PHYSICALLY CONSTRAINED KINEMATIC SALT FLOW RESTORATION

Ulisses T. Mello (1) , Garry D. Karner (2)

(1) Petrobrás Research Center, Cidade Universitária, Qd 7, Ilha do Fundão, Rio de Janeiro, RJ, CEP 21910, Brazil.
Current address: IBM Thomas J. Watson Research Center, Yorktown Heights, NY 10598.
(2) Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York, 10964, U.S.A.

Abstract

In this paper we propose some techniques to simulate kinematically the salt flow lines during its motion. The internal salt flow is constrained by the imposed velocity field on the deforming boundaries, mass conservation and the incompressibility condition of during the salt deformation. This approach has the advantage of reproducing exactly the geologist's view of the salt evolution and the very complex salt shapes observed in the field can be simulated without the difficulties normally involved in the solution of dynamic viscous flow formulations. Therefore, this approach is alternative to the traditional ones that calculate the salt motion dynamically using continuity and momentum conservation equations, in which the salt is driven by the sediment loading and buoyancy. In our approach the salt is assumed an incompressible slow (creeping) viscous fluid with constant viscosity that is in steady-state between the time interval considered in the deformation. Under these conditions the internal salt flow is governed by the Stokes flow equation. Two techniques are introduced to restore the internal salt flow with time. In the first one, for salt motion in its early stages of diapirism, it is assumed that the salt layer is constrained in between two sediment layer and it has a horizontal parabolic flow pattern similar to the pipe flow models. The second one, can be used for any arbitrary salt shape but it is more costly because it uses finite element method to calculate the flow path lines.