New Scaling Criteria And Their Relative Merits For Steam Recovery Experiments

Abstract

Abstract New scaling criteria for steam and steam additive recovery experiments are presented in this paper. The mathematical development of different scaling criteria for a variety of scaling options and their relative merits are discussed. Past papers have reported similarity groups governing the scaling of steam additive processes to be incompatible. The scaling criteria presently available for steam processes, which permit the use of the same fluids in the model as those found in the prototype, require high pressure models and different porous media. This causes difficulties in scaling properties which depend on pressure or the porous media. Methods are presented which, by relaxing the requirement of geometric similarity, allow the same fluids and the same porous media to be used to scale steam or steam additive processes/or horizontal reservoirs. These methods allow scaling of all properties which depend on pressure and temperature, such as the saturated steam properties. A set of similarity groups is derived by inspectional and dimensional analysis for the steam additive process. Relaxed sets of scaling criteria, particular to the major mechanisms of a process, are then determined. The relative merits and potential applications of the various approaches are compared with (hose published m the literature. A means of selecting, or developing. If necessary, an approach which best scales the major aspects of a particular recovery process IS outlined. Introduction Steamflooding is a known method for recovering oil from some heavy oil reservoir For a number of years, emphasis has been placed on improving the steam flooding process. Many laboratory studies have been conducted in an effort to achieve this goal. Some of the experiments were designed to study the various mechanisms of a process and to extend the results to make field predictions by using numerical simulators. Other experiments, referred to as scaled experiments, were designed allow the relative influence of the various mechanismsobserved in an experiment to be similar to that expected in the field and to permit interpretation of the results to predict field performance. It is difficult to satisfy all of the criteria required to design scaled experiments of steamflooding processes. Consequently, some of the scaling requirements must be relaxed. The choice of which requirements to relax will depend on the particular process being modelled. Scaling of the phenomena considered to be least Important to a particular process might be relaxed without significantly affecting the major features of the process. Background to Scaling Steam Processes Scaled model experiments have been used to predict the effect of various parameters on the production response of a reservoir undergoing steam injection. The parameters include injection rate, production pressure, slug size, completion intervals, well pattern geometry, steam additives, bottom water, reservoir heterogeneities, and steam quality. Scaled models are also used to calibrate numerical models and provide insight into the effects of mechanisms which may not be properly incorporated in numerical simulators. A number of approaches to scaling steam processes have been used by previous investigators.