| This study presents the new procedure that simultaneously generates consistent distributions of categorical lithofacies and continuous petrophysical properties, i.e., porosity and permeability. The technique used is the conditional simulation method which is capable of honoring the original distribution of the data and the associated spatial relationship. The co-simulation procedure simultaneously uses sequential Gaussian simulation and conditional distribution principles. Additionally, indicator kriging and truncated Gaussian simulation technique are also used to complete the simulation of lithofacies. For practical reasons, two options in sampling permeability are provided, the Gaussian-based sampling and the random number-based sampling technique.;Previously, to generate petrophysical properties consistent with geological description, investigators have used two step approach where geological description is constructed first, followed by the description of the petrophysical properties through a filtering process. In contrast, in the approach used in this study, each grid block is visited only once. Using the same search neighborhood, the geological facies is estimated first, followed by porosity and permeability values. The method accounts for correlations among these variables as well as the spatial relationships. This reduces the storage requirements and makes the process computationally efficient.;The method was successfully validated using both synthetic and field data. For the synthetic case, qualitative as well as quantitative results are presented. For field case, both sandstone and carbonate fields were used to generate the facies/rock type, porosity, and permeability distributions. The simulated geological descriptions matched well with the geologists' interpretation. Further, the results were consistent with the observed production performance in terms of quality of rocks and petrophysical properties.;The implementation of this new procedure is done using the C++ language. The implementation includes the user interface program which operates in Windows 95/NT system. Using this program, the user is able to perform spatial relationship analysis, to prepare the necessary input for simulation, to run multiple realizations of the co-simulation, to rank them based on various criteria, and to view the graphical results, i.e., the cross sections, directly from the screen. |
