, we propose various analytical models allowing one to estimate poroelastic and failure properties of limestones and sandstones directly from their porosity and, in the specific case of sandstone poroelastic characteristics, their mineralogical content. The properties obtained are in reasonable agreement with experimental data. The second step of the project will be to actually infer the input data for the models (here porosity and mineral content) from drilling logs and to compare the results obtained to tests on core samples. A geomechanical log could then be automatically created from standard logs and help to optimize drilling. We also intend to test the same approaches on rock plastic properties and shale behavior.