The workflow described in this paper involves multi specialists and multi scales data (from nanopore to seismic) to characterize best targets for well placement in unconventional shale play. This implies understanding sedimentary facies and associated basin scale morphologies, lithological changes in relation with depositional environments, and finally the intimate relationship between the most carbonaceous facies (HC production and storage) and those ensuring the rigid frame of the reservoir (hydraulic frac design and management). Final control has to be ensured reconciling core scale petrophysics and production data.
The sedimentary model assesses geological facies definition, their lateral and vertical distribution in relation with sequence stratigraphy. It is the key to predict the areas combining the best factors in terms of kerogen content and lithological composition. Facies calibration is based on core micro- and macro-lithological description (including local microfauna), mineralogical and petrophysical analyses. The sedimentologist's eyes are also calibrated using continuous elemental profiling of the cores to help differentiating between apparently similar cryptic black mudstones.
The good consistency between depositional facies and their mineralogical composition leads to successfully complete log based shale types prediction along all the studied wells. Large scale correlations then underline the links between facies associations and the stratigraphic patterns highlighted on seismic profiles.
Beside the geological approach and its concepts, well completion and hydraulic fracturing treatments proceed on the basis of geomechanical acquisitions. In the one hand, core measurements help defining the main parameters for designing the stimulation job and assessing long term performance. In parallel to classic brittleness indexes, specific models are prepared to predict formation mechanical behavior using core mechanical tests as learning data and wireline logs as propagators. On the other hand, large scale data such as fracture calibration tests, microseismic survey or production profiles deliver precious information on the Stimulated Rock Volume creation.
This innovative project combines the geomechanicist view and the geological understanding of the reservoir. The sedimentary model allows focusing on the best landing points while facies definition helps predicting the quality of the reservoir and its mechanical properties.
