Timing of fracturing of sedimentary beds around evolving salt shapes: Self-consistent behaviors and Mohr`s Criterion
- Univ. of South Carolina, Columbia, SC (United States)
For the intertwined evolution of both salt and sediments, a self-consistent quantitative model has been constructed that can be used to provide automatically information on the changing bed geometries with time in a manner guaranteed to be consistent with present-day observations of salt bodies and sediment geometries. Instead of trying to specify a large number of mechanical properties to calculate the stress in the evolving salt-sediment system, and then attempting to calculate the corresponding strain, the procedure simplifies this process by reversing the order: (1) determine the strain; (2) define the response of the sediments to stress (for instance, elastic); and (3) calculate the corresponding stress. If the mass m and acceleration a are given, the force F can be calculated. (Conversely, if the force F and mass m are known, the acceleration can be calculated.) Two cases exemplify how the strain/stress patterns in the sediments depend on the evolving geometry of the salt through time. A large salt overhang results in massive strain next to, and immediately below, the overhang due to the horizontal spreading of the salt and the associated void space created near the salt stem. Because no void can exist, the sediments must deform to fill the void. Therefore, the sediments below the overhang {open_quotes}slide{close_quotes} into the space created as the salt structure feeds the overhang development from deeper salt. From the calculated strain behavior of the sediments, the stress associated with the strain can be evaluated once the spatial variations of the sedimentary Lame constants are specified. Knowledge of the spatial fracture pattern and its temporal evolution is crucial to the evaluation of hydrocarbon migration pathways and trap development near salt structures. The timing of oil generation, which depends on the thermal history of the sediments, can then be compared and contrasted to the timing of migration through the fractured regime.
- OSTI ID:
- 96254
- Report Number(s):
- CONF-941065-; ISSN 0149-1423; TRN: 95:005100-0058
- Journal Information:
- AAPG Bulletin, Vol. 78, Issue 9; Conference: 44. annual convention of the Gulf Coast Association of Geological Societies and the 41st annual convention of the Gulf Coast Section of the Society of Economic Paleontologists and Mineralogists, Austin, TX (United States), 5-7 Oct 1994; Other Information: PBD: Sep 1994
- Country of Publication:
- United States
- Language:
- English
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