Abstract

The objective of this study is to estimate numerically the in-situ stress field in a tectonically active marine sedimentary basin. The Levantine basin in Eastern Mediterranean which is currently explored for gas and oil reservoirs is used as a case study. The study was based on elasticity, and poroelastoplasticity constitutive equations which were calibrated with material parameters derived from seismic data and correlation functions. The geometry of the Mechanical Earth Model is also constructed from seismic data. The equilibrium and constitutive equations are solved with the finite element method. The model simulates a basin area initially at rest and then loaded by horizontal motion to simulate the active tectonic movement of the plates over the geological time. The effect of boundary conditions and initial conditions are studied along with other important parameters that influence the problem such as the interface strength of fault surfaces and the plate movement. Information based on mud-density in drilled nearby wells are used to calibrate the horizontal motion and constrain the insitu stresses at the well locations and hence within a good approximation elsewhere. We found that in the active tectonic regime of East Mediterranean the horizontal stress increases in such extent that it can be compared with the vertical stress. The adhesive behavior between the walls of a fault can cause interlocking resulting to even larger horizontal stress values. Smaller stresses are generated in sliding conditions between the fault surfaces due to the dissipated energy in the sliding process. Finally, the stress distributions become highly complex with stress rotation and arching close to the fault area.

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