Guy Chavent

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When estimating hydraulic transmissivity the question of parameterization is of great importance. The transmissivity is assumed to be a piecewise constant space dependent function and the unknowns are both the transmissivity values and the zonation, the partition of the domain whose parts correspond to the zones where the transmissivity is constant.(More)
  • Guy Chavent, Ren E-Edouard Plessix, Le Chesnay, Cedex
  • 1998
In order to deene an optimal true amplitude prestack depth migration for mul-tishot and multitrace data, we develop a general methodology based on the least squares data misst function associated with a forward model. The amplitude of the migrated events are restored at best for any given geometry and any given preliminary ltering and amplitude correction(More)
We introduce a new global pressure formulation for immiscible three-phase compressible flows in porous media which is fully equivalent to the original equations, unlike the one introduced in [5]. In this formulation, the total volumetric flow of the three fluids and the global pressure follow a classical Darcy law, which simplifies the resolution of the(More)
We introduce a new global pressure formulation for immiscible three-phase compressible flows in porous media which is fully equivalent to the original equations, unlike the one introduced in [5]. In this formulation, the total volumetric flow of the three fluids and the global pressure follow a classical Darcy law, which simplifies the resolution of the(More)
The estimation of distributed parameters in a partial differential equation (PDE) from measures of the solution of the PDE may lead to underdetermination problems. The choice of a parameterization is a frequently used way of adding a priori information by reducing the number of unknowns according to the physics of the problem. The refinement indicators(More)
We consider the problem of determining the diffusion coefficient ax in a 2D elliptic equation from a distributed measurement z in H 1 of the solution u of the equation. For a problem with a simple geometry, we give conditions under which the first derivative of the b = 1=a 7 ,! u mapping is coercive. Then we show that its non linearity in a direction d(More)