Fourth SPE Comparative Solution Project: Comparison of Steam Injection Simulators
Authors: Aziz K. , Ramesh A.B. , Woo P.T. 
Published: December 2007

Summary.
Three related stream injection problems are presented along with simulation results for them obtained from six organizations. The problem selected for six comparison were intended to exercise many of the problem selected for six comparison were intended to exercise many of the features of thermal models that are of practical and theoretical interest. The first problem deals with three cycles of cyclic steam injection and the other two problems deal with steam displacement in an inverted nine-spot pattern. The first two problems are of "black-oil" type and the third of compositional type. Complete data are presented for these problems. The comparison of solutions indicates good agreement for problems. The comparison of solutions indicates good agreement for most of the results of importance in field operations.

Introduction
Validation of reservoir simulators for complex recovery, processes is a particularly difficult problem because analytical solutions are available under only a few limiting conditions. While good agreement between the results from different simulators for the same problem does not ensure validity of any of the results. a lack of problem does not ensure validity of any of the results. a lack of agreement does give cause for some concern. Such comparisons can also be useful in the development of new models and in optimizing the performance of existing reservoir simulators. This is the fourth in a series of simulation problems for which results from a number of commercial simulators have been obtained and reported in the SPE literature. The first such study was organized and conducted by Odeh on the simulation of a three-dimensional (3D). two-phase, black-oil case. Seven companies participated in that project. This was followed by a comparative participated in that project. This was followed by a comparative solution project developed b,. the program committee for the 1982 SPE Reservoir Simulation Symposium in New Orleans. The problem selected was a three-phase, single-well radial cross-section coning problem. Eleven companies participated in this study. Chappelear problem. Eleven companies participated in this study. Chappelear and Nolen were responsible for organizing this study and for reporting the results at the symposium. A similar approach was adopted by the program committee for the 1983 SPE Reservoir Simulation Symposium in San Francisco. In this case, the problem selected was to study gas cycling in a rich-gas retrograde condensate reservoir. In the first part of the study, the participants matched their phase-behavior packages to the data supplied, and in the second part they considered two options for the depletion of the reservoir. This study required a 3D, three-phase. multicomponent compositional model. Nine companies participated in this study. Kenyon and Behie organized the project and reported the results at the symposium. The enthusiastic response of industry and the academic community to the three problems encouraged the program committee for the 1985 SPE Reservoir Simulation Symposium to continue the tradition and to develop a set of problems suitable for the comparison of steam injection models. We were given the task of organizing this project. The objective of this paper is to present selected results submitted by the participants in this project with a minimum of commentary. It is worth emphasizing that the type of comparison presented here and in previous reports is different from other kinds of-comparisons discussed in the literature (e.g., Refs. 4 and 5). In the SPE comparisons, the problems are designed by one or more knowledgeable people, and model results are provided directly by those who have built or acquired suitable models. This is different from a study where the person doing the comparison develops new software using published descriptions of several models. It is possible-although we have tried to minimize this-that some of possible-although we have tried to minimize this-that some of the differences in the results compared here could be a result of different interpretations of the problem, while differences in a com-parison of the type discussed in Ref. 4 may be caused by differences in the interpretation of the published procedures. Furthermore, the models used in our comparison are all commercial in nature. Some of these models have been in existence for several years and others are new.
Problem Statement Problem Statement We have selected three related but independent problems for the comparison of steam injection models:cyclic steam injection in a nondistillable oil reservoir with a two-dimensional (2D) radial cross-sectional grid,nondistillable oil displacement by steam in an inverted nine-spot pattern by considering one-eighth of the full pattern (see Fig. 1), anddisplacement of an oil consisting of two volatile components and one nonvolatile component in the same pattern as Problem 2.
The oil properties were the same in the first two problems. The participants had the option to submit results for one, two, or all three problems. In addition we invited optional runs. A complete statement of the problems as offered to the participants is contained in Appendix A. (We have deleted the section on reporting requirements to save space.)The problems were selected to exercise features of the models that are important in practical applications they do not necessarily represent real field situations. In particular. we wanted to see the influence of grid orientation on the results of the steam displacement problems. The inverted nine-spot appeared to us to be ideal for this purpose. Six companies (see Appendix B) participated in the project with only three submitting results for the compositional case (Problem 3). Four of the other companies contacted indicated an interest in the project during the early stages but were unable to provide results for the comparison for a variety of reasons. In addition to providing numerical results, the participants were also asked to providing numerical results, the participants were also asked to describe their model briefly and to answer a number of questions about the model. These descriptions with only minor editorial changes are given in the next section.
Description of Models Used
p. 1576