ABSTRACT

The 3D Finite Element Program FRACTure was intensively developed in the years 1990-1992 with the specific aim of studying the coupling of interactive mechanisms relevant to the long term behaviour of a Hot Dry Rock reservoir. The flexible modular structure facilitated in subsequent years the addition of further processes and elements to existing libraries and thus created a tool which can now be applied for the simulation of various transport processes in geosciences. FRACTure offers full 3-D solutions to problems related to 

as well as to their interactions. 

Hydraulic processes can be treated as laminar Darcy including the Boussinesq assumption on density driven flow or turbulent flow. For thermal processes several mechanisms can be activated from pure diffusion (incorporating non-linear dependency of thermal conductivity with temperature or pressure) to fluid flow or mass advection over heat generation and, additionally, dispersion and absorption coefficients for solute transport. The elastic processes account for stress perturbations arising from linear poro- or thermo-elastic effects in the rock matrix and of a non-linear, stress dependent joint closure law. Apart of simulating coupled Hot Dry Rock behaviour, the code has been successfully practised in a variety of applications such as the analysis of geoelectric measurements, radon transport, solute tracer tests, simulations of heat probe operations, Alpine tectonics and hydrogeologic system modelling.

The FRACTure FE Software package comes along with the graphical mesh generator program WinFra which runs on a Win32 system. Thereby, special emphasis is devoted to the discretization of irregular finite element networks. Supported by a graphical user interface which allows to create complex 2-D or 3-D FE meshes several interfaces have been developed to import external DXF files or digital terrain models.

EXAMPLES / SCREEN-DUMPS:

Fig.1: Structure of the WinFra mesh generation procedure
Fig.2: WinFra screen (Version 0.59)
Fig.3: FRACTure calculations, performed on different scales
Fig.4: 3-D FE Mesh from Gotthard area in Central Switzerland (>500'000 nodes)
Fig.5: Surface temperature distribution at Gotthard area in Central Switzerland

Fig.1: Structure of the WinFra mesh generation procedure       

Fig.2: WinFra screen (Version 0.59)                                               

Fig.3: FRACTure calculations, performed on different scales       

Fig.4: 3-D FE Mesh from Gotthard area in Central Switzerland (>500'000 nodes)       

Fig.5: Surface temperature distribution at Gotthard area in Central Switzerland