Representing Steam Processes With Vacuum Models

Scaled models of steam processes have contributed significantly to the design and implementation of many field projects. These models provide a means of answering pertinent questions, including the effect of (1) injection rate, (2) production pressure, (3) completion interval, (4) pattern size and type, (5) aquifers, (6) heterogeneities, and (7) steam quality. Parameters are presented for scaling up physical-model results to full scale and for relating physical-model results to full scale and for relating one oil field to another. These relationships are generated by casting the governing equations in dimensionless form. A set of similarity parameters then are determined by inspectional analysis. In physical models, unfortunately, it is not possible to physical models, unfortunately, it is not possible to match all similarity parameters. Consequently, based on engineering judgment, a set containing a reduced number of parameters, called scaling parameters, is generated that generally can be matched between scaled model and field prototype. Techniques to implement this scaling are discussed, including a description of the laboratory models, typical materials, and procedures for conducting the experiments. Results of model studies for Mt. Poso and Midway Sunset prototypes are presented. presented. Introduction Physical modeling technology has been developed to Physical modeling technology has been developed to the extent that detailed descriptions of steam processes can be provided for field projects in which processes can be provided for field projects in which the number of wells is large, patterns are irregular, or asymmetry occurs from dip or water influx. In many of these cases, sufficient complexity can be introduced to provide both prediction of overall response and specific guidance for operating policies on a well-by-well basis. The fine detail attainable in physical models arises from the large number of physical models arises from the large number of beads or sand grains, typically in excess of 10 million, that are used in the packed bed. By comparison, present-day numerical steam simulators are limited present-day numerical steam simulators are limited practically to about 1,000 grid blocks. Besides practically to about 1,000 grid blocks. Besides offering this capability of representing additional geometrical and geological complexity, the physical models have the advantage that physical phenomena are not constrained by specified relationships but are free to interact subject only to scaling factors. This additional insight can be important in new processes for which relationships are not known or are difficult to formulate. Limitations of physical models arise because of the unavailability of materials and fluids having physical properties that will satisfy all scaling requirements. properties that will satisfy all scaling requirements. Effects of compromises in scaling often can be observed with simple geometric configurations in mathematical simulators. Conversely, improved mathematical simulation often is possible after determining important parameters experimentally. Consequently, the two serve complementary roles in determining the important mechanisms for a particular process. particular process.Our thermal models do not represent processes in which steam distillation, solution gas, chemical reactions, or compressibility are important. The choice of whether to model physically or to calculate numerically depends on the actual process being studied and the capabilities one has developed in each of these technologies. Scaling rules for steam-injection processes have evolved from those for isothermal and hot-water processes. Isothermal reservoir processes have been processes. Isothermal reservoir processes have been the subject of a number of scaling studies. Scaling for the hot-water drive has been reported in the work of Geertsma et al., Baker, and Dietz; scaling for combustion processes has been given by Binder et al. SPEJ P. 151