oa Feasibility study of steam injection in one of Iranian naturally fractured heavy-oil fields

Steam injection in naturally fractured heavy-oil reservoirs provides an extremely challenging problem but also a potentially effective and efficient improved-oil-recovery method. Coupling of the two distinct and contrasting matrix and fracture systems results in a highly non-linear problem, which becomes even more complicated due to the steep changes in fluid properties caused by the thermal effects of steam injection. Modeling and designing an optimum steam-injection operation in such systems requires an accurate characterization and representation of a naturally fractured heavy-oil reservoir and steam injection operation parameters and dynamics. This study focused on an undeveloped Iranian fractured heavy-oil field. A thermal dual-porosity model was developed for a sector of this field, and some sensitivity analysis tests were performed. A comprehensive and comparative study was conducted in order to understand the relative effects of naturally fractured heavy-oil system and injection operation properties on the oil-recovery performance. This work showed that steam injection could take oil recovery from zero to about 17%, and therefore would qualify for producing this field. The results indicated the importance of grid-block size, injection rates, temperature and quality of injections on the simulation process. The study should help us to design the optimal recovery operation and pressure-maintenance program. It also determines the confidence level for an oil-recovery operation in this field using steam injection.