iTOUGH2 is a program for parameter estimation, sensitivity analysis, and uncertainty propagation analysis. It is based on the TOUGH2 simulator for non-isothermal multiphase flow in fractured and porous media. Extensive experience in using TOUGH2 is a prerequisite for using iTOUGH2. The preparation of an input file for TOUGH2 or its derivatives is described in separate manuals and is not part of this report.
The iTOUGH2 user's guide summarizes the inverse modeling theory pertaining to iTOUGH2, and describes the program output. Furthermore, information about code architecture and installation are given. In Chapter 2 of this report, a brief summary of inverse modeling theory is given to restate the main concepts implemented in iTOUGH2 and to introduce certain definitions. Chapter 3 introduces the basic concepts of the iTOUGH2 input language and the main structure of an iTOUGH2 input file. Chapter 4, the main part of this report, provides detailed descriptions of each iTOUGH2 command in alphabetical order. It is complemented by a command index in Appendix B in which the commands are given in logical order. The content of Chapter 4 is also available on-line using command t2help, as well as on this Web Site (click on Command Index).
Chapter 5 describes the usage of the UNIX script files for executing, checking, and terminating iTOUGH2 simulations.
A variety of inverse problems solved by iTOUGH2 are discussed in a collection of sample problems, which includes a tutorial example illustrating the main features of iTOUGH2. Complete examples of iTOUGH2 input files are given along with interpretations of the corresponding output files.
The key to a successful application of iTOUGH2 is (i) a good understanding of multiphase flow processes, (ii) the ability to conceptualize the given flow and transport problem and to develop a corresponding TOUGH2 model, (iii) detailed knowledge about the data used for calibration, (iv) an understanding of parameter estimation theory and the correct interpretation of inverse modeling results, (v) proficiency in using iTOUGH2 options. This report addresses issue (v) only.