Print this pageEvolution from Salt Ridge to Diapirs and Impact from Deformation: Input from Analogue Models
Salt related structures hold a large economical interest in oil exploration, not only for creation of traps or seal, but also for development of reservoirs in adjacent sediments. A common feature shown by most of the salt basins is the progressive evolution of the salt structures from elongated linear or polygonal salt ridges to more circular bodies, i.e. salt diapirs.
In order to study the parameters which control the transition from ridges to circular structures, we performed sand/silicon models imaged with X-ray tomography and reconstructed by 3D geomodelling for the study of (1) the interaction between host rock and salt diapir during diapir growth, and (2) the control on the style of deformation exerted by slat structures. X-ray tomography is a non destructive imaging technique which allows us to follow the 4D evolution of the analogue model. Salt is modelled by Newtonian silicone putty and the internal rock stringers, as well as the sedimentary host rocks, by a granular Mohr-Coulomb material, generally sand or corundum. The growth and geometry of the salt structure is mostly controlled and driven by the overburden deposition, but extensional tectonics may be applied as well.
The relative importance of (1) the salt basin geometry; (2) the mechanism initiating salt movement; (3) the sedimentation/erosion pattern; and (4) the late tectonic deformation have been investigated. In particular, attention is put both on the distribution of sediment bodies around the salt structures, and the geometry of the folds and thrusts formed during late shortening. The models are then compared to field and seismic data from two major salt and hydrocarbon provinces: the South Permian salt basin and the Middle East Zagros fold and thrust belt. The impact of salt structure evolution on the associated petroleum plays evolution are discussed, as well as the control of salt structure on the geometry of folding.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009