ABSTRACT: The objective of this paper is to characterize a reservoir in Western Algeria basin, based on an integrated 3D geomechanical model built on the basis of 3D seismic cube and well logs data. A well database has been built of the wells already drilled in the region which contains density and sonic logs to construct 1D geomechanical model in each well of the study. Sonic scanner log was used in two wells to evaluate the mechanical anisotropy in shale units. Consequently, these 1D models do not translate exactly the complexities and heterogeneous of subsurface geology for the entire reservoir area.

3D seismic data have been integrated to insure the distribution of the different mechanical properties along the reservoir. With the seismic inverted data 3-D dynamic moduli properties can be retrieved from P-wave and S-wave velocity models (Azevedo 2014). 3D dynamic moduli are then used to construct stress field magnitudes (horizontal minimal stress, horizontal maximal stress and vertical stress), that are calibrated at the level of each well.

Results indicate a regional a present day normal to strike-slip stress regime, high effective stress ratio close to 0.92 psi/ft has been interpreted against Silurian hot shale units and overpressure regime against hot shale interpreted from 1D models.

The outline gives an estimation of elastic properties, mechanical properties and stress magnitudes in each point of the seismic cube.3D stress model allows to better make the development plan of the reservoir because errors are reduced due to the presence of calibrated well data and 3D reverse seismic data.

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