Petrophysical Electrofacies for Sizing Completion Screens: Rosa Field
Patrick Henriquel, François Jaffuel, Eric Braccini, and Yann Cogrel
Total E & P Angola, Luanda, Angola
Sedimentary facies defined in cores provide good geological information but of limited lateral extent. In order to extrapolate this information to the complete well dataset, log responses are calibrated on cored intervals. An automatic classification based on GR, Neutron, Density and Neutron-Density separation is realized providing an Electrofacies log (cluster of homogeneous well logs values defined by statistical analysis).
On Rosa field (Oligocene turbiditic systems), this method allows a good identification of the main reservoir facies and is applied on LWD real-time data. The main use, at the end of drilling, is the definition of the completion.
The reservoirs are completed with Stand Alone Screens and their size is linked to the sand facies granulometry. Electrofacies interpretation provides the necessary data to adapt the sand control strategy (slot size) to the main facies difference.
This methodology allows also evaluating on each well the petrophysical properties of each facies, their relative proportions and at field scale the various trends providing a better description of reservoir heterogeneities to integrate in the geological model.
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