Using recent results from fine-scale, multi-pattern, geostatistical models of the Kern River field, California, this paper reviews key issues related to steamflood modeling and shows that fine-grid models depict the near-vertical steam override, and corroborates that heavy oil steamflooding is not a displacement process; rather the oil drains by gravity. Further, models with unconfined boundaries result in steam zone pressures similar to those observed in field. Including the common operating practice of cyclic steaming of producers at early time reduces pressures and accelerates steam breakthrough time and recovery.
Furthermore, pattern element and single sand models used in many previous studies are not sufficient to explain observed field performance, and that larger, heterogeneous model give more realistic recovery predictions. Discontinuous shales allow significant drainage to occur from the upper to the lower sands. Consequently, the upper zones may contain less reserve than expected and the lower zones can give apparent high recovery. Use of parallel models showed significant speed up over serial models allowing significantly larger models to be run in a reasonable time. Apparent higher speed up is gained for larger models.
The paper demonstrates that the current improvements make larger-scale modeling of steamflood projects viable compared with what was possible earlier and that a realistic forecast of steamflood performance is attained when the necessary details are included in the model.