Integrated inverse method to estimate virgin stress state in reservoirs and overburden

Antoine Mazuyer and Richard Giot and Paul Cupillard and Marianne Conin and Pierre Thore. ( 2016 )
in: 2016 RING Meeting, ASGA

Abstract

Stress estimation in petroleum reservoirs is a key point during exploration and production to prevent borehole instability and fault reactivation. Tine-lapse seismic enables to access relative stress changes. In the present paper, we open the path to the absolute value of the stress by proposing an integrated method to estimate such a value in reservoirs and overburden before oil and gas production. The computed stress is constrained by wellbore data using an inverse ap- proach. The forward problem is solved using a Finite Element Analysis on a geological model of the reservoirs created with the Gocad software and meshed with the VorteXLib software developed in our laboratory. Assuming that the mechanical behavior is linear elastic, we perturb the elastic coefficients and the boundary conditions to produce various admissible (i.e. satisfying the equilib- rium equations) stress states. Elastic parameters are relatively well constrained thanks to well logs, so the parameter perturbation is performed on the boundary conditions only. Misfit between stress computation and wellbore data minimization is done using CMA-ES, an evolutionary algorithm suitable for ill-conditionned problem. We validate and test the behaviour of our method through a synthetic case.

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BibTeX Reference

@INPROCEEDINGS{,
    author = { Mazuyer, Antoine and Giot, Richard and Cupillard, Paul and Conin, Marianne and Thore, Pierre },
     title = { Integrated inverse method to estimate virgin stress state in reservoirs and overburden },
 booktitle = { 2016 RING Meeting },
      year = { 2016 },
 publisher = { ASGA },
  abstract = { Stress estimation in petroleum reservoirs is a key point during exploration and production to
prevent borehole instability and fault reactivation. Tine-lapse seismic enables to access relative
stress changes. In the present paper, we open the path to the absolute value of the stress by
proposing an integrated method to estimate such a value in reservoirs and overburden before oil
and gas production. The computed stress is constrained by wellbore data using an inverse ap-
proach. The forward problem is solved using a Finite Element Analysis on a geological model of
the reservoirs created with the Gocad software and meshed with the VorteXLib software developed
in our laboratory. Assuming that the mechanical behavior is linear elastic, we perturb the elastic
coefficients and the boundary conditions to produce various admissible (i.e. satisfying the equilib-
rium equations) stress states. Elastic parameters are relatively well constrained thanks to well logs,
so the parameter perturbation is performed on the boundary conditions only. Misfit between stress
computation and wellbore data minimization is done using CMA-ES, an evolutionary algorithm
suitable for ill-conditionned problem. We validate and test the behaviour of our method through a
synthetic case. }
}