MODELING TRANSPORT OF NONISOTHERMAL, MULTIPHASE ORGANIC CONTAMINANTS USING T2VOC AND THE PETRASIM PRE- AND POST-PROCESSOR

T2VOC is a three dimensional numerical simulation program for modeling the transport of organic chemical contaminants in nonisothermal multiphase systems. The code is an extension of TOUGH2, developed at Lawrence Berkeley National Laboratory, and can simulate processes such as the migration of hazardous nonaqueous phase liquids (NAPLs) and air injection into the saturated zone for removal of volatile organics (air sparging).

Although powerful, the T2VOC/TOUGH2 codes were developed as research tools, using a text-based input file. This presents significant hurdles to a new user, who must create an input file that describes a valid mesh and activates the appropriate solution controls. Possible simulator options are often activated by flags that are confusing and may appear in unrelated locations in the input file. It is hard enough to solve non-isothermal, multi-component, multi-phase problems without the additional difficulty of preparing complex and lengthy input files. In addition, the user must develop their own toolkit to display results. Even experienced users may need additional help to exploit models with tens of thousands of cells or to enable rapid remeshing for convergence studies.

The solution to this problem has four key features: (1) use of a high level model description based on geometric features of the reservoir (stratigraphy, well coordinates), (2) presentation of the required input options grouped in a logical format with appropriate default options activated, (3) automatic writing of the simulator input file in the correct format, and (4) rapid access to visualization of results. Such a program should be interactive, with immediate visual confirmation of any user actions.

PetraSim is a new pre- and post-processor for T2VOC/TOUGH2 that incorporates these features into an integrated program for model creation and results display. To allow cross-platform execution, it uses Java for the graphical user interface with native implementation of compute intensive algorithms.

Application of the PetraSim and T2VOC programs is demonstrated using field scale simulation of o-xylene displaced by steam injection.