An Integrated Model for Characterizing Heterogeneous Carbonate Reservoirs

Abstract

Raising the world's demand for energy accompanied by decrease in the ease of oil exploration and production, has forced the oil industry to investigate novel and advanced techniques for different stages of providing the energy; from early stages of oil exploration to increasing the production from oil reservoirs by secondary or tertiary recovery. A critical phase that plays an important role in simulating oil reservoirs and therefore managing the different field's development plans is reservoir characterization. Poor reservoir characterization may lead to implementation incorrect methods in field development and reservoir management and cause losing unrecoverable sources and costs. Characterization of carbonate rocks is a vital process, because carbonate systems constitute more than half of the oil reservoirs of the world and also most of the reservoirs in the Middle East. On the other hand heterogeneity is a problem that causes these types of reservoirs not to obey from general rules and formula. Due to the need for a comprehensive model for characterizing carbonate reservoirs, a very extensive integrated study of all the methods available for different stages of a reservoir characterization process (reservoir rock typing, rock type prediction, saturation distribution and modeling, dynamic reservoir characterization, absolute permeability and relative permeability prediction) is done in this paper. For providing the best model, geophysical and petrophysical approaches are taken into consideration and are discussed in detail and the best combination and integration of them is presented as a comprehensive model for characterizing heterogeneous carbonate reservoirs. Then using conventional core and different wireline logs and also seismic data, this model is used to characterize numbers of carbonate oil reservoirs of Sarvak formation of Iran. Applying this model can save time of characterizing carbonate reservoirs and lead to best images of petrophysical properties of reservoir rocks and the most accurate reservoir simulation models.