Stress Distribution Around Complex Salt Structures : a New Approach Using Fast 3D Boundary Element Method

Frantz Maerten and Laurent Maerten. ( 2017 )
in: 2017 Ring Meeting, pages 12--15, ASGA

Abstract

During the last decade geologists and engineers have used the Finite Element Method (FEM) with elasto-plastic or visco-plastic behavior to simulate salt in order to gain a better understanding of the in-situ stress distribution. However, building such FEM models can become time consuming and challenging, especially when complex geometry is involved, and modeling elaborated non-linear salt behavior can take hours to days to process. We have developed a different approach using a fast 3D Boundary Element Method (BEM) and which allows fast model construction and computation (order of minutes). Instead of using non-linear mechanical behavior of salt, we use the assumption that salt can be viewed as a pressurized cavity for which unknown parameters like the far field stress and salt pressure gradient are inverted using available data such as observed natural fracture (e.g., joints, faults) or recorded data (e.g., breakout, LOT, micro-seismicity, gps, InSAR, tiltmeter) associated to past or actual deformation around salt. To verify this approach, BEM results have been validated against known 3D analytical solution for pressurized deviated well subjected to an Andersoninan far field stress and compared to published, more complex, 3D FEM salt models. The efficiency of this new approach, in terms of model construction and mechanical simulation, is demonstrated through a natural example of faults associated to salt diapirs in the Gulf of Mexico.

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BibTeX Reference

@INPROCEEDINGS{Maerten2017,
    author = { Maerten, Frantz and Maerten, Laurent },
     title = { Stress Distribution Around Complex Salt Structures : a New Approach Using Fast 3D Boundary Element Method },
 booktitle = { 2017 Ring Meeting },
      year = { 2017 },
     pages = { 12--15 },
 publisher = { ASGA },
  abstract = { During the last decade geologists and engineers have used the Finite Element Method (FEM) with elasto-plastic or visco-plastic behavior to simulate salt in order to gain a better understanding of the in-situ stress distribution. However, building such FEM models can become time consuming and challenging, especially when complex geometry is involved, and modeling elaborated non-linear salt behavior can take hours to days to process. We have developed a different approach using a fast 3D Boundary Element Method (BEM) and which allows fast model construction and computation (order of minutes). Instead of using non-linear mechanical behavior of salt, we use the assumption that salt can be viewed as a pressurized cavity for which unknown parameters like the far field stress and salt pressure gradient are inverted using available data such as observed natural fracture (e.g., joints, faults) or recorded data (e.g., breakout, LOT, micro-seismicity, gps, InSAR, tiltmeter) associated to past or actual deformation around salt. To verify this approach, BEM results have been validated against known 3D analytical solution for pressurized deviated well subjected to an Andersoninan far field stress and compared to published, more complex, 3D FEM salt models. The efficiency of this new approach, in terms of model construction and mechanical simulation, is demonstrated through a natural example of faults associated to salt diapirs in the Gulf of Mexico. }
}