3-D Structural modeling requires to build a consistent model with integration of many different data types [1] (picked horizons, well data, etc.). It also usually involves to interactively manipulate and modify horizons or faults surfaces. Two kinds of surface representations are often used in the oil industry: triangulated and parametric surfaces. Triangulated surfaces are suitable for modeling complex geometries [2] but cannot easily be modified interactively whereas parametric surfaces cannot be used in very complex cases but are easier to manipulate. We present here a method that conciliates these two representations and enables easier interactive manipulations of triangulated surfaces through the use of parametric patches.